Discussion
NSCLC, MRD, noncancer deaths, tumor
TUMOR, RECURRENCE, DISEASE, ADVERSE EFFECT, ADVERSE EFFECTS, NSCLC, RESIDUAL DISEASE, SECONDARY MALIGNANCIES
The advantage of alternate-day S-1 administration instead of daily use of S-1 is to reduce adverse effect especially of the gastrointestinal tract while maintaining the anticancer effect [In the current study, both alternate-administration of S-1 (Arm A) and daily administration (Arm B) were feasible in terms of the treatment completion at 6 months, whereas there is a trend of unfavorable prognosis in Arm A. Especially, the trend of unfavorable prognosis is noted in patients without completion of S-1 administration at 6 months. However, there were no significant differences of actual administered dose of S-1 between Arm A and Arm B in patients without treatment completion at 6 months. The result of disease-specific survival showed no difference in both arms, suggesting the competing risks, such as noncancer deaths and secondary malignancies. As for patient characteristics, Arm A had male and ever smoker cases more frequently compared to Arm B, which was different from our similar study SLCG1301 [It is important but difficult to select the appropriate patients after surgical resection for postoperative adjuvant chemotherapy. A recent study indicated that the detection of molecular residual disease (MRD) by circulating tumor DNA (ctDNA) profiling identified residual/recurrent disease earlier than standard-of-care radiologic imaging, and thus could facilitate personalized adjuvant treatment at early time points when disease burden is lowest [The current study has some limitation. Planned total dose of S-1 was different. Total planned dose of S-1 in Arm A is about 82.5% compared to Arm B. Our study design lacked the pill counts. Confirmation of drug compliance should be important. We only collected In conclusion, although several adverse effects were less frequent in Arm A, both alternate-day and daily oral administration of S-1 were demonstrated to be feasible as adjuvant chemotherapy in elderly patients with stage IA to IIIA NSCLC. Although there is no standard care of postoperative adjuvant chemotherapy for elderly patients with completely resected NSCLC, future investigation should be focused on high-risk populations for recurrence.