Spontaneous regression of crizotinib-associated complex renal cysts during continuous crizotinib treatment.

This study describes the development and regression of crizotinib-associated complex renal cysts (CACRCs) in a female patient with ALK-positive advanced non-small cell lung cancer with an ongoing complete response while on continuous crizotinib treatment. The clinical context of crizotinib use requires frequent imaging studies; therefore observation is probably the best approach to CACRC management in asymptomatic patients. The natural history of CACRCs remains unknown, and large-scale longitudinal follow-up studies of these cysts are eagerly awaited.