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[Optimal margin in nephron-sparing surgery for renal cell carcinoma 4 cm or less in diameter]
Quan-lin Li1, Hong-wei Guan, Li-zhi Zhang
1Department of Urology, First Affiliated Hospital, Dalian Medical University, Dalian 116011, China.
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 pseudocapsule 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 (chi(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.
Insights
For renal cell carcinoma (RCC) 4 cm or less, a margin exceeding 5 mm during nephron-sparing surgery (NSS) is recommended. Enucleation alone increases recurrence risk, especially with incomplete pseudocapsules or high PCNA indices.
Area of Science:
- Urology
- Oncology
- Surgical Pathology
Context:
- Nephron-sparing surgery (NSS) is a standard treatment for small renal cell carcinoma (RCC).
- Determining the optimal surgical margin is crucial for preventing local recurrence.
- Previous studies have not definitively established the required margin for complete tumor excision in smaller RCCs.
Purpose:
- To determine the optimal margin for nephron-sparing surgery (NSS) in renal cell carcinoma (RCC) measuring 4 cm or less.
- To assess the relationship between pseudocapsule integrity, PCNA expression, and the presence of extra-pseudocapsule cancer lesions.
- To evaluate the risk of incomplete excision with different surgical margins.
Summary:
- Analysis of 82 RCCs (≤4 cm) revealed incomplete pseudocapsules in 31.7% and extra-pseudocapsule lesions in 17.1%.
- The maximum distance of extra-pseudocapsule lesions was 5 mm, suggesting a >5 mm margin is needed.
- Higher PCNA indices and incomplete pseudocapsules were significant predictors of extra-pseudocapsule spread (P=0.019).
Impact:
- Findings suggest a >5 mm parenchymal margin is necessary for NSS in small RCCs to minimize recurrence risk.
- Enucleation alone poses a significant risk of incomplete excision.
- Patients with incomplete pseudocapsules or high PCNA indices require closer follow-up post-NSS.