Purpose: the frequency of point mutation at codon 12 of the K<FONT FACE=Symbol>¾</FONT>ras gene was determined in paraffin blocks of surgical specimens from patients who had ductal invasive breast cancer. Material and Methods: Fifty surgical specimens blocked in paraffin from patients with ductal invasive breast cancer, with histological degree II and III, were used. The polymerase chain reaction (PCR) was used for amplification of DNA fragments studied. The material cleavage was obtained with restriction fragment length polymorphisms (RFLP). The electrophoresis in agarose gel, with Ladder 123 (GIBCO-BRL) marker, was employed to verify if some mutation had occurred. The results were shown using ultraviolet beam and recorded by photos. Results: mutations at codon 12 of K-ras gene were found in five samples (10%) and all of them were polymorphic for this caracter. The five patients whose tumors expressed mutation were in the postmenopausal period. Four patientes had tumors of histological degree II and one, III.
Breast neoplasms; Polymerase chain reaction; Oncogenes
