Adjuvant Paclitaxel Plus Carboplatin Compared With Observation in Stage IB Non–Small-Cell Lung Cancer: CALGB 9633 With the Cancer and Leukemia Group B, Radiation Therapy Oncology Group, and North Central Cancer Treatment Group Study Groups

Three hundred-forty-four patients were randomly assigned. Median follow-up was 74 months. Groups were well-balanced with regard to demographics, histology, and extent of surgery. Grades 3 to 4 neutropenia were the predominant toxicity; there were no treatment-related deaths. Survival was not significantly different (hazard ratio [HR], 0.83; CI, 0.64 to 1.08; P = .12). However, exploratory analysis demonstrated a significant survival difference in favor of adjuvant chemotherapy for patients who had tumors > or = 4 cm in diameter (HR, 0.69; CI, 0.48 to 0.99; P = .043).

Because a significant survival advantage was not observed across the entire cohort, adjuvant chemotherapy should not be considered standard care in stage IB NSCLC. Given the magnitude of observed survival differences, CALGB 9633 was underpowered to detect small but clinically meaningful improvements. A statistically significant survival advantage for patients who had tumors > or = 4 cm supports consideration of adjuvant paclitaxel/carboplatin for stage IB patients who have large tumors.