Changeable prognosis and associated prognostic factors for conditional survival estimates in metastatic renal cell carcinoma patients receiving the first-line targeted therapy.
587 Background: Conditional survival (CS) indicates the probability that patient would survive additional periods, given that the patients has previous survivorship after diagnosis or initial treatment. Here, we aim to evaluate the CS probabilities in mRCC patients who underwent targeted therapy with tyrosine kinase inhibitors (TKI) and to identify the significant prognostic factors of the CS over time. Methods: A total of 1,498 mRCC patients receiving 1st line TKI was finally analyzed from Korean multicenter database of mRCC. Kaplan-Meier survival estimates was used to calculate overall and cancer-specific CS rates by using following formula: CS(α│β) = S(α+β)/S(β), where CS(α│β) indicates the likelihood of additional α years survivorship in the person who has already survived for β years after initial diagnosis or treatment, and S(χ) is the actual survival rate. The Cox regression analysis was used to determine the predictors of CS depended on clinicopathological features. Results: We observed that 1, 2, 3, 4, and 5-year conditional cancer-specific survival (CSS) gradually increased as patients who have all additional survivorships after initial treatment, compared to those with baseline survival estimation. Also, 1, 2, 3, 4, and 5-year conditional OS rates also increased after additional 1, 2, 3, 4, and 5 year survivorships following first-line TKI treatment. Furthermore, we found that key predictive factors of OS and CSS were changed over time in multivariate analysis. While several variables, such as BMI, histologic subtypes, pT stage, were identified as prognosticators of CSS at baseline, they were not remained as independent predictors after 1 yr survivorship. Conversely, only previous metastatectomy was determined as a key prognostic factor for conditional OS over time until 4 yr survivorship after initial TKI treatment. Conclusions: Our study offers valuable information for practical survival estimation and relevant predictive factors for patients with mRCC receiving targeted therapy.