Kane CJ et al. (2008) Renal cell cancer stage migration: analysis of the National Cancer Data Base. Cancer 113: 78–83

In the US, evidence indicates that newly diagnosed renal cell carcinoma (RCC) is more likely to be low-stage disease today than formerly. The effect of this trend towards a lower stage of RCC at diagnosis, however, requires evaluation. Kane and colleagues, therefore, used data from the National Cancer Data Base to reveal changes in RCC stage distribution over time, and to determine whether these changes influenced patients' outcomes.

Data were analyzed from 205,963 patients diagnosed with RCC between 1993 and 2004 for whom information on RCC stage at diagnosis was available. Of their tumors, 50.6% were stage I, 26.7% were stage II or III, and 22.7% were stage IV. Over a 12-year period, the percentage of patients with stage I tumors at diagnosis increased from 43.0% to 57.1%, counterbalanced by a decreased percentage of patients diagnosed with stage II–IV tumors (e.g. the proportion of stage IV tumors decreased from 27.4% to 18.7%). The average size of stage I tumors at detection decreased from 4.1 cm to 3.6 cm over this period. The observed downward stage migration resulted in a small but significant improvement in overall 5-year survival (63.3% of patients diagnosed in 1993 survived for 5 years, compared with 66.6% of patients diagnosed in 1998).

This study confirmed that stage migration—a shift in the distribution of RCC stages at presentation—has occurred in the US, primarily because of incidental detection of RCCs during abdominal imaging studies for non-RCC indications.