Effect of Adjuvant Chemotherapy after Complete Resection for Pathologic Stage IB Lung Adenocarcinoma in High-Risk Patients as Defined by a New Recurrence Risk Scoring Model

PURPOSE: We conducted a retrospective analysis to determine if adjuvant chemotherapy prolongs overall survival in patients with pathologic stage IB lung adenocarcinoma who had undergone complete resection and were defined as high-risk by a newly developed recurrence risk scoring model. MATERIALS AND METHODS: Patients who underwent curative resection for stage IB lung adenocarcinoma were analyzed with a newly developed recurrence risk scoring model and divided into a low-risk group and a high-risk group. The patients in the high-risk group were retrospectively divided into two groups based on whether they underwent adjuvant chemotherapy or observation. Recurrence-free survival and overall survival were compared between these two groups. RESULTS: A total of 328 patients who underwent curative resection between 2000 and 2009 were included in this study, of whom 110 (34%) received adjuvant chemotherapy and 218 (67%) underwent observation without additional treatment. According to our risk model, 167 patients (51%) were high-risk and 161 (49%) were low-risk. The 5-year recurrence-free survival rates and overall survival were 84.4% and 91.5% in low-risk patients and 53.9% and 74.7% in high-risk patients (p < 0.001). In high-risk patients, the 5-year overall survival rates were 77% among patients who underwent observation and 87% among those who underwent adjuvant chemotherapy (p=0.019). CONCLUSION: Adjuvant chemotherapy prolonged overall survival among high-risk patients who had undergone complete resection for stage IB lung adenocarcinoma.