# Impact of Dermatologic Screening and Methods on Breslow Thickness in Melanoma: A Retrospective Cohort Study

## TL;DR

This study shows that dermatologic screening, especially digital mole mapping, leads to earlier detection of thinner melanomas, particularly in high-risk patients.

## Contribution

The study demonstrates that digital mole mapping improves melanoma detection in high-risk patients, supporting risk-adapted screening strategies.

## Key findings

- Dermatologic screening is associated with thinner melanomas and more in situ diagnoses compared to first-visit diagnoses.
- Digital mole mapping identifies significantly thinner invasive melanomas than dermoscopy in high-risk patients.
- High-risk patients benefit most from frequent screening and digital mole mapping, while low-risk patients do not.

## Abstract

This retrospective cohort study of 475 cases of melanoma diagnosed at Erasme University Hospital (2017–2024) shows that dermatological screening is associated with thinner tumours and more melanoma in situ compared with first-visit diagnoses. Full-body examination detected earlier-stage disease than lesion-directed screening, while digital mole mapping identified significantly thinner invasive melanomas than dermoscopy, even after excluding first-visit cases. Screening and digital mole mapping had no significant benefit in low-risk patients. However, in high-risk patients, tumour thickness decreased with screening and digital mole mapping. These findings support risk-adapted screening strategies, with intensified, digitally supported follow-up recommended for high-risk groups.

Background/Objectives: Melanoma is the most lethal cutaneous neoplasm, with Breslow thickness being a key prognostic factor. This retrospective cohort study aimed to assess the impact of screening frequency and diagnostic methods on tumour stage at diagnosis and to explore implications for risk-adapted strategies. Methods: Between 2017 and 2024, 475 cases of melanoma were diagnosed in 397 patients. Screening frequency, diagnostic method, and patient risk were analyzed in relation to tumour stage. Results: Compared with first-visit cases, patients who underwent screening within two years prior to diagnosis were more often diagnosed with melanoma in situ (32.6% vs. 44–51%; p < 0.05) and had thinner invasive tumours (0.68–0.73 mm vs. 1.8 mm; p ≤ 0.001), though no differences were seen between screening frequencies. Full-body examination was associated with more in situ melanomas (46% vs. 34%; p = 0.016) and thinner invasive tumours (0.92 vs. 2.05 mm; p = 0.2) compared with lesion-directed screening, but this effect disappeared after excluding first-visit cases. Invasive melanomas diagnosed by mole mapping were significantly thinner than by dermoscopy (0.55 vs. 1.07; p = 0.035). In high-risk patients, tumour thickness decreased with more frequent visits (0.905 mm without screening vs. 0.40–0.55 mm with ≥1 visit; p = 0.001). Moreover, mole mapping identified thinner melanomas in the high-risk group compared with dermoscopy (0.47 vs. 0.60 mm; p = 0.02). Conclusions: Screening is associated with thinner melanomas and more in situ diagnoses. Digital mole mapping offers additional benefits, with high-risk patients profiting most, while low-risk individuals could be managed with less resource-intensive approaches. These findings support risk-adapted screening strategies focusing on intensive, digitally supported modalities for high-risk groups.