Epidemiological Data Gaps in Breast Cancer Research in Cameroon: A Meta-analysis

Abstract

Background: Breast cancer is the leading malignancy among women in Cameroon, yet national decision-making still relies heavily on international estimates, isolated hospital series and incompletely documented registries. This limitation weakens the interpretation of incidence, prevalence, mortality, survival and treatment indicators, and may delay evidence-based cancer control planning. This systematic review and meta-analysis aimed to synthesize the published evidence on breast cancer in Cameroon, quantify key epidemiological and clinical outcomes, and identify methodological gaps that compromise national comparability. Methods: We conducted a systematic review and meta-analysis of observational studies reporting breast cancer data from Cameroon between 1 January 2000 and 30 April 2025. MEDLINE/PubMed, EMBASE, Google Scholar and the WHO Global Health Library were searched without language restriction. Eligible designs included cohort, cross-sectional, case-control and retrospective hospital-based studies reporting at least one of the following outcomes: prevalence, incidence, mortality, five-year survival, clinical stage, histological profile, immunohistochemistry or treatment patterns. Study quality was assessed using the Newcastle-Ottawa Scale. Pooled proportions were estimated using random-effects models after Freeman-Tukey double-arcsine transformation, with heterogeneity quantified using Cochran's Q and I2 statistics. Results: Fifty-six studies including 41,494 breast cancer patients were retained. The mean age was 45.97 ± 5.53 years, and women represented 96.3% of reported cases. Breast cancer accounted for a pooled 32% of female cancers (95% confidence interval [CI]: 14%-57%; I2=97%). The pooled mortality proportion was 72% (95% CI: 6%-99%; I2=97.7%), while pooled five-year overall survival was 36% (95% CI: 26%-47%; I2=92.2%). Most patients were diagnosed at advanced stages, with stage III and IV disease accounting for the majority of reported cases. Ductal carcinoma was the dominant histology. Hormone receptor positivity was frequent (estrogen receptor: 82%; progesterone receptor: 56%), whereas HER2 overexpression was less frequently reported (14%). Treatment reporting was incomplete: chemotherapy and radiotherapy were commonly documented, but endocrine therapy and palliative care were substantially underreported. Conclusion: Published breast cancer research from Cameroon indicates a severe clinical burden marked by late diagnosis, high mortality and poor five-year survival. However, the extreme heterogeneity and inconsistent reporting across studies show that the country's breast cancer evidence base remains structurally fragile. Standardized cancer registration, harmonized minimum datasets, routine immunohistochemistry, active survival follow-up and transparent treatment documentation are urgently needed to support effective breast cancer control in Cameroon.