Análise de linfonodos no câncer colorretal: o impacto do uso de uma solução clareadora de gorduras

Abstract

Background: Lymph node (LN) involvement is one of the most important criteria for staging colorectal cancer (CRC). Special procedures have been recommended in order to improve LN analysis and metastasis detection. The aims of this study were to evaluate the impact of using a fat clearance solution in LN dissection. Method: We analysed prospectively 74 CRC (35 men, median age 62.9 years-old). After routine (conventional - CM ) LN dissection, the fat was emerged in a mixture containing 65%alcohol, 20% ether, 5% acetic acid and 10% formalin (at 10%) for 36 hours (3 changes). A new LN search was performed. LN diameters were measured using a computerized system (KS400, Karl Zeiss, Germany). The number of positive and negative LN with <4mm was determined. The number and measures of the LN obtained by both methods were compared and analysed in respect to patients and tumour characteristics. Results: All CRC were adenocarcinomas, 81% moderately differentiated and 69% pT3; 3167 LN (42.8/case) were dissected: 1814 (24.5/case) by the CM and 1355 (18.3/case) after the use of the clearing solution (CS). Metastasis were detected in 196 LN: 170 (86.7%) by the CM and 26 (13.2%) after CS; 59% of the LN dissected conventionally had <4mm (n=1068, 14.4/case; range 0.4-23mm); 93% of the LN dissected after CS had <4mm (n=1261, 17/case; range 0.2-11mm). Among the 170 positive LN (LN+) conventionally dissected, 39 (22.9%) had <4mm; 73% of the LN+ dissected after CS measured <4mm (p=0.000). The use of the CS increased the LN number in 74.7% (p=0.000), the detection of small LN in 118% (p=0.000), and metastasis in 15.3% of the cases (p=0.003). The number of LN dissected in both groups was correlated (r=0.3; p=0.004) and the number of LN+after CS was higher when at least one metastasis was previously detected (p=0.007); pN changed in 5 cases (p=0.03); 90% of the LN+ cases were detected only after the dissection of 40 LN. Patients age (r=-0,2; p=0.04), LN diameter (smallest: r=- 0.3;p=0.01; biggest: r=0.3;p=0.004) and the number of <4mm LN (r=0.9; p=000) weresignificantly associated with LN number. The number of LN was independently predicted by the pT, the number of <4mm LN and the diameter of the biggest LN. Conclusion: A large number of small LN must be dissected to adequately stage CRC. Fat clearing solutions simple to apply and neither expensive nor time consuming, might be useful for this propose. Key Words: colorectal cancer, lymph node metastases, staging, fat clearance solution.