Accuracy of determining nodal negativity in colorectal cancer on the basis of the number of nodes retrieved on resection.
BACKGROUND
Correct determination of nodal status is pivotal to accurate staging and predicting survival.


METHODS
This is a secondary analysis of INT0089, an intergroup trial of adjuvant chemotherapy for high-risk stage II and III colon cancer. A subset of patients was studied who underwent right or left hemicolectomy and from whom at least 10 lymph nodes were examined. A mathematical model was created to estimate the probability of a true negative result on the basis of the number of nodes examined. The number of nodes needed to predict nodal negativity with 85%, 50%, and 25% probability on the basis of tumor stage was calculated.


RESULTS
In this analysis, 1585 patients were studied. The average number of nodes removed at surgery was comparable between treatment groups at 18.5 (median of 16 in all groups). With this model, when 18 nodes are removed at resection, there is a <25% probability of true node negativity in T1/T2 tumors, whereas <10 nodes need to be examined in T3 and T4 tumors to achieve the same probability.


CONCLUSIONS
Tumor stage and the number of nodes retrieved at resection influence the accuracy of determining nodal status in colon cancer. Most patients are understaged. Underestimating nodal stage may influence decisions regarding adjuvant therapy, as well as overall prognosis.
Joseph
Natalie E
NE
Department of Surgical Oncology, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111, USA.
Sigurdson
Elin R
ER
Hanlon
Alexandra L
AL
Wang
Hao
H
Mayer
Robert J
RJ
MacDonald
John S
JS
Catalano
Paul J
PJ
Haller
Daniel G
DG
D000328:Adult; D000368:Aged; D017024:Chemotherapy, Adjuvant; D003082:Colectomy; D003110:Colonic Neoplasms / Q000188:drug therapy / Q000473:pathology* / Q000601:surgery*; D003131:Combined Modality Therapy; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008197:Lymph Node Excision; D008207:Lymphatic Metastasis / Q000175:diagnosis* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D009367:Neoplasm Staging; D011379:Prognosis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity