Can the Memorial Sloan-Kettering Cancer Center nomogram predict the likelihood of nonsentinel lymph node metastases in breast cancer patients in the Netherlands?
BACKGROUND
According to Dutch guidelines, an axillary lymph node dissection (ALND) is recommended whenever a sentinel lymph node (SLN) contains metastatic disease. However, only in approximately 50% of patients with metastatic disease in the SLN are additional nodal metastases detected in the completion ALND. To identify the individual patient's risk for non-SLN metastases, a nomogram containing eight predictors was developed by the Breast Service of Memorial Sloan-Kettering Cancer Center (New York, NY). The aim of this study was to test the accuracy of the nomogram on a population of Dutch breast cancer patients.


METHODS
Patient, tumor, and SLN metastasis characteristics were collected for 222 consecutive patients who underwent a completion ALND. The data of the index and test populations were compared. A receiver operating characteristic curve was drawn, and the area under the curve was calculated to assess the discriminative power of the nomogram.


RESULTS
Even though our patient population differed in many respects from the source population, the area under the receiver operating characteristic curve amounted to .77, a value very much comparable to the one found in the source population.


CONCLUSIONS
The nomogram provides a fairly accurate predicted probability for the likelihood of non-SLN metastases in a general population of breast cancer patients at a regional teaching hospital in The Netherlands. This suggests that the nomogram's originally calculated predictive accuracy may be valid for patient populations that differ considerably from the population in which it was developed.
Smidt
Marjolein L
ML
Department of Surgical Oncology, C22, Canisius Wilhelmina Hospital, P.O. Box 9015, Nijmegen, 6500 GS, The Netherlands, marjoleinsmidt@yahoo.com.
Kuster
Deborah M
DM
van der Wilt
Gert Jan
GJ
Thunnissen
Frederik B
FB
Van Zee
Kimberley J
KJ
Strobbe
Luc J A
LJ
D001943:Breast Neoplasms / Q000453:epidemiology / Q000473:pathology*; D005260:Female; D006801:Humans; D016013:Likelihood Functions; D008197:Lymph Node Excision; D008207:Lymphatic Metastasis; D008875:Middle Aged; D009426:Netherlands; D049451:Nomograms; D016612:Paraffin Embedding; D011237:Predictive Value of Tests; D012372:ROC Curve