The lymph node ratio does not provide additional prognostic information compared with the N1/N2 classification in Stage III colon cancer.
OBJECTIVE
The ratio of positive nodes to total nodes, the lymph node ratio (LNR), is a proposed alternative to the current N1/N2 classification of nodal disease. The true clinical benefit of adopting the LNR, however, has not been definitively demonstrated. This study compared the LNR with the current N1/N2 classification of Stage III colon cancer.


METHODS
Patients with Stage III colon cancer were identified from a prospectively maintained database (1996-2012). The specificity and sensitivity of the N1/N2 classification in the prediction of overall survival were determined using R. A cut-off point for the LNR was determined by setting the specificity the same as for the N1/N2 classification. The sensitivity of the two methods was then compared, and bootstrapping 1000-fold was performed. This was then repeated for disease-specific survival.


RESULTS
The specificity and sensitivity of the N1/N2 classification in predicting 3-year overall survival in this cohort (n = 402) was 62.2% and 52.1%, respectively. The cut-off point for the LNR was determined to be 0.27 for these data. On comparing LNR with the N1/N2 classification showed that for a given specificity, the LNR did not provide a statistically significant improvement in sensitivity (52.8% vs 52.1%, P = 0.31). For disease-specific death at 3 years, the specificity and sensitivity were 60.8% and 54.6%, respectively. The LNR did not provide a statistically significant improvement (55.4% vs 54.6%, P = 0.44).


CONCLUSIONS
Both the N1/N2 system and the LNR predict survival in colon cancer, but both have low specificity and sensitivity. The LNR does not provide additional prognostic value to current staging for overall or disease-specific survival for a given cut-off point.
Centre for Colorectal Disease, St Vincent's University Hospital, Dublin, Ireland.|School of Medicine and Medical Sciences, University College Dublin, Dublin, Ireland.
H M
HM
Mohan
Department of Statistics, Trinity College Dublin, Dublin, Ireland.|Department of Mathematics and Statistics, University of Limerick, Dublin, Ireland.
C
C
Walsh
Centre for Colorectal Disease, St Vincent's University Hospital, Dublin, Ireland.
R
R
Kennelly
Centre for Colorectal Disease, St Vincent's University Hospital, Dublin, Ireland.
C H
CH
Ng
Centre for Colorectal Disease, St Vincent's University Hospital, Dublin, Ireland.|School of Medicine and Medical Sciences, University College Dublin, Dublin, Ireland.
P R
PR
O'Connell
Centre for Colorectal Disease, St Vincent's University Hospital, Dublin, Ireland.
J M
JM
Hyland
Centre for Colorectal Disease, St Vincent's University Hospital, Dublin, Ireland.|School of Medicine and Medical Sciences, University College Dublin, Dublin, Ireland.
A
A
Hanly
Centre for Colorectal Disease, St Vincent's University Hospital, Dublin, Ireland.
S
S
Martin
Centre for Colorectal Disease, St Vincent's University Hospital, Dublin, Ireland.
D
D
Gibbons
Centre for Colorectal Disease, St Vincent's University Hospital, Dublin, Ireland.|School of Medicine and Medical Sciences, University College Dublin, Dublin, Ireland.
K
K
Sheahan
Centre for Colorectal Disease, St Vincent's University Hospital, Dublin, Ireland.|School of Medicine and Medical Sciences, University College Dublin, Dublin, Ireland.
D C
DC
Winter
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003110:Colonic Neoplasms / Q000401:mortality / Q000473:pathology*; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology*; D008875:Middle Aged; D009367:Neoplasm Staging; D011379:Prognosis; D015996:Survival Rate
Lymph node ratio; nodal count; nodal status