A Clinical Aid for Detecting Skin Cancer: The Triage Amalgamated Dermoscopic Algorithm (TADA)

T. Rogers, MFA; M. L. Marino, MD; S. W. Dusza, DrPH; S. Bajaj, MD; R. P. Usatine, MD; M. A. Marchetti, MD; A. A. Marghoob, MD

Disclosures

J Am Board Fam Med. 2016;29(6):694-701. 

In This Article

Discussion

More than half of all physician office visits in the US are to PCPs, including FPs.[33] These physicians are increasingly confronted with the management of skin lesions and are often the first line for skin cancer detection.[15,34] In one study, 63% of patients with newly diagnosed melanoma had visited PCPs within the year before their diagnoses.[35] Despite this, PCPs seem to lack sufficient knowledge and experience for evaluating malignant skin lesions, failing to identify as many as one third of skin cancers.[36] Lack of training has been a reported barrier preventing these physicians from gaining the confidence and abilities necessary for skin cancer management. Although 54% of PCPs suggest having sufficient skills for diagnosing skin cancer,[37] greater than 50% are requesting further knowledge to aid in the process.[38]

Several studies have demonstrated that dermoscopy can improve PCPs' abilities to accurately identify malignant skin lesions.[14,15,17] In 2009, the American Academy of Family Physicians held the first dermoscopy course at their Annual Scientific Assembly Meeting. Since then, the demand for this course has increased and is currently being offered at 4 different times during the meeting, up from 3 times the previous year, to accommodate increased interest (published American Academy of Family Physicians program schedules). Although dermoscopy has been a proposed addition to PCPs' skin cancer curricula,[16] the best dermoscopic method to learn is unknown. The classic approach to dermoscopy relies on users' expert knowledge of myriad and often nuanced dermoscopic structures and patterns necessary to generate the correct diagnosis. This requires significant training and practice to implement with high accuracy.[23] To make dermoscopy easier to use for nondermatologists and to aid in its widespread adoption in general practice, several simplified screening algorithms have been introduced.[18,19] The validation of these algorithms has shown that the inclusion of a select group of dermoscopic features is sufficient to allow inexperienced users to correctly identify a large proportion of skin cancers. However, the fact that these algorithms were designed for the detection of specific subsets of pigmented skin cancers, primarily pigmented melanoma, highlights the need for a new algorithm designed to detect both pigmented and nonpigmented malignancies.

In this study, 34% of the 120 participants were PCPs and 43% of the study population had no previous dermoscopy training before the first day of the course. This allowed us to evaluate the potential utility of TADA as an aid for skin cancer evaluations in primary care settings. TADA achieved an overall sensitivity for all skin cancers of 94.8%. This value was not influenced by participants' previous training or experience with dermoscopy, or medical specialty. The fact that training improves the diagnostic accuracy of inexperienced users has been demonstrated in previous studies.[14–18] However, the amount and type of training provided in these studies has varied considerably, from a 1-hour web-based tutorial plus a 15 lesion training set,[18] to a 1-day training course,[16] to the use of a dermoscopy textbook plus a 245 lesion training set.[14] Future studies can help to elucidate whether the training modality for TADA can be further streamlined.

The specificity of TADA for all users was 72.3%. Remarkably, participants without dermoscopy training before the study correctly identified around 74% of benign lesions. These results compare favorably to the values reported from studies evaluating the performance of inexperienced dermoscopists when using other screening algorithms (32.8%–72%),[18,19,39] with the added benefit of identifying a greater number and more varied types of malignancies overall. It can thus be concluded that the high sensitivity we observed with TADA would not have been at the expense of an increase in the number of unnecessary biopsies or referrals. In addition, the specificities for the 3 types of benign lesions included in the TADA algorithm ranged from 73.0% to 93.0%. This finding substantiates our view that it is possible to rather quickly train beginners to accurately identify classic examples of certain common, benign lesions. Although requiring users to gain additional rudimentary dermoscopic knowledge to identify these lesions is arguably a limitation of TADA, it also seemed to strengthen the algorithms indicated by the high specificities achieved for these lesions.

The results of this pilot study suggest that TADA can help inexperienced users who are motivated to learn dermoscopy detect both pigmented and nonpigmented skin cancers with very high sensitivities and specificities. As such, our results may not be generalizable to all PCPs. To make definitive statements about the usefulness of TADA as a clinical tool in primary care, our findings would need confirmation in a larger study with more PCPs evaluating a more diverse and larger sample size. Providing participants with clinical images in addition to dermoscopic images would also more closely correlate with the real-life situation in which the algorithm would be applied. Ideally, this would be achieved with a prospective study performed in a clinical setting. In addition, reader studies, such as this one, are often performed with photographic representations of dermoscopic images. This is not the same as viewing lesions in vivo. A prospective, clinical study would also allow us to account for the logistical aspects of operating a dermoscope. Further, by randomizing participants to various levels and durations of training, we might determine the most efficient teaching method for PCPs. To overcome some of these limitations, we plan to reevaluate the diagnostic accuracy of TADA as a function of training duration and didactic method with a large sample of FPs and family medicine residents.

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