Presentation Authors: Toshio Takagi*, Kazuhiko Yoshida, Tsunenori Kondo, Junpei Iizuka, Hirohito Kobayashi, Hideki Ishida, Masayoshi Okumi, Yoji Nagashima, Kazunari Tanabe, Tokyo, Japan
Introduction: Tumor enucleation is expected to preserve more renal parenchyma and avoid damaging renal vessels or the collecting system for hilar tumors by providing a negative surgical margin. Although peritumoral PCs are a landmark for tumor enucleation, all renal tumors were not surrounded by PC. Determining whether or not a PC exists is useful for avoiding a positive cancer margin when tumor enucleation is employed for RAPN; however, there are a few reports discussing the factors associated with the presence/absence of a PC. In the present study, we examined peritumoral PC status in patients with localized RCC who underwent RAPN in relation to patient or tumor characteristics including pathological findings, and carried out a multivariate analysis to identify factors that would allow prediction of the absence of a PC.
Methods: A total of 367 patients with clinical T1 RCC who underwent RAPN were divided into two groups according to PC status. The groups were compared in terms of patient and tumor characteristics. A PC was defined as present if it completely surrounded the tumor. Four micrometer-thick paraffin sections were stained with hematoxylin-eosin staining and observed by an authorarized pathologists (YN). Multivariate logistic regression analysis was performed to identify predictive factors for the absence of PC.
Results: Of the 367 tumors, 323 (88%) were surrounded by a PC. Mean tumor size was 30 mm and 70% of patients were male. Tumors with a PC had a larger diameter than those without (31 vs. 26 mm; P = 0.0008). A PC was observed in 92% of clear cell, 89% of papillary, and 86% of clear cell papillary RCC cases compared to only 50% in chromophobe RCC cases (P < 0.0001). Sex, age, Furman grade, and tumor complexity did not differ among patients. A multivariate analysis showed that smaller tumor size (â‰¥ 34 vs. < 34 mm, odds ratio [OR]: 3.31; P = 0.0023) and chromophobe RCC (vs. other subtypes, OR: 12.5; P < 0.0001) predicted an absence of PC.
Conclusions: Small tumor size and chromophobe RCC were significant predictors of a lack of PC, suggesting that a positive surgical margin must be avoided for these tumors when an enucleation technique is employed for partial nephrectomy.