Association of ABO and Rh blood groups with clinicopathological features and lymph node involvement in surgically treated thyroid malignancies: a retrospective single-center study

Abstract This study investigated the association between ABO and Rh blood group antigens and the clinicopathological features of 418 patients who underwent thyroidectomy for primary thyroid malignancy between December 2016 and June 2023. Since continuous variables did not follow a normal distribution ( p < 0.05), data were presented as median and interquartile range (IQR). The distribution of ABO blood groups was A (44.5%), O (31.8%), B (16.0%), and AB (7.7%), with 90.9% of patients being Rh-positive. The median age of the cohort was 48 years (IQR: 19). While ABO groups showed no significant difference in age, Rh-negative patients were significantly older than Rh-positive patients (52.5 vs. 48.0 years; p = 0.027). No direct association was identified between ABO groups and the overall clinicopathological features such as tumor size or multifocality (p > 0.05). However, significant differences were observed regarding pathologically confirmed lymph node (LN) involvement. Pathologically confirmed LN involvement was significantly more prevalent in the Rh-negative group compared to the Rh-positive group (15.8% vs. 5.5%; p = 0.027). Most notably, a subgroup analysis revealed that patients with the AB blood group had a significantly higher rate of pathologically confirmed LN involvement compared to non-AB groups (15.6% vs. 5.7%; p = 0.028). To confirm the independence of this association, a multivariable logistic regression analysis was performed. After adjusting for potential confounders including age and tumor size, the AB blood group was independently associated with pathologically confirmed LN metastasis in an exploratory multivariable model (OR: 3.114, 95% CI: 1.085–8.938, p = 0.035). These findings suggest that while ABO and Rh blood groups are not significantly associated with most clinicopathological variables in this cohort, they demonstrate specific correlations with nodal disease. These findings may represent exploratory signals that warrant further validation, rather than clinically applicable biomarkers at this stage. Further multicenter prospective studies are warranted to validate these associations across all histological subtypes.