Identification of high-risk patients among those diagnosed with thin cutaneous melanomas.
OBJECTIVE
Most patients with melanoma have microscopically thin (< or = 1 mm) primary lesions and are cured with excision. However, some develop metastatic disease that is often fatal. We evaluated established prognostic factors to develop classification schemes with better discrimination than current American Joint Committee on Cancer (AJCC) staging.


METHODS
We studied patients with thin melanomas from the US population-based Surveillance, Epidemiology, and End Results (SEER) cancer registry (1988 to 2001; n = 26,291) and those seen by the University of Pennsylvania's Pigmented Lesion Group (PLG; 1972 to 2001; n = 2,389; Philadelphia, PA). AJCC prognostic factors were thickness, anatomic level, ulceration, site, sex, and age; PLG prognostic factors also included a set of biologically based candidate prognostic factors. Recursive partitioning was used to develop a SEER-based classification tree that was validated using PLG data. Next, a new PLG-based classification tree was developed using the expanded set of prognostic factors.


RESULTS
The SEER-based classification tree identified additional criteria to explain survival heterogeneity among patients with thin, nonulcerated lesions; 10-year survival rates ranged from 89.1% to 99%. The new PLG-based tree identified groups using level, tumor cell mitotic rate, and sex. With survival rates from 83.4% to 100%, it had better discrimination.


CONCLUSIONS
Prognostication and related clinical decision making in the majority of patients with melanoma can be improved now using the validated, SEER-based classification. Tumor cell mitotic rate should be incorporated into the next iteration of AJCC staging.
Gimotty
Phyllis A
PA
The Melanoma Program of the Abramson Cancer Center, Center for Clinical Epidemiology and Biostatistics, Department of Biostatistics and Epidemiology, University of Pennsylvania School of Medicine, Philadelphia, PA, USA. pgimotty@cceb.med.upenn.edu
Elder
David E
DE
Fraker
Douglas L
DL
Botbyl
Jeffrey
J
Sellers
Kimberly
K
Elenitsas
Rosalie
R
Ming
Michael E
ME
Schuchter
Lynn
L
Spitz
Francis R
FR
Czerniecki
Brian J
BJ
Guerry
DuPont
D
D000368:Aged; D015331:Cohort Studies; D003663:Decision Trees; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008545:Melanoma / Q000175:diagnosis* / Q000401:mortality / Q000473:pathology; D008875:Middle Aged; D008940:Mitotic Index; D009367:Neoplasm Staging; D011379:Prognosis; D011446:Prospective Studies; D012372:ROC Curve; D015203:Reproducibility of Results; D018570:Risk Assessment; D018426:SEER Program; D012737:Sex Factors; D012878:Skin Neoplasms / Q000175:diagnosis* / Q000401:mortality / Q000473:pathology; D016019:Survival Analysis; D013997:Time Factors; D014481:United States