Purpose: This paper is a retrospective analysis of patients with clinical Stage I non-small cell carcinoma of the lung treated with definitive radiation therapy alone. The results of therapy, patterns of failure and the relationship of technical aspects of the delivery of radiotherapy to outcome are presented.
Materials and methods: From 1980 through 1990, 53 patients with Stage I non-small cell lung cancer were treated with definitive radiation therapy alone at the Radiation Oncology Center of the Mallinckrodt Institute of Radiology and its affiliated hospitals. All patients had a pathologic diagnosis of non-small cell lung cancer and were not candidates for surgical resection because of either patient refusal (10 patients), poor performance status (5 patients), or premorbid medical problems (38 patients). The median age was 73 years. Histologic cell type included squamous (32), adenocarcinoma (11), large cell (4), and unclassified non-small cell (6). Initial tumor size was < or = 3 cm in 23 patients, between 3 and 5 cm in 13 patients and > or = 5 cm in 17 patients. Diagnostic staging varied during the study period. All patients had chest X-rays and computed tomography scans of the chest. A majority had liver and bone scans, but only four underwent mediastinoscopy. The radiation therapy was of megavoltage energy in all patients, with a median primary prescription tumor dose of 63.2 Gy. Survival was measured from the date radiation therapy was initiated.
Results: The actuarial overall survival rate for the entire group was 19% at 3 years and 6% at 5 years, with a median survival time of 20.9 months. Of the 49 deaths, 35 died of lung cancer; 13 died of intercurrent illness, and one died of pancreatic cancer, which made the actuarial cause-specific survival 33% at 3 years and 13% at 5 years. The actuarial 3-year disease-free survival was 33%. Local primary tumor progression occurred in 22 patients, resulting in a 51% 3-year actuarial freedom from local progression. An additional four patients failed in regional lymph nodes that were included in the original treatment portals. Multivariate analysis found only T stage to be associated with overall survival (p = .02). However multivariate analysis showed age as a prognostic factor to be approaching statistical significance (p = .07). Patients under 70 years of age showed an increased survival rate compared to patients over 70 years. Radiation therapy doses > or = 65 Gy appeared to result in a decreased proportion of patients dying of lung cancer with no apparent increase in either acute or long-term complication rates.
Conclusion: Results of definitive radiation therapy for inoperable Stage I non-small cell lung remain inferior to surgical therapy. Potential methods to improve local control with radiotherapy are discussed.