Metastatic patterns and hormone receptor status among breast cancer patients in Tanzania

Abstract

Introduction: Metastatic breast cancer is a common presentation in Tanzania. Estrogen-receptor (ER)-positive tumors are known to metastasize to the bones and require hormonal treatment as first-line therapy. Challenges with accessing immunohistochemistry services can delay information on breast cancer subtypes, further delaying treatment with effective hormonal therapy.

Objectives: This study aimed to assess the pattern of distribution of metastatic lesions in patients with metastatic breast cancer and evaluate its association with their hormone and HER-2 status, which could help provide recommendations on the use of front-line hormone therapy in areas where access to immunohistochemistry is a challenge.

Methods: A retrospective study covering histologically confirmed breast cancer patients in 2020 with metastatic lesions and complete medical records at Ocean Road Cancer Institute. Clinical information on the number, state and sites of metastasis, presence of symptoms and treatment received, and pathological variables, including histology, ER, PR and HER-2 status, were documented.

Results: Forty-nine (96.1%) of 51 patients analysed were female, with a mean age of 49.5 years. 47% presented with up-front metastatic disease. Lung was the most common metastatic site (76.5%) followed by bone/spine (53%). About half the patients had multiple sites involved. ER-positive tumors accounted for 47%, PR positive for 31% and HER-2 positive 39.2%. ER-positive tumors were more likely to present as a recurrence than up-front metastasis. ER-positive tumors were significantly more likely to be associated with bone and spine metastasis (59%) compared to ER-negative tumors (29%)

Conclusion: The clinical and pathological features of MBC in Tanzanian women are similar in many ways to those in other African regions. However, the ER positivity rate is lower. This study found a significant association between ER-positive tumours and skeletal metastasis, which has implications for the up-front treatment of these patients, especially where access to immunohistochemistry can be a challenge.