A Preliminary Analysis of Ki-67 Expression in Breast Cancer in the Caribbean

Objective: There has been a void of data regarding Ki-67 expression in breast cancer in the Caribbean. Ki-67 is a widely used marker to determine the grade and prognosis of breast cancer. Ki-67 has been shown to be a valuable tool in predicting the response to chemotherapy and hormonal therapy in breast cancer patients. The objective of this preliminary study aims to describe the Ki-67 (Ki) status in this population and its correlations with other parameters in breast cancer histology. This study also aims to lay the groundwork for Ki-67 analysis in this population so that future studies may better describe it. Method: The methodology involved gathering data from histology reports for all breast cancer-related biopsies from the 1st of January 2018 to the 12th of July 2021. This data was retrospectively analyzed. Results: Twenty-three Ki-67 cases were obtained, 19 of which had Ki expression >10%. This >10% group was mostly staged from T1c up (one T1, three T1c cases, two T2 cases, four T3 cases while nine were not T staged). Two were N2/M1 while 9 were N0 and two were M0, the rest were not staged. The mean age was 65.6 years with a range of 54 and a standard deviation of 12.5. Lymphovascular invasion was confirmed in four cases and suspected in three. Axillary lymph node dissection (ALND) yielded >10 nodes involved in two cases while <5 nodes in the remaining. The most common receptor status was hormone positive/ human epidermal growth factor receptor-2 (HER) negative (eight). Invasive Ductal Carcinoma (IDC) occurred in 10 cases while intermediate grade was in 14 cases. The Ki 6-10 % group consisted of two cases, one staged at T1aN0Mx while the other T2NxMx. Lymphovascular invasion was suspected in one. The average age was 67.5 years. ALND yielded less than five nodes in one case and 5-10 nodes in the other. Grades were high and intermediate. Histology was invasive ductal carcinoma/ductal carcinoma in situ (IDC/DCIS), and ductal carcinoma in situ ( DCIS) respectively. The Ki <6% group comprised two cases, staged at T1NxMx and T3N2M1. Lymphovascular invasion was absent in both. The mean age was 58.5 years. ALND yielded >10 nodes in one case and <5 in the other. Grades were high and intermediate. Histology was IDC/DCIS in both. There were no sentinel nodes involved in all but two cases belonging to the Ki >10% group. Conclusion: This preliminary study was the first to describe the Ki-67 marker in the Caribbean population. The vast majority of this population has a Ki-67 level of>10%. Higher Ki-67 expression is associated with larger tumors, lymphovascular invasion, metastases, and higher tumor grades. There is a need for consistent Ki-67 reporting in histology samples before follow-up studies are conducted.