Bladder Metastases from Lung Cancer: Clinical and Pathological Implications: A Systematic Review.

Lung cancer is the tumor with the highest incidence in males worldwide and the most common cause of death from cancer overall; its high mortality is mostly due to its propensity to spread to other organs through lymphatic and blood vessels in spite of proper treatment. Bladder metastases from lung cancer are rare, with only 11 cases having been reported, all in recent years. This review aims to discuss some critical points regarding this uncommon condition, namely: (a) lung and bladder tumors share similar etiologic features; (b) almost all bladder metastases from lung cancer arise from lung adenocarcinomas; (c) cytology and superficial bladder biopsy may be falsely negative, since the neoplastic cells coming through the hematogenous route are typically located in the lamina propria and/or muscularis propria of the bladder wall; and (d) the differential diagnosis with primary bladder adenocarcinoma as well as primary and secondary small-cell carcinomas may be challenging. Though no definite conclusions can be drawn regarding treatment, we herein propose a practical algorithm to manage such patients based on available data.