Skin melanoma. Cured fraction and survival time as functions of thickness, site, histologic type, age, and sex.
BACKGROUND
Previously, nonparametric or semiparametric methods have been used to determine the relationship of various prognostic covariates with survival of skin cancer. Unfortunately, these methods do not readily distinguish between factors that modulate cure and those that modulate survival time among uncured patients.


METHODS
The multivariate lognormal model can be used to detect the association of cured fraction and median survival time with specific prognostic covariates. This model was applied to survival data from 2004 patients with skin melanoma using the following prognostic covariates: thickness, site, and histologic type of the tumor and sex and age of the patient.


RESULTS
This analysis revealed that a low cured fraction was associated with thick lesions and location other than trunk or extremity, whereas a short median survival time was associated with thick lesions and tumor located on the trunk. Advanced age was highly associated only with short median survival time.


CONCLUSIONS
The lognormal survival model offers insight into the biology of skin melanoma by distinguishing the roles played by likelihood of cure and survival time. The differential associations of various covariates with these two parameters suggest that biologic mechanisms that govern cure are not identical to those that govern survival time.
Gamel
J W
JW
Veterans Administration Medical Center, Louisville, Kentucky.
George
S L
SL
Stanley
W E
WE
Seigler
H F
HF
D000367:Age Factors; D005260:Female; D006801:Humans; D008297:Male; D008545:Melanoma / Q000401:mortality* / Q000473:pathology; D012737:Sex Factors; D012878:Skin Neoplasms / Q000401:mortality* / Q000473:pathology; D015996:Survival Rate