Radioactive seed migration after transperineal interstitial prostate brachytherapy and associated development of small-cell lung cancer

Abstract

Purpose: We report a case of lung carcinoma developing in the location of a migrated prostate brachytherapy seed.

Methods and materials: A 57-year-old male nonsmoker was originally diagnosed with prostate adenocarcinoma Group IIB in October 1999. Treatment was completed at an outside local hospital and consisted of hormone suppression, pelvic external beam radiation, and transperineal interstitial permanent prostate brachytherapy with loose iodine-125 seeds.

Results: The treatment was unremarkable for any complications, and immediate postimplant evaluation did not reveal any loose seeds. The patient remained clinically without evidence of disease and was asymptomatic until an isolated episode of hematuria in December 2009. Radiographic evaluation noted an incidental right lower lobe lung mass with a 4-mm hyperdensity slightly off-center. Biopsy confirmed Stage IB limited-stage small-cell lung cancer, and he underwent thoracic radiation with concurrent systemic chemotherapy. The mass remained mildly avid on a positron emission tomographic scan after treatment, and he underwent surgical evaluation with final pathology demonstrating no residual tumor but a metal rod-like implant consistent with a migrated radioactive brachytherapy seed.

Conclusions: To our knowledge, this is the first case of a long-term adverse sequela seen in the location of a migrated brachytherapy seed. Although reported incidence of pulmonary seed emboli remains low with little measurable consequence on pulmonary function, we must appreciate that a theoretical risk for secondary malignancy remains not only locally within the periprostatic region but also at any site of seed migration.