William M. Wara

THERAPEUTIC IRRADIATION AND BRAIN INJURY

Abstract This is a review and reanalysis of the literature on adverse effects of therapeutic irradiation on the brain. Reactions have been grouped and considered according to time of appearance. The emphasis of the analysis is on delayed reactions, especially those that occur from a few months to several years after irradiation. Over 100 such cases are reported in the literature. Eighty cases were identified in which the patient was given a single course of radiation therapy and in which reasonable estimates of the time-dose-fractionation regimen could be made. Eleven of these patients had been irradiated for cancer of the skin, 17 for other extracranial tumors, 20 for either a pituitary tumor or a craniopharyngioma and 32 for primary brain tumors. All dose specifications were converted into equivalent megavoltage rads. The data were analyzed in terms of total dose, overall treatment time and number of treatment fractions. The data were also analyzed in terms of time-dose-fractionation (TDF) and nominal standard dose (NSD). NSD calculations were done according to the usual Ellis formula and also according to a modification in which the N exponent was −0.44 and the T exponent −0.06. When total dose was plotted against number of fractions, a line with slope 0.44 fitted well with the lower dose limits at which brain necrosis has been reported. Also discussed were acute radiation reactions, early delayed radiation reactions, somnolence and leukoencephalopathy post-irradiation/chemotherapy and combined effects of radiation and chemotherapy.

Treatment of Children With Medulloblastomas With Reduced-Dose Craniospinal Radiation Therapy and Adjuvant Chemotherapy: A Children's Cancer Group Study

PURPOSE Medulloblastoma is the most common malignant brain tumor of childhood. After treatment with surgery and radiation therapy, approximately 60% of children with medulloblastoma are alive and free of progressive disease 5 years after diagnosis, but many have significant neurocognitive sequelae. This study was undertaken to determine the feasibility and efficacy of treating children with nondisseminated medulloblastoma with reduced-dose craniospinal radiotherapy plus adjuvant chemotherapy. PATIENTS AND METHODS Over a 3-year period, 65 children between 3 and 10 years of age with nondisseminated medulloblastoma were treated with postoperative, reduced-dose craniospinal radiation therapy (23.4 Gy) and 55.8 Gy of local radiation therapy. Adjuvant vincristine chemotherapy was administered during radiotherapy, and lomustine, vincristine, and cisplatin chemotherapy was administered during and after radiation. RESULTS Progression-free survival was 86% +/- 4% at 3 years and 79% +/- 7% at 5 years. Sites of relapse for the 14 patients who developed progressive disease included the local tumor site alone in two patients, local tumor site and disseminated disease in nine, and nonprimary sites in three. Brainstem involvement did not adversely affect outcome. Therapy was relatively well tolerated; however, the dose of cisplatin had to be modified in more than 50% of patients before the completion of treatment. One child died of pneumonitis and sepsis during treatment. CONCLUSION These overall survival rates compare favorably to those obtained in studies using full-dose radiation therapy alone or radiation therapy plus chemotherapy. The results suggest that reduced-dose craniospinal radiation therapy and adjuvant chemotherapy during and after radiation is a feasible approach for children with nondisseminated medulloblastoma.

Superiority of post-radiotherapy adjuvant chemotherapy with CCNU, procarrazine, and vincristine (PCV) over BCNU for anaplastic gliomas: NCOG 6G61 final report

Data from Northern California Oncology Group protocol 6G61, which was closed in February 1983, were reanalyzed in December 1988. The protocol called for a randomized trial that compared the effects of following 60 Gy radiation/oral hydroxyurea treatment with either carmustine (BCNU) or the combination of procarbazine, lomustine (CCNU), and vincristine (PCV) for two histologic strata: glioblastoma multiforme and other anaplastic gliomas. PCV produced longer survival and time to tumor progression than BCNU for both histologic groups, although the difference was statistically significant only for the anaplastic gliomas. With PCV treatment, time to progression and survival doubled for anaplastic glioma patients in the 50th and 25th percentiles.

Radiosurgery for brain metastases: is whole brain radiotherapy necessary?

PURPOSE Because whole brain radiotherapy (WBRT) may cause dementia in long-term survivors, selected patients with brain metastases may benefit from initial treatment with radiosurgery (RS) alone reserving WBRT for salvage as needed. We reviewed results of RS +/- WBRT in patients with newly diagnosed brain metastasis to provide background for a prospective trial. METHODS AND MATERIALS Patients with single or multiple brain metastases managed initially with RS alone vs. RS + WBRT (62 vs. 43 patients) from 1991 through February 1997 were retrospectively reviewed. The use of upfront WBRT depended on physician preference and referral patterns. Survival, freedom from progression (FFP) endpoints, and brain control allowing for successful salvage therapy were measured from the date of diagnosis of brain metastases. Actuarial curves were estimated using the Kaplan-Meier method. Analyses to adjust for known prognostic factors were performed using the Cox proportional hazards model (CPHM) stratified by primary site. RESULTS Survival and local FFP were the same for RS alone vs. RS + WBRT (median survival 11.3 vs. 11.1 months and 1-year local FFP by patient 71% vs. 79%, respectively). Brain FFP (scoring new metastases and/or local failure) was significantly worse for RS alone vs. RS + WBRT (28% vs. 69% at 1 year; CPHM adjustedp = 0.03 and hazard ratio = 0.476). However, brain control allowing for successful salvage of a first failure was not significantly different for RS alone vs. RS + WBRT (62% vs. 73% at 1 year; CPHM adjusted p = 0.56). CONCLUSIONS The omission of WBRT in the initial management of patients treated with RS for up to 4 brain metastases does not appear to compromise survival or intracranial control allowing for salvage therapy as indicated. A randomized trial of RS vs. RS + WBRT is needed to assess survival, quality of life, and cost in good-prognosis patients with newly diagnosed brain metastases.

Radiation therapy in the treatment of partially resected meningiomas

To address the question of whether radiation therapy is beneficial in the management of partially resected meningiomas, we reviewed the records of all patients admitted to the University of California, San Francisco, between 1968 and 1978 who had a diagnosis of intracranial meningioma. The patients were divided into three groups: 51 patients had gross total resection and did not receive radiation therapy, 30 patients had subtotal resection and no radiation therapy, and 54 patients had subtotal resection followed by radiation therapy. The subtotal resection groups were similar in average age, male:female ratio, and tumor location, which allowed a valid comparison of the effects of irradiation. The recurrence rate in the total resection group was 4% (2 of 51 patients). Among patients in the subtotal resection groups, 60% of nonirradiated patients had a recurrence, compared with only 32% of the irradiated patients. The median time to recurrence was significantly longer in the irradiated group than in the nonirradiated group (125 vs. 66 months, P less than 0.05). There was no complication related to irradiation. These results provide convincing evidence that radiation therapy is beneficial in the treatment of partially resected meningiomas.

Radiation tolerance of the spinal cord

A series of nine cases of radiation myelopathy seen at the University of California, San Francisco (UCSF) is reviewed, and their treatment data converted into nominal single doses (NSD) and equivalent single doses (ED). The 1% incidence level of myelopathy in the thoracic cord is 1015 rets (ED), and the 50% incidence level is 1476 rets (ED). Caution should be used when utilizing a rapid fractionation schedule; it appears that 2000 rads in 5 fractions and 3000 rads in 10 fractions is a safe regimen for the thoracic spinal cord.

Radiation pneumonitis following combined modality therapy for lung cancer: analysis of prognostic factors.

PURPOSE To identify factors associated with radiation pneumonitis (RP) resulting from combined modality therapy (CMT) for lung cancer. MATERIALS AND METHODS Series published before 1994 that used CMT for the treatment of lung cancer and explicitly reported the incidence of RP are the basis for this analysis. Factors evaluated included the radiation dose per fraction (Fx), total radiation dose, fractionation scheme (split v continuous), type of chemotherapy and intended dose-intensity, overall treatment time, histology (small-cell lung cancer [SCLC] v non-small-cell lung cancer [NSCLC]), and treatment schedule (concurrent v induction, sequential, or alternating CMT). RESULTS Twenty-four series, including 27 treatment groups and 1,911 assessable patients, met our criteria for inclusion in this analysis. The median total dose of radiation used in the trials analyzed was 50 Gy (range, 25 to 63 Gy). The median daily Fx used was 2.0 Gy (range, 1.5 to 4.0 Gy). Nineteen series included 22 treatment groups and 1,745 patients treated with single daily fractions. Among these patients, 136 received a daily Fx greater than 2.67 Gy. Five series used twice-daily radiotherapy and included 166 patients (Fx, 1.5 to 1.7 Gy). The incidence of RP was 7.8%. In a multivariate analysis, only daily Fx, number of daily fractions, and total dose were associated with the risk of RP (P < .0001, P < .018, and P < .003, respectively). CONCLUSION In this analysis, the use of Fx greater than 2.67 Gy was the most significant factor associated with an increased risk of RP. High total dose also appears to be associated with an increased risk, but twice-daily irradiation seems to reduce the risk expected if the same total daily dose is given as a single fraction. High-Fx radiotherapy should be avoided in patients who receive CMT with curative intent.

Radiation pneumonitis: A new approach to the derivation of time‐dose factors

A series of 51 patients treated with 92 separate lung fields for metastatic pulmonary disease between 1958 and 1971 is reviewed. The treatment data are converted into nominal single doses (NSD) and a newly derived formula for estimated single doses (ED). The 5% incidence level of pneumonitis without dactinomycin is 770 rets (NSD) and 510 rets (ED) and with dactinomycin, 520 rets (NSD) and 450 rets (ED). A safe treatment regimen for avoiding radiation pneumonitis is 1500 rads in 10 fractions with dactinomycin and 2500 rads in 20 fractions without dactinomycin.

EGFR overexpression and radiation response in glioblastoma multiforme

PURPOSE Recent studies have suggested relative radioresistance in glioblastoma multiforme (GM) tumors in older patients, consistent with their shorter survival. Two common molecular genetic abnormalities in GM are age related: epidermal growth factor receptor (EGFR) overexpression in older patients and p53 mutations in younger patients. We tested whether these abnormalities correlated with clinical heterogeneity in GM response to radiation treatment. METHODS AND MATERIALS Radiographically assessed radiation response (5-level scale) was correlated with EGFR immunoreactivity, p53 immunoreactivity, and p53 exon 5-8 mutation status in 170 GM patients treated using 2 prospective clinical protocols. Spearman rank correlation and proportional-odds ordinal regression were used for univariate and multivariate analysis. RESULTS Positive EGFR immunoreactivity predicted poor radiographically assessed radiation response (p = 0.046). Thirty-three percent of tumors with no EGFR immunoreactivity had good radiation responses (>50% reduction in tumor size by CT or MRI), compared to 18% of tumors with intermediate EGFR staining and 9% of tumors with strong staining. There was no significant relationship between p53 immunoreactivity or mutation status and radiation response. Significant relationships were noted between EGFR score and older age and between p53 score or mutation status and younger age. CONCLUSION The observed relative radioresistance of some GMs is associated with overexpression of EGFR.

Radiosurgery for brain metastases: Relationship of dose and pattern of enhancement to local control

PURPOSE This study aimed to analyze dose, initial pattern of enhancement, and other factors associated with freedom from progression (FFP) of brain metastases after radiosurgery (RS). METHODS AND MATERIALS All brain metastases treated with gamma-knife RS at the University of California, San Francisco, from 1991 to 1994 were reviewed. Evaluable lesions were those with follow-up magnetic resonance or computed tomographic imaging. Actuarial FFP was calculated using the Kaplan-Meier method, measuring FFP from the date of RS to the first imaging study showing tumor progression. Controlled lesions were censored at the time of the last imaging study. Multivariate analyses were performed using a stepwise Cox proportional hazards model. RESULTS Of 261 lesions treated in 119 patients, 219 lesions in 100 patients were evaluable. Major histologies included adenocarcinoma (86 lesions), melanoma (77), renal cell carcinoma (21), and carcinoma not otherwise specified (17). The median prescribed RS dose was 18.5 Gy (range, 10-22) and the median tumor volume was 1.3 ml (range, 0.02-30.9). The initial pattern of contrast enhancement was homogeneous in 68% of lesions, heterogeneous in 12%, and ring-enhancing in 19%. The actuarial FFP was 82% at 6 months and 77% at 1 year for all lesions, and 93 and 90%, respectively, for 145 lesions receiving > or = 18 Gy. Multivariate analysis showed that longer FFP was significantly associated with higher prescribed RS dose, a homogeneous pattern of contrast enhancement, and a longer interval between primary diagnosis and RS. Adjusted for these factors, adenocarcinomas had longer FFP than melanomas. No significant differences in FFP were noted among lesions undergoing RS for recurrence after prior radiotherapy (119 lesions), RS alone as initial treatment (45), or RS boost (55). CONCLUSION A minimum prescribed radiosurgical dose > or = 18 Gy yields excellent local control of brain metastases. The influence of pattern of enhancement on local control, a new finding in this retrospective analysis, needs to be confirmed.