Assessment of melanoma thickness based on dermoscopy images: an open, web-based, international, diagnostic study.

BACKGROUND: Preoperative assessment of whether a melanoma is invasive or in situ (MIS) is a common task that might have important implications for triage, prognosis and the selection of surgical margins. Several dermoscopic features suggestive of melanoma have been described, but only a few of these are useful in differentiating MIS from invasive melanoma. OBJECTIVE: The primary aim of this study was to evaluate how accurately a large number of international readers, individually as well as collectively, were able to discriminate between MIS and invasive melanomas as well as estimate the Breslow thickness of invasive melanomas based on dermoscopy images. The secondary aim was to compare the accuracy of two machine learning convolutional neural networks (CNNs) and the collective reader response. METHODS: We conducted an open, web-based, international, diagnostic reader study using an online platform. The online challenge opened on 10 May 2021 and closed on 19 July 2021 (71 days) and was advertised through several social media channels. The investigation included, 1456 dermoscopy images of melanomas (788 MIS; 474 melanomas ≤1.0 mm and 194 >1.0 mm). A test set comprising 277 MIS and 246 invasive melanomas was used to compare readers and CNNs. RESULTS: We analysed 22 314 readings by 438 international readers. The overall accuracy (95% confidence interval) for melanoma thickness was 56.4% (55.7%-57.0%), 63.4% (62.5%-64.2%) for MIS and 71.0% (70.3%-72.1%) for invasive melanoma. Readers accurately predicted the thickness in 85.9% (85.4%-86.4%) of melanomas ≤1.0 mm (including MIS) and in 70.8% (69.2%-72.5%) of melanomas >1.0 mm. The reader collective outperformed a de novo CNN but not a pretrained CNN in differentiating MIS from invasive melanoma. CONCLUSIONS: Using dermoscopy images, readers and CNNs predict melanoma thickness with fair to moderate accuracy. Readers most accurately discriminated between thin (≤1.0 mm including MIS) and thick melanomas (>1.0 mm).

Curettage vs. cryosurgery for superficial basal cell carcinoma: a prospective, randomised and controlled trial.

BACKGROUND: Basal cell carcinoma (BCC) is the most common cancer in the world and has a rising incidence. Current guidelines for low-risk BCC including superficial BCC (sBCC) recommend several treatment options including destructive treatment methods, such as cryosurgery with or without prior curettage or curettage and electrodesiccation. Curettage only (i.e. without subsequent cryosurgery or electrodesiccation) is a simple and quick destructive treatment method used for many benign skin lesions but has not been sufficiently evaluated for the treatment of sBCCs. OBJECTIVES: The objective was to compare the effectiveness of curettage vs. cryosurgery for sBCCs in terms of overall clinical clearance rates after 1 year as well as wound healing times. METHODS: A single-centre non-inferiority clinical trial was conducted. Non-facial sBCCs with a diameter of 5-20 mm were randomised to either cryosurgery using one freeze-thaw cycle or curettage. At follow-up visits, treatment areas were evaluated regarding the presence of residual tumour after 3-6 months and recurrence after 1 year. Further, wound healing times were assessed. RESULTS: In total, 228 sBCCs in 97 patients were included in the analysis. At 3-6 months, no residual tumours were seen in any of the treated areas. After 1 year, the clinical clearance rates for curettage and cryosurgery were 95.7% and 100%, respectively (P = 0.060). However, the non-inferiority analysis was inconclusive. Wound healing times were shorter for curettage (4 weeks) compared to cryosurgery (5 weeks; P < 0.0001). Overall, patient satisfaction at 1 year was high. CONCLUSIONS: Both treatment methods showed high clinical clearance rates after 1 year, whilst curettage reduced the wound healing time.

Methotrexate treatment for patients with psoriasis and risk of cutaneous melanoma: a nested case-control study.

BACKGROUND: Cutaneous malignant melanoma (CMM) is a highly immunogenic tumour. Patients with an impaired immune system have an enhanced risk for CMM and a worse prognosis. Methotrexate (MTX) is an anti-inflammatory and immunosuppressive drug frequently used to treat patients with psoriasis. An association between MTX and risk of CMM has previously been demonstrated in patients with rheumatoid arthritis. OBJECTIVES: To investigate whether MTX increases the risk of CMM among patients with psoriasis. METHODS: A nested case-control investigation from a Swedish cohort of patients with psoriasis was conducted. Data were obtained from available Swedish registers and included 395 patients with psoriasis who had previously been cancer-free and had a first CMM in the time period from 1 January 2010 to 31 December 2016. A total of 10 randomly selected cancer-free patients with psoriasis were matched per case with respect to age (same birth year) and sex. The accumulated MTX doses in both groups were obtained. Crude odds ratios (ORs) for the proportion of MTX in the respective group were calculated using conditional logistic regression analyses. RESULTS: Of 395 patients with psoriasis who had CMM, 97 (25%) had filled a prescription of MTX; of 3950 controls, the corresponding number was 954 (24%). In a conditional logistic regression analysis, no association between MTX exposure (ever use) and risk for CMM was observed (OR 1·0, 95% confidence interval 0·8-1·3). Moreover, no indication of a dose-response association was observed. CONCLUSIONS: In this Swedish nested case-control study, the use of MTX was not associated with an enhanced risk for CMM. These findings are reassuring for dermatologists in everyday clinical practice. What is already known about this topic? Methotrexate (MTX) treatment has been linked to an increased risk for cutaneous malignant melanoma (CMM) in an Australian cohort of patients with rheumatoid arthritis. In a previous retrospective Swedish cohort investigation, patients who had exclusively been prescribed MTX by a dermatologist did not have an enhanced risk for CMM compared with MTX-unexposed individuals. Nevertheless, this cohort did not specifically include patients with psoriasis. What does this study add? This Swedish nested case-control investigation included 395 previously cancer-free patients with psoriasis who had CMM (cases) and 3950 matched cancer-free patients with psoriasis (controls). No association between MTX exposure and risk for CMM in patients with psoriasis was observed. The results are reassuring for dermatologists using MTX to treat patients with psoriasis. Linked Comment: Haugaard and Egeberg. Br J Dermatol 2020; 183:608-609.

Effectiveness of photodynamic therapy in Bowen's disease: a retrospective observational study in 423 lesions.

BACKGROUND: Photodynamic therapy (PDT) is a well-known technique that is often used for treating superficial precancerous and cancerous skin lesions. However, only a handful of studies, with a relatively small number of treated lesions, have been carried out on the effectiveness of PDT for Bowen's disease (BD). OBJECTIVES: This study aimed to assess the effectiveness and recurrence risk of PDT in the treatment of BD. The secondary objectives were to determine what factors affected the response rates and the cosmetic result of the treatment. METHOD: In this retrospective observational study, the electronic patient charts at Sahlgrenska University Hospital (SUH) in Gothenburg, Sweden, were searched to find all patients diagnosed with BD who were treated with PDT between 1 January 2002 and 31 December 2014. Data were collected regarding clinical response at the first follow-up visit, recurrences during later follow-up visits and other relevant patient and tumour characteristics. RESULTS: In total, 423 BD lesions in 335 patients were included in the study. The mean FU duration was 11.2 months (range 0.2-151 months). The complete response rate at the first FU visit was 77.5% for all BD lesions. During later FU visits, another 60 recurrences were observed, which resulted in a recurrence rate of 18.3%. Thus, the overall clearance rate after FU was 63.4% for all BD lesions. Significant risk factors for unsuccessful treatment in this study were large lesion size (>2 cm) and a single PDT session. CONCLUSION: This study shows that PDT is a relatively effective treatment modality for BD.

Methotrexate treatment and risk for cutaneous malignant melanoma: a retrospective comparative registry-based cohort study.

BACKGROUND: Methotrexate (MTX) is frequently used as an immunosuppressive drug in inflammatory diseases. It is controversial and it has not been thoroughly investigated whether MTX increases the risk of cutaneous malignant melanoma (CMM). OBJECTIVES: The aim of the present study was to investigate whether MTX exposure increases the risk for CMM. METHODS: A retrospective cohort study was conducted using statistics from the National Board of Health and Welfare. All patients over 18 years in the time period August 2005 to December 2014 that were dispensed MTX from Swedish pharmacies were registered (n = 101 966). For every MTX-exposed patient, five age- and sex-matched patients who had been dispensed a random drug other than MTX during the same time period were randomly selected (n = 509 279). The lists were matched with the Swedish Cancer Registry. RESULTS: Overall, a small but statistically significant (P < 0·001) risk increase for CMM was observed in MTX-exposed patients compared with patients without MTX exposure. The Kaplan-Meier estimates for the 5-year risk of CMM was 0·48% [95% confidence interval (CI) 0·43-0·53] in the MTX-exposed group and 0·41% (95% CI 0·39-0·43) in the MTX-unexposed group. However, in a subgroup analysis, the difference between the groups was preserved only in women older than 70 years at treatment start. Moreover, there was no significant difference in incidences between the MTX-exposed and MTX-unexposed patients in the time period. CONCLUSIONS: Our results suggest a small but significant increase in risk for CMM in patients treated with MTX. However, the risk increase observed was considerably lower than in earlier observations.

Merkel cell carcinoma incidence is increasing in Sweden.

BACKGROUND: Merkel cell carcinoma (MCC) is a rare aggressive neuroectodermal skin cancer with a high recurrence rate and a high mortality rate. Risk factors for MCC are reported to include high age, UV exposure, Caucasian skin type and immunosuppression. The incidence is reported to be increasing. OBJECTIVE: The purpose of this study was to describe a Swedish cohort and calculate incidence. METHODS: The study design is a retrospective cohort study of population-based data for MCC collected by the Swedish Cancer Registry to determine the incidence of MCC in Sweden and the clinical characteristics of these tumours including demographics, TNM classification, body part distribution and overall survival after diagnosis. De-identified data were collected from 1993 to 2012. RESULTS: A total of 606 cases of MCC were identified during the study period. The median age was 81 years (range 21-99) and a majority, 54.4% were women but age-adjusted incidence is higher in men. The incidence (per 100,000) of MCC in Sweden in 1993-2012 increased from 0.09 to 0.20 for men and 0.12-0.17 for women, adjusted for age to the world standard population. For the both sexes, the increase was from 0.11 to 0.19 per 100 000, an increase of 73%. The most common site of the primary tumour was the head and neck, with 51.8% of the cases. The size of the tumour was <5 cm in 82.1% of the cases. The majority of the tumours (90.7%) had no known lymphatic spread and only a few patients had confirmed distant metastases (2.9%) when diagnosed. CONCLUSIONS: MCC is a rare disease in Sweden, but the incidence is increasing. This study supports the finding that high age, male sex and UV exposure are risk factors for MCCs. Interventions are required to increase awareness of MCC among clinicians and the public.

Aminolevulinic acid and methyl aminolevulinate equally effective in topical photodynamic therapy for non-melanoma skin cancers.

BACKGROUND: Topical photodynamic therapy (PDT) is an effective treatment for superficial non-melanoma skin cancers. Two prodrugs, 5-aminolevulinic acid (ALA) and methyl aminolevulinate (MAL), are available for clinical use. There is, however, a lack of studies comparing the clinical effectiveness of these two prodrugs. OBJECTIVE: The objective of the study was to compare the clinical response between ALA- and MAL-PDT when treating actinic keratosis (AK), Bowen's disease (BD), nodular basal cell carcinoma (nBCC) and superficial basal cell carcinoma (sBCC). METHODS: During the period 2002-2009, patients with AK, BD, nBCC and sBCC were treated with ALA- and MAL-PDT at the Department of Dermatology at Karlskoga Hospital in Sweden using a fixed protocol. All patients were followed up approximately 6 months after treatment to evaluate the clinical results, which were analysed retrospectively. RESULTS: In total, 116 patients with 203 tumours were treated with PDT during the study period. ALA- and MAL-PDT were used for 24 vs. 44 AK fields, 9 vs. 18 BD lesions, 19 vs. 25 nBCCs and 25 vs. 39 sBCCs. Response rates with ALA- and MAL-PDT, respectively, were 63% and 75% for AK, 89% and 78% for BD, 84% and 84% for nBCC and 88% and 87% for sBCC. There were no statistically significant differences in the complete clinical response rates for ALA- and MAL-PDT when used for any of the four lesion types. CONCLUSION: ALA- and MAL-PDT appear to be equally effective in the treatment of AK, BD, nBCC and sBCC. Nevertheless, larger, prospective, randomized and controlled studies should be carried out to confirm these results.