Local immune response in serous papillary carcinoma of the endometrium

Serous papillary carcinomas of the endometrium are aggressive tumors that tend to permeate, in a very extensive fashion, to uterine and adnexal lymphatic and vascular channels at an early stage in their evolution, and are associated with a particularly gloomy prognosis. It is generally thought that even tumors apparently limited to the endometrium or confined to an endometrial polyp have a poor outcome. Our study points towards the value of HLA-DR antigen in the outcome of serous papillary endometrial cancer. Our aim was to assess the HLA-DR expression in inactive, endometrial intraepithelial carcinoma (EIC), and invasive serous carcinoma curretage specimens from the endometrial cavity, suggesting a role in immune response to keep tumor proliferation in check.

Thirty-one cases of inactive endometrium, twelve cases of EIC, and thirty-nine cases of serous papillary invasive carcinoma curettings were evaluated for the detection of HLA-DR monoclonal antigen. T helper (TH) marker (CD4) in the tumor stroma of the relevant cases was also studied, given that it is now known that the dependence of immune responsiveness on the class II antigens reflects the central role of these molecules in presenting antigen to TH cells.

HLA-DR was expressed in 20 of 31 inactive endometrium (64.5%), 4 of 12 in EIC (33.3%), and in 10 of 39 serous papillary invasive carcinomas (25.6%). CD4 was expressed in 9 of 31 inactive endometrium (29%), 5 of 12 in EIC (42%), and in 26 of 39 serous papillary invasive carcinomas (67%).

The results showed decreased expression of HLA-DR and increased expression of CD4 as the lesion progressed to malignancy. The aberrant expression of HLA-DR by epithelial cells of inactive endometrium, of EIC and of serous papillary invasive carcinomas agrees with the hypothesis of the inactive endometrium - carcinoma in situ sequence as the usual route for the development of serous papillary invasive carcinoma. The immune attract mechanism by low HLA-DR signaling seems to be of minor importance in the malignant and metastatic potential of the serous papillary endometrial tumours.