Melanoma staging: Varying precision and terminal digit clustering in Breslow thickness data is evident in a population-based study - 18/06/18
Abstract |
Background |
Errors in Breslow thickness reporting can give misclassification of T category, an important classifier in melanoma staging.
Objective |
We sought to investigate precision (number of digits) and terminal digit clustering in Breslow thickness and potential consequences for T category.
Methods |
All first primary and morphologically verified invasive melanomas in Norway between 2008 and 2015 were included. A smoothing model was fitted to estimate the underlying Breslow thickness distribution without digit clustering.
Results |
Thickness was reported for 13,057 (97.5%) patients; the median was 1.0 mm (range, 0.09-85). It was reported as whole numbers (15.6%), to 1 decimal (78.2%) and 2 decimal places (6.2%)—thin tumors with more precision than thick tumors. Terminal digit clustering was found with marked peaks in the observed frequency distribution for terminal digits 0 and 5, and with drops around these peaks. Terminal digit clustering increased proportions of patients classified with T1 and T4 tumors and decreased proportions classified with T2 and T3.
Limitations |
Breslow thickness was not reported in 2.5% of cases.
Conclusions |
The Norwegian recommendation of measurement to the nearest 0.1 mm was not followed. Terminal digit clustering was marked, with consequences for T category. Pathologists, clinicians, and epidemiologists should know that clustering of thickness data around T category cut points can impact melanoma staging with consequent effect on patient management and prognosis.
Le texte complet de cet article est disponible en PDF.Key words : Breslow thickness, melanoma, misclassification, precision, T category, terminal digit clustering
Abbreviations used : AJCC, ALM, CM, CRN, NM, NMMR, SEER
Plan
Funding sources: None. |
|
Conflicts of interest: None disclosed. |
|
Presented as a poster at the World Conference of Melanoma, Brisbane, Australia, October 18-21, 2017. |
|
Reprints not available from the authors. |
Vol 79 - N° 1
P. 118 - juillet 2018 Retour au numéroBienvenue sur EM-consulte, la référence des professionnels de santé.
L’accès au texte intégral de cet article nécessite un abonnement.
Déjà abonné à cette revue ?