Photosensitizing Drugs, Estrogen, and Diuretics Linked to Increased Skin Cancer Risk

A recent prospective study explored the association between commonly prescribed photosensitizing drugs and the risk of developing skin cancer in women.¹

Published in Photodermatology, Photoimmunology & Photomedicine, the study found that estrogen therapy and certain diuretics significantly increased the risk of basal cell carcinoma (BCC), cutaneous squamous cell carcinoma (cSCC), and cutaneous malignant melanoma (cM).

Squamous cell carcinoma on the face | Image Credit: © DermNet

Background and Methods

Previous research has examined the link between photosensitizing medications and skin cancer, but findings have often been inconsistent.² Given this uncertainty, researchers conducted a large-scale, population-based cohort study to evaluate the potential carcinogenic effects of these drugs.

The study analyzed prospectively collected data from a large cohort of women, incorporating detailed information on sun exposure, phenotypic traits, and pharmaceutical treatments. Skin cancer diagnoses were identified using national registries. Researchers categorized photosensitizing medications into nine groups based on the Anatomical Therapeutic Chemical classification system and assessed associations using multivariable Cox regression analysis. Additionally, the number of retrieved daily doses was analyzed to determine any dose–response relationship.

Findings

The study analyzed data from 21,062 women, with 1,875 participants developing at least 1 type of skin cancer: BCC, cSCC, or cM. The vast majority (89%) were diagnosed with only 1 form, while 140 participants had both BCC and cSCC, and 11 developed all 3 concurrently.

Researchers also evaluated the role of photosensitizing drug use in skin cancer risk, noting that individuals diagnosed with cM had a slightly higher prevalence of photosensitizing drug use compared to other groups.

Analysis of medication exposure revealed that female hormone therapies, particularly estrogen, were significantly associated with increased risk across all 3 cancer types. Estrogen alone demonstrated the strongest link, with hazard ratios of 1.25 for BCC, 1.23 for cSCC, and 1.35 for cM, with only the BCC association remaining statistically significant after Bonferroni correction.

Additionally, thiazide diuretics were linked to higher BCC and cM risk, while loop diuretics were strongly associated with cSCC.

Photosensitizing antibiotics and proton pump inhibitors showed weaker associations, with some losing statistical significance after adjustment. A dose-dependent effect was observed for estrogen, with higher doses increasing BCC risk by up to 60%.

Conclusions

While the study provides insights into the association between photosensitizing medications and skin cancer risk, certain limitations should be considered. The study’s applicability may be limited since all participants were drawn from a single geographic region, and researchers could not confirm whether the prescribed medications were consistently taken. Furthermore, grouping certain drug classes together made it difficult to determine the effects of individual medications, according to study authors Christensen et al.

Researchers emphasized the importance of considering medication history when evaluating skin cancer risk, urging clinicians to integrate these findings into patient counseling and preventive care strategies.

"We do not recommend discontinuation of any of the medications studied in this paper," study authors wrote. "Future well-designed prospective studies are warranted to further investigate the relationships between common photosensitizing drugs and the risk of skin cancer."

References

1. Christensen GB, Kappelin J, Sandgren J, Nielsen K, Ingvar Å. Photosensitizing drugs and risk of skin cancer in women-a prospective population-based study. Photodermatol Photoimmunol Photomed. 2025;41(2):e70013. doi:10.1111/phpp.70013
2. Robinson SN, Zens MS, Perry AE, Spencer SK, Duell EJ, Karagas MR. Photosensitizing agents and the risk of non-melanoma skin cancer: a population-based case-control study. J Invest Dermatol. 2013;133(8):1950-1955. doi:10.1038/jid.2013.33