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L J Peters

Publications and source records attributed to L J Peters.

At least 91 records · Page 5Linked to original sources
PubMed1995

Tumor reoxygenation as a mechanism of taxol-induced enhancement of tumor radioresponse.

Paclitaxel is a novel chemotherapeutic agent that arrests cells in the radiosensitive G2 and M phases of the cell cycle and as such may act as a specific cell cycle radiosensitizer. We recently reported that paclitexel induces mitotic arrest in the MCA-4 murine mammary carcinoma and enhances radio-response of this tumor. However, the greatest enhancement was observed not when radiation was given at the time of peak mitotic arrest, which was 9 h after paclitaxel administration, but when it was given 24 h after paclitaxel. This implied the involvement of other mechanisms in radiosensitization; we hypothesized that tumor reoxygenation was a likely mechanism based on the observed massive loss of mitotically arrested cells at 24 h. The present study shows that paclitaxel greatly enhanced MCA-4 tumor radioresponse when radiation was given under air-breathing conditions (DMF = 1.74), but not when it was performed under hypoxic conditions. This observation supports the hypothesis of tumor reoxygenation as a mechanism of enhancement of tumor radioresponse. That reoxygenation occurred in tumors treated with paclitaxel 24 h earlier was confirmed by direct measurements of pO2 values, using the Eppendorf pO2 histograph. Median pO2 values increased from 6.2 mmHg in untreated tumors to 10.0 mmHg in tumors treated with paclitaxel. These observations emphasize the importance of timing of paclitaxel administration in relation to radiation treatment.

Animals↗
PubMed1994

Postoperative radiotherapy for cutaneous melanoma of the head and neck region.

PURPOSE: To assess the efficacy and toxicity of elective-adjunctive radiotherapy given in five 6-Gy fractions to patients with cutaneous melanoma of the head and neck at high risk for local-regional relapse. METHODS AND MATERIALS: From 1983 to August 1992, 174 patients (132 men and 42 women) were enrolled. The ages ranged from 16 to 89 years (median: 54 years). One group (n = 79) received elective irradiation after wide local excision of lesions > or = 1.5 mm thick, or Clark's level IV-V, a second group (n = 32) received adjunctive irradiation after excision of primary lesions plus limited neck dissection, and a third group (n = 63) received irradiation after neck dissection for nodal relapse. Each group had a projected local-regional recurrence rate of approximately 50%. The radiotherapy consisted of five fractions of 6 Gy each, specified at Dmax, delivered twice a week, to a total dose of 30 Gy in 2.5 weeks. Electron beams of appropriate energies were used whenever possible. Junction lines between adjoining fields were moved twice to minimize dose heterogeneity. Patients were seen at regular intervals to assess disease status and therapy-related complications. Patients who relapsed were treated as indicated by the clinical status. RESULTS: With a median follow-up of 35 months, 111 of 174 patients were alive. The disease recurred above the clavicles only in six patients, at distant sites in 58 patients, and both local-regionally and at distant sites in nine patients. The actuarial 5-year local-regional control (LRC) and survival rates for the whole group were 88% and 47%, respectively. The thickness of the primary lesion, presence of more than three positive nodes, and extracapsular extension did not influence the LRC rate after radiotherapy (range: 85-92%). However, lesion thickness strongly affected the 5-year survival rate of group 1 patients (i.e., 100% for < or = 1.5 mm thick, but Clark's level IV, 72% for > 1.5-4 mm, and 30% for > 4 mm). In groups 2 and 3, the 5-year survival rate of patients with > three involved nodes was lower than that of patients with one to three positive nodes (23% vs. 39%). The acute tolerance to adjunctive radiotherapy was excellent. Late radiation complications were observed in only three patients. These were moderate neck fibrosis, mild ipsilateral hearing impairment, and transient exposure of external auditory canal cartilage. CONCLUSION: The safety of this hypofractionated radiotherapy regimen in the management of cutaneous melanoma was established in this study. The overall 5-year actuarial LRC rate of 88% was much higher than that of our historical group and that reported in the literature (50%). The survival rate of patients with lesion of 1.5-4 mm thickness was also higher than that observed in other series. Based on these results a prospective randomized study to further define the role of adjunctive postoperative radiotherapy is planned.

Adolescent↗
PubMed1994

Radiation response of the monkey kidney following contralateral nephrectomy.

PURPOSE: The long-term functional and morphologic responses of the hypertrophied monkey kidney after unilateral nephrectomy to fractionated irradiation were assessed. METHODS AND MATERIALS: The right kidney of 13 adult female rhesus monkeys was removed. Twelve weeks after unilateral nephrectomy (UN) the remaining kidney received fractionated doses of gamma-rays ranging from 35.2 Gy/16 fractions (F) up to 44 Gy/20 F. Glomerular filtration rate, effective renal plasma flow, blood urea nitrogen, serum creatinine, and hematocrit values were measured up to 107 weeks postirradiation (PI). The monkeys were killed and the remaining kidneys were removed 107 weeks PI or earlier when end-stage renal failure was exhibited. Glomeruli were scored for the presence/absence of several pathologic features including increased intercapillary eosinophilic material (ICE), ectatic capillaries, and thrombi. The relative proportion of renal cortex occupied by glomeruli, interstitium, normal tubules or abnormal tubules was determined using a Chalkley point grid. These quantal dose response data were analyzed using a logistic regression model. RESULTS: Irradiation of the remaining kidney in UN monkeys resulted in a dose-dependent reduction in renal function and anemia. Glomerular dysfunction preceded tubular dysfunction. Animals receiving 44 Gy all manifested progressive clinical renal failure. Conversely, those receiving < or = 39.6 Gy showed stable, albeit impaired, renal function for the duration of the observation period of 107 weeks. Morphologically, the incidence of ICE, ectatic glomerular capillaries, thrombi, and periglomerular fibrosis was significantly dose-related (p < 0.005). A significant (p < 0.001) dose-related increase in the relative proportion of renal cortex occupied by abnormal tubules was indicative of tubular injury. A highly significant (p < 0.001) dose-dependent increase in the proportion of abnormal to normal tubules was also seen. CONCLUSION: The pathogenesis of radiation nephropathy is difficult to fully understand because of the complex and dynamic interactions among all components of the nephron that make discrimination between primary radiation effects and secondary pathophysiological consequences very difficult. Notwithstanding, the current experiment shows that the functional and morphological expressions of radiation injury in the kidney are dose dependent. Renal failure occurs when both the glomeruli and tubules are dysfunctional. In monkeys following UN, a total dose of 44 Gy to the remaining kidney damages all components of the nephron and causes renal failure in less than 45 weeks. With lower doses, changes to the glomeruli predominate and the animals survive. Kidney doses of up to 39.6 Gy/18 fractions of 2.2 Gy are compatible with survival for at least 2 years in primates.

Animals↗
PubMed1994

Enhancement of tumor radioresponse of a murine mammary carcinoma by paclitaxel.

Paclitaxel is a chemotherapeutic agent with potent microtubule stabilizing activity that arrests cells in G2-M. Because G2 and M are the most radiosensitive phases of the cell cycle, paclitaxel has potential as a cell cycle-specific radiosensitizer. In this study, we investigated the ability of paclitaxel to increase tumor radioresponse in vivo using a murine mammary carcinoma and the dependency of this response on accumulation of tumor cells in mitosis. Mice bearing 8-mm tumors were treated with paclitaxel (60 mg/kg i.v.), 9, 15, or 21 Gy of single-dose radiation, or with a regimen of both agents in which radiation was given 1, 9, or 24 h after paclitaxel. The effect of the treatments was determined by tumor growth delay. Microscopically, the percentage of mitotically arrested cells was only 4% 1 h after treatment with paclitaxel, increased to a maximum value of 30% at 9 h, and decreased to 12% 24 h after paclitaxel. Paclitaxel enhanced tumor radioresponse by factors of 1.21 to 2.49. The degree of enhancement increased with increases in both the dose of radiation and the time between paclitaxel administration and radiation delivery. Radiation efficiently destroyed mitotically arrested cells by apoptosis. The greatest enhancement of radiation response was not at the time of the highest mitotic arrest but at 1 day after paclitaxel treatment, showing that paclitaxel potentiates tumor radioresponse by mechanisms in addition to blocking the cell cycle in mitosis, possibly by tumor reoxygenation. Thus, these results show that paclitaxel is a potent in vivo radiopotentiating agent and has the potential to be usefully combined with radiotherapy.

Animals↗
PubMed1994

Postoperative radiation therapy for malignant tumors of minor salivary glands. Outcome and patterns of failure.

BACKGROUND: In the treatment of major salivary gland cancers, the addition of adjuvant postoperative radiation therapy for patients with high risk features has been shown to reduce the incidence of local failure. This retrospective study was done to determine the effectiveness of this approach for minor salivary gland cancers, to document patterns of failure, and to define prognostic variables for treatment outcome. METHODS: Between 1961 and 1990, 160 patients received postoperative radiation at the University of Texas M. D. Anderson Cancer Center (UTMDACC) after gross total removal of their tumors. These operations ranged from excisional biopsies to craniofacial resections with orbital exenterations depending on the original site and size of the tumor. The primary tumor site was in the oral cavity-oropharynx in 111 patients and in the nasal cavity or paranasal sinuses in 46 patients. The most prevalent histologic type was adenoid cystic carcinoma (71%). Microscopic positive margins were present in 64 (40%) patients. Half of the patients had pathologic evidence of perineural invasion. Radiation therapy techniques varied, depending on the site and extent of disease and the era of treatment. Doses ranged from 50 to 75 Gy (median, 60 Gy; mean 59.2 Gy). Follow-up for surviving patients ranged from 24 to 270 months (median, 110 months). RESULTS: Fifty-seven (36%) patients experienced disease relapse. Nineteen (12%) patients had a local recurrence: 6 within 5 years of treatment, 8 between 5 and 10 years, and 5 after 10 years. Regional failures occurred in 3 of 13 patients with initially node-positive disease but were uncommon (less than 5%) in patients with node-negative disease, regardless of elective neck treatments. Distant metastases developed in 43 patients, mostly (79%) within 5 years of treatment. Actuarial overall survival rates at 5, 10, and 15 years were 81%, 65%, and 43%, respectively. Complications occurred in 51 patients and were of three predominate types: hearing loss (26 patients), ocular injury (15 patients), and bone exposure/necrosis (12 patients). Improved techniques, including better immobilization, customized beam shaping, and treating multiple fields per day, have substantially reduced the risk of serious complications during the past decade. CONCLUSIONS: Postoperative radiation therapy is effective in preventing local recurrence in most patients with minor salivary gland tumors after gross total excision. When local failure occurs, it tends to be a late event. For most patients, the authors recommend a postoperative dose of 60 Gy in 30 fractions to the operative bed; if there is named nerve invasion, the path of the nerve is treated electively to its ganglion.

Adolescent↗
PubMed1994

Volume effects in rhesus monkey spinal cord.

PURPOSE: An experiment was conducted to test for the existence of a volume effect in radiation myelopathy using Rhesus monkeys treated with clinically relevant field sizes and fractionation schedules. METHODS AND MATERIALS: Five groups of Rhesus monkeys were irradiated using 2.2 Gy per fraction to their spinal cords. Three groups were irradiated with 8 cm fields to total doses of 70.4, 77, and 83.6 Gy. Two additional groups were irradiated to 70.4 Gy using 4 and 16 cm fields. The incidence of paresis expressed within 2 years following the completion of treatment was determined for each group. Maximum likelihood estimation was used to determine parameters of a logistic dose response function. The volume effect was modeled using the probability model in which the probability of producing a lesion in an irradiated volume is governed by the probability of the occurrence of independent events. This is a two parameter model requiring only the estimates of the parameters of the dose-response function for the reference volume, but not needing any additional parameters for describing the volume effect. RESULTS: The probability model using a logistic dose-response function fits the data well with the D50 = 75.8 Gy for the 8-cm field. No evidence was seen for a difference in sensitivities for different anatomical levels of the spinal cord. Most lesions were type 3, combined white matter parenchymal and vascular lesions. Latent periods did not differ significantly from those of type 3 lesions in humans. CONCLUSION: The spinal cord exhibits a volume effect that is well described by the probability model. Because the dose response function for radiation myelopathy is steep, the volume effect is modest. The Rhesus monkey remains the animal model most similar to humans in dose response, histopathology, and latency for radiation myelopathy.

Animals↗
PubMed1994

Radiation-induced injury to the visual pathway.

Radiation-induced injury to the visual pathway was reviewed in a cohort of patients treated for various cancers of the nasal cavity and paranasal sinuses between 1969 and 1985. The study subjects consisted of 219 patients, 137 men and 82 women, in whom detailed records were available on the extent of orbital shielding, treatment plan for estimating doses delivered to various optic structures, and visual acuity follow-up information. There was a wide range in doses administered to various optic structures because patients with different primary lesion types were included and the radiotherapy techniques used varied during this era. The endpoint of the study was visual acuity < 20/100. The Cox proportional hazard model was used to assess the influence of various factors on the latent time to visual impairment and to fit the LQ model to the failure-time data. Actuarial curves showing the proportion of patients with visual impairment as a function of dose and time were generated. Corneal injury occurred in 24 of the 49 patients treated with the 3-field technique without any orbital shielding; variables affecting the incidence of cornea injury were total radiation dose and chemotherapy. Symptomatic retinopathy was diagnosed in 7 of 77 patients who received irradiation to a relatively large retinal surface, but no variables were found to correlate with this complication. Eight patients developed ipsilateral blindness due to optic neuropathy and 11 patients had bilateral visual impairment secondary to chiasm injury. The total radiation dose was identified as the predominant determinant. None of patients receiving a dose of < 50 Gy developed optic neuropathy or chiasm injury.(ABSTRACT TRUNCATED AT 250 WORDS)

Blindness↗
PubMed1994

Effects of speech intelligibility level on concurrent visual task performance.

Four experiments were performed to determine if changes in the level of speech intelligibility in an auditory task have an impact on performance in concurrent visual tasks. The auditory task used in each experiment was a memory search task in which subjects memorized a set of words and then decided whether auditorily presented probe items were members of the memorized set. The visual tasks used were an unstable tracking task, a spatial decision-making task, a mathematical reasoning task, and a probability monitoring task. Results showed that performance on the unstable tracking and probability monitoring tasks was unaffected by the level of speech intelligibility on the auditory task, whereas accuracy in the spatial decision-making and mathematical processing tasks was significantly worse at low speech intelligibility levels. The findings are interpreted within the framework of multiple resource theory.

Adult↗
PubMed1993

Prospective comparison of in vitro normal cell radiosensitivity and normal tissue reactions in radiotherapy patients.

PURPOSE: This pilot study was undertaken to assess the relationship between in vitro radiosensitivity of different normal cell types and the type and severity of normal tissue reactions in individual patients after radiotherapy. METHODS AND MATERIALS: Twenty-one patients with head and neck cancer were studied prospectively; four with head and neck and two with breast cancer were studied retrospectively. The retrospective cases were chosen because they exhibited unusual (severe or minimal) normal tissue reactions after radiotherapy. Small skin biopsies and blood samples were obtained and used to generate in vitro fibroblast and lymphocyte cultures, respectively. Clonogenic assays were used to measure in vitro fibroblast and lymphocyte radiosensitivity after high- and low-dose rate irradiation. Head and neck patients were treated by conventional, hyperfractionated, or concomitant boost regimens, which have been found to yield an equal probability of late normal tissue reactions. The highest dose received by each normal tissue in the target volume was estimated using computed tomography treatment plans. The median patient follow-up time was 19 months (range: 13-25). RESULTS: The distributions of in vitro radiosensitivity parameters and the grade of tissue reaction scores in the patients showed a broad range between individuals. When in vitro parameters were compared to the acute and late tissue reactions, the radiosensitivity of fibroblasts, measured as surviving fraction at 2 Gy after high-dose rate irradiation, showed a highly significant correlation with the maximum grade of late effects (p < 0.0001 for the whole group and p = 0.0013 for the group of patients studied prospectively). No significant correlation was found between fibroblast radiosensitivity and maximum grade of acute effects or between lymphocyte radiosensitivity and either acute or late effects. CONCLUSION: We conclude that individuals vary in normal cell radiosensitivity, and that in vitro measurements of fibroblast radiosensitivity may predict the magnitude of late normal tissue reactions after radiotherapy. These preliminary results, however, need to be validated in a larger group of patients.

Biopsy↗
PubMed1993

Neutron vs. photon radiation therapy for inoperable regional non-small cell lung cancer: results of a multicenter randomized trial.

PURPOSE: To determine, with a prospective, multicenter randomized study, whether fast neutron radiation therapy improves the outcome for patients with non-small cell lung cancer, as compared to conventional photon radiotherapy. METHODS AND MATERIALS: From September 1986 to March 1991, a total of 200 patients with inoperable regional non-small cell lung cancer were randomized to 20.4 Gy in 12 fractions with neutrons versus 66 Gy in 33 fractions with photons. Inoperable patients with Radiation Therapy Oncology Group Stages I, II, III, or IV(M0) disease, Karnofsky Performance Score > or = 70, and who had received no previous therapy for their non-small cell lung cancer were eligible for the study. Of the 200 patients randomized, a total of 193 patients, 99 on the neutron arm and 94 on the photon arm, were eligible for analysis. The two treatment groups were balanced with regards to prognostic factors. At the time of this analysis, the median at-risk follow-up was 33 months, with a minimum follow-up of 16 months. RESULTS: No difference in overall survival was observed; however, there was a statistically significant improvement in survival for patients with squamous cell histology (p = 0.02), and a trend toward improved survival for those with favorable prognostic factors (i.e., patients who were not T4, N3, and had no pleural effusion or weight loss > 5% from baseline) (p = 0.15), favoring the neutron-treated group. With the exception of skin and subcutaneous changes, acute and late toxicity was similar in both arms. CONCLUSION: In selected patients with inoperable regional non-small cell lung cancer (e.g., squamous cell histology, favorable prognostic factors), fast neutron irradiation provides a therapeutic benefit over conventional photon radiotherapy.

Adult↗
PubMed1993

Evaluation of the dose for postoperative radiation therapy of head and neck cancer: first report of a prospective randomized trial.

PURPOSE: This study was designed to determine in a prospective randomized trial the optimal dose of conventionally fractionated postoperative radiotherapy for advanced head and neck cancer in relation to clinical and pathologic risk factors. METHODS AND MATERIALS: Between January 1983 and March 1991, 302 patients were enrolled on the study. This analysis is based on the first 240 patients entered through September 1989, of whom 221 (92%) had AJC Stage III or IV cancers of the oral cavity, oropharynx, hypopharynx, or larynx. The patients were stratified by postulated risk factors and randomized to one of three dose levels ranging between 52.2 Gy and 68.4 Gy, all given in daily doses of 1.8 Gy. Patients receiving > 57.6 Gy had a field reduction at this dose level such that boosts were only given to sites of increased risk. RESULTS: The overall crude and actuarial 2-year local-regional recurrence rates were 25.4% and 26%, respectively. Patients who received a dose of < or = 54 Gy had a significantly higher primary failure rate than those receiving > or = 57.6 Gy (p = 0.02). No significant dose response could be demonstrated above 57.6 Gy except for patients with extracapsular nodal disease in the neck in whom the recurrence rate was significantly higher at 57.6 Gy than at > or = 63 Gy. Analysis of prognostic factors predictive of local-regional recurrence showed that the only variable of independent significance was extracapsular nodal disease. However, clusters of two or more of the following risk factors were associated with a progressively increased risk of recurrence: oral cavity primary, mucosal margins close or positive, nerve invasion, > or = 2 positive lymph nodes, largest node > 3 cm, treatment delay greater than 6 weeks, and Zubrod performance status > or = 2. Moderate to severe complications of combined treatment occurred in 7.1% of patients; these were more frequent in patients who received > or = 63 Gy. CONCLUSION: With daily fractions of 1.7 Gy, a minimum tumor dose of 57.6 Gy to the whole operative bed should be delivered with a boost of 63 Gy being given to sites of increased risk, especially regions of the neck where extracapsular nodal disease is present. Treatment should be started as soon as possible after surgery. Dose escalation above 63 Gy at 1.8 Gy per day does not appear to improve the therapeutic ratio.

Adult↗
PubMed1993

The tolerance of primate spinal cord to re-irradiation.

PURPOSE: This study was designed to assess the tolerance of the cervical spinal cord of rhesus monkeys to re-irradiation. This information is essential for treatment recommendations in previously irradiated patients. METHODS AND MATERIALS: Control animals received a single course of treatment to total doses of 70.4 Gy, 77.0 Gy, or 83.6 Gy in daily fractions of 2.2 Gy. Twelve asymptomatic animals that received 70.4 Gy were re-irradiated two years later to cumulative doses of 83.6, 92.4, or 101.2 Gy. Another group of 15 animals received 44 Gy and two years later were re-irradiated to cumulative doses of 83.6, 92.4, 101.2, or 110 Gy. The clinical endpoint was myeloparesis. A complete necropsy was performed in all animals when myeloparesis manifested or at the end of observation period. RESULTS: Only two of the 12 asymptomatic animals of the 70.4 Gy dose-response study group and two of the 15 animals that had received 44 Gy initially developed myelopathy within two years of re-irradiation. The ED50 value of the single-course irradiation was 76.1 +/- 1.9 Gy, while the extrapolated ED50 for retreatment after 44 Gy was > or = 110 Gy. The lesions of the two symptomatic animals that received 70.4 Gy initially were mixtures of white matter and vascular lesions similar to those observed after single course irradiation. However, both symptomatic animals given 44 Gy initially had hemorrhagic infarcts in the white matter. CONCLUSION: The results of this study indicate that substantial recovery of occult injuries induced by the initial 44 Gy had occurred within two years. The difference between the types of lesions observed after a single course and re-irradiation suggests that vascular injury may recover less efficiently or at slower rate than white matter damage. The dependence of the extent of recovery on the initial dose and the time course of such recovery in primates are being investigated.

Animals↗
PubMed1993

Heterogeneity in the development of apoptosis in irradiated murine tumours of different histologies.

Fifteen different murine tumours were evaluated with respect to the degree of apoptosis development that occurs in the tumour tissue in the first few hours following irradiation in vivo. Animals were killed at 3 or 6 h following irradiation with 0, 2.5, 10 or 25 Gy. Apoptosis was scored as percent aberrant nuclei by microscopic examination of histological sections made from the tumour specimens. Results showed that three of four mammary adenocarcinomas, one ovarian adenocarcinoma, and one lymphoma displayed at least 10% apoptotic cells after 25 Gy, whereas five sarcomas, three squamous cell carcinomas, and a hepatocarcinoma did not. The time courses and dose responses were similar in those tumours that responded. These data were compared with the known response of these same tumours when analysed using conventional assays. The tumours that did respond by significant apoptosis had longer specific growth delays and lower TCD50 (dose to cure 50% of animals) doses, thus suggesting that an acute apoptotic response following irradiation may be a feature of certain tumours that respond well to irradiation. Additionally, this analysis revealed heterogeneity in the apoptotic response both within an individual tumour specimen and among different tumour types. These observations of intra and intertumour heterogeneity are consistent with the idea that the propensity for apoptosis in tumours is genetically regulated.

Adenocarcinoma↗
PubMed1993

Effectiveness of combined induction chemotherapy and radiotherapy in advanced nasopharyngeal carcinoma.

PURPOSE: This prospective trial was conducted with the goal of achieving an improvement in both overall and progression-free survival in previously untreated patients with stage IV nasopharyngeal carcinoma who received an induction chemotherapy regimen of fluorouracil (5-FU) and cisplatin followed by radiotherapy. PATIENTS AND METHODS: From January 1985 to January 1990, 47 patients with T1-4N2-3M0 squamous cell carcinoma of the nasopharynx were treated at The University of Texas M.D. Anderson Cancer Center with two to three cycles of 5-FU (1,000 mg/m2 continuous infusion per day x 5 days) plus cisplatin (100 mg/m2 continuous infusion on day 1 only) followed by radiotherapy using the conventional time/dose schedule. RESULTS: The response rate to chemotherapy was 93.2% (20.5% complete response [CR]; 72.7% partial response [PR]), and the overall CR rate after radiotherapy was 86%. With a median follow-up period of 53 months, the 2-, 4-, and 6-year survival rates were 80%, 71.6%, and 67.4%; the overall treatment failure rate was 27%. Treatment was well tolerated and without significant acute or chronic toxic effects. CONCLUSION: The results of this prospective study demonstrate that 5-FU plus cisplatin followed by radiotherapy can induce a durable remission in a high proportion of patients with poor-prognosis stage IV nasopharyngeal carcinoma.

Adolescent↗
PubMed1992

Intrinsic radiosensitivity of normal human fibroblasts and lymphocytes after high- and low-dose-rate irradiation.

The existence of heritable radiosensitivity syndromes and clinical observations in radiotherapy patients suggests that human cellular radiosensitivity differs among individuals. We report here an in vitro study of radiosensitivity in 30 fibroblast and 29 lymphocyte cultures obtained from cancer patients and controls. In 25 cases, both fibroblasts and lymphocytes were obtained from the same donors. Fibroblasts were cultured from skin biopsy samples, and peripheral T-cell lymphocytes were cultured from blood. Clonogenic survival assays were performed by using high- and low-dose-rate irradiation; lymphocytes were in G0 phase and fibroblasts in confluent plateau phase. Various end points were calculated and compared (i.e., surviving fraction at 2 Gy, initial slope of the survival curve, and doses resulting in 10 and 1% survival, respectively). Depending on the end point, the coefficient of variation of the survival parameters ranged from 31 to 68% for lymphocytes and 21 to 41% for fibroblasts following high-dose-rate irradiation. Similar ranges were obtained after low-dose-rate irradiation. Variance analysis performed on replicate assays in cultures derived from the same patient showed that variation due to technical or sampling errors was significantly lower than variation between individuals (P = 0.00034 and 0.014 for fibroblasts and lymphocytes, respectively). No correlation was observed between the radiosensitivity of lymphocyte and fibroblast cultures derived from the same donors. We conclude that there is significant variation in normal cell radiosensitivity among individuals. On the other hand, comparisons of lymphocyte and fibroblast radiosensitivities suggest that tissue-specific characteristics, such as differentiation status, may variably modulate radiosensitivity.

Breast Neoplasms↗
PubMed1992

Carcinomas of the nasal cavity.

Between 1969 and 1985, 45 patients with carcinomas of the nasal cavity proper received curative treatment. Thirty patients had squamous cell carcinoma, one had undifferentiated carcinoma, 9 had adenocarcinoma, and 5 had adenoid cystic carcinoma. Eighteen patients were treated with definitive radiotherapy (interstitial brachytherapy in 5 and external beam therapy in 13 patients), and 27 received surgery and radiotherapy. The median length of follow-up was 11 years (range: 2.8-16.8 years). Thirty-six patients had no evidence of disease at the last follow-up visit. All 14 patients with carcinoma of the nasal septum had the disease controlled. Nine of 31 patients with lesions of the lateral wall and floor died of the disease, 5 of uncontrolled local disease, 2 of distant metastases, and 2 of both. The disease-specific survival rates at 5 and 10 years were 83 and 80%, respectively, and the corresponding overall survival rates were 75 and 60%, respectively. Blindness occurred in 4 patients, 2 due to orbital exenteration and 2 to radiation injury to the cornea and optic pathway. Other infrequent side effects were bone necrosis, dental decay, nasal stenosis, and septal perforation. This study indicated that the prognosis of patients with nasal cavity carcinoma was better than that of patients with maxillary sinus cancer treated during the same era. In addition, the study showed that carcinomas of the nasal septum were smaller than those of lateral wall and floor at diagnosis, so that excellent control could be achieved by definitive radiotherapy; when accessible, interstitial brachytherapy might be the treatment of choice in such patients.

Adenocarcinoma↗