408MO - Determining the optimal timing of adjuvant chemotherapy initiation after concurrent chemoradiotherapy in locoregionally advanced nasopharyngeal carcinoma

Background

Studies on several malignancies have suggested that the time to commencement of adjuvant chemotherapy (AC) is associated with survival outcomes. However, there have been no relevant reports of nasopharyngeal carcinoma (NPC).

Methods

This clinical study examined newly diagnosed patients between April 2017 and December 2020. The primary endpoint was progression-free survival (PFS). Inverse probability of treatment weighting (IPTW) was used to control for confounding factors. Cox models with restricted cubic splines (RCS), Kaplan–Meier method and log-rank tests were used to evaluate the relationship between AC timing and survival.

Results

A total of 551 patients were identified (median age, 45 years [IQR 36-52]; 383 [69.5%] male). RCS demonstrated that the timing of AC initiation had a U-shaped association with PFS. The risk of disease progression decreased within 37 days and subsequently increased. From 37 to 90 days, each additional 7-day delay conferred worse PFS of 1.32 months (HR 1.14 [95% CI 1.01-1.28], p = .04). The cutoff value of the ROC curve for initiation was 69.5 days. At a median follow-up of 48 months, the PFS was significantly better in patients initiated within 69.5 days (HR 2.18 [95% CI 1.17-4.06], log-rank p = .009), with a higher 3-year rate (78.8% [95% CI 75.1-82.7] vs. 59.0% [95% CI 42.2-82.5]) than beyond 69.5 days. Positive results were also observed in secondary endpoints. The initiation group was an independent prognostic factor (HR 2.28 [95% CI 1.42-3.66], p < .001).

Conclusions

The optimal timing of AC initiation is approximately 37 days after concurrent chemoradiotherapy in patients with locoregionally advanced NPC. A delay beyond 69.5 days is associated with compromised survival. Efforts should be made to address the reasons for delays and ensure the timely initiation of AC.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

the National Key Research and Development Program of China.

Disclosure

All authors have declared no conflicts of interest.