Using REP resources, we identified 256 young adults between the ages of 18 and 39 years who were residents of Olmsted County, Minnesota, at their first lifetime diagnosis of melanoma between 1970 and 2009. Characteristics of the 256 young adults under study are summarized in .
Summary of Characteristics of 256 Young Adults With Melanomaa
Histologic slides were available for 220 of the 256 melanomas. On the basis of reanalysis, the diagnosis of melanoma was confirmed for all tumors. The histologic subtype was changed from unknown to a known category in 12 melanomas. Two tumors were changed from superficial spreading to spitzoid type.
The overall age- and sex-adjusted incidence of melanoma for these young adults was 16.9 cases per 100,000 person-years (). The age-adjusted incidence was higher for women than men (23.2 vs 10.8 cases per 100,000 person-years; P<.001). The incidence of melanoma increased with age at diagnosis (P=.05) and by calendar year of diagnosis (P<.001) for both women and men. Median age and female-male sex distribution at time of diagnosis did not change over time.
Incidence of Melanoma for Young Adults Stratified by Advanced and Invasive Disease, 1970-2009
Among the 250 patients with available pathologic stage, 24 (10%) were classified as having pathologic stage IIA or higher disease and 205 (82%) had invasive disease, classified as pathologic stage IA or higher. Incidence rates for patients with and without stage II, III, or IV disease and patients with and without invasive disease by sex and decade are summarized in .
A comparison of features by decade is given in . No statistically significant change in Breslow thickness by decade was found (P=.12; Kruskal-Wallis test). However, evidence indicated that stage II, III, or IV disease decreased by decade (P=.007; Fisher exact test), particularly in the 2000-2009 period compared with the earlier decades combined (P=.002; χ2 test).
Comparison of Characteristics by Decade in the 256 Study Patientsa,b
Site of disease varied significantly between men and women (P=.003; χ2 test) but not by histologic subtype (P=.07; χ2 test) ().
Comparison of Site by Histogenic Typea,b
At last follow-up, 12 patients were dead, with a mean survival of 5.2 years after diagnosis (median, 3.1 years; range, 0.3-21.1 years). Among the 244 patients still alive at last follow-up, the mean duration of follow-up was 7.7 years (median, 4.4 years; range, 0.0-36.8 years). Among the 12 patients who died, 8 died of melanoma, 1 died of another cause, and 3 had unknown causes of death and were therefore excluded from analyses of disease-specific survival.
Each 1-year increase in calendar year of diagnosis was associated with a significantly decreased risk of death from any cause (HR, 0.92; 95% CI, 0.86-0.97; P=.005). Similarly, each 1-year increase in calendar year of diagnosis was associated with a significantly decreased risk of death due to metastatic melanoma (HR, 0.91; 95% CI, 0.85-0.98; P=.01). Kaplan-Meier curves comparing survival by decade of diagnosis are shown in the .
Kaplan-Meier curves comparing overall survival (A) and disease-specific survival (B) by decade of diagnosis.
Sex and histologic subtype were not significantly associated with mortality. Patients with stage II, III, or IV disease were more than 35 times more likely to die compared with patients with stage I disease (HR, 35.61; 95% CI, 7.68-165.13; P<.001), a difference that persisted after adjusting for year of diagnosis (HR, 28.53; 95% CI, 6.09-133.59; P<.001). Nine of the 24 patients (38%) with stage II, III, or IV disease died compared with only 2 of the 226 patients (1%) with stage I disease. Patients with Breslow thickness greater than 2.0 mm were more than 9 times more likely to die compared with patients with Breslow thickness of 2.0 mm or less (HR, 9.42; 95% CI, 2.52-35.20; P<.001), a difference that persisted after adjusting for year of diagnosis (HR, 8.45; 95% CI, 2.26-31.62; P=.002).