IARC Classifies Three Medicines as Carcinogenic

The International Agency for Research on Cancer (IARC), a cancer research agency of the World Health Organization (WHO), classified hydrochlorothiazide, voriconazole and tacrolimus as carcinogenic to humans in Group 1 in Volume 137 of the IARC Monographs. The three medicines are widely prescribed for hypertension, fungal infections and organ transplant rejection, and they are included in the WHO Model List of Essential Medicines.

IARC and the Monographs Programme

The IARC Monographs programme began in 1970 and assesses whether an agent can cause cancer under some circumstances. The programme classifies agents into groups such as Group 1, which is used for substances with sufficient evidence of carcinogenicity in humans.

Medicines Classified in Group 1

Hydrochlorothiazide is a thiazide diuretic used as a first-line treatment for high blood pressure. Voriconazole is an antifungal medicine used for serious fungal infections, and tacrolimus is an immunosuppressant used to prevent organ transplant rejection.

• Hydrochlorothiazide has been linked with squamous cell skin carcinoma and lip cancer.
• Hydrochlorothiazide has evidence of increasing skin sensitivity to ultraviolet radiation.
• Tacrolimus has been associated with non-Hodgkin lymphoma and post-transplant lymphoproliferative disorder.
• Voriconazole was placed in Group 1 on the basis of carcinogenic hazard identification.

Hazard Classification and Medical Use

IARC classification identifies carcinogenic hazard and does not measure the actual risk faced by a patient at prescribed doses. Medical experts have stated that patients should not stop treatment without consulting a doctor, because the classification does not replace clinical risk assessment.

Important Facts for Exams

• Group 1 in the IARC system means carcinogenic to humans.
• The IARC Monographs programme was launched in 1970.
• The WHO Model List of Essential Medicines includes medicines considered necessary for priority health needs.
• Hydrochlorothiazide is commonly used in hypertension management.

Clinical and Public Health Context

Hydrochlorothiazide is used in many countries, including India, as a common antihypertensive medicine. Tacrolimus is used after kidney, liver and heart transplantation, and voriconazole is used against invasive fungal infections.