RESUMEN
BACKGROUND: Tissue homeostasis and the maintenance of cell populations depend on a delicate balance between the rates of cell proliferation and cell death. Disruption of this balance is an important factor in development and progression of tumors. In the present study we evaluated the growth index in a large group of breast cancer patients and correlated it with various clinical and histopathological features of the tumor. METHODS: Estimation of apoptosis was determined by TUNEL assay while immunocytochemistry for proliferating nuclear cell antigen (PCNA) was used as a measure of proliferation. Necrosis was identified morphologically by haematoxylin and eosin staining. RESULTS: A positive correlation was observed between the percentage of PCNA positive cells and the frequency of mitosis (r=0.6117, p<0.0001). A highly statistical significant correlation was observed between type of tissue analyzed and growth index (r=0.46869, p<0.0001). No significant association was observed between hormone receptor status and growth index. CONCLUSIONS: The growth index was found to be higher in carcinoma cells that metastasised into lymph nodes compared with primary lesions with no nodal metastasis. Growth index was particularly prominent in high-grade tumors in which increased proliferative activity was evident. Apoptotic cells were detected more frequently in tumor cells with higher rather than lower proliferative activity. This suggests that not only proliferative activity but also capacity for apoptosis is altered in breast tumors.