Widely Used Drug Azathioprine Linked To Skin Cancer

A study has linked the drug azathioprine, commonly used for a variety of conditions, with skin cancer development.

The drug, which sold under the brand names Imuran and Azasan, is used to treat inflammatory bowel disease, arthritis and vasculitis, and prevent organ rejection in transplant patients. Researchers identified it as “strong case for an association” to the mutational signature found in cases of cutaneous squamous cell carcinoma.

Researchers at the University of Dundee, Queen Mary University of London and the Wellcome Sanger Institutepublished their findings Monday in the journal Nature Communications on the drug, which is sold under the brand names Imuran and Azasan.

In a mutational signature analysis of cSCC tumors, they found a new mutational signature, Signature 32, was correlated to the use of azathioprine. By identiftying the molecular landscape of cSCC, researchers believe potential treatments can be developed.

Researchers analyzed 40 tumor samples from 37 patients, including 29 organ transplant recipients treated with immunosuppressive drugs, as well as one immunosuppressed for Crohn’s disease.

“Although patient numbers were small and these findings should be verified in a larger independent cohort, this molecular study provides a strong case for an association between this novel mutational signature and long-term azathioprine use,” Dr. Gareth Inman, part of the research team at Dundee and now at the Cancer Research UK Beatson Institute and the University of Glasgow, said in a press release.

Skin cancer is the most common cancer in the United States, according to the Centers for Disease Control and Prevention. Among 100,000 people, 22 new melanomas of the skin cases were reported and two died from the cancer.

Azathioprine previously had been identified to increased photosensitivity to UVA light — a link to skin cancer. The new study further implicated the drug.

“We recommend all physicians give appropriate advice on UVA avoidance including year-round sun protection for their patients on azathioprine,” Dr. Charlotte Proby, professor of dermatology in the School of Medicine at Dundee, said. “As with all medications the risks must be balanced against the benefits, particularly with the need to treat potentially life-threatening diseases with an effective drug.”

She recommended appropriate sun protection, skin surveillance, early diagnosis and lesion removal for patients on azathioprine.

“It’s important to protect your skin from the sun when it’s strong, especially if you burn easily or are taking medications which make you more sun-sensitive,” said Dr. Sophia Lowes, a researcher at Cancer Research UK. “The most effective protection is to spend time in the shade and cover up with a hat, long-sleeved top and sunglasses. For the bits you can’t cover, use sunscreen with at least 4 stars and SPF 15 or higher for protection against both UVA and UVB rays.”