Impact of the Interval Between Neoadjuvant Chemotherapy and Gastrectomy on Short- and Long-Term Outcomes for Patients with Advanced Gastric Cancer.

Background: The optimal time between neoadjuvant chemotherapy (NAC) and gastrectomy for gastric cancer (GC) remains unknown. This study aimed to investigate the association between the time-to-surgery (TTS) interval and the major pathologic response (mPR).

Methods: In this study, 280 consecutive GC patients who underwent NAC followed by gastrectomy between 2014 and 2018 were retrospectively analyzed by the use of prospectively collected databases from three major GC treatment centers in Lithuania and Estonia. Based on TTS, they were grouped into three interval categories: the early-surgery group (ESG: ≤ 30 days; n = 70), the standard-surgery group (SSG: 31-43 days; n = 138), and the delayed-surgery group (DSG: ≥ 44 days, n = 72). The primary outcome of the study was the mPR rate. The secondary end points were postoperative morbidity, mortality, oncologic safety (measured as the number of resected lymph nodes and radicality), and long-term outcomes.

Results: The mPR rate for the ESG group (32.9%) was significantly higher than for the SSG group (20.3%) or the DSG group (16.7%) (p = 0.047). Furthermore, after adjustment for patient, tumor, and treatment characteristics, the odds for achievement of mPR were twofold higher for the patients undergoing early surgery (odds ratio [OR] 2.09; 95% conflidence interval [CI] 1.01-4.34; p = 0.047). Overall morbidity, severe complications, 30-day mortality, R0 resection, and retrieval of at least 15 lymph nodes rates were similar across the study groups. In addition, the long-term outcomes did not differ between the study groups.

Conclusions: This study suggests that an interval of more than 30 days between the end of NAC and gastrectomy is associated with a higher mPR rate, the same oncologic safety of surgery, and similar morbidity and mortality.