Male and female breast cancer--differences in DNA ploidy, p21 and p53 expression reinforce the possibility of distinct pathways of oncogenesis.
OBJECTIVE
The purpose of this study was to compare the immunohistochemical profile of cell cycle inhibitors of G1/S phase transition (p21, p53 and pRb), Ki-67 proliferation marker and DNA ploidy in male (MBC) and female breast cancer (FBC).


METHODS
One hundred patients (50 non-consecutive cases of FBC and an equal number of MBC) were selected according to homogeneous features regarding age, histological type, tumour grading, nodal status and absence of neoadjuvant therapy. The expression of p21, p53, pRb and Ki-67 was assessed by immunohistochemistry, and DNA ploidy was analysed by flow cytometry. Correlations between variables were evaluated using the chi(2) test.


RESULTS
The incidence of DNA aneuploid, p21-positive and p53-negative tumours was significantly higher in MBC than in FBC; pRb and Ki-67 revealed no statistically significant differences between the two entities. In MBC, high tumour grade correlated with aneuploidy, Ki-67 and pRb positivity; ploidy and p53 were also associated. In FBC, only ploidy and grade showed a strong correlation.


CONCLUSIONS
The significant dissimilarities regarding DNA ploidy, p21 and p53 in these quite homogeneous groups of FBC and MBC point to different genomic instability and to differences in cell cycle proliferative control, reinforcing the view of somewhat distinct tumour oncogenesis.
André
Saudade
S
Serviço de Anatomia Patológica, Instituto Português de Oncologia de Lisboa Francisco Gentil, E.P.E., Lisboa, Portugal.
Pinto
António E
AE
Laranjeira
Cátia
C
Quaresma
Manuela
M
Soares
Jorge
J
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000235:genetics* / Q000473:pathology; D018567:Breast Neoplasms, Male / Q000235:genetics* / Q000473:pathology; D018270:Carcinoma, Ductal, Breast / Q000235:genetics* / Q000473:pathology; D018797:Cell Cycle Proteins; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000378:metabolism; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000096:biosynthesis*; D004273:DNA, Neoplasm / Q000235:genetics; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007150:Immunohistochemistry; D019394:Ki-67 Antigen / Q000096:biosynthesis; D008297:Male; D008875:Middle Aged; D009687:Nuclear Proteins / Q000096:biosynthesis; D011003:Ploidies; D012097:Repressor Proteins / Q000096:biosynthesis; D016159:Tumor Suppressor Protein p53 / Q000096:biosynthesis*
D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D004273:DNA, Neoplasm; C416925:EID1 protein, human; D019394:Ki-67 Antigen; D009687:Nuclear Proteins; D012097:Repressor Proteins; D016159:Tumor Suppressor Protein p53