Stopping Renal Cell Carcinoma Drugs May Lead to Tumor Flare

Among 63 patients with metastatic renal cell carcinoma who discontinued tyrosine kinase therapy (sunitinib or pazopanib) due to disease progression, intolerable toxicity, or sustained response, tumor growth rate before treatment discontinuation was 0.16 cm per month, while the growth rate after treatment discontinuation was 0.70 cm per month. The tumor regrowth rate was higher in patients who discontinued treatment because of disease progression, and lower in patients who discontinued treatment because of a sustained response. Patients with higher tumor growth rates had shorter survival times. The findings are published in European Urology.