Purpose: The incidence of renal cancer is increasing, while cases series suggest that tumor size is decreasing. This has important implications for treatment planning. We evaluated national trends in renal cancer size and observed survival in patients diagnosed in the 3 periods 1988 to 1992, 1993 to 1997 and 1998 to 2002.
Materials and methods: From the Surveillance, Epidemiology, and End Results database we identified 29,053 patients diagnosed with primary renal cancer. Patients were stratified into size categories and 5-year time cohorts. Size distribution was compared across cohorts. Kaplan-Meier survival curves and Cox proportional hazards modeling were used to examine trends in overall and stage specific survival.
Results: From 1988 through 2002 renal tumor size decreased from 66.8 to 58.6 mm, while the age adjusted incidence of renal cancer increased from 8.6 to 11.2 cases per 100,000 individuals. Kaplan-Meier analysis showed steadily deteriorating survival with increased cancer size above 4 cm with a median survival of 105 months for 4 to 7 cm vs 46 months for more than 7 cm. Cox modeling demonstrated significantly improved survival in patients diagnosed in the latter cohorts. With adjustment for size the latter cohorts remained significantly improved compared to the earliest cohort, although the 1998 to 2002 cohort was no longer significantly different than the 1993 to 1997 cohort.
Conclusions: Nationally renal tumor size at presentation has steadily and consistently decreased. Patients more recently diagnosed had improved survival, which could be attributable to decreased tumor size in the latter cohorts. Patients more recently diagnosed also demonstrated a relative survival advantage independent of size compared to the earliest patients studied.