Why Catching Skin Cancer Early Is a Home Robotics Problem — Marion Lepert

A mole I'd had my entire life looked different in the mirror one morning. I'm high-risk for melanoma, and I knew what "different" could mean. The doctor agreed: very suspicious, biopsy it now. In the days that followed, waiting for my results, I felt ravaged with regret that so many months had gone by since I had done my last self skin-check. Melanoma is visible to the naked eye in its earliest stages. I felt angry that I had not been more diligent about my skin checks but also angry at the health care system. Luckily, it turned out not to be cancer, but I refuse to experience such regret again.

The screening problem

The current standard of care for skin cancer detection for high risk patients is woefully inadequate. A doctor inspects a patient’s skin once a year for a few minutes and reminds them that it’s their responsibility to check their skin regularly for any changes. This approach is poorly suited to melanoma, a cancer for which survival depends heavily on the stage at detection: five-year relative survival is greater than 99% for localized melanoma but falls to approximately 35% once the cancer has spread to distant organs.1National Cancer Institute. SEER Cancer Stat Facts: Melanoma of the Skin. Five-year relative survival based on SEER 21 data, 2016–2022. It also places the hardest part of the problem on the patient: early melanomas can appear as tiny, ambiguous changes in color, shape, or size, often hidden among dozens or hundreds of benign spots. Detecting them requires not merely looking at the skin, but remembering what every region looked like months earlier and recognizing which subtle changes matter.

The usual advice to “watch your moles” also understates the difficulty of the problem. Only about 30% of melanomas arise from an existing mole; roughly 70% appear as entirely new lesions on previously normal-looking skin.2Pampena R, Kyrgidis A, Lallas A, et al. A meta-analysis of nevus-associated melanoma: Prevalence and practical implications. Journal of the American Academy of Dermatology. 2017;77(5):938–945.e4. Tracking changes in every known mole is difficult. Recognizing that one tiny spot among hundreds of moles, freckles, and other benign features was not present six months earlier is even harder. A highly motivated patient can photograph their entire skin surface (I did this), but comparing those images over time is an enormous registration problem: differences in body position, camera angle, distance, lighting, and skin deformation make it difficult to align the same regions across scans. Finding a tiny new lesion therefore requires painstakingly matching and comparing hundreds of corresponding patches of skin.

The limits of total-body photography

We need a system that can create a high-resolution, repeatable map of the entire skin surface and automatically register each new scan to the last: total-body photography (TBP). Existing TBP systems such as Canfield’s VECTRA WB360 or Neko’s skin scan surround a standing patient with dozens of cameras, capture nearly the entire skin surface at once, and reconstruct a 3D model on which lesions can be mapped and tracked over time. This makes longitudinal surveillance far more systematic, particularly for people at high risk of melanoma. Yet these systems remain available primarily through a few specialized centers and are far from routine or broadly accessible. They are large and capital-intensive, and suspicious lesions must still be examined individually using higher-resolution dermoscopy. Most importantly, the evidence that adding 3D total-body photography improves melanoma detection over usual clinical surveillance remains mixed: a recent randomized trial found that the VECTRA WB360 did not increase the average number of melanomas detected.3Soyer HP, Jayasinghe D, Rodriguez-Acevedo AJ, et al. 3D Total-Body Photography in Patients at High Risk for Melanoma: A Randomized Clinical Trial. JAMA Dermatology. 2025;161(5):472–481., 4Lindsay D, Soyer HP, Janda M, et al. Cost-Effectiveness Analysis of 3D Total-Body Photography for People at High Risk of Melanoma. JAMA Dermatology. 2025;161(5):482–489.

Why, then, has total-body photography not transformed melanoma screening? The first limitation is image resolution. Fixed camera arrays are designed to capture the entire body quickly, so each lesion occupies only a small portion of the resulting image. The images may be sufficient to flag a spot as new or changing, but they generally do not preserve the fine structural detail available through close-range or dermoscopic imaging. This creates two problems. Clinically, every flagged lesion must still be located on the patient and inspected individually by a dermatologist, turning automated screening into a tedious follow-up workflow. Scientifically, the images collected during routine total-body scans may not contain enough detail to train models to recognize the earliest...