RESUMO
The aim of this study was to evaluate the S-phase fraction (SPF) of tumors in breast cancer patients in Pakistan. Its association with the traditional morphological prognostic markers, i.e., axillary lymph node metastasis, tumor size and grade, was also studied. Flow cytometry was used to estimate SPF on breast cancer tissues from 166 patients reported at the Aga Khan University Hospital between the years 1997 and 2000. Univariate analysis was done to find any association between SPF and the aforesaid variables. For the ease of analysis, the cases were subdivided into two categories depending on the SPF value, i.e., <10% (low-risk group) and > or = 10% (high-risk group). The mean and median SPF values were 21.45% and 20.035%, respectively, with a range of 3.26% to 54.30%. Twenty-six (15.66%) of the cases had SPF <10%, 57 (34.34%) had SPF from 10%-20%, and 83 (50%) had SPF >20%. A significant correlation between SPF and nodal metastasis was observed (p = 0.0111), but not between SPF and the number of lymph nodes involved when metastatic cases were subdivided into <4 lymph node-positive cases and > or =4 lymph node-positive cases. Significant correlations were also found between SPF and tumor grade (p = 0.0244), as well as between SPF and tumor size (p = 0.048). In conclusion, DNA flow cytometric analysis of SPF carried out in our laboratory could reasonably predict the chances of lymph node metastasis, tumor grade and size in breast cancer patients, thus proving to be an important prognostic marker in the Pakistani setting. This requires further investigations regarding the survival of patients so as to evaluate its capacity of predicting the outcome of Pakistani patients.