Tumour markers in breast carcinoma correlate with grade rather than with invasiveness

Ductal breast carcinoma in situ (DCIS) is regarded as a precursor to invasi ve breast cancer. The progression from in situ to invasive cancer is howeve r little understood. We compared some tumour markers in invasive and in sit u breast carcinomas trying to find steps in this progression. We designed a semi-experimental setting and compared histopathological grading and tumou r marker expression in pure DCIS (n = 194), small invasive lesions (n = 127 ) and lesions with both an invasive and in situ component (n = 305). Gradin g was done according to the Elston-Ellis and EORTC classification systems, respectively. Immunohistochemical staining was conducted for p53, c-erbB-2, Ki-67, ER, PR, bcl-2 and angiogenesis. All markers correlated with grade r ather than with invasiveness. No marker was clearly associated with the pro gression from in situ to invasiveness. The expression of tumour markers was almost identical in the 2 components of mixed lesions. DCIS as a group sho wed a more 'malignant picture' than invasive cancer according to the marker s, probably, due to a higher proportion of poorly differentiated lesions. T he step between in situ and invasive cancer seems to occur independently of tumour grade, The results suggest that well-differentiated DCIS progress t o well-differentiated invasive cancer and poorly differentiated DCIS progre ss to poorly differentiated invasive cancer. (C) 2001 Cancer Research Campa ign.