Tumor regression grade in gastric cancer: Predictors and impact on outcome

BackgroundThe clinical value and prognostic implications of histologic response to neoadjuvant chemotherapy in gastric cancer is unknown. MethodsTumor regression grade (TRG) was recorded in 58 gastric cancer patients identified from two institutional surgical databases. TRG 1a/b represented histologic responders (<10% viable tumor), while TRG 2/3 represented non-responders (>10% viable tumor). ResultsTRG 1a/b was recorded in 10 patients (17%), while 48 patients (83%) had a TRG 2/3 response. Larger tumor size (OR 0.24; 95%CI 0.09, 0.64; P=0.004) and clinical downstaging (OR 30.0; 95%CI 3.26, 276; P=0.003) were the only factors predictive of histologic response. TRG 1a/b responders had 3-year survival of 70.0% and an estimated overall survival of >69.8 months compared to 38.2% and 22.8 months in non-responders; however, this trend was not statistically significant (P=0.535). While TRG could not predict survival (OR 2.40; 95%CI 0.46, 12.57; P=0.300), patient age (OR 1.06; 95%CI 1.00, 1.11; P=0.035), and the number of positive lymph nodes (7; OR 0.05; 95%CI 0.07, 0.27; P<0.001) were independent predictors of survival. ConclusionsFew gastric cancers demonstrate histologic response to neoadjuvant chemotherapy. While TRG may be a valid marker for treatment response, its predictive value and clinical application in gastric cancer remains unclear. J. Surg. Oncol. 2016;114:434-439. (c) 2016 Wiley Periodicals, Inc.