PURPOSE: Purpose: Some of the most serious complications of radiation therapy, including pneumonitis, fistulas, bronchial/esophageal strictures, and hemorrhage are risked when treating lesions in the mediastinum and hilum. Here we assess the early toxicity and crude local control of stereotactic radiosurgery with the CyberKnife in this difficult region.
METHODS: Methods: Thirty patients were treated for tumors in contact with or within the mediastinum and hilum; these included primary, metastatic, or recurrent lesions or oligometastases from other organs. Many were within the 2 cm bronchial exclusion zone mentioned in RTOG 2816. Dose depended on tumor size, proximity to critical structures, and prior radiation.
RESULTS: Results: Thirty patients with 36 tumors were identified and followed. Median follow-up was 9.6 months (range 0.9 - 26.2 months). Kaplan-Meier survival rate was 34% at 26 months. Tumor size as greatest diameter ranged from 0.8 - 9.8 cm, median 3.8 cm. GTV's ranged from 1.1 –708 cc, median of 33.5 cc. Doses ranged from 20 Gy to 60 Gy (median 36 Gy) in one to five fractions. Sixteen patients (53%) had prior radiation to the target, and 21 (70%) had prior chemotherapy. Of 36 tumors, 32 had radiographic follow-up; 26 showed radiographic stability, partial response, or complete response (crude local control rate of 81%). Fatigue or minor dermatitis (2 pts) usually resolved within a month. Pain was either stable or improved. Many had severe baseline COPD with baseline dyspnea. Five patients started with dyspnea with ADLs (four of whom were on oxygen–equivalent of Grade 3 toxicity). Two patients (both on Coumadin) had post-treatment bleeding (grades 1 and 5). One died after refusing correction of his INR >6, resulting in the only death directly related to SRS.
CONCLUSION: Conclusions: We obtained a relatively low rate of serious early complications and reasonable local control in this group of patients with few options.
CLINICAL IMPLICATIONS: Clinical Implications: This study suggests that mediastinal and hilar lesions can be treated with stereotactic radiosurgery with less toxicity at these higher doses.
DISCLOSURE: Andrew Fink, No Product/Research Disclosure Information; Consultant fee, speaker bureau, advisory committee, etc. Consulting with Accuray Incorporated on educational materials for surgeons.