Predictors and imaging-based tropism of metastatic breast cancer in patients attending a referral oncology hospital in Cameroon

Background Breast cancer (BC) is the most frequent cancer in sub-Saharan Africa and the leading cause of all cancer-related deaths. Late presentation at advanced stage of disease is characteristic of low- and middle-income countries (LMICs). The presence and specific sites of metastatic disease affects treatment planning, response and prognosis. Given the genetic heterogeneity of metastatic breast cancer (mBC), this study aspired to determine the prevalence, determinants and tropism in a Central African setting. Methods Data was extracted from a prospectively collected hospital-based cancer registry at a specialized university-affiliated oncology center. Multivariable logistic regression modeling was used to determine the predictors of tumor spread whilst the pattern of spread was illustrated using a Sankey diagram. All statistical tests were two-tailed and the threshold for significance was set at 0.05. Results Data was extracted from the medical records of 271 patients with breast cancer. The sex-ratio was 1:270 and median age (range) 47 (16–91) years. A total of 148/271 (54.6%) BC occurred at the left breast (p < 0.01). Invasive ductal carcinoma (IDC) accounted for 76.4% (204/267) of all histologic subtypes whilst triple negative breast cancer (TNBC) was the predominant molecular subtype (55.9%, 146/261). Tumor staging at baseline was as follows: stage I, 2.7% (17/271); stage II, 36.2% (98/271); stage III, 43.5% (118/271); stage IV, 14% (38/271). During follow-up there was imaging evidence of metastasis in 40.2% (109/271) of patients. mBC was independently associated to histologic (p = 0.03) and molecular subtypes (p < 0.01), with IDC and TNBC representing 83.9% (89/106) and 72.4% (76/105) of all cases of metastases respectively. In the multivariable modeling patient’s age < 42 years (aOR = 2.1, 95%CI: 1.1–4.1, p = 0.03) and TNBC (aOR = 2.4, 95%CI: 1.3–4.5, p < 0.01) were associated to mBC. Right breast cancers were more likely to spread to the lungs and liver (p < 0.01). Conclusion TNBC is predominant in the study population and with young age are associated with mBC and thus poor outcomes. Strategies that improve the uptake of screening and facilitate access to quality care are likely to reduce BC disease burden in LMICs.