A delay in initiation of adjuvant chemotherapy following resection for non–small-cell lung cancer (NSCLC) was not associated with any increase in mortality, according to a retrospective analysis. Those treated with delayed chemotherapy fared better than those treated with surgery alone.

Several studies have shown a survival benefit with chemotherapy following surgery for NSCLC. “While a consensus has been established regarding the indications for adjuvant chemotherapy, the optimal timing following surgical resection remains poorly defined,” wrote study authors led by Michelle C. Salazar, MD, of Yale School of Medicine in New Haven, Connecticut. Some clinicians endorse starting therapy within 6 weeks of surgery, but recovery times from resection vary and that is not always feasible.

The new study included 12,473 patients from the National Cancer Database; it was limited to patients with lymph node metastases, tumors 4 cm or larger, or local extension. The median time to chemotherapy initiation was 48 days, and 3 timing intervals were defined: the reference group initiated therapy between 39 and 56 days after resection, the “early” group started between days 18 and 38, and the “late” group initiated therapy between days 57 and 127. The results were published in JAMA Oncology.

The 5-year overall survival rate was 55% in the reference group, compared with 53% in the early group and 53% in the later group (P = .23). An adjusted model confirmed no significant differences between the groups, with a hazard ratio (HR) for survival for the earlier group of 1.009 (95% CI, 0.944–1.080; P = .79) and for the later group of 1.037 (95% CI, 0.972–1.105; P = .27).

A propensity-matched analysis found that adjuvant chemotherapy is beneficial over surgery alone, regardless of timing. For the early chemotherapy group, the HR compared with surgery alone was 0.672 (95% CI, 0.626–0.720; P < .001). For the reference group, the HR was 0.645 (95% CI, 0.608–0.683; P < .001); and for the later group, the HR was 0.664 (95% CI, 0.623–0.707; P < .001).

A number of factors were found to be predictive of later initiation of chemotherapy. These included increased age, being nonwhite, having Medicaid or no insurance, and lower education, among others.

“These findings indicate that patients who receive adjuvant chemotherapy up to 4 months after surgery may continue to derive benefit from chemotherapy,” the authors concluded. “Clinicians should still consider chemotherapy in appropriately selected patients that are healthy enough to tolerate it, up to 4 months after NSCLC resection.”