Independent value of tumor size and DNA ploidy for the prediction of disease progression in patients with organ-confined renal cell carcinoma.

BACKGROUND Greater than 20% of patients with apparently localized renal cell carcinoma (RCC) present with disease progression after surgery. The objective of the current study was to improve the ability of clinicians to predict prognosis in patients with localized RCC. METHODS The authors studied 154 patients with organ-confined RCC classified as pT1 to pT2–pN0–M0 who underwent radical nephrectomy. Follow-up ranged from 24–128 months (median, 72 months). Several morphologic parameters of the tumor were considered. DNA content was analyzed by flow cytometry and tumor size was determined from the surgical specimen. A Cox proportional hazards regression model was used to identify significant independent prognostic factors for disease progression. RESULTS At 5 and 10 years of follow-up, disease free survival was found to be 87% and 86%, respectively. Univariate analysis revealed that DNA content, Furhman grade, and tumor size had a statistically significant predictive value for disease progression, whereas, with regard to grade, the difference was significant only between patients with Grade 3 tumors and all other patients with Grade 1–2 tumors (P < 0.0001). Although DNA content was found to correlate with tumor size (P < 0.0001), multivariate analysis showed that these were the only significant independent predictors of disease progression. The sum of DNA content and tumor size therefore was considered to distinguish separate risk groups. For a patient with diploid RCC, the risk of progression increased from 4% if the tumor size was 3 cm to 43% if the tumor size was 10 cm. For a patient with nondiploid RCC, this risk was 32% if the tumor size was 3 cm, increasing to 99% for tumors measuring 10 cm. CONCLUSIONS Stratification of organ-confined RCC according to tumor size and DNA content could possibly provide more information that could be useful in the selection of individuals with significantly different risks of disease progression. Cancer 2000;88:835–43. © 2000 American Cancer Society.