Interventions for basal cell carcinoma of the skin.

BACKGROUND

Basal cell carcinoma (BCC) is the commonest cancer affecting white-skinned individuals, and worldwide incidence is increasing. Although rarely fatal, BCC is associated with significant morbidity and costs. First-line treatment is usually surgical excision, but alternatives are available. New published studies and the development of non-surgical treatments meant an update of our Cochrane Review (first published in 2003, and previously updated in 2007) was timely.

OBJECTIVES

To assess the effects of interventions for BCC in immunocompetent adults.

SEARCH METHODS

We updated our searches of the following databases to November 2019: Cochrane Skin Group Specialised Register, CENTRAL, MEDLINE, Embase, CINAHL, and LILACS.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of interventions for BCC in immunocompetent adults with histologically-proven, primary BCC. Eligible comparators were placebo, active treatment, other treatments, or no treatment.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. Primary outcome measures were recurrence at three years and five years (measured clinically) (we included recurrence data outside of these time points if there was no measurement at three or five years) and participant- and observer-rated good/excellent cosmetic outcome. Secondary outcomes included pain during and after treatment, early treatment failure within six months, and adverse effects (AEs). We used GRADE to assess evidence certainty for each outcome.

MAIN RESULTS

We included 52 RCTs (26 new) involving 6690 participants (median 89) in this update. All studies recruited from secondary care outpatient clinics. More males than females were included. Study duration ranged from six weeks to 10 years (average 13 months). Most studies (48/52) included only low-risk BCC (superficial (sBCC) and nodular (nBCC) histological subtypes). The majority of studies were at low or unclear risk of bias for most domains. Twenty-two studies were industry-funded: commercial sponsors conducted most of the studies assessing imiquimod, and just under half of the photodynamic therapy (PDT) studies. Overall, surgical interventions have the lowest recurrence rates. For high-risk facial BCC (high-risk histological subtype or located in the facial 'H-zone' or both), there may be slightly fewer recurrences with Mohs micrographic surgery (MMS) compared to surgical excision (SE) at three years (1.9% versus 2.9%, respectively) (risk ratio (RR) 0.64, 95% confidence interval (CI) 0.16 to 2.64; 1 study, 331 participants; low-certainty evidence) and at five years (3.2% versus 5.2%, respectively) (RR 0.61, 95% CI 0.18 to 2.04; 1 study, 259 participants; low-certainty evidence). However, the 95% CI also includes the possibility of increased risk of recurrence and no difference between treatments. There may be little to no difference regarding improvement of cosmetic outcomes between MMS and SE, judged by participants and observers 18 months post-operatively (one study; low-certainty evidence); however, no raw data were available for this outcome. When comparing imiquimod and SE for nBCC or sBCC at low-risk sites, imiquimod probably results in more recurrences than SE at three years (16.4% versus 1.6%, respectively) (RR 10.30, 95% CI 3.22 to 32.94; 1 study, 401 participants; moderate-certainty evidence) and five years (17.5% versus 2.3%, respectively) (RR 7.73, 95% CI 2.81 to 21.3; 1 study, 383 participants; moderate-certainty evidence). There may be little to no difference in the number of participant-rated good/excellent cosmetic outcomes (RR 1.00, 95% CI 0.94 to 1.06; 1 study, 326 participants; low-certainty evidence). However, imiquimod may result in greater numbers of good/excellent cosmetic outcomes compared to SE when observer-rated (60.6% versus 35.6%, respectively) (RR 1.70, 95% CI 1.35 to 2.15; 1 study, 344 participants; low-certainty evidence). Both cosmetic outcomes were measured at three years. Based on one study of 347 participants with high- and low-risk primary BCC of the face, radiotherapy may result in more recurrences compared to SE under frozen section margin control at three years (5.2% versus 0%, respectively) (RR 19.11, 95% CI 1.12 to 325.78; low-certainty evidence) and at four years (6.4% versus 0.6%, respectively) (RR 11.06, 95% CI 1.44 to 84.77; low-certainty evidence). Radiotherapy probably results in a smaller number of good participant- (RR 0.76, 95% CI 0.63 to 0.91; 50.3% versus 66.1%, respectively) or observer-rated (RR 0.48, 95% CI 0.37 to 0.62; 28.9% versus 60.3%, respectively) good/excellent cosmetic outcomes compared to SE, when measured at four years, where dyspigmentation and telangiectasia can occur (both moderate-certainty evidence). Methyl-aminolevulinate (MAL)-PDT may result in more recurrences compared to SE at three years (36.4% versus 0%, respectively) (RR 26.47, 95% CI 1.63 to 429.92; 1 study; 68 participants with low-risk nBCC in the head and neck area; low-certainty evidence). There were no useable data for measurement at five years. MAL-PDT probably results in greater numbers of participant- (RR 1.18, 95% CI 1.09 to 1.27; 97.3% versus 82.5%) or observer-rated (RR 1.87, 95% CI 1.54 to 2.26; 87.1% versus 46.6%) good/excellent cosmetic outcomes at one year compared to SE (2 studies, 309 participants with low-risk nBCC and sBCC; moderate-certainty evidence). Based on moderate-certainty evidence (single low-risk sBCC), imiquimod probably results in fewer recurrences at three years compared to MAL-PDT (22.8% versus 51.6%, respectively) (RR 0.44, 95% CI 0.32 to 0.62; 277 participants) and five years (28.6% versus 68.6%, respectively) (RR 0.42, 95% CI 0.31 to 0.57; 228 participants). There is probably little to no difference in numbers of observer-rated good/excellent cosmetic outcomes at one year (RR 0.98, 95% CI 0.84 to 1.16; 370 participants). Participant-rated cosmetic outcomes were not measured for this comparison. AEs with surgical interventions include wound infections, graft necrosis and post-operative bleeding. Local AEs such as itching, weeping, pain and redness occur frequently with non-surgical interventions. Treatment-related AEs resulting in study modification or withdrawal occurred with imiquimod and MAL-PDT.

AUTHORS' CONCLUSIONS: Surgical interventions have the lowest recurrence rates, and there may be slightly fewer recurrences with MMS over SE for high-risk facial primary BCC (low-certainty evidence). Non-surgical treatments, when used for low-risk BCC, are less effective than surgical treatments, but recurrence rates are acceptable and cosmetic outcomes are probably superior. Of the non-surgical treatments, imiquimod has the best evidence to support its efficacy. Overall, evidence certainty was low to moderate. Priorities for future research include core outcome measures and studies with longer-term follow-up.