RESUMEN
<p><b>OBJECTIVE</b>To study the relation between histopathologic grading and some of the cytogenetic and molecular biology characteristics of breast cancer.</p><p><b>METHODS</b>On the basis of estrogen receptor (ER) expression, DNA content, S-phase fraction (SPF), bcl-2 and mutant p53 protein (mtp53) expression were examined by FCM in 121 breast cancer patients. In 66 patients with invasive ductal breast cancer, histopathologic grading was also examined.</p><p><b>RESULTS</b>The aneuploidy rate and DNA index (DI) were significantly different in grade I, II and III breast cancer. SPF and mtp53 expression significantly increased with increase in histopathologic grading (P < 0.05), but bcl-2 did not show this trend. SPF and mtp53 expression were significantly more in breast cancer with negative ER than in those with positive ER (P < 0.05). Again, no such differences in bcl-2 regardless of ER expression. Correlations existed between DI vs SPF, DI vs mtp53, and SPF vs mtp53 expressions (P < 0.01) but bcl-2 did not correlate with any one of them.</p><p><b>CONCLUSION</b>Cytogenetic and molecular biology studies on the basis of histopathologic grading may provide more information in prognostic prediction of breast cancer.</p>