The distribution of reproductive risk factors disclosed the heterogeneity of receptor-defined breast cancer subtypes among Tanzanian women

Abstract

Background Recent epidemiological studies suggest that reproductive factors are associated with breast cancer (BC) molecular subtypes. However, these associations have not been thoroughly studied in the African populations. The present study aimed to investigate the prevalence of BC molecular subtypes and assess their association with reproductive factors in Tanzanian BC patients. Methods This hospital-based case-only cross-sectional study consisted of 263 histologically confirmed BC patients in Tanzania. Clinico-pathological data, socio-demographic characteristics, anthropometric measurements, and reproductive risk factors were examined using the Chi-square test and one-way ANOVA. The association among reproductive factors and BC molecular subtypes was analyzed using multinomial logistic regression. The heterogeneity of the associations was assessed using the Wald test. Results We found evident subtype heterogeneity for reproductive factors. We observed that post-menopausal status was more prevalent in luminal-A subtype, while compared to luminal-A subtype, luminal-B and HER-2 enriched subtypes were less likely to be found in post-menopausal women (OR: 0.21, 95%CI 0.10–0.41, p = 0.001; OR: 0.39, 95%CI 0.17–0.89, p = 0.026, respectively). Also, the luminal-B subtype was more likely to be diagnosed in patients aged ≤ 40 years than the luminal-A subtype (OR: 2.80, 95%CI 1.46–5.32, p = 0.002). Women who had their first full-term pregnancy at < 30 years were more likely to be of luminal-B (OR: 2.71, 95%CI 1.18–4.17, p = 0.018), and triple-negative (OR: 2.28, 95%CI 1.02–4.07, p = 0.044) subtypes relative to luminal-A subtype. Furthermore, we observed that breastfeeding might have reduced odds of developing luminal-A, luminal-B and triple-negative subtypes. Women who never breastfed were more likely to be diagnosed with luminal-B and triple-negative subtypes when compared to luminal-A subtype (OR: 0.46, 95%CI 0.22–0.95, p = 0.035; OR: 0.41, 95%CI 0.20–0.85, p = 0.017, respectively). . Conclusion Our results are the first data reporting reproductive factors heterogeneity among BC molecular subtypes in Tanzania. Our findings suggest that breast-feeding may reduce the likelihood of developing luminal-A, luminal-B, and triple-negative subtypes. Meanwhile, the first full-term pregnancy after 30 years of age could increase the chance of developing luminal-A subtype, a highly prevalent subtype in Tanzania. More interventions to promote modifiable risk factors across multiple levels may most successfully reduce BC incidence in Africa.

The interplay between XPG‐Asp1104His polymorphism and reproductive risk factors elevates risk of breast cancer in Tanzanian women: A multiple interaction analysis

“…Tumor biomarkers including ER, PR, and HER2/neu were determined by immunohistochemistry upon the formalin fixed paraffin‐embedded blocks of BC tissues as described elsewhere. 13 …”

“…The BC samples were histologically and pathologically examined at Muhimbili National Hospital (MNH), Bugando Medical Center (BMC), or Kilimajaro Christian Medical Center (KCMC). Tumor biomarkers including ER, PR, and HER2/neu were determined by immunohistochemistry upon the formalin fixed paraffin‐embedded blocks of BC tissues as described elsewhere 13 …”

“…Tumor biomarkers including ER, PR, and HER2/neu were determined by immunohistochemistry upon the formalin fixed paraffin-embedded blocks of BC tissues as described elsewhere. 13 The control group was composed of 250 age-group matched cancer-free women who voluntarily attended the ORCI facility for cancer screening programs. Subjects with previous history of cancer and psychiatric diseases were exluded from the study.…”

Breast cancer in East Africa: Prevalence and spectrum of germline SNV/indel and CNVs in BRCA1 and BRCA2 genes among breast cancer patients in Tanzania

“…Further details about the ORCI facility are described elsewhere. 26 , 27 To be eligible for this study, patients had to fulfill the following inclusion criteria: being indigenous Tanzanian, and having a complete histopathological report that shows the estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor‐2 (HER‐2) statuses. The exclusion criteria were: being non‐indigenous Tanzanian, failure/denial to sign a consent form, and having incomplete histopathological report in the hospital medical file.…”

Association of risk factors and breast cancer among women treated at Tikur Anbessa Specialized Hospital, Addis Ababa, Ethiopia: a case–control study

“…3 Similarly study from Tanzania found that women who had their first full-term pregnancy at <30 years were more likely to have luminal-B and triple negative subtypes relative to luminal-A subtype. 4 Another study done in Cairo also revealed that the most common risk factors for breast cancer were family history of breast cancer and using hormonal contraceptives. 5 Breast cancer poses a substantial public health threat in Ethiopia.…”