Abstract
INTRODUCTION: Multiple primary cancers in one person are uncommon, yet their incidence is rising due to advancements in cancer treatment, enhanced screening, and increased life expectancy. This case report details the presentation, diagnosis, and management of a 56-year-old female patient diagnosed with metachronous right breast ductal carcinoma and adenocarcinoma of the rectum. CASE PRESENTATION: We present the case of a 56-year-old nulliparous, postmenopausal Ethiopian woman initially diagnosed with right breast ductal carcinoma (cT2 N3c M1, ER/PR positive, Her-2 negative). She received palliative chemotherapy and bisphosphonate therapy, followed by hormonal therapy. Approximately two years after her initial breast cancer diagnosis and while on follow-up, she developed rectal bleeding and tenesmus of 1-2 months' duration. Subsequent MRI revealed a rectal mass, and biopsy confirmed adenocarcinoma of the rectum. Given the locally advanced nature of the rectal disease, neoadjuvant chemotherapy was advised. The patient's subsequent course was complicated by chemotherapy-induced toxicity, highlighting the challenges in managing such complex cases. DISCUSSION: The co-occurrence of metachronous breast and rectal cancers is rare and poses significant diagnostic and therapeutic challenges. This case underscores the critical role of vigilant surveillance and a highly personalized, multidisciplinary treatment approach for patients with a history of malignancy. Immunohistochemistry, combined with a detailed medical history, is essential for definitive diagnosis and differentiating primary tumor origins. The development of metachronous cancers raises concerns about shared genetic, environmental, and therapeutic factors, necessitating a holistic view of patient care. CONCLUSION: The diagnosis and treatment of metachronous malignancies, particularly involving the breast and rectum, are inherently complex. Optimal patient outcomes necessitate a comprehensive, coordinated, and individualized approach, emphasizing the importance of long-term surveillance and adaptable management strategies.