Optimal margin in nephron-sparing surgery for renal cell carcinoma 4 cm or less in diameter

Objective To investigate the optimal margin in nephron sparing surgery (NSS) for renal cell carcinoma (RCC) 4 cm or less in diameter. Methods Eighty two kidneys with RCC 4 cm or less in diameter resected by radical nephrectomy were prospectively studied The kidney samples were sectioned at 3 mm interval and examined for multicentricity. On each layer of tissue sectioned, parenchyma margin of 15 mm beyond pseudocapsule was continuously sectioned and examined for completeness of pseudocapsule and extra pseudocapsule cancer lesion. The farthest distance between extra pseudocapsule lesion and primary tumor was measured PCNA expression was detected in 41 patients by using standard SP immunohistochemistry technique Results The diameter of 82 primary tumors was 3 4±0 8 cm (range 1 5-4 0 cm) Of these, 31 7% (26/82) were found without intact pseudocapsules and 17 1% (14/82) with positive cancer lesions beyond pseudocapsule The average distance between extra pseudocapsule cancer lesion and primary tumor was 0 5±1 3 mm (range 0-5 0 mm), with a confidential interval (CI) of 95% (0 11, 0 94) Statistically, the one side percentile P 95 was 4 9 mm, P 97 5 was 5 0 mm and P 100 was 5 0 mm The mean PCNA index in the 41 patients with RCC was (29 5±17 6)%,which was (49 6±21 5)% in the group with extra pseudocapsule cancer lesions and (24 6±12 7)% in the group without ( t =3 162, P =0 013) The ratio of strong expression was 5/8 in the group with extra pseudocapsule cancer lesions,and 18 2%(6/33)in the group without the lesions(χ 2=6 442, P =0 011) Logistic regression analysis showed that completeness of pseudocapsule and PCNA index were significant predictors of extra pseudocapsule cancer lesions ( P =0 019). Conclusions These data suggest that when NSS is performed in RCC 4 cm or less in diameter, a margin of more than 5 mm of adjacent parenchyma should be excised with the tumor Enucleation alone was associated with a significant risk of incomplete excision, and therefore liable for local recurrence Tumors with incomplete pseudocapsule and (or) high PCNA indices are more likely to have extra pseudocapsule cancer lesions, so intensive follow up is necessary after NSS.