Melanoma as a detection-dependent cancer: proxy measures of screening and surveillance associated with 3-year incidence of detection procedures for skin cancer in a national prospective study

Abstract

Abstract Background Increased levels of skin detection activities are suspected of driving recent rapid increases in melanoma incidence. While ecological studies report rising rates of skin biopsies in many industrialised populations, few studies have accessed individual-level clinical data to test the hypothesis that people exposed to skin screening and surveillance go on to experience higher levels of biopsies and excisions, and higher incidence of melanoma. Objective To measure the incidence rates of detection events and melanoma diagnoses in a national cohort during follow-up, stratified according to screening or surveillance activities in the index year. Methods We conducted a prospective cohort study of 10,674,200 men and women using linked data from Australia’s universal health insurance scheme (2011-2016). Participants who underwent biopsies or who were diagnosed in skin cancer in 2011/2012 were excluded. We then defined participants as surveilled, screened, or unscreened for skin cancer based on medical claims occurring in 2013. We compared rates of biopsies, excisions for suspected melanoma, and excisions for histologically confirmed melanoma during follow-up (2014-2016). Results After adjusting for socio-demographic factors, screened people were significantly more likely than unscreened people to undergo skin biopsies (RR 2.59, 95% CI 2.56-2.63), excisions for suspected melanoma (RR 2.57, 95%CI 2.53-2.60), and excisions for confirmed melanoma (hazard ratio 3.32, 95% CI 3.24-3.40) during follow-up. Similarly elevated rates of subsequent diagnostic events were observed for the surveilled group. Importantly, rates of detection and rates of melanoma remained elevated in each of the subsequent years of follow-up among those who were screened or surveilled in the index year. Conclusions People undergoing skin screening or surveillance subsequently experience higher rates of diagnostic scrutiny and higher rates of melanoma.