Metastasis of primary lung carcinoma to the breast: a systematic review of the literature.

ABSTRACT

BACKGROUND: The purpose of this systematic review was to summarize previously published case reports of primary lung carcinoma metastasis to the breast to assess common clinical and pathologic features and management strategies. MATERIALS AND METHODS: Case reports describing breast metastasis of primary lung carcinoma were systematically evaluated in MEDLINE and EMBASE. RESULTS: Thirty-one reported cases of non-small-cell lung carcinoma (NSCLC) metastasized to the breast were identified, along with eight cases of small-cell lung carcinoma. Sixty-seven percent of reported NSCLC metastases to the breast were detected metachronously with the primary lung abnormality, whereas 80% of small-cell lung carcinoma breast metastases appeared synchronously. Thyroid transcription factor 1 was found to be expressed in 58% of total NSCLC breast metastases, including 83% of those of adenocarcinoma origin. Therapeutic strategies among NSCLC cases varied widely, and only 36% of NSCLC breast metastasis patients were administered chemotherapy. Additional sites of metastasis in these cases are summarized as well. CONCLUSIONS: It is recommended to include metastatic lung cancer in the differential diagnosis of patients presenting with a breast abnormality in the context of a suspected lung cancer. Thyroid transcription factor 1 expression should be examined in these cases. The metachronous versus synchronous nature of lung carcinoma metastasis to the breast has consequences for both detection of the primary and secondary lesions and patient outlook. Clinical correlation is vital to effective management of the care of patients harboring these atypical secondary lesions.