Diabetes, Obesity, and Pathological Upstaging in Renal Cell Carcinoma: Results From a Large Multi-institutional Consortium.

PURPOSE: We sought to determine whether clinical risk factors and morphometric features on preoperative imaging can be utilized to identify those patients with cT1 tumors who are at higher risk of upstaging (pT3a). MATERIALS AND METHODS: We performed a retrospective international case-control study of consecutive patients treated surgically with radical or partial nephrectomy for nonmetastatic renal cell carcinoma (cT1 N0) conducted between January 2010 and December 2018. Multivariable logistic regression models were used to study associations of preoperative risk factors on pT3a pathological upstaging among all patients, as well as subsets with those with preoperative tumors ≤4 cm, renal nephrometry scores, tumors ≤4 cm with nephrometry scores, and clear cell histology. We also examined association with pT3a subsets (renal vein, sinus fat, perinephric fat). RESULTS: Among the 4,092 partial nephrectomy and 2,056 radical nephrectomy patients, pathological upstaging occurred in 4.9% and 23.3%, respectively. Among each group independent factors associated with pT3a upstaging were increasing preoperative tumor size, increasing age, and the presence of diabetes. Specifically, among partial nephrectomy subjects diabetes (OR=1.65; 95% CI 1.17, 2.29), male sex (OR=1.62; 95% CI 1.14, 2.33), and increasing BMI (OR=1.03; 95% CI 1.00, 1.05 per 1 unit BMI) were statistically associated with upstaging. Subset analyses identified hilar tumors as more likely to be upstaged (partial nephrectomy OR=1.91; 95% CI 1.12, 3.16; radical nephrectomy OR=2.16; 95% CI 1.44, 3.25). CONCLUSIONS: Diabetes and higher BMI were associated with pathological upstaging, as were preoperative tumor size, increased age, and male sex. Similarly, hilar tumors were frequently upstaged.