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Keywords:

  • cured-fraction survival model;
  • cutaneous melanoma;
  • log-normal survival model;
  • prognostic factors;
  • recurrence

Abstract

BACKGROUND

The clinical course of cutaneous melanoma is associated with pathologic and clinical factors, such as thickness, ulceration, and location of tumor and gender of the patient. The authors used a parametric survival model that incorporated a cured fraction of patients to translate these factors into specific estimates of long-term outcome.

METHODS

A cohort study was conducted of 5837 patients who were treated for localized cutaneous melanoma between 1978 and 1990 at the Duke Comprehensive Cancer Center. Of these, 495 patients were excluded because the survival status or one or more of the prognostic factors was unknown. Maximum follow-up was 22 years. The primary outcome measures examined were cured fraction (probability of cure), median tumor specific survival (i.e., median time to death from tumor), and the probability of tumor-related survival at fixed intervals after treatment.

RESULTS

For an example of a class of patients with a relatively good prognosis, consider women with nonulcerated lesions measuring 0.5 mm thick on an extremity. The probability of cure (± standard error) for these patients was estimated at 80.8% ± 2.0%, and the median tumor specific survival was 10.0 years ± 0.8 years. This suggests that, in these patients, half of the deaths from melanoma will occur more than 10 years after treatment, barring death from other causes. Conversely, men with ulcerated lesions measuring 8.00 mm thick on the trunk have a relatively poor prognosis. The probability of cure for these patients was 16.8% ± 2.4%, and the median tumor specific survival was 2.7 years ± 0.2 years. Despite this poor initial prognosis, the conditional probability of cure increased to 90%; after 15 years of recurrence free survival.

CONCLUSIONS

Parametric statistical analysis provides quantitative measures of long-term survival. These measures show that late recurrence—longer than a decade after treatment—is to be expected in a significant portion of patients, although the probability of cure increases with progressively longer recurrence free survival. Cancer 2002;95:1286–93. © 2002 American Cancer Society.

DOI 10.1002/cncr.10813