Breast cancer molecular subtypes and its associated risk factors among patient with breast cancer attending at Muhimbili National Hospital.

Abstract

ABSTRACT Background; Breast cancer is the malignant neoplastic changes that arise from epithelia cells of ducts and lobules of the breast. Breast cancer comprises number of breast tumor subtypes that differ in molecular and cellular origin with different treatment and prognosis. Molecular subtypes such as triple negative subtype, they have poor prognosis, and limited treatment options. This highlights the importance of identifying risk factors associated with specific molecular subtype. In developing countries, the incidence of breast cancer is expected to increase further due to westernization of life style that led to increased risk for breast cancer, however, there is limited number of studies that have been done in Africa addressing the association between molecular subtypes and risk factors for breast cancer with inconsistent findings. Aim; The study was aimed to determine the association between risk factors for breast cancer and breast cancer molecular subtypes among female patients with breast cancer at Muhimbili national hospital from march 2023 to April 2024. Methodology; This was a hospital based. Prospective analytical cross-sectional study. Risk factors and other patient information were collected through interviewing the patient and histological information from medical records through a structured questionnaire. Odds ratio was calculated by Multinomial logistic regression to assess association as well to control for confounding variable, p value <0.05 was considered significant were computed by SPSS version 27. Results: The study enrolled 168 female patients with histological confirmed breast cancer, with the mean age at diagnosis of 49±11.2 years,78% (132) were diagnose at the age above 40 years, 54% (91) had ER receptor positive,43% (73) were positive for Progesterone receptor, Her 2 enriched receptor positive by 43% (73), majority 87% (155) of the patients, Ki 67 was not done. Invasive ductal carcinoma was prevalent 64% (107). Luminal A was the most common subtypes and grade II were the leading histological finding 38.1% (61), while 64% (59) of the total patients enrolled in the study, the pathological grade was not documented, Breast Cancer stage III was highly observed by 43% (73) while stage II and I were the least encountered. xii Molecular subtype had revealed association with modifiable risk factors for breast cancer among patients with alcohol use (P 0.04, AOR 0.22,95%CI 0.52-0.94), history of contraceptive use (P 0.028, AOR 0.365, 95%CI 0.149-0.895) and normal body mass index (P 0.031, AOR 3.66,95%CI 1.13-11.3) were negatively associated Luminal B compared with luminal A, Age at menarche above 12 years have revealed significant negative association with Triple negative subtypes (P 0.013, AOR 0.167, 95%CI ,0.41-0.69) and Her 2 subtypes (P 0.014, OAR 0.147,95% CI 0.32-68), other modifiable and non-modifiable risk factors were not associated with breast cancer molecular subtypes. Conclusion: Alcohol intake and history of contraceptive use had shown to have protective effect on luminal B compared to luminal A, while Body mass index had positive association with luminal B, however other modifiable risk factors were not associated with breast cancer molecular subtypes. Age at menarche above 12 years has protective effect on Tripple negative and Her 2 molecular subtypes while other non- modifiable risk factors were not associated with breast cancer molecular subtypes. Recommendation: Large sample size and multicenter study may help in addressing inconsistencies and risk factors with less prevalence. Addressing one molecular subtype will increases the accuracy of ascertaining the association with risk factors. Improvement in investigating patient with breast cancer especially KI 67 will help in subtyping luminal A and Luminal B breast cancers.