3 widely used medicines classified as carcinogenic by WHO research agency, Pg12

Key Highlights:

• The International Agency for Research on Cancer (IARC), a World Health Organization (WHO) research agency, has classified three widely used medicines as "carcinogenic to humans" (Group 1).
• The medicines are hydrochlorothiazide (for high blood pressure), voriconazole (for fungal infections), and tacrolimus (an immunosuppressant for organ transplant rejection).
• These three drugs are included in the WHO Model List of Essential Medicines, indicating their widespread use globally.
• Hydrochlorothiazide is linked to squamous cell skin carcinoma and lip cancer.
• Voriconazole is associated with squamous cell skin carcinoma in transplant recipients on prolonged therapy.
• Tacrolimus is linked to non-Hodgkin lymphoma and post-transplant lymphoproliferative disorder, with limited evidence for leukaemia and skin carcinoma.

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Detailed Insights:

• The IARC classification is a hazard identification, meaning it indicates the potential to cause cancer, but does not assess the level of risk based on exposure.
• Medical experts advise patients not to discontinue these treatments without consulting their doctors, as the benefits may outweigh the risks for individual cases.
• The assessment was published as Volume 137 of the IARC Monographs, building upon conclusions initially released in The Lancet Oncology in November 2024.
• In India, concerns exist regarding the irrational prescribing, over-the-counter availability, and poor adherence to ethical prescribing practices for such medications.
• Hydrochlorothiazide has long been recognized for its risk, particularly in sun-exposed populations and outdoor workers.
• Voriconazole is also a concern due to its known association with skin cancer risk and its frequent prescription for off-label indications.

Scientific/Technical Concepts Involved:

• International Agency for Research on Cancer (IARC): The specialized cancer agency of the World Health Organization (WHO), responsible for conducting and coordinating research on the causes of cancer.
• WHO Model List of Essential Medicines: A list published by the WHO containing medicines considered most effective and safe to meet the most important health needs in a health system.
• Group 1 Carcinogen: A classification by IARC indicating that there is sufficient evidence that an agent causes cancer in humans.
• Squamous cell skin carcinoma: A common type of skin cancer that begins in the squamous cells, which are thin, flat cells in the outer layer of the skin.
• Non-Hodgkin lymphoma: A type of cancer that starts in white blood cells called lymphocytes, which are part of the body's immune system.
• Post-transplant lymphoproliferative disorder (PTLD): A condition where white blood cells (lymphocytes) multiply uncontrollably after an organ transplant, potentially leading to lymphoma.