Session: PD08: Kidney Cancer: Epidemiology & Evaluation/Staging/Surveillance I
PD08-12: Predictors of progression and delayed intervention in small renal mass patients undergoing active surveillance without health-related selection bias
Introduction: Active surveillance (AS) allows many patients with small renal masses (SRM) to avoid treatment, however study of progression and delayed intervention (DI) outcomes has been limited by high proportions of observation patients who are unfit for treatment. We recently described our initial clinical experience prospectively using pre-defined progression criteria for intervention (PCI) in a unique AS cohort of SRM patients lacking health-related selection. Our current objective was to identify predictors of PCI development and DI in this cohort. Methods: From January 2013-March 2019, all patients with non-hereditary SRM seen by a single urologic oncologist at a National Comprehensive Cancer Network institute were recommended AS if predefined PCI were absent. PCI were defined prospectively as any SRM-related symptoms, unfavorable biopsy histology, cT3a stage, or any of the following without benign neoplastic biopsy histology: longest tumor diameter (LTD) >4 cm; growth rate >5 mm/year for LTD =3 cm or >3 mm/year for LTD >3 cm. DI was recommended during AS upon new PCI development. 5-year PCI-free and DI-free survival were assessed using Kaplan-Meier methods. Clinical variables at presentation or during AS (sex, age, race, body mass index, comorbidities, initial tumor number/size, biopsy histology) were tested for association with time to PCI development or DI. Results: Of 208 consecutive SRM patients, 201 were PCI-free at presentation and underwent AS. With median follow up of 46 months, there were no metastases, and new PCI was diagnosed in 30% of AS patients, of which 69% underwent DI. Only 1 (1%) patient crossed over to DI without tumor PCI. 5-year PCI- and DI-free rates were 60% and 71%, respectively. On univariable analyses, shorter time to PCI was significantly associated with non-Caucasian race, lower Charlson score, initial LTD, and clear cell biopsy histology, while the latter 3 variables also significantly predicted shorter time to DI. On multivariable analyses including all variables, only clear cell biopsy histology independently predicted PCI and DI. On multivariable analyses excluding biopsy histology, only initial LTD independently predicted PCI and DI. Conclusions: Among SRM patients undergoing AS without health-related selection, LTD and clear cell biopsy histology are primary drivers of PCI development and DI. Non-Caucasian race and fewer comorbidities increase progression risk but not independently of LTD and histology. These findings may be useful for counseling AS patient candidates. SOURCE OF Funding: None
