WHO Carcinogenic List

Why in News?

Recently, the WHO’s International Agency for Research on Cancer (IARC) classified 3 widely prescribed medicines — hydrochlorothiazide, voriconazole, tacrolimus — as Group 1 carcinogenic to humans in IARC Monographs.

Key Findings

• Hydrochlorothiazide – Hypertension therapy.
• Voriconazole – Antifungal drug.
• Tacrolimus – Immunosuppressant for organ transplant rejection.
• Status – All three widely-prescribed medicines have been classified as carcinogenic to humans (Group 1).

Evidence

• Hydrochlorothiazide – Strong evidence causing squamous cell skin carcinoma, lip cancer and phototoxicity increases UV sensitivity causing DNA damage.

Carcinoma – A common type of cancer that starts in epithelial cells, which are the cells lining the outer surface of the body, internal organs, and glands.

• Voriconazole – Associated with squamous cell carcinoma in transplant patients; same phototoxic mechanism.

Squamous Cell Carcinoma – Arises in flat, scale-like cells found in the skin and organ linings.

• Tacrolimus – Linked to non‑Hodgkin lymphoma, post‑transplant lymphoproliferative disorder, with limited evidence for leukaemia and skin carcinoma.
• But it risks stems from immunosuppression weakening the body’s ability to clear abnormal cells.

Indian Context

• Usage
  • Hydrochlorothiazide - Common in hypertension therapy;
  • Voriconazole - Widely prescribed in immunocompromised patients.
  • Tacrolimus - Central to transplant care.
• Concerns – High UV exposure in rural, coastal, hilly regions especially for farmers, increases risk.
• Issues – Irrational prescribing, over‑the‑counter availability, poor adherence to ethical practices.

Recommendations

• Hydrochlorothiazide/Voriconazole – Use sunscreen, limit UV exposure, periodic skin checks.
• Tacrolimus – Routine monitoring for skin cancers and lymphoproliferative disorders.

Reference

The Hindu | WHO Carcinogenic List