Relationship between tumour size and response to neoadjuvant chemotherapy among breast cancer patients in a tertiary center in Nigeria.

Background: Tumour biology, physiologic features such as growth fraction and physical features such as size may influence response of breast cancer to neoadjuvant chemotherapy. Molecular biology is an established basis for predicting response and selecting neoadjuvant chemotherapy. Whether physical characteristics such as size should influence chemotherapy regimen is inconclusive and has not been adequately studied in developing countries. Aim: To determine the relationship between breast tumour size and response to neoadjuvant chemotherapy and hence define the role of tumour size during selection of neoadjuvant chemotherapy regimen for locally advanced breast cancer. Method: Records of women managed at the University of Ilorin Teaching Hospital, Ilorin Nigeria, with neoadjuvant chemotherapy (NAC) for locally advanced breast cancer were reviewed between January 2013 and June 2015. Data was analyzed as 2 subgroups; primary tumour ≥100mm as group 1 and primary tumour ≥100mm as group 2. Primary outcome was 50% reduction in tumour size. Comparison was by chi-square test of independence at p value 0.05. Results: 57 records were reviewed (group1=24, group2=33). Majority (37( 65%)) were premenopausal. Mean age was 47.9 ± 13.1 (range 28-85). NAC was either taxane or anthracycline based regimen. Median chemotherapy dose was 4 (range 2-6). Widest diameter of tumours was 30mm to 180mm (mean 96 ±3.8mm, median 100mm). Mean tumour diameter for groups 1 and 2 was 7.2 ±1.6mm and 12.2± 2.9mm respectively. 50% reduction in tumour size was 45.8% and 6.0% for groups 1 and 2 respectively (p=0.0001). Conclusion: There was relationship between breast tumour size and response to neoadjuvant chemotherapy at a cut-off of 10mm. Well-designed prospective studies are required to confirm this relationship.