Characteristics of breast metastases from non-breast solid tumors in 22 patients from a southern Chinese population.

Breast metastases from solid non-breast tumor types are rare; however, they should be always considered in the differential diagnosis of a breast lesion owing to the associated poor patient prognosis and the requirement of different therapeutic strategies compared with those used to treat primary breast cancer. The aim of the current study was to summarize the characteristics of metastases to the breast in a southern Chinese population. The medical records and pathological sections of 22 patients with pathologically confirmed extra-mammary metastases to the breast that presented to Sun Yat-sen University Cancer Center between January 2000 and December 2015 were retrospectively reviewed. The median age of onset for breast metastasis was 43 years (range, 10-62 years) and 19 (86.4%) patients had a known history of a primary tumor. The mean interval from diagnosis of the primary tumor to breast metastasis was 16.5 months (range, 6-56 months). A unilateral (45.5% left, 36.4% right), upper outer quadrant (15/22, 68.2%) lesion of the breast was most frequently initially detected by self-checking (63.6%). The most common origin of the primary tumor was the lung (22.7%). Nasopharyngeal carcinoma accounted for a high proportion of the metastases (18.2%). The median duration of survival from the time of diagnosis of a breast metastasis was 14 months (range, 2-74 months). A total of 10 patients (45.5%) succumbed to the disease. The results also indicated that overall survival in patients that underwent surgery was improved compared with patients who did not undergo surgery. The results of the present study demonstrated that clinical history, imaging findings, pathology from the primary tumor and immunostaining were required in combination to establish an accurate diagnosis. Further investigation into the improvement of the prognosis of patients with metastases to the breast following surgery is required.