Recurrence after treatment of nonmelanoma skin cancer: a prospective cohort study.

OBJECTIVE: To determine long-term tumor recurrence rates after treatment of primary nonmelanoma skin cancer (NMSC). Data are currently insufficient to permit evidence-based choices among treatments for NMSC.

DESIGN: Prospective study of an inception cohort observed for a median of 6.6 years after treatment.

SETTING: Dermatology clinic at a Veterans Affairs hospital. Care was provided by dermatology resident or attending physicians.

PATIENTS: Consecutive sample of all 495 patients with 616 primary NMSCs diagnosed in 1999 and 2000 and treated with electrodessication and curettage (ED&C), excision, or Mohs surgery. Follow-up was available for 608 tumors (99%).

MAIN OUTCOME MEASURE: Tumor recurrence, determined by medical record review, with validation by clinical examination.

RESULTS: The mean age at diagnosis was 71 years; 97% were men. Overall, 127 tumors were treated with ED&C (20.9%); 309 with excision (50.8%); and 172 with Mohs surgery (28.3%). Over the course of the study, 21 tumors recurred (3.5% [95% confidence interval (CI), 2.2%-5.2%]): 2 after ED&C (1.6% [95% CI, 0.2%-5.6%]), 13 after excision (4.2% [95% CI, 2.2%-7.1%]), and 6 after Mohs surgery (3.5% [95% CI, 1.3%-7.4%]).

CONCLUSIONS: Recurrence of primary NMSC after treatment occurred in less than 5% of tumors. The recurrence rate after ED&C was lower than expected, and the recurrence rate after Mohs surgery was higher than expected. These findings may be related to the risk for recurrence in the treatment groups.