Intensive melanoma screening: feasible and reliable in the long term

Skin cancers

By Mardi Chapman

18 Mar 2021

Structured surveillance incorporating six-monthly total body photography (TBP) and sequential digital dermoscopy imaging (SDDI) for high melanoma risk patients results in consistent and sustainable benefits such as early detection and excision rates.

A prospective study comprised 593 patients with histories such as multiple primary melanoma, dysplastic nevus syndrome, and previous melanoma, attending four high-risk clinics in NSW.

The follow-up showed the overall benign to malignant excision ratio, including keratinocyte carcinomas, was 0.8:1.0; the benign melanocytic to melanoma excision ratio was 2.4:1.0; and the melanoma in situ to invasive melanoma ratio was 2.2:1.0.

Excision ratios were similar across the three dermatology clinics in Sydney and a primary care skin cancer clinic in Newcastle.

“The mean melanoma incidence rate was 0.09 (95%CI,0.08-0.12) per person-year of follow-up in the first 2 years of high risk clinic surveillance (equivalent to a 9.0% annual risk of melanoma in each of the first 2 years) and 0.15 (95% CI, 0.11-0.20) per person year of follow-up in years 2 to 4 (equivalent to a 15.0% annual risk of melanoma in years 2-4),” the study said.

The study, published in JAMA Dermatology, said the sustained long-term results were reassuring because they indicated that thick melanomas were unlikely to be missed despite a low benign to malignant excision ratio.

“The overall benign to malignant excision ratio of 0.8:1.0 and the overall benign melanocytic to melanoma ratio of 2.4:1.0 in this cohort were better than the commonly accepted benign to malignant excision ratios of 5:1 for dermatology specialists and 20:1 for generalists.”

The median Breslow thickness of lesions across all centres was in situ to 0.4mm.

An accompanying editorial in the journal said the ultimate goal of early detection was not to find thinner melanomas but to reduce melanoma-associated morbidity and mortality.

“Given the strong association of melanoma thickness with prognosis, it is tempting to conclude that an intervention that results in finding more thin melanomas will also result in fewer melanoma-associated deaths. Although this makes sense intuitively, it has yet to be definitively established as an outcome of screening.”

The editorial also questioned the benefit of high-intensive screening versus the risk of potential harms such as high rates of biopsies.

“When the risk for melanoma is high, the threshold for biopsy may be particularly low for both patient and physician. In the hands of experienced clinicians, tools such as dermoscopy may improve efficiency by reducing the number of benign nevi biopsied among high-risk patients.”

It also noted that different strategies were required for the large portion of the population whose primary melanoma risk factor was age.

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