Influence of the Exposome on Skin Cancer

Skin cancer is the most frequent type of cancer in humans. While exposure to solar radiation is the most widely known and relevant causal factor, the different degrees of individual risk have not been fully elucidated. Epidemiological studies show how the risk of skin cancer is affected by other types of radiation (eg, ionizing radiation), pesticides, particulate matter in air pollution, toxins (eg, arsenic) in water and some foods. Some living entities, such as polyomavirus and human papillomavirus, can also cause specific types of cancer. Lastly, lifestyle factors such as stress, sleep, and exercise may play a role, although only a few studies shed light on these factors. The abovementioned factors make up the exposome of skin cancer, that is, the set of environmental exposures that, together with the genome and microbiome, determine the onset of disease.

Photocarcinogenic Risk Associated With Narrowband UV-B Phototherapy: An Epidemiologic Study in a Tertiary Care Hospital

BACKGROUND

The risk of skin cancer in patients treated with narrowband (NB) UV-B phototherapy is not well understood. Although experimental studies have shown that there is a risk, clinical studies have not detected an increased incidence of cancer following treatment. The aim of this study was to determine the incidence of nonmelanoma skin cancer (NMSC) in patients treated with NB UV-B phototherapy at a tertiary care hospital in the Mediterranean area.

MATERIAL AND METHODS

We conducted a retrospective chart review of 474 patients who received whole-body NB UV-B phototherapy at our hospital between 2002 and 2016 and identified those diagnosed with NMSC during follow-up. We calculated the corresponding crude and standardized incidence rates and compared these with rates in the general population in a similar geographic area.

RESULTS

Of the 474 patients, 193 (40.7%) were men and 281 (59.3%) were women. The mean (SD) follow-up period was 5.8 (3) years. The prevalence of NMSC at the end of the study period was 1.9% and the standardized incidence was 108.3 cases per 100 000 patient-years. The SIR of 1.9 in the study group was not significantly different from that of the general population. The number of patients who needed to be treated with NB UV-B phototherapy for 1 case of NMSC to occur was 1900.

CONCLUSION

NB UV-B phototherapy does not appear to be associated with an increased risk of NMSC.