Superficial bladder cancer metastatic to the lungs: two case reports and review of the literature.

Bladder cancer remains a significant cause of morbidity and mortality in the United States, with mortality related predominantly to metastasis. Approximately 70% of newly diagnosed cases of bladder cancer represent superficial disease that, despite a high risk of local recurrence, rarely progress to invasive or metastatic disease. The present cases demonstrate isolated pulmonary metastases associated with low-grade superficial bladder cancer, without previous evidence of muscle-invasive disease. Distant spread of low-grade superficial tumors is extremely unusual, and we review the literature and discuss the management of this rare entity.