Lymphatic vascularization in primary breast cancer: HER2 overexpressing tumors contain more lymphatics than steroid receptor positive, triple-positive and triple negative breast carcinomas.

OBJECTIVE The aim of this study was to examine the relationship between the immunohistochemical subtypes of invasive breast cancer and lymphatic vascularization. MATERIAL AND METHOD One hundred and seventy nine cases of randomly selected invasive breast cancer patients, surgically treated between 2004 and 2007, were retrospectively studied. These were classified into steroid receptor positive (steroid receptor positive/ HER2 negative), triple positive (steroid receptor and HER2 positive), triple negative (steroid receptor and HER2 negative) and HER2 overexpressing (steroid receptor negative /HER2 positive) carcinomas. Appropriate immunostaining and in-situ hybridization techniques were applied and results were statistically analyzed. RESULTS The median intra-tumor lymphatic vascular density and the median intra-tumor relative lymphatic vascular area were found to differ significantly among the studied groups of breast cancer (KW =49.8611; p < 0.0001 and KW =21.5122; p=0.0001 respectively). There was no significant difference in the incidence rate of axillary node involvement among the studied groups of breast cancer (χ < sup > 2 < /sup > =1.66; Df=3; p=0.6460). CONCLUSION The present study indicates that HER2 overexpressing breast carcinomas have a consistent increase of intra-tumor lymphatic vessel counts as compared to all other subtypes. It is suggested that the newly formed vessels are probably not the only essential factor for lymphogenic spread of HER2 overexpressing breast carcinomas as they are not related to an increased incidence of lymph node metastases compared to the other studied subgroups.