Aims and background: Surgical resection remains the mainstay for the treatment of colorectal lung metastasis, but a group of patients who are medically inoperable or unsuitable for surgery are treated with radiotherapy. The purpose of this multi-institutional study was to evaluate the clinical outcome and investigate the prognostic factors affecting local control and survival in this subset of patients.
Methods: We retrospectively analyzed 30 patients with 43 lesions who underwent curative radiotherapy for isolated lung metastasis from colorectal cancer at nine institutions from 2003 and 2008. A total dose of 42-75 Gy at the peripheral planning target volume was administered in 3-35 fractions. The median biologically equivalent dose was 84 Gy (range, 58.5-180).
Results: Treatment response was complete in 10 (33.3%), partial in 13 (43.3%), stable in six (20.0%), and progressive in one patient (3.3%). The median follow-up period for all patients was 29.0 months (range, 5.0-93.8). Kaplan-Meier local control at 5 years was 44%. The median survival was 46.2 months, and the 5-year overall survival was 47%. Twenty-three patients (77%) experienced treatment failure, most of which were intrapulmonary failure. The intrapulmonary relapse-free survival and overall relapse-free survival at 5 years were 22% and 19%, respectively. Treatment response and preradiotherapy carcinoembryonic antigen level were significant prognostic factors for local control and survival. Grade 3-5 toxicity occurred in 7 patients. Three patients had grade 5 toxicity, including radiation pneumonitis, a tracheoesophageal fistula, and hemoptysis.
Conclusions: . Curative radiotherapy for isolated lung metastasis from colorectal cancer in patients who are medially inoperable or unsuitable for surgery results in long-term survival, comparable to surgical resection. Curative radiotherapy could be an effective and noninvasive alternative if dose-limiting toxicity is carefully considered, particularly in patients with bilateral or central lesions.