Does single receptor positive breast carcinoma differ with regard to age, tumor grade, and HER2 amplification status?

PURPOSE To investigate whether there is a difference in patient and tumor characteristics in cases with single receptor positive (SRP) (ER-/PR+ and ER+/PR-) breast carcinoma in comparison with the double receptor positive (DRP) (ER+/PR+) and double receptor negative (DRN) (ER-/PR-) tumors. METHODS A total of 255 breast cancer patients were categorized on the basis of their tumor hormonal receptor phenotype, age, grade, and HER2 amplification status. The study focused on the SRP phenotype (ER+/PR- and ER-/PR+) and compared it with the DRP (ER+/PR+rpar; and DRN (ER-/PR-) tumors. RESULTS There were 103 (40.3%) DRP tumors, 98 (38.4%) DRN tumors and 54 (21%) SRP tumors, 41 (16.1%) of which were ER+/PR- and 13 (5.1%) were ER-/PR+. Compared to DRP tumors, the SRP group was more likely to be associated with grade 3 tumors and higher frequency of HER2 amplification status. ER-/PR+ tumors were more likely to be associated with younger age at diagnosis compared to ER+/PR- tumors. HER2 amplification, age, and grade were not significantly different between ER-/PR+ and DRN groups. Compared to the DRN group, the ER+/PR- group had lower grade. CONCLUSIONS Our findings demonstrated that SRP phenotype including ER+/PR- and ER-/PR+ tumors is different from DRP group with regard to age, grade, and HER2 amplification status. Moreover, our data showed that ER-/PR+ tumors are associated with younger age.