Upfront stereotactic radiosurgery in patients with brain metastases from small cell lung cancer: retrospective analysis of 41 patients

Abstract

Background: Although the efficacy of prophylactic or therapeutic whole brain radiotherapy (WBRT) for brain metastases (BM) from small cell lung cancer (SCLC) is well established, the role of stereotactic radiosurgery (SRS) has yet to be determined. In the present retrospective analysis, we investigated whether upfront SRS might be an effective treatment option for patients with BM from SCLC.

Methods: We analyzed 41 consecutive patients with a limited number of BM (≤ 10) from SCLC who received SRS as the initial treatment. No prophylactic and therapeutic WBRT was given prior to SRS. The median patient age was 69 years and the median Karnofsky performance status (KPS) score was 90. Repeat SRS was given for new distant lesions detected on follow-up neuroradiological imaging, as necessary. Overall survival, neurological death, and local and distant BM recurrence rates were analyzed. The survival results were tested with three prognostic scoring systems validated for SCLC: Diagnosis-specific graded prognostic assessment (DS-GPA), Radiation therapy oncology group -recursive partitioning analysis and Rades's survival score.

Results: One- and 2-year overall survival rates were 44% and 17%, respectively. The median survival time was 8.1 months. Survival results replicated the DS-GPA (P = 0.022) and Rades's survival score (P = 0.034). On multivariate analysis, patients with high KPS (hazard ratio (HR): 0.308, P = 0.009) and post-SRS chemotherapy (HR: 0.324, P = 0.016) had better overall survival. In total, 95/121 tumors (79%) in 34 patients (83%) with sufficient radiological follow-up data were evaluated. Six- and 12-month rates of local control failure were 0% and 14%, respectively. Six- and 12-month distant BM rates were 22% and 44%, respectively. Repeat SRS, salvage WBRT and microsurgery were subsequently required in 18, 7 and one patient, respectively. Symptomatic radiation injury developed in two patients and both were treated conservatively.

Conclusions: Our survival analyses with the validated prognostic grading systems suggested upfront SRS for limited BM from SCLC to be a potential treatment option, with patient survival being slightly more than eight months after SRS. Although SRS provided durable local tumor control, repeat treatment was needed in nearly half of patients to achieve control of distant BM.

Figure 1

Contrast-enhanced T1-weighted MR images from 5 patients treated with 2-session SRS. The upper and lower images were obtained at the time of the initial SRS and the latest follow-up, respectively. A 71-year-old man with a tumor 19.2 mL in volume (upper), 3 months post-treatment (lower): (A). A 60-year-old man with a tumor 14.3 mL in volume (upper), 11 months post-treatment (lower): (B). A 64-year-old man with a tumor 15.2 mL in volume (upper), 8 months post-treatment (lower): (C). A 61-year-old man with a tumor 17.0 mL in volume (upper), 14 months post-treatment (lower): (D). An 80-year-old woman with a tumor 22.3 mL in volume (upper), 9 months post-treatment (lower): (E).

Figure 2

Overall treatment results of patients with BM from SCLC treated with SRS. OS after initial SRS: (A) The MST was 8.1 months (95% CI: 6.2-15.6). Cumulative incidence of cause-specific mortality: (B) The solid and dotted lines represent neurological and non-neurological death rates, respectively.

Figure 3

Survival results stratified with prognostic scoring systems. Diagnosis-specific graded prognostic assessment (DS-GPA): (A). Rades’s survival score: (B).

Figure 4

Cumulative incidence of local and distant brain failure. The 6- and 12-month local tumor control failure rates were 0% and 14%, respectively: (A). The 6- and 12-month distant intracranial recurrence rates were 22% and 44%, respectively: (B).