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Biomedical subjects

D A Larson

Publications and source records attributed to D A Larson.

At least 55 records · Page 3Linked to original sources

Pineoblastoma in adults.

This is the first report of a series of adults (> 16 years of age) with pineoblastomas who had their entire neuraxis staged at the time of diagnosis. Between 1975 and 1992, seven men and four women with histologically proven pineoblastomas were evaluated at the University of California, San Francisco. The median age at diagnosis was 36 years (range, 17-59 yr). All patients presented with symptomatic hydrocephalus. One patient had a complete surgical resection, eight had subtotal resections, and two had biopsies only. One patient refused any treatment or follow-up review and died 6 months after diagnosis. The five patients with positively staged disease had progression either focally or in the spine 8 to 49 months (median, 10 mo) after initial diagnosis and died 1 to 20 months after recurrence; the median overall survival time from the date of surgery was 30 months. In contrast, all five patients with negatively staged disease were alive without disease progression after a median of 26 months of follow-up. Our retrospective review shows that the extent of disease at diagnosis seems to be an important prognostic factor for pineoblastomas, as is true for medulloblastomas and other primitive neuroectodermal tumors. Initial staging should include examination of the cerebrospinal fluid and magnetic resonance imaging of the spine. Although patients with pineoblastomas are often treated with adjuvant systemic chemotherapy after craniospinal irradiation, the benefits of this approach are unclear.

Adolescent↗

Pattern of recurrence of medulloblastoma after low-dose craniospinal radiotherapy.

PURPOSE: We retrospectively evaluated relapse of medulloblastoma after low- or high-dose craniospinal radiotherapy, and after conventional or hyperfractionated posterior fossa irradiation. METHODS AND MATERIALS: Ninety-two pediatric patients were treated postoperatively since 1970 at the University of California, San Francisco. Until 1989, we employed conventional fractionation with low (< or = 30 Gy) or high-dose craniospinal fields and low-dose (< or = 56 Gy) posterior fossa boosts. Recently, hyperfractionation delivered low- or high-dose to the craniospinal axis and high-dose to the posterior fossa. Most patients treated after 1979 received chemotherapy. RESULTS: Median follow-up was 70 months. Five-year disease-free survival was 36% (22% for poor-risk vs. 59% for good-risk patients). Five-year overall survival was 52% (43% for poor vs. 68% for good-risk). Neither the dose to the posterior fossa nor the craniospinal axis was statistically related to recurrence. Failure in the posterior fossa occurred despite boosts greater than 56 Gy. Females, over the age of 6 years, had significantly better relapse-free survival than males of the same age. Six of the 54 patients who relapsed were long-term survivors. CONCLUSIONS: Low-dose craniospinal radiotherapy, where the majority of patients received chemotherapy, was not associated with increased failure. High-dose posterior fossa hyperfractionation did not improve control. Long-term survival was noted in a number of patients after relapse. We recommend 60 Gy or greater with conventional fractions to the primary area, and continued study of low-dose craniospinal irradiation with adjuvant chemotherapy.

Adolescent↗

Patterns of recurrence of glioblastoma multiforme after external irradiation followed by implant boost.

PURPOSE: To study patterns of recurrence in patients with focal primary glioblastoma treated on Northern California Oncology Group protocol 6G-82-2 including surgery, focal external beam radiotherapy (59.4-60 Gy) with oral hydroxyurea followed by temporary brain implant with high-activity iodine-125 sources (50 Gy), and six cycles of chemotherapy with procarbazine, lomustine, and vincristine. METHODS AND MATERIALS: Serial brain imaging scans were available for review in 25 of 34 patients with glioblastoma who underwent brain implant boost. Of 381 scans performed between the date of diagnosis and the date of death or last follow-up, 362 (95%) were re-reviewed. Disease progression was scored as local (within 2 cm of the implant site), separate within the brain parenchyma (> or = 2 cm from the implant site), subependymal, or systemic. Both initial and subsequent failures were scored. RESULTS: Three patients are 5-year survivors, without evidence of disease, at 267, 292, and 308 weeks. Of the 22 initial sites of failure, 17 (77%) were local, three (14%) were separate brain lesions (one of which was due in retrospect to multicentric disease at diagnosis), one (5%) subependymal, and one (5%) systemic. Five patients with local failure later had other sites of failure, including a separate brain lesion in 1, subependymal spread in 3, and both in 1. One patient with separate brain failure later had local progression and then subependymal spread. CONCLUSION: Although there was a significant risk of separate brain lesions or subependymal spread over time, local tumor progression was the predominant pattern of failure.

Adult↗

Radiotherapy of primary central nervous system lymphoma in patients with and without human immunodeficiency virus. Ten years of treatment experience at the University of California San Francisco.

BACKGROUND: Classic human immunodeficiency virus (HIV) negative primary central nervous system lymphoma (PCNSL) is a relatively uncommon occurrence, whereas the incidence of HIV positive PCNSL has increased dramatically during the past 5 years. Between 2% and 6% of all patients with acquired immune deficiency syndrome (AIDS) will have PCNSL develop clinically, and as many as 11% will have PCNSL found at autopsy. In the United States, some of the earliest and most extensive experience with HIV positive PCNSL has occurred in San Francisco. This article reports on PCNSL in patients with and without HIV. METHODS: Using our diagnosis-based computer retrieval system, we identified all patients treated with radiotherapy for PCNSL between January 1982 and January 1992 and reviewed their medical records. Population characteristics, risk factors and length of survival (LOS), were analyzed. Statistical methodology included the Cox proportional hazards model and Kaplan-Meier survival curves. RESULTS: Fifty-six patients were identified with PCNSL, of which 41 were HIV positive and 15 were HIV negative. There was a fourfold increase in the total number of PCNSL cases during the time period 1987-1991 as compared with the preceding 5 years; these cases primarily were in the HIV positive group. The average Karnofsky performance score (KPS) in the HIV positive group was 50, whereas in the HIV negative group, the KPS was 35. However, the median LOS in the HIV positive group was 3 months, whereas in the HIV negative group it was 20 months. Within each group, there was a statistically significant correlation between KPS and LOS. CONCLUSIONS: Patients with HIV and PCNSL have a much shorter median LOS than do patients with PCNSL but without HIV; however, the outcome for both groups is dismal. Randomized clinical trials are needed to determine which patients with HIV might benefit from more aggressive therapy and to determine the optimal choice and dosages of chemoradiation therapy for patients with PCNSL without HIV.

Adolescent↗

Current radiosurgery practice: results of an ASTRO survey. Task Force on Stereotactic Radiosurgery, American Society for Therapeutic Radiology and Oncology.

PURPOSE: Although there is increasing interest in radiosurgery, little quantitative data regarding current patterns of radiosurgery practice are available. We developed a radiosurgery questionnaire to obtain information on radiosurgery practice. METHODS AND MATERIALS: We distributed the questionnaire to the entire membership of the American Society of Therapeutic Radiology and Oncology in early 1993. Responses were obtained from 74 facilities that practice radiosurgery, corresponding to over 6000 treatments carried out since 1983 by 135 radiation oncologists and 130 physicists. RESULTS: Most respondents were found to work within a multidisciplinary team, consisting of the following specialists (average hours devoted per patient on day of treatment in parentheses): radiation oncologist (3.8), neurosurgeon (3.2), physicist (6.1), radiologist (0.7), nurse (2.7), other (3.0). On average, neurosurgeons and nurses who perform Gamma Knife radiosurgery devote significantly more time-per-patient on the day of treatment than their peers who perform linac radiosurgery. On average, less experienced radiation oncologists and physicists (< or = 24 months experience, or < or = 50 patients treated) devote significantly more time-per-patient on the day of treatment than their more experienced peers. Although there are many more linac radiosurgery facilities than Gamma Knife facilities, on average the number of patients treated per month per facility is significantly larger at the latter. On average, follow-up responsibilities are nearly equally shared by radiation oncologists and neurosurgeons, except at Gamma Knife facilities, where neurosurgeons assume a larger percentage of follow-up responsibility. The percentages of patients treated at linac facilities for metastases or primary CNS malignancy are larger than the corresponding percentages at Gamma Knife facilities; the opposite is true for arteriovenous malformation, acoustic neuroma, and meningioma. CONCLUSION: Current radiosurgery practice usually involves a team approach, with participation of specialists from radiation oncology, neurosurgery, physics, radiology, and nursing. The average number of M.D. and Ph.D. hours required per treatment on the day of radiosurgery is high.

Canada↗

Radiation-induced telangiectasia in the brain simulates cryptic vascular malformations at MR imaging.

PURPOSE: To analyze the magnetic resonance (MR) imaging, clinical, and pathologic features of radiation-induced telangiectasia of the brain. MATERIALS AND METHODS: The clinical and radiation therapy records were reviewed of 20 patients who developed focal hypointense lesions on T2-weighted MR images obtained after radiation therapy of the central nervous system. Pathologic material was reviewed in six patients. RESULTS: Eleven patients had solitary lesions, and nine had multiple foci on MR images. Fourteen of the 20 patients were less than 20 years old. The appearance ranged from small hypointense foci to larger regions of acute hemorrhage. Hematomas occurred at the site of a previously identified focus of T2 shortening in five patients. Pathologic findings included ectatic thin-walled vessels surrounded by hemosiderin and gliosis, with minimal evidence of necrosis. CONCLUSION: Radiation-induced telangiectasia in the brain results in varying amounts of hemorrhage and, occasionally, parenchymal hematomas, and may appear similar to cryptic vascular malformations on T2-weighted MR images.

Adolescent↗

The role of radiation therapy in the treatment of craniopharyngioma.

The role of radiotherapy in the management of patients with craniopharyngiomas is still controversial. Many articles have been published reviewing retrospective patient information with subsequent treatment recommendations which are not randomized and are biased. Treatment at the University of California, San Francisco, with radiation and surgery yields a 10-year disease-free survival of 77%. No difference in overall survival was found based on sex, age, or type of surgery. A review of the literature shows that radiation added to surgery results in a 50-80% disease-free survival. Patients undergoing a complete resection may be observed for subsequent recurrence. If a subtotal resection or biopsy is obtained, that patient should be irradiated with modern techniques to a dose of 5,400 cGy at 180 cGy/fraction.

Adolescent↗

Postoperative irradiation for subtotally resected meningiomas. A retrospective analysis of 140 patients treated from 1967 to 1990.

The authors retrospectively analyzed 140 patients treated at the University of California, San Francisco, from 1967 to 1990 to evaluate the results of radiation therapy (median 5400 cGy) given as an adjuvant to subtotal resection of intracranial meningioma. Of the 140 meningiomas, 117 were benign and 23 were malignant. The median follow-up period was 40 months. The overall survival rate at 5 years was 85% for the benign and 58% for the malignant tumor groups (p = 0.02); the 5-year progression-free survival rates were 89% and 48%, respectively (p = 0.001). For patients with benign meningioma, the 10-year overall and progression-free survival rates were 77%. An improved progression-free survival rate in that group was not related to tumor size but was associated with a younger age (p = 0.01) and treatment after 1980 with innovative technologies (p = 0.002); none of those variables affected the progression-free survival rate in the patients with malignant meningioma. Increased progression-free survival in the benign tumor group was also significantly associated with increasing the minimum radiation dose (p = 0.04). The 5-year progression-free survival rate for patients with benign meningioma treated after 1980 (when computerized tomography or magnetic resonance imaging was used for planning therapy) was 98%, as compared with 77% for patients treated before 1980 (p = 0.002). There were no second central nervous system tumors. Morbidity (3.6%) included sudden blindness or cerebral necrosis and death. When total resection of benign meningioma is not feasible, subtotal resection combined with precise treatment planning techniques and adjuvant radiation therapy can achieve results comparable to those of total resection.

Adolescent↗

Stereotactic radiosurgery for intracranial malignancies.

Stereotactic radiosurgery has historically been used for arteriovenous malformations and benign tumors but has rather recently been used as a tool in the multimodality management of intracranial malignancies. Radiosurgery has been shown to be highly effective in the management of small metastatic brain tumors and has proven effective in controlling small brain metastases that progress after prior fractionated radiotherapy. The technique is also a reasonable, low morbidity alternative to surgical resection in the initial management of patients with solitary brain metastasis. In selected patients with small, relatively spherical, high-grade gliomas, radiosurgery appears to produce tumor control, survival, and toxicity similar to that of brachytherapy. However, compared with brachytherapy, radiosurgery has the advantage of lower initial morbidity, reduced hospital stay, reduced radiation exposure to personnel, and lower costs. Future clinical trials should further define dose-response relationships and the optimum role for radiosurgery in the management of malignant intracranial neoplasms.

Brain Neoplasms↗

Structural modification of 5-aryl-2,3-dihydroimidazo[2,1-a]isoquinoline platelet activating factor receptor antagonists.

In an effort to determine the effect of modification of the imidazo[2,1-a]isoquinoline portion of the PAF-receptor antagonist SDZ 64-412 (1), several new analogs were prepared and evaluated in vitro and in vivo. One of these, 5-[4-[2-(3,4,5-trimethoxyphenyl)ethyl]phenyl]-2,3-dihydroimidazo [1,2-a]thieno[2,3-c]pyridine (6) was 4-5 times more potent than 1 in inhibiting PAF-induced bronchoconstriction and hemoconcentration when administered po to the guinea pig.

Animals↗

Intracranial myxopapillary ependymoma: case report.

The authors report an unusual case of a myxopapillary ependymoma arising from the lateral ventricle. The patient, a 37-year-old woman, developed recurrent symptoms including scotomata, disorientation, and headache during two successive pregnancies before the definitive diagnosis. The causes of this ependymoma variant and its relationship to pregnancy are discussed.

Adult↗