Overview
The International Agency for Research on Cancer, commonly known as IARC, is the specialised cancer research agency of the World Health Organization.
It was established in 1965 and is headquartered in Lyon, France.
Its main purpose is to coordinate and conduct international research on:
- causes of cancer;
- cancer prevention;
- cancer epidemiology;
- environmental and occupational carcinogens;
- global cancer burden.
IARC does not function as a hospital or treatment agency. Its primary role is scientific research, evidence evaluation and cancer surveillance.
Major Functions
IARC works in several important areas.
Cancer Epidemiology
It studies patterns, causes and risk factors of cancer across populations and countries.
Cancer Surveillance
It supports cancer registries and produces global estimates of cancer incidence, mortality and prevalence.
Research on Causes
It examines links between cancer and factors such as:
- tobacco;
- alcohol;
- radiation;
- occupational exposure;
- infections;
- air pollution;
- chemicals;
- diet and lifestyle.
Cancer Prevention
IARC develops scientific evidence that can support prevention policies and public-health interventions.
IARC Monographs
IARC is particularly well known for its Monographs on the Identification of Carcinogenic Hazards to Humans.
These assessments classify agents according to the strength of evidence that they can cause cancer.
The principal categories are:
- Group 1: Carcinogenic to humans
- Group 2A: Probably carcinogenic to humans
- Group 2B: Possibly carcinogenic to humans
- Group 3: Not classifiable as to its carcinogenicity to humans
The classification may apply to:
- chemicals;
- occupations;
- physical agents;
- biological agents;
- lifestyle exposures;
- environmental conditions.
Hazard and Risk
An important distinction is that IARC classifications identify hazard, not the actual level of risk from a specific exposure.
A substance may be classified as carcinogenic because it is capable of causing cancer under some circumstances.
However, actual risk depends on factors such as:
- dose;
- duration of exposure;
- frequency of exposure;
- route of exposure;
- individual susceptibility.
Therefore, two substances in the same IARC category may create very different real-world risks.
Global Cancer Observatory
IARC also operates the Global Cancer Observatory, which provides international data and estimates on cancer.
It supports analysis of:
- incidence;
- mortality;
- prevalence;
- geographic variation;
- long-term trends.
These data help governments and researchers identify priority cancers and allocate health resources.
IARC also supports population-based cancer registries in low- and middle-income countries where reliable cancer data may be limited.
Importance and Limitations
IARC plays an important role in:
- identifying cancer hazards;
- supporting evidence-based regulation;
- guiding occupational and environmental standards;
- strengthening cancer surveillance;
- informing prevention strategies.
However, its classifications are sometimes misunderstood.
An IARC classification:
- does not automatically determine a legal ban;
- does not directly measure the magnitude of risk;
- does not replace national risk assessment;
- does not mean that all exposure levels are equally dangerous.
National governments and regulatory agencies use IARC evidence together with exposure data, economic considerations and local conditions when developing policy.
Conclusion
The International Agency for Research on Cancer is the WHO’s specialised scientific agency for studying cancer causes, patterns and prevention. Its major global contribution lies in cancer surveillance and the systematic identification of carcinogenic hazards through independent scientific evaluation.
