Many drugs and therapies have been associated with an increased risk of developing cutaneous malignancies.
All three major skin cancers—basal cell carcinoma, squamous cell carcinoma, and melanoma—have been linked to ultraviolet light B (UVB) exposure.
More studies are needed to establish causative relationships between these treatments and skin cancer.
Immunosuppressant drugs may put patients at greater risk for not only skin cancer but also other types of neoplasms.
Drugs used to treat certain types of skin cancer can lead to the development of other cutaneous malignancies.
Drugs with photosensitizing properties could be linked to an increased risk of skin cancer.
PATIENT EDUCATION POINTS
Most drugs and therapies used today come with a side-effect profile that can include serious complications, such as neoplasm formation. This chapter gives an overview of a variety of chemicals and treatments that have the potential to cause skin malignancies. As physicians, it is important to be aware of these associations when treating patients to effectively minimize exposures. These potential complications should be discussed at length with patients, and physicians should use their clinical judgment as well as evidence-based medicine when assessing the benefits and risks of certain therapies to avoid cancer development and progression.
DRUGS/THERAPIES ASSOCIATED WITH SKIN CANCER
The use of tar to treat cutaneous disorders was first documented thousands of years ago.1 Tar has many characteristics that make it an appealing topical treatment, including anti-inflammatory, antipruritic, and antimicrobial properties.2 It has been used as a treatment modality for many dermatologic conditions, including psoriasis, atopic dermatitis, scabies, and sarcoidosis.1 The present-day use of tar, however, is mainly limited to psoriasis treatment. This is due to a variety of factors, including side effects such as folliculitis and its possible carcinogenic properties. Tar contains polycyclic aromatic hydrocarbons (PAHs), which are potential tumor initiators. These tar constituents are metabolized by cytochrome P450 enzymes into reactive metabolites that can bind to DNA and play a role in carcinogenesis.2 Studies have shown that occupational exposure to PAHs and tar have led to increased skin cancer incidence.3-5 However, most studies remain inconclusive as to whether the therapeutic use of tar poses a carcinogenic risk.5 One large cohort study of 13,200 patients with psoriasis and eczema found that tar treatment was not associated with an increased risk of skin cancer.6 In studies that looked at skin cancer rates in tar-exposed patients, the ratio of squamous cell carcinoma (SCC) ...