Synchronous primary malignancies of the lung and breast: a rare case report

Multiple Primary Malignant Tumors (MPMT) are two or more distinct primary cancers in a single patient, either occurring simultaneously (synchronous) or at different times (metachronous). MPMTs are very rare, with an incidence of 0.73% to 11.7% among cancer patients. Breast and lung cancers are the most common malignancies in women, but their coexistence as MPMT is uncommon.

We report the case of a 51-year-old non-smoking woman who had a productive cough with bloody sputum for a week, after a two-month history of dry cough. She was diagnosed with a high-grade, poorly differentiated non-keratinizing squamous-cell carcinoma in the right lung. A PET scan also revealed a poorly defined soft tissue mass in the central sector of the right breast, which was confirmed to be a primary invasive ductal carcinoma.

The etiology and pathogenesis of MPMT are unclear, but several factors such as genetic predisposition, environmental exposure, immunodeficiency, and treatment-related effects have been proposed. The diagnosis and management of MPMT are challenging, as they require careful evaluation of each tumor and individualized treatment plans. The prognosis of MPMT depends on the stage and histology of each tumor, as well as the patient’s performance status and comorbidities.

This case report highlights the rare occurrence of synchronous primary malignancies in the lung and breast, underreported in the medical literature. This case adds to the existing knowledge of MPMT and may stimulate further research on this topic. Clinicians should be aware of the possibility of MPMT in cancer patients and perform thorough investigations to rule out secondary or metastatic tumors.