444 Background: The clinical course of metastatic renal cell carcinoma (mRCC) has a wide spectrum that ranges from indolent to rapidly progressive disease. Initial active surveillance (AS) followed by deferred systemic target therapy might be a treatment option in a subpopulation of patients with indolent mRCC. However, very few studies have been published about AS and its outcome as well as potential predictive factor that might be associated with indolent mRCC. Here, we report clinical outcomes of mRCC patients who initially were monitored by AS. Methods: We retrospectively reviewed and analyzed the clinical and pathological data of mRCC patients who initially were monitored by planned AS prior to systemic therapy due to asymptomatic or slowly progressive disease at National Cancer Center Hospital East between 2000 and 2011. The primary outcome measures were progression-free survival (PFS) and overall survival (OS). Results: A total of 29 patients were eligible for this analysis. The median age at diagnosis was 69 years, and all patients had a good general condition with a performance status of 0 or 1. A total of 65% of patients had recurrent disease and 35% were in stage 4. All of the patients had undergone nephrectomy, and 86% had clear cell carcinoma. None of the patients was categorized into a poor risk group according to both MSKCC and Heng criteria. The median follow-up period was 35.4 months. During the follow-up period, disease progression was observed in 72% of patients but only 14% died. The median PFS time was 26.1 months. After disease progression was observed, only 58% of these patients received treatment or intervention. The median OS have not been reached yet, but 12, 24 and 48 months OS rates were 96.4, 88.7 and 83.8%, respectively. Conclusions: PFS and OS of patients who underwent AS were extremely favorable. For these indolent subpopulations, AS might be a treatment option, so toxic and expensive systemic target therapy could be deferred for a significant period of time without prognostic disadvantage. However, further observational study with a larger sample size might be needed in order to identify the exact subpopulation eligible for AS.
Active surveillance of metastatic renal cell carcinoma: Results from a prospective observational study (MaRCC)
