Faced with the growing incidence of nonmelanoma skin cancer (NMSC), clinicians continue to seek guidance on the best method of tumor removal. Simple excision, electrodessication and curretage (ED&C), and Mohs micrographic surgery (MMS) all are acceptable methods for tumor removal and are generally associated with reasonably low risks for recurrence. Each approach has been suggested to have benefits over the others, especially in particular cases. A new analysis sheds light on tumor recurrence after each treatment.1 The findings, largely consistent with previous research, offer points for critical consideration and suggest that successful long-term treatment probably depends on careful patient follow-up.
The current study of NMSC recurrence is based on an analysis of patients from a single dermatology clinic at a Veterans Affairs hospital. Follow-up was available for 487 patients treated for 608 tumors. A total of 616 primary NMSCs were removed from 495 patients during the two-year period from January 1999 through December 2000. Median follow-up time was 6.6 years. Based on analysis of patient records, the overall recurrence rate for NMSC in this cohort was 3.5 percent. Specifically, two recurrences were seen after ED&C (1.6 percent [95 percent CI, 0.2 percent–5.6 percent]), 13 after excision (4.2 percent [95 percent CI, 2.2 percent– 7.1 percent]), and six after MMS (3.5 percent [95 percent CI, 1.3 percent–7.4 percent]).
Five-year recurrence rates were calculated using survival analysis techniques to account for differential follow-up. The adjusted recurrence rates were 1.8 percent (95 percent CI, 0.4 percent–6.9 percent) after ED&C, four percent (95 percent CI, 2.2 percent–7.4 percent) after excision, and 2.6 percent (95 percent CI, 0.8 percent–7.7 percent) after MMS.
An interesting aspect of this study is that it incorporated blinded investigator evaluation of previously treated tumor sites of available subjects rather than relying solely on records. Of the total 249 patients alive at the time of recruitment for examination (treated for 301 tumors), 127 patients treated for 152 tumors consented to participate. Evidence of possible tumor recurrence was found in 21 tumor sites (14 percent). Subsequent chart review led to the determination that four of these were recurrent tumors, while 16 were not recurrent. Insufficient records existed to make a determination of recurrence of one tumor.
The median time to detection of recurrence overall was 4.2 years. Recurrent tumors were detected earliest after ED&C, at a median 1.5 years, and latest after MMS, at a median six years. Recurrence was detected a median 3.8 years post-excision.
The rate of recurrence was highest for BCCs: 3.4 percent of all BCCs recurred, accounting for 71 percent of all recurrences, compared to SCC. There was no significant difference in the size of tumors that did or did not recur. The only anatomic factor associated with a difference in the rate of recurrence was a somewhat higher likelihood of recurrence in the Hzone of the face (4.9 percent in this zone versus 2.4 percent at other sites).
The study authors acknowledge that there were differences in patients, tumors, and care in the three treatment groups. They note that tumors in the H-zone of the face were more frequently treated with MMS. This is not surprising, given the desire to minimize unnecessary tissue destruction in this high-visibility anatomic area. There were also differences in who provided care. In the ED&C and excision groups, treatment was most often provided by a resident; almost no MMSs performed by dermatology residents.
These differences could contribute to variability in the recurrence rates found between these groups. More importantly, these differences between the groups reflect a clinical reality that underlies any comparison of outcomes in skin cancer removal. While clinicians would prefer to treat patients with the intervention that poses the lowest risk for recurrence, issues such as anatomic location of lesions, lesion number, and lesion size may favor one treatment over another. Furthermore, while ED&C and excision are widely available, there may be limited access to MMS in some areas, as it must be performed by a fellowship- trained dermatologic surgeon.
This study had a minimum of five years follow-up. According to the authors, up to 25 percent of published studies on recurrence had less than five years of data. The rate of recurrence following MMS in this study, at 3.5 percent, may be higher than expected, while the rate of recurrence associated with standard excision in this study is somewhat lower than anticipated. Variation from other published findings is not substantial, nor do these current figures require us to reassess conventional thinking about recurrence rates. Instead, this study reminds that outcomes are variable, and the risk for recurrence—and development of a second primary NMSC— always exists.
Choosing a method of tumor removal is rarely a decision based on general reported recurrence rates. As noted above, lesion location, patient history, characteristics of the patient, and characteristics of the lesion all influence the decision. There are certain high-risk tumor types for which MMS provides clear advantages, while there are other classic presentations in which more conventional approaches are clearly indicated. Providing treatment according to current standards of care is essential (proper margins, etc.), but long-term patient follow-up remains critical. Any patient who has a NMSC removed must perform skin self-exams and be followed-up by a dermatologists at appropriate intervals for skin exams.
Dr. Wolfe has no relevant disclosures.
Jonathan Wolfe, MD, FAAD is in private practice in Plymouth Meeting, PA and is on staff at the Pigmented Lesion Clinic, University of Pennsylvania, Philadelphia.