# Timing of postoperative chemotherapy and prognosis in neoadjuvant-treated gastric cancer patients: a multicenter real-world cohort study

## TL;DR

Starting chemotherapy 6-8 weeks after surgery improves survival and delays cancer recurrence in patients with advanced gastric cancer who had pre-surgery treatment.

## Contribution

Identifies a 6-8 week optimal window for postoperative chemotherapy in neoadjuvant-treated gastric cancer patients.

## Key findings

- Patients with 6-8 week TTC had significantly lower 3-year mortality rates compared to other groups.
- Shorter or longer TTC intervals were linked to higher risks of cancer-specific and all-cause mortality.
- The 6-8 week TTC group experienced delayed cancer recurrence compared to other timing groups.

## Abstract

The optimal time to chemotherapy (TTC) in locally advanced gastric cancer (LAGC) patients treated with neoadjuvant chemotherapy (NLAGC) remains unclear.

Consecutive 524 patients with NLAGC between Jan. 2010 and Dec. 2022 were identified. Patients were categorized into three groups: TTC < 6w, 6w ≤ TTC ≤ 8w, and TTC > 8w. Survival analysis was conducted using the Cox proportional hazards model to assess the impact of TTC on gastric cancer-specific mortality (GCSM) and all-cause mortality (ACM). Cumulative competing risk curves were employed to evaluate the incidence of competing events.

Overall, 451 patients were included.Cumulative competing risk curves showed that the 3-year ACM and GCSM were significantly lower in the 6w ≤ TTC ≤ 8w group (ACM: 19.7% vs. 37.2% vs. 39.7%, GCSM: 19.7% vs. 35.2% vs. 38.8%) compared to the TTC < 6w and TTC > 8w groups. Compared to patients with 6w ≤ TTC ≤ 8w, those with TTC < 6w or >8w had an increased risk of GCSM (HR: 2.792 and HR: 2.343, respectively) and ACM (HR: 3.102 and HR: 2.719, respectively) after adjusting for confounders. Furthermore, 6w ≤ TTC ≤ 8w had later peak recurrence compared to TTC < 6w and TTC > 8w (Peak months: 9.7 vs. 4.3 vs. 3.1).

A postoperative chemotherapy timing of 6–8 weeks was associated with better survival and delayed recurrence in NLAGC patients. These findings suggest that the 6–8 week time-window should be a key timeframe for personalized postoperative adjuvant chemotherapy decisions.