Biomedical subjects

R L Foote

Publications and source records attributed to R L Foote.

At least 19 recordsLinked to original sources

PubMed2000

Decreasing the dosimetric effects of misalignment when using a mono-isocentric technique for irradiation of head and neck cancer.

PURPOSE: The purpose of this study was to quantify and develop methods to decrease inhomogeneities created with field edge mismatch when using a mono-isocentric beam-split technique. METHODS AND MATERIALS: We validated techniques to determine dose across a half-blocked field edge and quantified potential sources of systematic matchline error. Then, two methods were used to evaluate matchline doses. The first used film dosimetry data from a half-beam field and a spreadsheet. Duplication and reversal provided two columns, each representing a beam-split field edge. Summation simulated perfect abutment and shifting created various gaps and overlaps. The second method involved obtaining dose profiles at midfield along the ray perpendicular to abutted, overlapped, and gapped beam-split fields on six linear accelerators. To enlarge the penumbra, we designed several field edge modifiers, then re-evaluated matchline doses. The field edge modifiers applicability to a 3-field head and neck treatment technique was also examined. RESULTS: Film-determined dose profiles provide similar information across a beam-split field edge as an ionization chamber. With the mono-isocentric beam-split technique, a 4-mm overlap or gap produces inhomogeneities nearly 60% above or below the intended dose. A 2-mm overlap or gap produces inhomogeneities nearly 30% above or below the intended dose. A customized penumbra generator decreased the magnitude of these inhomogeneities to 20% and 10%, respectively. CONCLUSION: The two methods of evaluating matchline dose described above gave similar results. When using the mono-isocentric half-field technique, small misalignments produce worrisome regions of inhomogeneity. Our penumbra generator substantially decreases the magnitude of the dose inhomogeneities, although the volume receiving an inhomogeneous dose increases.

Film Dosimetry↗

PubMed2000

The rationale and technique of staged-volume arteriovenous malformation radiosurgery.

PURPOSE: Stereotactic radiosurgery is an effective management strategy for properly selected arteriovenous malformation (AVM) patients. However, the risk of postradiosurgical radiation-related injury generally limits this procedure to patients with AVMs of an average diameter of 3 cm or less. Radiosurgery of large AVMs in a planned staged fashion was undertaken to limit the radiation exposure to the surrounding normal brain. METHODS AND MATERIALS: Between April 1997 and December 1999, 10 patients with a median AVM volume of 17.4 cm(3) (range, 7.4-53.3 cm(3)) underwent staged-volume radiosurgery (23 procedures). At the first radiosurgical procedure, the total volume of the AVM is estimated and a dose plan calculated that covers 10 cm(3)-15 cm(3), or one-half the nidus volume if the AVM is critically located (brainstem, thalamus, or basal ganglia). At 6-month intervals thereafter, radiosurgery was repeated to different portions of the AVM with the previous dose plan(s) being re-created utilizing intracranial landmarks to minimize radiation overlap. Radiosurgical procedures were continued until the entire malformation has been irradiated. RESULTS: The radiation dosimetry of staged-volume AVM radiosurgery was compared to hypothetical single-session procedures for the 10 patients. Staged-volume radiosurgery decreased the 12-Gy volume by an average of 11.1% (range, 4.9-21%) (p < 0.001). The non-AVM 12-Gy volume was reduced by an average of 27.2% (range, 12.5-51.3%) (p < 0.001). DISCUSSION: Staged-volume radiosurgery of large AVMs results in less radiation exposure to the adjacent brain. Further follow-up is needed to determine whether this technique provides a high rate of AVM obliteration while maintaining an acceptable rate of radiation-related complications.

Adolescent↗

PubMed2000

An analysis of facial nerve function in irradiated and unirradiated facial nerve grafts.

PURPOSE: The effect of high-dose radiation therapy on facial nerve grafts is controversial. Some authors believe radiotherapy is so detrimental to the outcome of facial nerve graft function that dynamic or static slings should be performed instead of facial nerve grafts in all patients who are to receive postoperative radiation therapy. Unfortunately, the facial function achieved with dynamic and static slings is almost always inferior to that after facial nerve grafts. In this retrospective study, we compared facial nerve function in irradiated and unirradiated nerve grafts. METHODS AND MATERIALS The medical records of 818 patients with neoplasms involving the parotid gland who received treatment between 1974 and 1997 were reviewed, of whom 66 underwent facial nerve grafting. Fourteen patients who died or had a recurrence less than a year after their facial nerve graft were excluded. The median follow-up for the remaining 52 patients was 10.6 years. Cable nerve grafts were performed in 50 patients and direct anastomoses of the facial nerve in two. Facial nerve function was scored by means of the House-Brackmann (H-B) facial grading system. Twenty-eight of the 52 patients received postoperative radiotherapy. The median time from nerve grafting to start of radiotherapy was 5.1 weeks. The median and mean doses of radiation were 6000 and 6033 cGy, respectively, for the irradiated grafts. One patient received preoperative radiotherapy to a total dose of 5000 cGy in 25 fractions and underwent surgery 1 month after the completion of radiotherapy. This patient was placed, by convention, in the irradiated facial nerve graft cohort. RESULTS: Potential prognostic factors for facial nerve function such as age, gender, extent of surgery at the time of nerve grafting, preoperative facial nerve palsy, duration of preoperative palsy if present, or number of previous operations in the parotid bed were relatively well balanced between irradiated and unirradiated patients. However, the irradiated graft group had a greater proportion of patients with pathologic evidence of nerve invasion (p = 0.007) and unfavorable type of nerve graft (p = 0.04). Although the irradiated graft cohort had more potentially negative prognostic factors, there was no difference in functional outcome (H-B Grade III or IV) between irradiated and unirradiated graft patients. H-B Grades III, IV, V, and VI were the best postoperative facial nerve functions achieved in 35%, 39%, 13%, and 13% of patients, respectively. The patient with preoperative radiotherapy never recovered any facial nerve function (H-B Grade VI). Median time to best facial nerve function after surgery was longer in the irradiated patients (13.1 vs. 10.8 months), but this was not statistically significant (p = 0.10). Presence of preoperative facial nerve palsy (p = 0.005), duration of preoperative palsy (p = 0.003), and age greater than 60 years at the time of grafting (p = 0. 04) were all negative prognostic factors for achieving a functional facial nerve on univariate analysis. Analysis of age as a continuous variable (p = 0.12) and pathologic evidence of nerve invasion (p = 0. 1) revealed a trend toward negative prognostic factors. Gender, number of previous operations in the parotid bed, extent of surgery at the time of nerve grafting, and type of grafting procedure were not significant prognostic factors. Whether radiotherapy was delivered less than 6 weeks after nerve grafting or more than 6 weeks had no impact on achievement of a functional facial nerve. CONCLUSION: Negative prognostic factors for achieving a functional facial nerve in our series include the presence of preoperative facial nerve palsy, duration of preoperative palsy, and age greater than 60 years. Radiotherapy was not a negative prognostic factor. Comparing irradiated and unirradiated grafts revealed no difference in best facial nerve function achieved, despite the presence of a greater proportion of negative prognostic factors in

Adolescent↗

PubMed2000

Stereotactic radiosurgery for recurrent ependymoma.

BACKGROUND: Patients with recurrent intracranial ependymomas were evaluated to assess local control, overall survival, and complications from stereotactic radiosurgery (SRS). METHODS: Twelve patients (with a total of 17 tumors) with recurrent ependymoma underwent SRS. Local failure was defined as tumor progression within the prescription isodose volume, and marginal failure was defined as tumor progression adjacent to the SRS prescription isodose volume. Tumor progression away from the prescription volume was considered distant failure. Eleven of the 12 patients had undergone previous resection and external beam radiation therapy (46-56 Grays [Gy]; median, 54 Gy) before radiosurgery, and 1 patient had failure after complete resection alone. Age at SRS ranged from 5-56 years (median, 29 years). Three patients were female. The marginal tumor dose was 12-24 Gy (median, 18 Gy). One to 14 isocenters (median, 4 isocenters) were utilized to irradiate volumes of 0.3-15.5 cm(3) (median, 3.2 cm(3)). RESULTS: The duration of follow-up ranged from 2.5-60 months (median, 22.5 months). The median overall survival after SRS was 3.4 years (range, 1.4-5 years). In-field local control was achieved in 14 of the 17 tumor sites and estimated 3-year local control was 68%. There were two in-field failures and one marginal failure. Distant failure occurred in two patients. Two patients developed treatment-related complications after SRS. CONCLUSIONS: SRS provides good local tumor control for patients with recurrent intracranial ependymoma and may have a favorable impact on survival. SRS should be evaluated more extensively in the initial treatment of patients with ependymoma to minimize local failure after surgical management.

Adolescent↗

PubMed2000

Stereotactic radiosurgery for tumor-related trigeminal pain.

OBJECTIVE: Between 1 and 6% of patients who are diagnosed with facial pain syndromes have tumors that involve the trigeminal nerve. We report the effects of stereotactic radiosurgery on tumor-related trigeminal pain. METHODS: We reviewed results, from a prospective database, for 24 consecutive patients with cranial base tumors and either trigeminal neuralgia (n = 9) or painful trigeminal neuropathy (n = 15) who underwent stereotactic radiosurgery during an 8-year period. The tumor was the radiosurgical target for these patients (not the trigeminal nerve or ganglion). The median clinical follow-up period after radiosurgery was 45 months (range, 12-90 mo); the median neuroimaging follow-up period was 36 months (range, 5-86 mo). RESULTS: There were 20 women and 3 men, with an average age of 57 years (range, 33-79 yr). One patient had bilateral facial pain and underwent staged radiosurgery. Pathological classification indicated 16 meningiomas and 8 malignant cranial base tumors (adenoid cystic carcinoma, n = 6; squamous cell carcinoma, n = 2). Twelve of 24 patients (50%) were initially free of pain, and another 11 patients (46%) reported that they experienced significant improvements in their trigeminal pain syndromes after radiosurgery. The tumor histological type, quality of facial pain, preexisting facial numbness, and marginal and maximal radiation doses were not related to postradiosurgical facial pain outcomes. Three patients with malignant cranial base carcinomas developed recurrent facial pain, 1 to 9 months after radiosurgery, which was related to tumor progression outside the irradiated volume. One patient (4%) developed new partial V2 numbness after radiosurgery. CONCLUSION: Radiosurgery proved to be effective in improving tumor-related trigeminal pain for the majority of patients with either benign or malignant cranial base tumors. Recurrence of trigeminal pain is frequent for patients with malignant cranial base carcinomas and is related to tumor progression.

Adult↗

PubMed2000

Stereotactic radiosurgery for cavernous malformations.

OBJECT: The use of stereotactic radiosurgery to treat cerebral cavernous malformations (CMs) is controversial. To evaluate the efficacy and safety of CM radiosurgery, the authors reviewed the experience at the Mayo Clinic during the past 10 years. METHODS: Seventeen patients underwent radiosurgery for high-surgical-risk CMs in the following sites: thalamus/basal ganglia (four patients), brainstem (12 patients), and corpus callosum (one patient). All patients had experienced at least two documented hemorrhages before undergoing radiosurgery. Stereotactic magnetic resonance (MR) imaging was used for target localization in all cases. The median margin radiation dose was 18 Gy and the median maximum dose was 32 Gy. The median length of follow-up review following radiosurgery was 51 months. The annual hemorrhage rate during the 51 months preceding radiosurgery was 40.1%, compared with 8.8% in the first 2 years following radiosurgery and 2.9% thereafter. In 10 patients (59%) new neurological deficits developed that were associated with regions of increased signal on long-repetition time MR imaging performed a median of 8 months (range 5-16 months) after radiosurgery. Three patients recovered, giving the group a permanent radiation-related morbidity rate of 41%. Compared with 31 patients harboring arteriovenous malformations (AVMs) of sizes and in locations similar to those of the aforementioned CMs, who underwent radiosurgery during the same time period, the patients with CMs were more likely to experience radiation-related complications (any complication, 59% compared with 10%; p < 0.001; permanent complication, 41% compared with 10%; p = 0.02). CONCLUSIONS: It is impossible to conclude that radiosurgery protects patients with CMs against future hemorrhage risk based on the available data, although it appears that some reduction in the bleeding rate occurs after a latency interval of several years. The risk of radiation-related complications after radiosurgery to treat CMs is greater than that found after radiosurgery in AVMs, even when adjusting for lesion size and location and for radiation dose.

Adolescent↗

PubMed2000

Gamma knife radiosurgery as a primary treatment for prolactinomas.

OBJECT: The purpose of this study was to estimate the efficacy of gamma knife radiosurgery (GKS) in controlling tumor growth and endocrinopathy associated with prolactinomas. METHODS: Between 1993 and 1997, 164 of 469 patients with pituitary adenomas treated by GKS harbored prolactinomas. The dose to the tumor margin ranged from 9 to 35 Gy (mean 31.2 Gy), and the visual pathways were exposed to a dose of less than 10 Gy. The mean tumor diameter was 13.4 mm. The mean follow-up time for 128 cases was 33.2 months (range 6-72 months). Tumor control was observed in all but two patients who underwent surgery 18 and 36 months, respectively, after GKS. Clinical cure was achieved in 67 cases. Clinical improvement was noted with a decrease in the hyperprolactinemia after GKS. Nonetheless, in 31 (29%) of 108 patients who were followed for more than 2 years no improvement in serum prolactin levels was demonstrated, although this could be normalized by bromocriptine administration after treatment. Nine infertile women became pregnant 2 to 13 months after GKS and all gave birth to normal children. There was no visual deterioration related to GKS. Five women experienced premature menopause. In these patients there was subtotal disappearance of the tumor and an empty sella developed. CONCLUSIONS: Gamma knife radiosurgery as a primary treatment for prolactinomas can be safe and effective both for controlling tumor growth and for normalization of prolactin hypersecretion. A higher margin dose (> or = 30 Gy) seemed to be associated with a better clinical outcome. Gamma knife radiosurgery may make prolactinomas more sensitive to the bromocriptine.

Humans↗

PubMed1999

Frequency of noncontiguous lymph node involvement in patients with resectable nonsmall cell lung carcinoma.

BACKGROUND: This study was undertaken to investigate the patterns of lymph node spread and the frequency of involvement of noncontiguous lymph node stations in patients with nonsmall cell lung carcinoma who had complete surgical resection. METHODS: All patients who had surgical resection as their sole treatment for nonsmall cell lung carcinoma during the years 1987-1990 were reviewed. All patients were treated similarly. Generally, complete mediastinal lymph node dissection was performed after resection of the primary lesion and N1 lymph nodes. Patients were assessed for patterns of involvement of N1 and N2 lymph node stations. The frequency of noncontiguous involvement of lymph nodes (involvement of N2 lymph nodes without involvement of N1 lymph nodes) was determined. Patient and tumor characteristics were assessed to ascertain whether certain factors were likely to predict this noncontiguous pattern of lymph node spread. RESULTS: During the 4-year period of study, 336 patients with nonsmall cell lung carcinoma were managed with surgical resection alone. Of the 336, 100 had no involvement of lymph nodes, 108 had involvement of N1 lymph nodes only, 76 had involvement of N1 and N2 lymph nodes, and 52 had involvement of N2 lymph nodes only. Therefore, 52 of all 336 patients (15%) and 52 of 236 patients with lymph node involvement (22%) had noncontiguous lymph node spread. A review of the initial patient and tumor characteristics revealed that patients with a suggestion of enlarged mediastinal lymph nodes on preoperative computed tomography scans of the chest (compared with negative findings) and patients with T1 and T2 lesions (compared with T3 and T4) were more likely to have noncontiguous lymph node spread; the odds ratios (with 95% confidence intervals) were 2.18 (1.01-4.71) and 2.82 (1.36-5.84), respectively. CONCLUSIONS: Noncontiguous involvement of thoracic lymph nodes occurred in approximately 15% of patients who had complete surgical resection of nonsmall cell lung carcinoma. This factor suggests that lack of involvement of N1 lymph nodes does not rule out mediastinal involvement and provides important information for complete surgical staging.

Carcinoma, Non-Small-Cell Lung↗

PubMed1999

Predictors of subclinical nodal involvement in clinical stages I and II non-small cell lung cancer: implications in the inoperable and three-dimensional dose-escalation settings.

PURPOSE: When mediastinal lymph nodes are clinically uninvolved in the setting of inoperable non-small cell lung cancer, whether conventional radiation techniques or three-dimensional dose-escalation techniques are used, the benefit of elective nodal irradiation is unclear. Inclusion of the clinically negative mediastinum in the radiation portals increases the risk of lung toxicity and limits the ability to escalate dose. This analysis represents an attempt to use clinical characteristics to estimate the risk of subclinical nodal involvement, which may help determine which patients are most likely to benefit from elective nodal irradiation. METHODS: From 1987 to 1990, 346 patients undergoing complete resection of non-small cell lung cancer underwent a preoperative computed tomographic scan revealing no clinical evidence of N2/N3 involvement. Multivariate regression and regression tree analyses attempted to define which patients were at highest risk for subclinical mediastinal involvement (N2) and which patients were at highest risk for subclinical N1 and/or N2 involvement (N1/N2). Immunohistochemical data suggest that the conventional histopathologic techniques used during this study somewhat underestimate the true degree of lymph node involvement; therefore, a third end point was also evaluated: N1 involvement and/or N2 involvement and/or local-regional recurrence (N1/N2/LRR). RESULTS: Regression analyses revealed that the following factors were independently associated with a high risk of more advanced disease: positive preoperative bronchoscopy (N2, p = 0.02; N1/N2, p < 0.0001; N1/N2/LRR, p < 0.001) and tumor grade 3/4 (N1/N2/LRR, p < 0.01). A regression tree analysis was then used to separate patients into risk groups with respect to N1/N2/LRR. CONCLUSION: In inoperable non-small cell lung cancer, the patients for whom mediastinal radiation therapy may most likely be indicated are those with a positive preoperative bronchoscopy, especially with large (> 3 cm) primary tumors.

Analysis of Variance↗

PubMed1999

Decrease in cranial nerve complications after radiosurgery for acoustic neuromas: a prospective study of dose and volume.

PURPOSE: To determine whether tumor control can be maintained, and cranial nerve complications decreased by reducing the radiosurgical dose to acoustic neuromas. METHODS AND MATERIALS: Forty-two consecutive patients with acoustic neuromas were treated prospectively using an initial standard-dose protocol in which the tumor-margin dose (50% isodose) was 20, 18, and 16 Gy for tumor diameters < or =2 cm, 2.1-3 cm, and 3.1-4 cm, respectively. After analysis of tumor control and complications, the next 40 patients were treated using a reduced-dose protocol in which the tumor-margin dose was 16, 14, and 12 Gy for tumor volumes < or =4.2 cm3, 4.2-14.1 cm3, and > or =14.1 cm3, respectively. RESULTS: Median follow-up was 2.3 years (range 0.1-6) for 80 of 82 patients. The actuarial incidence (Kaplan-Meier) of facial neuropathy at 2 years was 38% (95% confidence interval [CI], 23-53%) for the standard-dose protocol and 8% (95% CI, 0-17%) for the reduced-dose protocol (p = 0.006). Univariate analysis revealed an association between risk of facial neuropathy and use of CT planning, higher radiosurgical dose, and neurofibromatosis, type 2. Multivariate analysis revealed that the only factor associated with increased risk of post-treatment facial neuropathy was a tumor margin dose > or =18 Gy. The incidence of trigeminal neuropathy at 2 years was 29% (95% CI, 15-43%) for the standard-dose protocol and 15% (95% CI, 3-27%) for the reduced-dose protocol (p = 0.17). Univariate analysis revealed an association between maximal tumor diameter and increased risk of trigeminal neuropathy; multivariate analysis revealed no additional statistically significant associations between tumor and dosimetric and patient characteristics and risk of trigeminal neuropathy. Two tumors in the standard-dose protocol required salvage surgery for progression. To date, no tumor in the reduced-dose protocol has shown progression. CONCLUSION: Our analysis suggests that a tumor margin dose of > or =18 Gy is the most significant risk factor for facial nerve complications after acoustic neuroma radiosurgery. Patients receiving a minimal tumor dose of < or =16 Gy are at significantly lower risk for permanent facial neuropathy after radiosurgery. Longer follow-up is required before definitive conclusions can be made about the ultimate rate of tumor control using reduced radiosurgical doses.

Adult↗

PubMed1999

Factors predicting patterns of recurrence after resection of N1 non-small cell lung carcinoma.

BACKGROUND: Although irradiation and chemotherapy are unproved adjuvant treatments for completely resected N1 non-small cell lung carcinoma, previous studies may have been diluted by the inclusion of low-risk patients. Risk factors in this situation, however, are not yet well defined. METHODS: One hundred seven consecutive patients with complete resection of N1 disease who received no other therapy were studied to identify factors independently predicting the risk of freedom from local recurrence (FFLR), freedom from distant metastasis (FFDM), and overall survival (OS). RESULTS: Twelve factors were assessed for a potential prognostic relationship with FFLR, FFDM, and OS. Regression analyses revealed that the factors independently associated with an improved outcome were positive bronchoscopic findings (FFLR, p = 0.005), a greater number of dissected N1 nodes (FFDM, p = 0.02), and a lesser T stage (OS, p = 0.01). Classification and regression tree analyses were then used to separate the patients into risk groups. CONCLUSIONS: Although these results require corroboration in further studies, they may aid the design of trials examining therapies used to decrease rates of local recurrence or distant metastasis.

Adult↗

PubMed1999

Risk of injury to cranial nerves after gamma knife radiosurgery for skull base meningiomas: experience in 88 patients.

OBJECT: In this study the authors sought to determine the neurological risks and potential clinical benefits of gamma knife radiosurgery for skull base meningiomas. METHODS: A consecutive series of 88 patients harboring skull base meningiomas were treated between 1990 and 1996 by using the Leksell gamma knife in a prospective clinical study that included a strict dose-volume protocol. Forty-nine patients had previously undergone surgery, and six had received external-beam radiotherapy. The median treatment volume was 10 cm3, and the median dose to the tumor margin was 16 Gy. The radiosurgical dosage to the optic nerve, the cavernous sinus, and Meckel's cave was calculated and correlated with clinical outcome. The median patient follow-up time was 35 months (range 12-83 months). Two tumors (2.3%) progressed after radiosurgery; the progression-free 5-year survival rate was 95%. At last follow-up review, 60 (68%) tumors were smaller and 26 (29.5%) remained unchanged. Clinical improvement (in vision, trigeminal pain, or other cranial nerve symptoms) occurred in 15 patients. Functioning optic nerves received a median dose of 10 Gy (range 1-16 Gy), and no treatment-induced visual loss occurred. Among nine patients with new trigeminal neuropathy, six received doses of more than 19 Gy to Meckel's cave. CONCLUSIONS: Gamma knife radiosurgery appeared to be an effective method to control the growth of most skull base meningiomas in this intermediate-term study. The risk of trigeminal neuropathy seemed to be associated with doses of more than 19 Gy, and the optic apparatus appeared to tolerate doses greater than 10 Gy. Considering the risks to cranial nerves associated with open surgery for comparable tumors, the authors believe that gamma knife radiosurgery is a useful method for the management of properly selected recurrent, residual, or newly diagnosed skull base meningiomas.

Adult↗

PubMed1999

Cerebral toxicity in patients treated for small cell carcinoma of the lung.

OBJECTIVE: To present the clinical characteristics of patients enrolled in a trial of treatment of small cell carcinoma (SCC) of the lung and to describe the central nervous system toxicity associated with the chemotherapy and prophylactic cranial irradiation (PCI). MATERIAL AND METHODS: We performed a retrospective analysis of 60 patients with SCC who received chemotherapy and thoracic radiation therapy. PCI was administered to patients who had limited disease or who had extensive disease that was subsequently down-staged to only residual chest disease after initial treatment. The total PCI dose was 3,200 cGy administered in 16 fractions of 200 cGy, given concurrently with systemic chemotherapy. Diagnostic criteria for leukoencephalopathy were based on previously published guidelines. RESULTS: Of the 60 eligible and enrolled patients, 35 received PCI and 25 did not. Leukoencephalopathy developed in 5 of the 35 patients (14%) who received PCI. The median age of the patients in whom leukoencephalopathy developed was 64 years (range, 57 to 69), and the median follow-up time was 59 months. The most common signs and symptoms of leukoencephalopathy were intellectual changes, memory alterations, and motor abnormalities. The mean time to onset of symptoms after termination of irradiation was 357 days (range, 30 to 524). Of all 60 patients, 6 were still alive 4 years after enrollment, and 3 of them (50%) already had leukoencephalopathy. CONCLUSION: Small dosage fractions of PCI may still result in leukoencephalopathy. The routine use of PCI in the management of SCC should be reassessed because of increasing evidence of the toxicity associated with it.

Aged↗

PubMed1998

Adjuvant radiotherapy for squamous cell carcinoma of the tongue base: improved local-regional disease control compared with surgery alone.

PURPOSE: The purpose of this retrospective study is to present the results of postoperative adjuvant radiotherapy after primary surgery for squamous cell carcinoma of the tongue base and to compare these results to those obtained with surgery alone. METHODS: Between 1974 and 1993, continuous-course postoperative radiotherapy was delivered to 24 patients (Adjuvant Radiotherapy Group). Results were compared to those from a group of 55 patients treated with surgery alone (Surgery Group). RESULTS: Characteristics of the two groups were similar, except that a larger proportion of patients in the Adjuvant Radiotherapy Group had higher pathologic TNM stages. Ipsilateral neck control (87% vs. 68%, p = 0.04), contralateral neck control (100% vs. 76%,p = 0.002), relapse-free survival (64% vs. 46%,p = 0.04), and control above the clavicles (80% vs. 48%, p = 0.007) were significantly higher in the Adjuvant Radiotherapy Group compared to those in the Surgery Group (5-year figures shown). CONCLUSION: The use of adjuvant radiotherapy after surgical resection of tongue base squamous cell carcinoma significantly decreased the rate of local-regional recurrence and improved relapse-free survival compared with surgery alone but did not alter cause-specific or overall survival.

Adult↗

PubMed1998

Combined neck dissection and postoperative radiation therapy in the management of the high-risk neck: a matched-pair analysis.

PURPOSE: The purpose of this study was to determine the efficacy of postoperative adjuvant radiation therapy with regard to reducing the rate of recurrence in the neck, cancer-related death, and death from any cause in patients with squamous cell carcinoma of the head and neck region metastatic to neck nodes. METHODS: This was a retrospective review of patients with pathologically confirmed nodal metastases who underwent neck dissection and postoperative adjuvant radiation therapy for squamous cell carcinoma of the head and neck region. Time to recurrence in the dissected area of the neck, any recurrence in the neck, cancer-related death, and death from any cause were estimated with the Kaplan-Meier method. A matched-pair analysis was performed utilizing a cohort of patients who underwent neck dissection without postoperative radiation therapy. The patients from the two cohorts were matched according to previously reported high-risk features for cancer recurrence and death. Cox hazards models for the matched pairs were used to evaluate the relative risk of subsequent recurrence in the dissected side of the neck, any neck recurrence, cancer-related death, and overall survival. MATERIALS: The medical records and pathologic slides of 95 consecutive patients with pathologically confirmed nodal metastases from squamous cell carcinoma of the head and neck region who underwent neck dissection and postoperative adjuvant radiation therapy between January 1974 and December 1990 were reviewed. Previously published data from 284 patients with squamous cell carcinoma of the head and neck region treated with neck dissection alone between January 1970 and December 1980 were used for a matched-pair analysis. RESULTS: The relative risks for recurrence in the dissected side of the neck, any neck recurrence (dissected neck or delayed undissected neck metastasis), cancer-related death, and death from any cause for patients treated with operation alone relative to those treated with operation and postoperative radiation were 5.82, 4.72, 2.21, and 1.67, respectively. CONCLUSION: This study provides evidence that postoperative adjuvant radiation therapy for the high-risk neck can reduce the rate of recurrence within a dissected neck, delayed metastasis within an undissected neck, cancer-related death, and death from any cause.

Adult↗

PubMed1998

Spinal cord localization in the treatment of lung cancer: use of radiographic landmarks.

PURPOSE: In the treatment of thoracic malignancies with radiotherapy, the critical dose-limiting structure is the spinal cord. Oblique fields typically are designed to exclude the spinal cord, and by convention, the field edge that shields the spinal cord is placed at the anterior border of the vertebral pedicles. Thus, the purpose of our study was to estimate the distance between the field edge and spinal cord in oblique fields that were designed by using the vertebral pedicle as a radiographic landmark. METHODS AND MATERIALS: The spinal cord of a cadaver was wrapped in wire, and oblique fields were simulated at 15 degree intervals. The distance from the spinal cord to a field edge placed at the anterior border of the pedicle was measured. In the second investigation, a three-dimensional treatment planning system was used to simulate hypothetical fields using actual patient data from computed tomography (n = 10), and measurements identical to those in the anatomical model were made (n = 1,100). RESULTS: The results of the anatomical and computed tomographic models were in close agreement (mean difference, 0.6 mm). The computed tomographic model predicted a mean field edge to spinal cord distance of 8.7 mm (95% confidence interval, 5.6-11.8 mm) for 30 degree/150 degree oblique fields and 8.0 mm (95% confidence interval, 4.7-11.7 mm) for 45 degree/135 degree oblique fields. This distance was greatest at levels T-1, T-2, and T-11 (8 to 20% greater). CONCLUSIONS: The mean distance from a field edge placed at the anterior border of a vertebral pedicle to the spinal cord for commonly used oblique angles constitutes a sufficient margin to account for expected differences in daily positional variations and mechanical uncertainties.

Cadaver↗

PubMed1998

Planned postradiotherapy neck dissection in patients with advanced head and neck cancer.

BACKGROUND: Metastatic neck nodes in patients with squamous cell carcinoma of the head and neck are most commonly managed by surgery, radiotherapy, or combined-modality therapy. For combined-modality cases, the sequencing of surgery and radiotherapy is generally guided by which modality is considered preferable for treatment of the primary tumor. A postradiotherapy neck dissection is often considered for those patients with > N1 disease in which the primary is treated with radiotherapy alone. METHODS: Between February 1991 and October 1995, 25 patients with node-positive squamous cell carcinoma of the head and neck were treated with planned unilateral (n = 22) or bilateral (n = 3) neck dissection following high-dose radiotherapy. The primary tumor sites included: tongue base (n = 11), tonsil (n = 6), nasopharynx (n = 3), pyriform sinus (n = 2), supraglottic larynx, (n = 1), soft palate (n = 1), and unknown head and neck primary (n = 1). The specific nodal stage breakdown of the 28 individual neck dissections (25 patients) was N1 (n = 1), N2A (n = 5), N2B (n = 15), N3 (n = 7). RESULTS: Nineteen of the 28 neck dissections (68%) demonstrated no evidence of residual carcinoma. Of the nine positive neck dissections, six revealed malignant cells in a single nodal echelon. The 1- and 2-year rate of neck control in all 25 patients was 100% and 93%, respectively. The 1- and 2-year disease-specific survival for all 25 patients was 83% and 60%, respectively. With a minimum follow-up of 2 years, 64% of the 25 patients remain alive with no evidence of disease or dead of non-cancer causes. CONCLUSION: In this series of postradiotherapy neck dissections, two thirds of the dissections demonstrated no evidence of residual tumor (19/28, or 68%). However, there was not a direct correlation between pretreatment nodal size (neck staging), radiation dose delivered, and the likelihood of achieving a cancer-free neck dissection. Only one of 28 postradiotherapy neck dissections identified tumor outside of nodal stations II-IV. The predictable pattern of residual disease in pathologically positive cases suggests that a selective neck dissection encompassing levels II-IV may be appropriate in a majority of patients.

Adult↗

PubMed1998

Vestibular schwannoma management. Part II. Failed radiosurgery and the role of delayed microsurgery.

OBJECT: The indications, operative findings, and outcomes of vestibular schwannoma microsurgery are controversial when it is performed after stereotactic radiosurgery. To address these issues, the authors reviewed the experience at two academic medical centers. METHODS: During a 10-year interval, 452 patients with unilateral vestibular schwannomas underwent gamma knife radiosurgery. Thirteen patients (2.9%) underwent delayed microsurgery at a median of 27 months (range 7-72 months) after they had undergone radiosurgery. Six of the 13 patients had undergone one or more microsurgical procedures before they underwent radiosurgery. The indications for surgery were tumor enlargement with stable symptoms in five patients, tumor enlargement with new or increased symptoms in five patients, and increased symptoms without evidence of tumor growth in three patients. Gross-total resection was achieved in seven patients and near-gross-total resection in four patients. The surgery was described as more difficult than that typically performed for schwannoma in eight patients, no different in four patients, and easier in one patient. At the last follow-up evaluation, three patients had normal or near-normal facial function, three patients had moderate facial dysfunction, and seven had facial palsies. Three patients were incapable of caring for themselves, and one patient died of progression of a malignant triton tumor. CONCLUSIONS: Failed radiosurgery in cases of vestibular schwannoma was rare. No clear relationship was demonstrated between the use of radiosurgery and the subsequent ease or difficulty of delayed microsurgery. Because some patients have temporary enlargement of their tumor after radiosurgery, the need for surgical resection after radiosurgery should be reviewed with the neurosurgeon who performed the radiosurgery and should be delayed until sustained tumor growth is confirmed. A subtotal tumor resection should be considered for patients who require surgical resection of their tumor after vestibular schwannoma radiosurgery.

Aged↗