In this study, levels of CLN3 expression in 75 paired invasive ductal carcinomas (IDC) and their corresponding non-tumor freshly dissected breast tissues and another 189 breast cancer tissue paraffin blocks and corresponding normal tissue paraffin blocks from the same patient are compared by quantitative real-time polymerase chain reaction (qRT-PCR). The gene discussed is CLN3; the disease is breast carcinoma.