Upstaging benefits and accuracy of sentinel lymph node mapping in colorectal adenocarcinoma nodal staging.
OBJECTIVE
Sentinel lymph node (SLN) mapping is an additional method for improving colorectal cancer nodal staging. The purpose of the study was to define the method's accuracy in nodal staging, its upstaging benefits and to identify the predictive factors for its failure.


METHODS
Lymphatic mapping was performed using technetium-99m-phytate and patent blue in 52 consecutive colorectal adenocarcinoma patients. Enhanced pathological examination was carried out on SLNs with hematoxylin-eosin step-sectioning and immunochemistry.


RESULTS
The patients studied had an average tumor size of 6.5 cm; 85% had T3/T4 tumors; and rectal tumors represented 57.7% of the group. Overall SLN mapping accuracy was 79.5%, with sensitivity of 65.2% and 34.8% false negatives. Upstaging with SLN mapping was 23.1%. Colon tumors had an SLN identification rate of 90.9% and rectal tumors had 63.3% (P = 0.023). Multivariate statistical analysis identified lower rectal tumor (P = 0.009), neoadjuvant treatment (P = 0.029) and tumor size (P = 0.036) as independent risk factors for the inability to detect SLNs.


CONCLUSIONS
Upstaging benefits of SLN mapping should be considered in colon and mid- and upper rectal tumors. The method should be avoided in patients with lower rectal tumors, large tumors and having had neoadjuvant therapy.
Quadros
Claudio Almeida
CA
Colorectal Division, Aristides Maltez Hospital, Salvador, Brazil. caquadros@gmail.com
Lopes
Ademar
A
Araujo
Iguaracyra
I
Fregnani
Jose Humberto
JH
Fahel
Fernanda
F
D000230:Adenocarcinoma / Q000473:pathology*; D000328:Adult; D000368:Aged; D015179:Colorectal Neoplasms / Q000473:pathology*; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011237:Predictive Value of Tests; D012307:Risk Factors; D012680:Sensitivity and Specificity; D021701:Sentinel Lymph Node Biopsy / Q000379:methods*