Combination of anti-PD-1 treatment with chemotherapy in a patient with metaplastic breast cancer during lactation.

Metaplastic breast cancer (MpBC) is a rare and aggressive subtype of breast cancer with a poor prognosis. Recent studies have shown that anti-PD-1 therapy is effective in treating this type of cancer. We described a rare case of MpBC during lactation that worsened quickly post-surgery. Despite receiving chemotherapy and immunotherapy, the patient passed away from respiratory failure caused by tumor compression. Subsequent genetic testing revealed the presence of the resistance gene CDKN2A. Lactating women should promptly get checked for abnormal breast symptoms to catch breast cancer early. More research is needed to determine how effective anti-PD-1 therapy is for MpBC. PD-L1 is not usually tested in clinical settings, but it's important to check for CDKN2A when looking at resistance targets for PD-L1.