Nonmelanoma skin cancer is the most frequent malignancy in veterans, with an incidence exceeding that of all noncutaneous malignancies combined. The conventional goal of therapy is destruction of the primary cancer and prevention of its recurrence, a long-term outcome that cannot be assessed adequately before five years after therapy. For most tumors, many therapies can prevent recurrence, and although therapies vary in cost, existing data about effectiveness in preventing recurrence are insufficient to permit evidence-based choices among therapies.
Our immediate objective was to determine the effectiveness of different therapies in preventing tumor recurrence of primary and already recurrent nonmelanoma skin cancers.
This study was a prospective longitudinal study of a cohort of patients assembled at the time of diagnosis of nonmelanoma skin cancer (NMSC). The NMSC Cohort consists of all 1545 patients with new primary NMSC diagnosed in 1999-2000 at the San Francisco VAMC and the private practice of the dermatology department of the University of California at San Francisco. We reviewed medical records to compare tumor recurrence at at least five years after the three most common therapies -- electrodessication & curettage (ED&C), excision, and Mohs surgery. These treatments were used in 1213 patients with 1552 primary cancers. Based on our preliminary data, we had hypothesized that tumor recurrence would be highest after electrodessication & curettage, and similar after excision and Mohs surgery. We focused first on primary tumors, since far fewer tumors were recurrent at the time of presentation. Mixed effects generalized linear models were used to model the effect of procedure on outcomes, adjusting for patient, tumor, and clinician factors that might likely have affected tumor recurrence at five years after therapy. Multivariate Cox proportional hazards models were also used to explore the distribution of time to detection of first tumor recurrence.
Data collection is complete from the patients in the cohort who were treated for primary tumors at the VA site. A total of 495 patients had 616 primary NMSCs in 1999 and 2000. The mean age was 71 years; 97% were men. Follow-up data were available for 487 patients with 608 tumors (99%), for a median of 6.6 years after treatment [interquartile range (IQR) 4.5 years]. Overall, 127 (20.1%) tumors were treated with ED&C, 309 (50.8%) with excision, and 172 (28.2%) with Mohs surgery. Over the course of the study, 21 (3.5%) tumors recurred; the median time of detection of recurrence was 4.2 years after treatment (IQR 3.4 years). With respect to the treatment types, 2 of the recurrences (1.6%) were after ED&C, 13 (4.2%) after excision, and 6 (3.5%) after Mohs surgery. The recurrence rate among treatments was not significantly different (p=0.45). With survival analysis techniques and propensity-adjustment methods, no significant effect on recurrence rate differences was seen from risk factors in patients or tumors, including age, body location or size of tumor, or basal cell vs. squamous cell histology.
Based on the VA data, we conclude that recurrence of primary nonmelanoma skin cancer long-term after treatment occurred in 3.1% of tumors, and was not significantly different after ED&C, excision, or Mohs surgery. These results will be combined with that from data collected from records of patients in the cohort who were treated at the university-affiliated site.
Given the high prevalence of NMSC in older veterans, comparative effectiveness of therapies is important. The role for tumor destruction (ED&C) should be examined: the recurrence rate after ED&C was lower than previously thought. Results of this project so far suggest that recurrence outcomes are similar after the other two common therapies, excision and Mohs surgery, which vary in cost. These results provide a strong basis for a randomized trial of excision and Mohs surgery in selected subgroups of patients with nonmelanoma skin cancer.
- Chren MM, Torres JS, Stuart SE, Bertenthal D, Labrador RJ, Boscardin WJ. Recurrence after treatment of nonmelanoma skin cancer: a prospective cohort study. Archives of dermatology. 2011 May 1; 147(5):540-6.
- Chren MM, Sahay AP, Bertenthal DS, Sen S, Landefeld CS. Quality-of-life outcomes of treatments for cutaneous basal cell carcinoma and squamous cell carcinoma. The Journal of Investigative Dermatology. 2007 Jun 1; 127(6):1351-7.
- Chren MM. Determining the value of surgical therapies for basal cell carcinoma. [Editorial]. Archives of dermatology. 2006 Feb 1; 142(2):231-2.
- Chren M, Torres J, Stuart S, Labrador R, Bertenthal DS, Boscardin WJ. Tumor recurrence after treatment of keratinocyte carcinoma. Paper presented at: Society for Investigative Dermatology Annual Meeting; 2009 May 7; Montréal, Canada.
- Chren MM. Patient satisfaction with treatments of nonmelanoma skin cancer. Paper presented at: Society for Investigative Dermatology Annual Meeting; 2007 May 9; Los Angeles, CA.
- Chren M. Quality-of-Care Research in Dermatology: the Example of Nonmelanoma Skin Cancer. Paper presented at: University of Alabama Department of Dermatology Meeting; 2007 Feb 28; Birmingham, AL.