Risk of Invasive Cutaneous Squamous Cell Carcinoma After Different Treatments for Actinic Keratosis: A Secondary Analysis of a Randomized Clinical Trial.

Importance: Treatment of actinic keratosis (AK) aims to prevent cutaneous squamous cell carcinoma (cSCC). However, whether AK can progress into invasive cSCC is a matter of debate, and little is known about the effect of treatment on preventing cSCC. Objectives: To evaluate the risk of invasive cSCC and factors that may contribute to increased risk in patients with multiple AKs. Design, Setting, and Participants: In this secondary analysis of a multicenter randomized clinical trial, 624 patients with a minimum of 5 AKs within an area of 25 to 100 cm2 on the head were recruited from the Department of Dermatology of 4 hospitals in the Netherlands. Long-term follow-up was performed from July 1, 2019, to December 31, 2020. Interventions: Patients were randomized to treatment with 5% fluorouracil, 5% imiquimod cream, methylaminolevulinate photodynamic therapy, or 0.015% ingenol mebutate gel. Main Outcomes and Measures: The primary outcome was the proportion of patients with invasive cSCC in the target area during follow-up. Secondary outcomes were the associations between risk of invasive cSCC and a priori defined potential prognostic factors, including type of treatment, severity of AK (Olsen grade), history of nonmelanoma skin cancer, and additional treatment. Results: Of the 624 patients (558 [89.4%] male; median age, 73 years [range, 48-94 years]) in the study, 26 were diagnosed with a histologically proven invasive cSCC in the target area during follow-up. The total 4-year risk of developing cSCC in a previously treated area of AK was 3.7% (95% CI, 2.4%-5.7%), varying from 2.2% (95% CI, 0.7%-6.6%) in patients treated with fluorouracil to 5.8% (95% CI, 2.9%-11.3%) in patients treated with imiquimod. In patients with severe AK (Olsen grade III), the risk was 20.9% (95% CI, 10.8%-38.1%), and the risk was especially high (33.5%; 95% CI, 18.2%-56.3%) in patients with severe AK who needed additional treatment. Conclusions and Relevance: In this secondary analysis of a randomized clinical trial, risk of invasive cSCC was highest in patients with Olsen grade III AK and was substantially increased in patients who received additional treatment. These patients should be closely followed up after treatment. Trial Registration: ClinicalTrials.gov Identifier: NCT02281682.

Trends in the Incidence of Bowen Disease Based on a Single-Center Study in the Netherlands.

BACKGROUND: Incidence trends of nonmelanoma skin cancer show an increase. Few data have been published about the incidence of Bowen disease (BD). Three previous studies, conducted more than 15 years ago in North America, found large variation in incidence rates in Caucasians, and trends over longer periods have never been studied. OBJECTIVE: To estimate the incidence of BD in a Caucasian population in Northern Europe (Maastricht, the Netherlands) between 2003 and 2013. METHODS: Primary and histologically confirmed BD, diagnosed in Maastricht, the Netherlands, in the years 2003, 2008, and 2013, was retrieved from a pathology database. Age-standardized and sex-specific incidence rates per 100,000 inhabitants were calculated by using the age distribution of the European standard population of 2013. RESULTS: A statistically significant increase in the annual age-standardized incidence rates per 100,000 people was found from 8.1 (95% confidence interval [CI] 3.7-12.5) in 2003 to 68.9 (95% CI 57.2-80.7) in 2013 (p < .001). For women, there was an increase from 7.7/100,000 (95% CI 2.0-13.4) in 2003 to 76.8/100,000 (95% CI 60.2-93.5) in 2013, respectively (p < .001). An increase from 8.8/100,000 (95% CI 1.8-15.9) in 2003 to 59.2/100,000 men (95% CI 42.8-75.6) in 2013 (p < .001) was found. CONCLUSION: These findings suggest an increase in the annual age-standardized incidence rates in BD.

Randomized Trial of Four Treatment Approaches for Actinic Keratosis.

BACKGROUND: Actinic keratosis is the most frequent premalignant skin disease in the white population. In current guidelines, no clear recommendations are made about which treatment is preferred. METHODS: We investigated the effectiveness of four frequently used field-directed treatments (for multiple lesions in a continuous area). Patients with a clinical diagnosis of five or more actinic keratosis lesions on the head, involving one continuous area of 25 to 100 cm2, were enrolled at four Dutch hospitals. Patients were randomly assigned to treatment with 5% fluorouracil cream, 5% imiquimod cream, methyl aminolevulinate photodynamic therapy (MAL-PDT), or 0.015% ingenol mebutate gel. The primary outcome was the proportion of patients with a reduction of 75% or more in the number of actinic keratosis lesions from baseline to 12 months after the end of treatment. Both a modified intention-to-treat analysis and a per-protocol analysis were performed. RESULTS: A total of 624 patients were included from November 2014 through March 2017. At 12 months after the end of treatment, the cumulative probability of remaining free from treatment failure was significantly higher among patients who received fluorouracil (74.7%; 95% confidence interval [CI], 66.8 to 81.0) than among those who received imiquimod (53.9%; 95% CI, 45.4 to 61.6), MAL-PDT (37.7%; 95% CI, 30.0 to 45.3), or ingenol mebutate (28.9%; 95% CI, 21.8 to 36.3). As compared with fluorouracil, the hazard ratio for treatment failure was 2.03 (95% CI, 1.36 to 3.04) with imiquimod, 2.73 (95% CI, 1.87 to 3.99) with MAL-PDT, and 3.33 (95% CI, 2.29 to 4.85) with ingenol mebutate (P≤0.001 for all comparisons). No unexpected toxic effects were documented. CONCLUSIONS: At 12 months after the end of treatment in patients with multiple actinic keratosis lesions on the head, 5% fluorouracil cream was the most effective of four field-directed treatments. (Funded by the Netherlands Organization for Health Research and Development; ClinicalTrials.gov number, NCT02281682.).

Histologic subtype of treatment failures after noninvasive therapy for superficial basal cell carcinoma: An observational study.

BACKGROUND: There have been concerns that recurrences after noninvasive therapy for basal cell carcinoma (BCC) transform into a "more aggressive" histologic subtype. OBJECTIVE: We sought to evaluate the proportion of patients with a nonsuperficial treatment failure after noninvasive therapy for superficial BCC. METHODS: An observational study was performed using data from a single blind, noninferiority, randomized controlled trial (March 2008-August 2010) with 5-year follow-up in patients with primary superficial BCC treated with methylaminolevulinate-photodynamic therapy, 5-fluorouracil, or imiquimod. Data were used from 166 adults with a histologically confirmed treatment failure. RESULTS: A nonsuperficial subtype was found in 64 of 166 treatment failures (38.6%). Proportions with a more aggressive subtype than the primary tumor were 51.3% (38/74) for early and 28.3% (26/92) for later treatment failures (P = .003). The proportion of more aggressive early failures was significantly lower after imiquimod (26.3%) compared with methylaminolevulinate-photodynamic therapy (54.8%, P = .086) and 5-fluorouracil (66.7%, P = .011). LIMITATIONS: There was limited information on the exact time of occurrence of treatment failures. CONCLUSION: More aggressive treatment failure recurrences after noninvasive therapy for superficial BCC occur most often within the first 3 months posttreatment, probably indicating underdiagnosis of more aggressive components in the primary tumor rather than transformation.

Five-Year Results of a Randomized Controlled Trial Comparing Effectiveness of Photodynamic Therapy, Topical Imiquimod, and Topical 5-Fluorouracil in Patients with Superficial Basal Cell Carcinoma.

For the treatment of superficial basal cell carcinoma, a prospective, noninferiority, randomized controlled multicenter trial with 601 patients showed that 5% imiquimod cream was superior and 5-fluorouracil cream not inferior to methyl aminolevulinate photodynamic therapy (MAL-PDT) at 1 and 3 years after treatment. No definite conclusion could be drawn regarding the superiority of imiquimod over 5-fluorouracil. We now present the 5-year follow-up results according to the intention-to-treat analysis. Five years after treatment, the probability of tumor-free survival was 62.7% for methyl aminolevulinate photodynamic therapy (95% confidence interval [CI] = 55.3-69.2), 80.5% for imiquimod (95% CI = 74.0-85.6), and 70.0% for 5-fluorouracil (95% CI = 62.9-76.0). The hazard ratio for treatment failure of imiquimod and 5-fluorouracil were 0.48 (95% CI = 0.32-0.71, P < 0.001) and 0.74 (95% CI = 0.53-1.05, P = 0.09), respectively, when compared with methyl aminolevulinate photodynamic therapy. Compared with 5-fluorouracil, imiquimod showed a hazard ratio of 0.65 (95% CI 0.43-0.98, P = 0.04). In conclusion, 5 years after treatment, the results of this trial show that 5% imiquimod cream is superior to both methyl aminolevulinate photodynamic therapy and 5-fluorouracil cream in terms of efficacy for superficial basal cell carcinoma. We therefore consider 5% imiquimod cream as the first choice for noninvasive treatment in most primary superficial basal cell carcinomas.