Total body photography for secondary prevention of melanoma
Authors: H. Kittler
Journal: British Journal of Dermatology (2021)

Linked Article: Ji-Xu et al. Br J Dermatol 2021; 185:302–312. In theory, total body photography (TBP) improves early recognition of melanoma because it facilitates the detection of small melanomas. In practice, TBP may also have undesirable effects, such as an inflation in the number of surgical procedures for benign lesions. In their excellent systematic review published in this issue of the BJD, Ji-Xu et al. provide summary estimates of the number needed to biopsy (NNB) of TBP for the diagnosis of melanoma in high-risk individuals.1 They summarized data from 10 studies and calculated that on average 8·6 biopsies were needed to detect one melanoma. To put their results into perspective, they compared their number with the aggregate NNB of 14·8 reported in another meta-analysis, which mostly included studies that used standard care without TBP.2 Therefore, it seems that TBP reduces the NNB. Although sensitivity and specificity could not be calculated, the smaller NNB suggests improved specificity in comparison with standard care. The fact that most melanomas detected by TBP were in situ indicates that the improved specificity is not outweighed by a decrease in sensitivity. However, the significance of comparing NNBs across different study settings and populations is limited and the authors correctly concluded that future studies should be prospective and compare TBP with standard care. Although the NNB of 8·6 seems appropriate by current standards, it is still too high. We can do better! TBP is just one of many noninvasive diagnostic procedures for melanoma detection. Dermatoscopy, for example, is a noninvasive examination technique that improves the accuracy of melanoma diagnosis in comparison with inspection with the unaided eye.3 Like TBP, sequential digital dermatoscopy detects inconspicuous melanomas by observing changes over time.4 By combining TBP with digital dermatoscopy, a recently published cohort study achieved an NNB of 6·6 in a high-risk population.5 Furthermore, recent advances in diagnostic artificial intelligence indicate that we can improve this number by supporting physicians in detecting outliers in wide-field images ('ugly duckling sign')6 or aiding inexperienced readers in the interpretation of dermatoscopy images.7 To improve melanoma detection we should not only use a panel of complementary diagnostic techniques, but also define the population of patients who will benefit from these techniques more precisely. The results of this review suggest that TBP should probably be confined to patients with a personal history of melanoma and multiple naevi. If used in a low-risk population the undesirable effects of TBP may increase. Finally, we need a shift in policy with regard to incentives. Reimbursements for monitoring techniques such as TBP or digital dermatoscopy should be in the range of that for excisions. Recently, Welch et al. suggested that we also should restrict biopsies to lesions that are larger than 6 mm to decrease the number of false-positives.8 This ignores all our achievements in the past 30 years, including those of TBP and dermatoscopy, and would throw us back into the dark ages of melanoma detection, when we let melanomas grow until we were able to detect them even with the unaided eye. Harald Kittler: Conceptualization (equal); Writing-original draft (equal); Writing-review & editing (equal).