Effect of third- and fourth-line systemic therapies for metastatic renal cell carcinoma.

Data on the outcomes of third- or fourth-line therapy for metastatic renal cell carcinoma (mRCC) are limited. The aim of our study was to evaluate the efficacy of therapy beyond the second line. We retrospectively analysed data of mRCC patients who underwent systemic therapy at Yamagata University Hospital. The best objective response (BOR), response rate (RR), and progression-free survival (PFS) were assessed for each line of treatment. To investigate the correlation between overall survival (OS) and the number of treatment lines during a patient's lifetime, the median OS was assessed using univariate and multivariate analyses. In the first-, second-, and third-line therapies, approximately 20% of patients had long PFS of >15 months. In targeted treatments beyond the third line, only one treatment suppressed disease progression for >10 months. Among patients who died during the follow-up period, those treated with triple and quadruple lines had similar OS (42.5 months vs. 48.4 months, respectively). Multivariate analysis showed that patients with triple or more lines of therapy had better OS; however, quadruple or more lines of therapy was not an independent prognostic factor. We concluded that third-line systemic therapy could improve OS; however, fourth-line therapy could not.