Impact of Blood Type on Treatment Response and Survival in HER2-Negative Metastatic Gastric Cancer

Objective: Metastatic gastric cancer is one of the most lethal malignancies. Recent studies indicate that the
O blood group has better survival than the non-O blood group. In this study, the aim was to evaluate the
impact of blood group O and non-O blood groups on survival outcomes and treatment responses in gastric
cancer patients.

Methods: Between January 2012 and June 2024, 187 patients with metastatic gastric cancer treated at Kartal
Dr. Lütfi Kırdar City Hospital were retrospectively analyzed. Patients were divided into 2 groups: O blood
group (n = 82) and non-O blood group (n = 105). The prognostic role of blood groups and their impact on
survival outcomes was investigated.

Results: Median overall survival was 15.7 months in the O blood group and 12.9 months in the non-O
blood group (P = .04). There was no significant difference between the groups in terms of progression-free
survival (7.9 months versus 7.0 months, P = .11). Disease control rates were 69.5% in the O Rh +/− group
and 63.3% in the other groups. In subgroup analyses, a borderline significant interaction (P = .08) was
observed between the blood group and Eastern Cooperative Oncology Group (ECOG) PS (Performance
Status). In multivariate analysis, ECOG performance score was found to be an independent prognostic factor
(hazard ratio = 1.6, P = .003), whereas blood group was not found to be an independent prognostic factor
(P = .16).

Conclusion: The study found thatpatients with bloodgroup O exhibited better survival rates inmetastatic gastric cancer; however, the blood group was not identified as an independent predictor of survival. The primary
determinant of survival outcomes remained the patient’s performance status. Therefore, while bloodgroup
may serveas an additionalprognostic indicator, its utility requires further validation throughlarger scale
studies.

Cite this article as: Yildirim S, Alan Ö, Turkoglu E, et al. Impact of blood type on treatment response and survival in HER2-negative metastatic gastric cancer. Cerrahpaşa Med J 2025, 49, 0042, doi: 10.5152/cjm.2025.25042.