The role of p53 and Ki67 in Paget's disease of the vulva and the breast.

OBJECTIVE

Paget's disease of the vulva (PDV) and Paget's disease of the breast (PDB) are uncommon diseases, accounting for approximately 1% of all vulval neoplasms and 0.5-4% of all breast cancers, respectively. In 10-30% of vulval cases an invasive adenocarcinoma is present. In such cases the disease is often aggressive and recurrence rate is high. This is in contrast to PDB where the general consensus is that almost all cases are associated with an in situ or invasive ductal carcinoma. Our aim was to examine the presence of the tumor suppressor protein p53 and the proliferation marker Ki67 in PDV and PDB and correlate any differences in the expression of these two proteins with the presence of an underlying carcinoma.

METHODS

Immunohistochemistry was performed on 52 archival cases of PDV, which included 10 with associated invasive adenocarcinoma of the vulva, and on 37 archival cases of PDB, including 26 with available associated ductal carcinoma in situ (DCIS) or invasive carcinoma of the breast. All cases were formalin-fixed and paraffin wax-embedded. Monoclonal antibodies were used with microwave antigen retrieval. Streptavidin-biotin-horseradish peroxidase and 3,3'-diaminobenzidine detection methods were employed to visualize antibody binding and staining. A section was scored positive for p53 if more than 10% of cell nuclei were stained brown and Ki67 was expressed as a percentage of positive cells to the nearest 5% of cells showing nuclear positivity (Ki67 staining index).

RESULTS

p53 was expressed in 15 of 52 (29%) PDV cases and 5 of 37 (13%) cases of PDB. Four of the ten cases (40%) of PDV associated with invasive disease expressed p53 compared with 11 of 42 (26%) cases without invasive disease. The mean Ki67 staining index for PDV associated with invasion was 19%, and for that without invasion, 16%. In the breast cases, the mean staining index was 11%.

CONCLUSION

Our data suggest that p53 may have a role to play in PDV progression, and may be a late event in some cases, especially those associated with invasive disease. Ki67 has no apparent prognostic role in PDV as there was no significant difference between those cases associated with and those without invasive disease. Neither p53 nor Ki67 appears to have a prognostic role to play in PDB.