Prognostic significance of CD24 and claudin-7 immunoexpression in ductal invasive breast cancer

This study aimed to identify the CD24 and CD44 immunophenotypes within invasiveductal breast carcinoma (IDC) subgroups defined by immunohistochesmistry markersand to determine its influence on prognosis as well as its association with theexpression of Ki-67, cytokeratins (CK5 and CK18) and claudin-7. Immunohistochemicalexpression of CD44 and CD24 alone or in combination was investigated in 95 IDCcases arranged in a tissue microarray (TMA). The association with subgroups definedas luminal A and B; HER2 rich and triple negative, or with the other markers andprognosis was analyzed. CD44+/CD24- and CD44-/CD24+ were respectively presentin 8.4% and 16.8% of the tumors, a lack of both proteins was detected in 6.3%,while CD44+/CD24+ was observed in 45.3% of the tumors. Although there was no significantcorrelation between subgroups and different phenotypes, the CD44+/CD24- phenotypewas more common in the basal subgroups but absent in HER2 tumors, whereas luminaltumors are enriched in CD44-/CD24+ and CD44+/CD24+ cells. The frequency of CD44+/CD24-or CD44-/CD24+ was not associated with clinical characteristics or biologicalmarkers. There was also no significant association of these phenotypes with theevent free (DFS) and overall survival (OS). Single CD44+ was evident in 57.9%of the tumors and was marginally associated to grading and not to any other tumorcharacteristics as well as OS and DFS. CD24+ was positive in 74.7% of the tumors,showing a significant association with estrogen receptor, progesterone receptorand Ki-67 and a marginal association with CK18 and claudin-7. Expression of claudin-7and Ki-67 did not associate with the cancer subgroups, while a positive associationbetween CK18 and the luminal subgroups was found (P=0.03). CK5, CK18 and Ki-67expression had no influence in OS or DFS. Single CD24+ (P=0.07) and claudin-7positivity (P=0.05) were associated with reduced time of recurrence, suggestinga contribution of these markers to aggressiveness of breast cancer.