Prevalence and genotypic distribution of high-risk human papillomavirus in primary breast tumors in Western Uganda: a case-control study

Although in vitro studies have demonstrated that HPV can immortalize mammary epithelial cells, its contribution to breast carcinoma development in living organisms remains debatable. Reports on HPV detection in breast tumors vary widely across regions, and data from East Africa are limited. This study investigated the prevalence and genotypic distribution of high-risk HPV in breast tumors in Western Uganda. This retrospective case-control study was conducted using archived formalin-fixed paraffin-embedded tissue specimens from 66 breast carcinomas (cases) and 42 fibroadenomas (controls) diagnosed between 2012 and 2018 at Mbarara Regional Referral Hospital. High-risk HPV DNA was detected using real-time polymerase chain reaction (rRT-PCR), and genotyping was performed using the AmpliSens HPV HCR genotype-titre-FRT PCR kit. To validate the assay, cervical squamous cell carcinoma samples served as technical controls. Associations between HPV prevalence and breast carcinoma were assessed using chi-square tests and odds ratios. High-risk HPV DNA was detected in 25 of 108 breast tumor specimens (23.1%). The prevalence of HPV was 24.2% (16/66) in breast carcinomas and 21.4% (9/42) in fibroadenomas, with no statistically significant difference between cases and controls (p = 0.735; OR = 1.17, 95% CI: 0.46-2.97). Detected HPV genotypes included 16, 18, 33, 39, 45, 51, 56, and 58. HPV genotype 39 was the most frequently detected genotype in both breast carcinomas (50% of HPV-positive cases) and fibroadenomas (44.4% of HPV-positive cases). High-risk HPV was detected in all cervical cancer control specimens, confirming assay validity. These findings indicate that although high-risk HPV DNA was detected in breast tissue in this population, its presence alone does not support a primary causal role in breast carcinogenesis. Further studies incorporating viral load and transcriptional activity are needed to clarify the biological relevance of HPV in breast tissue.