Clinical, ethnic and genetic risk factors associated with postoperative nausea and vomiting in patients undergoing cancer surgery: a case-control study.

Objectives: To identify the clinical, ethnic, and genetic factors contributing to the varying risks of postoperative nausea and vomiting (PONV) among a Brazilian population undergoing cancer surgery.

Methods: A case-control study was conducted involving 152 patients who experienced vomiting and/or retching (cases) and 158 patients who did not report nausea, vomiting, or retching (controls) within 24 h following oncological surgeries. This study is registered as 'Genetic Polymorphism and postoperative nausea and vomiting (PONV)' under registration number NCT03627780 (https://clinicaltrials.gov/study/NCT03627780). Thirty-two polymorphisms associated with PONV predisposition and 15 polymorphisms for ancestry analysis were genotyped via real-time polymerase chain reaction (PCR) with customised TaqMan low-density array (TLDA) cards.

Results: The C allele of the rs208294 polymorphism ( gene) was observed at a significantly higher rate in the control group than in the case group across the genotype (P=0.035), dominant (P=0.010) and allele (0.032) models, thus suggesting a protective effect against PONV. The genotype results for rs208294 were validated via Sanger sequencing, which confirmed the association in the dominant model (P=0.027). In a multivariate regression analysis that included rs208294 and clinical variables that were identified in the univariate analysis, only a prior history of PONV or motion sickness was observed to be a significant predictor of PONV (P<0.05). No association between rs208294 and PONV was detected in an external cohort consisting of 198 cases and 56 controls of Japanese descents (P>0.05). Additionally, ancestry analysis indicated a predominantly European genetic composition in the Brazilian cohort, which differed with the Asian composition of the independent validation cohort.

Conclusions: A previous history of PONV or motion sickness was identified as being the strongest predictor of PONV in our analysis. Genetic association, ancestry and external validation analyses suggest that genetic factors for PONV may significantly differ across populations of different continental origins.