The COVID-19 pandemic disrupted cancer care globally, creating concerns about delayed diagnosis and treatment for skin cancer. This population-based study compared changes in incidence and prognostic features of invasive cutaneous melanoma across two regions that implemented contrasting pandemic infection control strategies: Sweden, with relatively light, mostly voluntary measures, and Victoria, Australia, which applied strict and prolonged lockdowns. The primary objective was to evaluate whether the pandemic altered melanoma diagnosis rates and tumor prognostic markers.
The investigators performed a retrospective analysis using two registries: the Swedish quality registry for cutaneous melanoma (SweMR) and the Cancer Council registry in Victoria, Australia. Incident invasive melanomas diagnosed between 2013 and 2021 were included for trend analyses. The study compared predefined time periods ‘before COVID’ and ‘during COVID’, using 1 March 2020 as the interruption point to assess immediate and subsequent changes in incidence and tumor characteristics.
Monthly counts of incident invasive melanomas were analysed accounting for long-term underlying trends and seasonality. Regression models were applied to prognostic variables to compare outcomes before and after the interruption: Breslow thickness, presence of ulceration, and lymph node status. The analysis reported both level changes at the point of pandemic onset and subsequent slope changes to distinguish immediate from sustained effects.
Both regions experienced a significant immediate decline in overall melanoma incidence at the onset of the COVID-19 pandemic. This decline was driven primarily by reductions in diagnoses of thin melanomas. The immediate decrease was most prominent in older age groups in both Sweden and Victoria. However, the post-interruption patterns diverged between the regions. In Victoria the lower incidence level persisted through the study period without a detectable change in slope back toward the pre-pandemic trend. In contrast, Sweden’s melanoma incidence showed a gradual realignment with the pre-COVID trend after the initial drop, indicating a more transient disruption.
In Victoria, the median Breslow thickness remained 0.7 mm during the pandemic, but the overall distribution shifted significantly (P < 0.001). The authors report an 8% increase in the geometric mean ratio of thickness (95% confidence interval 5–12), indicating a modest shift toward thicker tumours on average.
In Sweden, measures of thickness did not change appreciably during the pandemic period. However, the odds of ulceration at diagnosis increased slightly (odds ratio 1.09, 95% CI 1.01–1.19), suggesting a small worsening in this prognostic marker. Rates of lymph node metastasis remained stable in both regions, with no reported increase attributable to the pandemic.
The combined evidence indicates that pandemic-related changes in healthcare access and patient behaviour reduced detection of early, thin melanomas and caused modest worsening in some prognostic features. The authors note two contributing processes: delayed detection of melanomas that could progress to cause harm, and reduced identification of lesions that would likely have been indolent (overdiagnosis). The more sustained reduction in diagnoses observed in Victoria is suggested to reflect the stricter and longer-lasting pandemic controls in that region compared with Sweden’s lighter measures.
Findings imply the need to preserve timely access to skin checks and diagnostic pathways during public health emergencies while avoiding excessive investigations that drive overdiagnosis. Prioritising resources to detect melanomas most likely to harm patients should be a focus of service planning. The study supports efforts to balance reducing unnecessary procedures with ensuring prompt assessment of suspicious lesions, particularly during periods of restricted access to routine care.
The report used high-quality registries and modelled seasonality and long-term trends, but the public summary does not provide all analytic details. Specific patient-level data, thresholds for clinical prioritisation, and potential confounders beyond age and time trends are not reported in the abstract and plain language summary. The authors’ discussion of overdiagnosis acknowledges uncertainty in the extent to which reduced thin-melanoma detection represents avoided overdiagnosis versus missed clinically relevant tumours. Further details would be available in the full text.
Using registry data for 2013–2021 and 30,000 invasive melanomas overall, the study demonstrates an immediate COVID-era decline in melanoma diagnoses in both Sweden and Victoria, primarily affecting thin tumors and older age groups. Prognostic markers changed modestly: a shift toward greater thickness distribution in Victoria and a small increase in ulceration odds in Sweden, while lymph node metastasis rates remained unchanged. The regional differences in persistence of reduced incidence align with the differing infection control strategies, and the authors emphasise maintaining access to timely skin evaluation while minimising unnecessary investigations.