**6. Biomarkers as a novel tool in monitoring ultraviolet skin damage to improve skin cancer prevention**

Biomarkers are defined as measurable cellular, biochemical or molecular alternations in biological media such as blood or tissue. Several FDA-approved multi-gene panel tests are now approved for risk prediction and diagnosis of various cancers; however, no similar biomarker tests exist for patient risk stratification of NMSC [92]. At present, there are no skin cancer screening guidelines in the United States. Despite this, physicians are routinely confronted with the decision of who should receive total body skin exams and at what time interval. The United States Preventive Task Force (USPSTF) has repeatedly stated that in the absence of randomized controlled clinical trials, there is insufficient evidence to recommend skin cancer screening in the general population [93]. While the majority of the USPSTF skin cancer screening report focuses on melanoma, one of the main arguments made against screening for NMSC is that there is limited evidence regarding the diagnostic accuracy of primary care physicians to correctly identify BCCs and SCCs. Given the lack of rigorous dermatology training in most medical school and primary care residencies, this argument is not necessarily unfounded [94]. Although there are several other arguments to be made against the USPSTF recommendations and reasoning, the lack of clear skin cancer screening guidelines is problematic.

It is unlikely the USPSTF will obtain a satisfactory level of evidence in the near future to recommend skin cancer screening in the United States given the large number of patients required to adequately power a clinical trial [95]. It thus behooves physicians and scientists to search for alternative measures as a means to quantify skin cancer risk. The presence of an objective UV biomarker test could facilitate patient triage by identifying high risk individuals for dermatology referral. Identification of susceptible patients in the primary care setting via the use of an accessible genetic screening test would thus provide physicians with an evidence based method to make informed decisions regarding which patients should receive regular skin cancer screening.

The development of a UV biomarker panel has the potential to have a profound impact on patient care. Breakthroughs in next generation sequencing technology have provided a powerful tool for identifying biomarkers of a given physiological status or exposure [96]. Many studies have attempted to identify biomarkers that correlate UV exposure and skin damage with variable success; however, no consensus UV biomarkers have been established to date. Various types of biomarkers have been investigated including DNA, RNA, and protein.
