Suggestion of optimal patient characteristics for sentinel lymph node mapping in colorectal adenocarcinoma.

Context: In a previously published study, the variables lower rectal tumor site, preoperative chemoradiotherapy and large tumors were considered as independent risk factors for the inability of sentinel lymph node identification in patients with colorectal adenocarcinoma.

Objectives: To determine if these variables could interfere in the precision and upstaging benefit of sentinel lymph node mapping in colorectal cancer.

Methods: A database composed of 52 patients submitted to lymphatic mapping using technetium-99m-phytate and patent blue was reviewed. Only patients with tumors smaller than 5.0 cm, not submitted to preoperative chemoradiotherapy and without lower rectal cancer were included.

Results: With these parameters, 11 patients remained to be studied. The sentinel lymph node identification rate was 100%, with a sensitivity of 100%, negative predictive value of 100%, no false negatives and accuracy of 100%. Sentinel lymph nodes were the only metastatic nodes in 36.4% of the patients, micrometastases (<0.2 cm or only identified by immunohistochemistry) provided an upstaging rate of 27.1% and metastases an upstaging rate of 9.1%.

Conclusion: The parameters proposed in this study for selection of colorectal adenocarcinoma patients to be submitted to sentinel lymph node mapping identified optimal accuracy and good upstaging results. As the number of included patients was low, these results could serve as guidance for proper patient selection in further prospective lymph node mapping studies in colorectal cancer patients.