Two popular European apps that purport to detect skin cancer have been deemed “inadequate” at doing so, following the findings of a recently published study.

The apps, skinScan and SkinVision, were reviewed by researchers at the U.K.’s University of Birmingham and the University of Nottingham. Each app, while popular in Europe, have not been verified by the U.S. Food and Drug Administration.

» RELATED: Teen use of smartphones, social media significantly affects mental health, report says

In an article published Feb. 10 in the British Journal of Medicine, the study's authors set out to verify past research that both apps, which have been given a class 1 medical device ranking in Europe, have a high risk of not detecting skin cancer. The Centers For Disease Control and Prevention reports skin cancer is the most common type of cancer in the U.S.

In a BMJ editorial, the apps were deemed "inadequate evaluation and regulation."

Birmingham’s Jon Deeks and Nottingham’s Hywel Williams located nine relevant studies that evaluated six different apps. The studies are small in size and poor in quality.

"Our review found poor and variable performance of algorithm-based smartphone apps, which indicates that these apps have not yet shown sufficient promise to recommend their use," the authors wrote. “The current CE marking assessment processes are inadequate for protecting the public against the risks created by using smartphone diagnostic or risk stratification apps.”

» RELATED: 3 Marietta brothers diagnosed with same form of cancer

A single study of 15 moles with five melanomas was used to evaluate skinScan, which failed to identify any cases of skin cancer. Researchers evaluated SkinVision in two studies. In one study, 108 moles, 35 of which were cancerous or precancerous, reached a sensitivity of 88% and a specificity of 79%. That means that in 12% of cases, canerous or precancerous moles would not be identified and 21% of non-cancerous moles would be misidentified as potentially cancerous, according to the American Association for the Advancement of Science.

“Smartphones and dedicated skin cancer apps can have other roles; for example, assisting in skin self-examination, tracking the evolution of suspicious lesions in people more at risk of developing skin cancer, or when used for store and forward teledermatology,” the authors wrote in their conclusion. “However, healthcare professionals who work in primary and secondary care need to be aware of the limitations of algorithm based apps to reliably identify melanomas, and should inform potential smartphone app users about these limitations.”

» RELATED: Everything you need to know about skin cancer and how to prevent it

SkinVision creators have not yet publicly responded to the findings of the study as of this writing. However, in a letter to the BMJ editor, Zeljko Ratkaj, CEO of TeleSkin ApS, which developed skinScan, took issue with the findings of the single study of the app.

“Application skinScan in the form it is known was mostly developed during the year 2014 and 2015, and it was released in Denmark (only in Denmark) in August 2015. In 2016, we released in Norway and other Scandinavian countries, and in NZ, Australia and UK we released the app in 2017 and 2018. We had this huge window of releases because ... we wanted to be compliant with the medical rules in the countries where we released the app,” Ratkaj wrote in part.

“That is also why is rather impossible that our app was the study subject in the paper that was being referenced to,” the CEO added.