Prevalence of skin examination behaviours among Australians over time

International patterns and trends in the incidence of melanoma and cutaneous squamous cell carcinoma, 1989-2020

BACKGROUND

Cutaneous squamous cell carcinoma (cSCC) and melanoma have different associations with sun exposure.

OBJECTIVES

To compare trends in the incidence rates of cSCC and melanoma, to provide insight into changing patterns of exposure to ultraviolet radiation (UVR).

METHODS

We compared trends in the incidence of cSCC and melanoma in seven susceptible populations residing at mid-to-high latitudes: Finland, Norway, Sweden, Denmark, Scotland, the Netherlands and Tasmania (Australia). We fitted Joinpoint models to describe trends in age-standardized incidence rates for melanoma and cSCC and calculated the average annual percentage rate of change for the period 1989-2020 (1989-2018 for Tasmania). We calculated the incident rate ratio (IRR) as the ratio of the age-standardized rates (European Standard Population) for cSCC to melanoma and conducted age-period-cohort modelling to compare age, period and cohort effects.

RESULTS

The ratio of cSCC-to-melanoma incidence increased with proximity to the equator and over time. In the most recent time period, the incidence of cSCC was higher than the incidence of melanoma for men and women in all seven populations. While the ratio of cSCC-to-melanoma incidence was higher for men vs. women, in most countries the cSCC-to-melanoma IRR increased over time to a greater extent in women than in men. Melanoma incidence was higher among younger people and cSCC incidence was higher among older people; the age at which the incidence of cSCC overtook the incidence of melanoma was progressively younger with proximity to the equator.

CONCLUSIONS

Despite concerted international efforts to preserve the ozone layer over the past four decades resulting in significant reductions in surface ultraviolet B at mid-latitudes, the incidence of skin cancer, particularly cSCC, continues to rise in those regions. Our findings are consistent with a stronger association with age-associated cumulative sun exposure for cSCC vs. melanoma and suggest that women are currently receiving greater UV radiation exposure than in the past.

Acceptability and appropriateness of a risk-tailored organised melanoma screening program: Qualitative interviews with key informants

INTRODUCTION

In Australia, opportunistic screening (occurring as skin checks) for the early detection of melanoma is common, and overdiagnosis is a recognised concern. Risk-tailored cancer screening is an approach to cancer control that aims to provide personalised screening tailored to individual risk. This study aimed to explore the views of key informants in Australia on the acceptability and appropriateness of risk-tailored organised screening for melanoma, and to identify barriers, facilitators and strategies to inform potential future implementation. Acceptability and appropriateness are crucial, as successful implementation will require a change of practice for clinicians and consumers.

METHODS

This was a qualitative study using semi-structured interviews. Key informants were purposively selected to ensure expertise in melanoma early detection and screening, prioritising senior or executive perspectives. Consumers were expert representatives. Data were analysed deductively using the Tailored Implementation for Chronic Diseases (TICD) checklist.

RESULTS

Thirty-six participants were interviewed (10 policy makers; 9 consumers; 10 health professionals; 7 researchers). Key informants perceived risk-tailored screening for melanoma to be acceptable and appropriate in principle. Barriers to implementation included lack of trial data, reluctance for low-risk groups to not screen, variable skill level in general practice, differing views on who to conduct screening tests, confusing public health messaging, and competing health costs. Key facilitators included the perceived opportunity to improve health equity and the potential cost-effectiveness of a risk-tailored screening approach. A range of implementation strategies were identified including strengthening the evidence for cost-effectiveness, engaging stakeholders, developing pathways for people at low risk, evaluating different risk assessment criteria and screening delivery models and targeted public messaging.

CONCLUSION

Key informants were supportive in principle of risk-tailored melanoma screening, highlighting important next steps. Considerations around risk assessment, policy and modelling the costs of current verses future approaches will help inform possible future implementation of risk-tailored population screening for melanoma.

Skin cancer-related conditions managed in general practice in Australia, 2000-2016: a nationally representative, cross-sectional survey

OBJECTIVE

Skin cancer is Australia's most common and costly cancer. We examined the frequency of Australian general practice consultations for skin cancer-related conditions, by patient and general practitioner (GP) characteristics and by time period.

DESIGN

Nationally representative, cross-sectional survey of general practice clinical activity.

SETTING, PARTICIPANTS

Patients aged 15 years or older having a skin cancer-related condition managed by GPs in the Bettering the Evaluation And Care of Health study between April 2000 and March 2016.

PRIMARY OUTCOME MEASURES

Proportions and rates per 1000 encounters.

RESULTS

In this period, 15 678 GPs recorded 1 370 826 patient encounters, of which skin cancer-related conditions were managed 65 411 times (rate of 47.72 per 1000 encounters, 95% CI 46.41 to 49.02). Across the whole period, 'skin conditions' managed were solar keratosis (29.87%), keratinocyte cancer (24.85%), other skin lesion (12.93%), nevi (10.98%), skin check (10.37%), benign skin neoplasm (8.76%) and melanoma (2.42%). Over time, management rates increased for keratinocyte cancers, skin checks, skin lesions, benign skin neoplasms and melanoma; but remained stable for solar keratoses and nevi. Skin cancer-related encounter rates were higher for patients aged 65-89 years, male, living in Queensland or in regional or remote areas, with lower area-based socioeconomic status, of English-speaking background, Veteran card holders and non-healthcare card holders; and for GPs who were aged 35-44 years or male.

CONCLUSION

These findings show the spectrum and burden of skin cancer-related conditions managed in general practice in Australia, which can guide GP education, policy and interventions to optimise skin cancer prevention and management.

The effect of screening on melanoma incidence and biopsy rates

BACKGROUND

Cutaneous melanomas are common cancers in white-skinned populations, and early detection is promoted as a means of reducing morbidity and mortality. There is concern that increased skin screening is leading to overdiagnosis of indolent melanomas with low risk of lethality. The extent of melanoma overdiagnosis associated with screening is unknown.

OBJECTIVES

To estimate possible overdiagnosis by comparing subsequent melanoma incidence and biopsy rates among people subjected to skin screening those who were not.

METHODS

We recruited 43 762 residents of Queensland, Australia, aged 40-69 years, with no prior history of melanoma, selected at random from a population register in 2010. At baseline, participants completed a comprehensive melanoma risk factor survey and were asked if their skin had been examined by a doctor in the 3 years prior to baseline. We calculated incidence and relative risk of histologically confirmed melanoma (invasive and in situ) in years 2-7 of follow-up, obtained through linkage to the cancer registry. In secondary analyses, we measured biopsy rates in years 2-6 of follow-up. We used propensity score analysis to calculate adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs).

RESULTS

In total, 28 155 participants underwent skin screening prior to baseline. We observed 967 first-incident melanomas (381 invasive) during 197 191 person-years of follow-up. Those screened had higher rates of melanoma (aHR 1·29, 95% CI 1·02-1·63) and subsequent skin biopses (aHR 1·85, 95% CI 1·69-2·04) than unscreened participants. The higher risk associated with skin screening was evident for in situ melanoma (aHR 1·45, 95% CI 1·09-1·92) but not invasive melanoma (aHR 1·05, 95% CI 0·72-1·54). In secondary analyses, where screening was defined as having a skin biopsy in the first year after baseline, we observed significantly increased risks of melanoma (aHR 1·53, 95% CI 1·23-1·89) and subsequent biopsies (aHR 2·64, 95% CI 2·46-2·84) relative to those who did not have a biopsy.

CONCLUSIONS

People who undergo skin screening subsequently experience higher rates of biopsies and melanoma (especially in situ melanoma), even after adjusting for all known risk factors, consistent with overdiagnosis. What is already known about this topic? Cutaneous melanomas are common cancers in white-skinned populations for which early detection is promoted as a means of reducing morbidity and mortality. There is concern that increased surveillance is leading to the overdiagnosis of indolent melanomas that are not destined to be lethal. The extent of melanoma overdiagnosis associated with surveillance is not known. What does this study add? People subjected to skin examinations by a doctor or who undergo skin biopsies subsequently have higher numbers of biopsies and higher rates of melanoma than people not subjected to either, even after adjusting for all known risk factors. These findings suggest that heightened surveillance leads to a proportion of melanomas being diagnosed that otherwise may not have come to clinical attention.

Incidence of in Situ vs Invasive Melanoma: Testing the "Obligate Precursor" Hypothesis

Background

Melanoma incidence has been rising in populations with predominantly European ancestry (White), speculated to be partly driven by heightened detection of indolent tumors. If in situ melanomas are destined to evolve to invasive cancers, detecting and removing them should deplete the pool of invasive lesions, and people with in situ melanoma should, on average, be younger than those with invasive melanoma.

Methods

We analyzed long-term incidence trends (1982-2018) for in situ and invasive melanomas in 3 predominantly White populations with high, medium, and low melanoma rates: Queensland (Australia), United States White, and Scotland. We calculated the incidence rate ratio (IRR) of in situ to invasive melanomas and estimated the contributions of age, period, and cohort effects. We compared age at diagnosis of in situ vs invasive melanomas overall and stratified by sex and anatomic site.

Results

In all 3 populations, the in situ to invasive incidence rate ratio increased statistically significantly from less than 0.3 in 1982 to 1.95 (95% confidence interval [CI] = 1.88 to 2.02) in Queensland, 0.93 (95% CI = 0.90 to 0.96) in the US White population, and 0.58 (95% CI = 0.54 to 0.63) in Scotland in 2018. The mean age at diagnosis of in situ melanomas was the same or higher than invasive melanomas for almost all time periods among men and women and on all body sites except the lower limbs.

Conclusions

The increasing ratio of in situ to invasive melanoma incidence over time, together with the high (and increasing) mean age at diagnosis of in situ melanomas, is consistent with more indolent lesions coming to clinical attention than in previous eras.

Genetically determined cutaneous nevi and risk of cancer

Numerous epidemiologic studies have reported positive associations between higher nevus counts and internal cancers. Whether this association represents a true relationship or is due to bias or confounding by factors associated with both nevus counts and cancer remains unclear. We used germline genetic variants for nevus count to test whether this phenotypic trait is a risk-marker for cancer. We calculated polygenic risk scores (PRS) for nevus counts using individual-level data in the UK Biobank (n = 394 306) and QSkin cohort (n = 17 427). The association between the nevus PRS and each cancer site was assessed using logistic regression adjusted for the effects of age, sex and the first five principal components. In both cohorts, those in the highest nevus PRS quartile had higher risks of melanoma than those in the lowest quartile (UK Biobank odds ratio [OR] 1.42, 95% confidence interval [CI]: 1.29-1.55; QSkin OR 1.58, 95% CI: 1.29-1.94). We also observed increases in risk of basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) associated with higher nevus PRS quartiles (BCC UK Biobank OR 1.38, 95% CI: 1.33-1.44; QSkin OR 1.20, 95% CI: 1.05-1.38 and SCC UK Biobank OR 1.41, 95% CI: 1.28-1.55; QSkin OR 1.44, 95% CI: 1.19-1.77). We found no consistent evidence that nevus count PRS were associated with risks of developing internal cancers. We infer that associations between nevus counts and internal cancers reported in earlier observational studies arose because of unmeasured confounding or other biases.

Association Between Melanoma Detected During Routine Skin Checks and Mortality

Importance

Early melanoma diagnosis is associated with better health outcomes, but there is insufficient evidence that screening, such as having routine skin checks, reduces mortality.

Objective

To assess melanoma-specific and all-cause mortality associated with melanomas detected through routine skin checks, incidentally or patient detected. A secondary aim was to examine patient, sociodemographic, and clinicopathologic factors associated with different modes of melanoma detection.

Design, Setting, and Participants

This prospective, population-based, cohort study included patients in New South Wales, Australia, who were diagnosed with melanoma over 1 year from October 23, 2006, to October 22, 2007, in the Melanoma Patterns of Care Study and followed up until 2018 (mean [SD] length of follow-up, 11.9 [0.3] years) by using linked mortality and cancer registry data. All patients who had invasive melanomas recorded at the cancer registry were eligible for the study, but the number of in situ melanomas was capped. The treating doctors recorded details of melanoma detection and patient and clinical characteristics in a baseline questionnaire. Histopathologic variables were obtained from pathology reports. Of 3932 recorded melanomas, data were available and analyzed for 2452 (62%; 1 per patient) with primary in situ (n = 291) or invasive (n = 2161) cutaneous melanoma. Data were analyzed from March 2020 to January 2021.

Main Outcomes and Measures

Melanoma-specific mortality and all-cause mortality.

Results

A total of 2452 patients were included in the analyses. The median age at diagnosis was 65 years (range, 16-98 years), and 1502 patients (61%) were men. A total of 858 patients (35%) had their melanoma detected during a routine skin check, 1148 (47%) self-detected their melanoma, 293 (12%) had their melanoma discovered incidentally when checking another skin lesion, and 153 (6%) reported "other" presentation. Routine skin-check detection of invasive melanomas was associated with 59% lower melanoma-specific mortality (subhazard ratio, 0.41; 95% CI, 0.28-0.60; P < .001) and 36% lower all-cause mortality (hazard ratio, 0.64; 95% CI, 0.54-0.76; P < .001), adjusted for age and sex, compared with patient-detected melanomas. After adjusting for prognostic factors including ulceration and mitotic rate, the associations were 0.68 (95% CI, 0.44-1.03; P = .13), and 0.75 (95% CI, 0.63-0.90; P = .006), respectively. Factors associated with higher odds of routine skin-check melanoma detection included being male (female vs male, odds ratio [OR], 0.73; 95% CI, 0.60-0.89; P = .003), having previous melanoma (vs none, OR, 2.36; 95% CI, 1.77-3.15; P < .001), having many moles (vs not, OR, 1.39; 95% CI, 1.10-1.77; P = .02), being 50 years or older (eg, 50-59 years vs <40 years, OR, 2.89; 95% CI, 1.92-4.34; P < .001), and living in nonremote areas (eg, remote or very remote vs major cities, OR, 0.23; 95% CI, 0.05-1.04; P = .003).

Conclusions and Relevance

In this cohort study, melanomas diagnosed through routine skin checks were associated with significantly lower all-cause mortality, but not melanoma-specific mortality, after adjustment for patient, sociodemographic, and clinicopathologic factors.

Impact of personal genomic risk information on melanoma prevention behaviors and psychological outcomes: a randomized controlled trial

Purpose

We evaluated the impact of personal melanoma genomic risk information on sun-related behaviors and psychological outcomes.

Methods

In this parallel group, open, randomized controlled trial, 1,025 Australians of European ancestry without melanoma and aged 18–69 years were recruited via the Medicare database (3% consent). Participants were randomized to the intervention (n = 513; saliva sample for genetic testing, personalized melanoma risk booklet based on a 40-variant polygenic risk score, telephone-based genetic counseling, educational booklet) or control (n = 512; educational booklet). Wrist-worn ultraviolet (UV) radiation dosimeters (10-day wear) and questionnaires were administered at baseline, 1 month postintervention, and 12 months postbaseline.

Results

At 12 months, 948 (92%) participants completed dosimetry and 973 (95%) the questionnaire. For the primary outcome, there was no effect of the genomic risk intervention on objectively measured UV exposure at 12 months, irrespective of traditional risk factors. For secondary outcomes at 12 months, the intervention reduced sunburns (risk ratio: 0.72, 95% confidence interval: 0.54–0.96), and increased skin examinations among women. Melanoma-related worry was reduced. There was no overall impact on general psychological distress.

Conclusion

Personalized genomic risk information did not influence sun exposure patterns but did improve some skin cancer prevention and early detection behaviors, suggesting it may be useful for precision prevention. There was no evidence of psychological harm.