Ki-67 Levels and Their Association With Response to Neoadjuvant Chemotherapy in Triple-Negative Breast Cancer: A Prospective Observational Study

Background Due to epigenetic changes in the breast cancer gene 1 (<i>BRCA-1</i>), triple-negative breast cancers (TNBC) are more responsive to platinum compounds. The prevalence of TNBC across India is found to be 27%-35%. The study was carried out to assess the Ki-67 expression and the response to neoadjuvant chemotherapy (NACT)-docetaxel-carboplatin (DC) regimen in patients with TNBC and to identify the association of Ki-67 expression with the NACT. Methodology All newly diagnosed TNBC patients over 18 years of age were subjected to NACT with the DC regimen. Three cycles of NACT had been given at three weekly intervals. The tumor response to NACT was assessed at the end of the third cycle using the response evaluation criteria in solid tumors (RECIST). All patients who completed NACT underwent a modified radical mastectomy (MRM), and the specimen was sent for histopathological examination (HPE). The response to NACT was correlated with the Ki-67 expression. After the surgery, the remaining three cycles of chemotherapy were completed, and adjuvant radiotherapy was given whenever required. The toxicities were documented. The patients were followed until the day of completion of the study. Results A total of 23 TNBC patients were included in this study, and the mean Ki-67 level was found to be 36%. There was no significant difference according to age (P = 0.3, 95% CI: -0.15 to 0.45), menopausal status (P = 0.66, 95% CI: -0.24 to 0.38), size (P = 0.22, 95% CI: -0.1 to 0.33), grade (P = 0.33, 95% CI: -0.08 to 0.35), and stage of the tumor (P = 0.17, 95% CI: -0.11 to 0.29) between the partial response and complete response patients. When the Ki-67 level was analyzed in relation to responders and non-responders, tumor size, grade, and nodal status, it was found to be insignificant. When the DC regimen was given to the TNBC patients, it was observed that the complete clinical response, complete imaging response, and complete pathological response were 39.13%, 34.78%, and 47.61%, respectively. The most common side effects of NACT were malaise, nausea, and hair loss. During the follow-up period, 20 patients had no local recurrence or metastatic features. Conclusion In the present study, the TNBC had high Ki-67 levels, which were insignificant when compared against age, menopause, tumor size, nodal status, and grade. There was no relation between the partial responder group and the complete response group in terms of age, menopausal status, tumor size, nodal size, and grade. When Ki-67 levels were correlated between responders and non-responders, they were also found to be insignificant. The DC regimen, as NACT, did not have any severe side effects.