Case report: Second primary small cell carcinoma of the trachea in a breast cancer survivor: a case report and literature review.

Small cell carcinoma of the trachea is a rare entity and only a few cases have been described, none as a second malignant neoplasm. This is the first report of a metachronous second primary of the trachea with small cell histology in a breast cancer survivor. A 25-year-old woman was diagnosed initially with an infiltrating ductal carcinoma of the breast, and was treated with modified radical mastectomy followed by adjuvant chemo-radiotherapy. 10 years later, she presented with breathlessness and central airway obstruction. Bronchoscopy revealed an intraluminal lesion in the proximal trachea, which was reported as small cell carcinoma on biopsy. There was no evidence of loco-regional recurrence of the previously treated breast cancer. Whole-body positron emission tomography did not show any distant metastases. As it was a small cell carcinoma, she was treated with concurrent chemo-radiotherapy and remains loco-regionally controlled. Decision-making in such instances should take into account prior treatment and needs to be individualized. There is a need for increased awareness amongst primary care physicians regarding second malignant neoplasms in the long-term follow-up of breast cancer patients treated with radiation and chemotherapeutic agents that have carcinogenic potential.