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- Presentation
Critique of Genetic Expression Profiling for Cutaneous Squamous Cell Carcinoma
Description
The speaker argues against using commercially available genetic expression profiling (GEP) tests for cutaneous squamous cell carcinoma, saying they do not reliably identify the small number of tumors that will metastasize and produce too many false positives when applied broadly. He emphasizes that most squamous cell carcinomas are cured by excision, so the key challenge is finding the rare high-risk cases, which current GEP tools fail to do. The talk criticizes the evidence behind the test, citing overfitting, use of training data in validation, and problems with combining multiple risk tiers into a binary outcome that can create a misleading impression of accuracy. Instead of relying on GEP, he recommends multidisciplinary tumor board review and holistic, individualized decision-making for patients, noting that he does not endorse genetic expression profiling at this point.
Conclusions
- The commercial cSCC gene expression profiling test appears to have very low positive predictive value in the broader patient population, meaning most positive results are false positives.
- The validation evidence for the test is weakened by overfitting because training and validation data were not sufficiently independent.
- Comparisons across different risk group slices can make the test look more accurate than it really is, so the reported performance may be misleading.
- The test does not clearly outperform standard staging, and the talk argues that existing clinical guidelines and multidisciplinary review remain the better basis for care.
- The presenters conclude that no commercially available genetic expression test currently provides a reliable standalone tool for identifying the rare patients who will metastasize.
- The recommended approach is multidisciplinary tumor board review and holistic individualized management rather than reliance on gene expression profiling.
- Overall, the presentation argues against endorsing the commercially available cSCC GEP test in its current form.
- Sax JL, McFarland CD, Carroll BT. Limitations of the commercially available gene expression test in predicting cutaneous squamous cell carcinoma metastasis and clinical outcomes. J Am Acad Dermatol. July 2025.#10.1016/j.jaad.2024.05.014
- Wysong A, et al. (referenced in slide tables on 40-GEP training and validation populations; exact citation not shown in OCR).