Adjuvant radiation therapy after surgical resection of solitary brain metastasis: association with pattern of failure and survival.

We reviewed patients treated by resection of solitary cerebral metastasis at the Mayo Clinic from January 1, 1972, to December 1, 1982. Eighty-five patients rendered clinically disease-free and who received intramural follow-up after craniotomy were studied. Adjuvant whole-brain radiation therapy (WBRT) was delivered to 34, and 51 were observed after craniotomy. Pattern-of-failure analysis showed a much smaller incidence of subsequent brain relapse in the adjuvant WBRT group than in the observation group (21% versus 85%, respectively). Multivariate analysis utilizing 17 patient, tumor, and treatment characteristics showed adjuvant WBRT to have the strongest association with brain control (p less than 0.0001). The only other variable which was significant (p less than 0.01) was multilobe involvement of the metastatic lesion, which was associated with a greater likelihood of brain failure. Systemic failures were more frequent (61% versus 37%), and the proportion of patients remaining disease-free (29% versus 4%) was higher in the adjuvant group. Those patients who received adjuvant WBRT to a dose of 39 Gy or greater manifested an 11% rate of subsequent brain failure versus a 31% rate when less than 39 Gy was delivered. The median survival was longer for the adjuvant WBRT group (21 months versus 11.5 months). Multivariate analysis indicated that adjuvant WBRT was one of several variables (including female gender, long disease-free survival, and good neurologic function prior to craniotomy) significantly associated with improved survival. This study suggests that adjuvant cranial irradiation may help prevent clinical recurrence of resected metastatic intracranial disease and that improved control of intracranial disease may be associated with an improved survival in patients without clinical evidence of systemic disease at the time of craniotomy.