Metachronous Contralateral Breast Cancer in Ahmadu Bello University Teaching Hospital, Zaria, Northwestern Nigeria.

Background: Breast cancer is the most frequent cancer of women. Metachronous contralateral breast cancer (MCBC) is a cancer in the contralateral breast after 6 months of the initial diagnosis of the first breast cancer. It is an important public health issue because of an increased incidence of a primary breast cancer and improved survival. There is a paucity of data in the Northwestern region of the country. The study was to document the incidence, the method of detection, clinicopathological features, and the treatment of MCBC in our hospital.

Patients And Methods: It was a 7-year prospective study from January 2011 to December 2017. Patients who had treatment for nonmetastatic breast cancer, American Joint Committee on Cancer (AJCC) Stages 1-111, were followed up. Those that developed MCBC were studied. Age, the method of detection, stage at presentation, pathological types, hormone receptor status, and treatment were documented. Data obtained were analysed using SPSS version 21.0. Results were presented as simple percentages and charts.

Results: Of 1285 women with nonmetastatic breast cancer, 47 had MCBC (incidence of 3.7%); 30 (63.8%) were aged 21-50 years; 23 (48.9%) detected by self-breast examination; 13 (27.7%) by clinical breast examination; seven (14.9%) by mammography; and four (8.5%) by breast ultrasound scan. Fourteen (29.8%) were AJCC stage I; 23 (48.9%), stage II; seven (14.9%), stage III; and three (6.4%), stage IV. Thirty-nine (83%) were invasive ductal carcinoma; 22 (50.0%) were estrogen receptor/progesterone receptor (ER/PR) positive, human epidermal receptor (HER)-2 neu negative; nine were (20.5%) ER/PR and HER-2 neu positive; six (13.6%) were ER/PR negative, HER-2 neu positive, whereas seven (15.9%) were triple negative. Forty-three (91.5%) had modified radical mastectomy and 19 (40.4%) had cytotoxics.

Conclusion: With an average of six cases in a year, MCBC is common in our hospital. Majority (63.8%) were young. The commonest method of detection was by self-breast examination. Majority (78.3%) presented at an early stage. Most (91.5%) still had modified radical mastectomy.