CU 41. The correlation between size of renal cell carcinoma and its histopathological characteristics - a single center study of 1867 renal cell carcinoma cases

Objective: To investigate the correlation between tumor size and histopathological characteristics of renal cell carcinoma (RCC).

Methods: A total of 1867 patients who underwent surgical operation between January 2002 and March 2010 due to RCC were included. Tumors were stratified by the largest pathologic diameter into 5 groups, the discrepancy of tumor grade between different groups and whether tumor size could predict histological subtype were analyzed. According to 1997 WHO recommendation about nuclear grading of RCC which criteria we used, Fuhrman 1 and Fuhrman 2 were merged to well differentiated tumor (G1), and Fuhrman 3 was considered to be intermediate differentiated tumor (G2), and Fuhrman 4 was considered to be poorly differentiated or undifferentiated tumor (G3).

Results: The largest diameter (mean ± SD) of G1, G2, and G3 tumors were 3.27±1.46 cm, 4.87±2.23 cm, and 7.39±3.11 cm, respectively. The percentage of extracapsular extension tumors in 2 cm or less, 2.1 and 4.0 cm, 4.1 to 7 cm, 7.1 to 10 cm, and more than 10 cm group were 0.5%, 4.3%, 19.8%, 57.9%, and 91.9%, respectively. The distribution of G1 tumors shows a decreasing trend with the diameter becoming larger, while the G3 tumors shows an opposite trend (P<0.05). Logistic regression analysis predicted that the odds of papillary, chromophobe, and other types versus clear cell decreased with increase in tumor size. If the tumor was complicated with hemorrhage or necrosis, the chance of being chromophobe was higher. For a tumor with cystic degeneration, the probability of being papillary and chromophobe decreased.

Conclusions: There was a significant correlation between tumor size and tumor grade and stage; Larger tumors were prone to have higher grade and stage, and the probability of being clear cell carcinoma grew higher as the tumor size increased.