More than 50 research papers were published during 1970 to 1980 on the link between Betel quid / Areca nut along with tobacco chewing and mouth & throat cancer. Many reports pointed out that the percentage of oral cancer among all cancers diagnosed in hospitals in Asia was always much higher than that usually found in western countries. In western countries, the habit of chewing betel quid, with or without tobacco, is virtually unknown. In many descriptive studies, investigators have obtained histories of chewing betel quid with tobacco from series of patients with oral cancer. In most of these studies, the percentage of patients who practice chewing habits is extremely large. Many research papers have revealed that a high incidence of oral, oro- and hypopharyngeal cancer is observed in regions of the world where a high proportion of the population practices betel-quid chewing. Out of the 2,67,000 new oral cancers estimated to occur in the year 2000 globally, 1,28,000 (48%) occur in South and South-East Asia. Out of 1,23,000 cases of oro- and hypopharyngeal (throat) cancer estimated to occur globally annually, 63 000 (51.2%) are accounted in South and South-Easts Asia as per an assessment by Ferley & coworkers of International Agency for Research on Cancer (IARC).
The
International Agency for Research on Cancer (IARC) is an intergovernmental
agency affiliated to World Health Organization (WHO) of the United Nations (UN).
IARC has its own governing council, comprising 27 member countries including
India as on today. Almost all the developed nations of the world are the
members of the governing council of IARC.
IARC was
stablished in 1965 by the World Health Assembly, as an autonomous agency of WHO
with the aim of promoting international collaboration in cancer research. Its
mission is to coordinate international studies on the causes of human cancer,
the mechanisms of carcinogenesis and strategies for cancer prevention, with a
particular focus on promoting research in regions of the world where it is
lacking. As IARC is affiliated to WHO independent of any government, there is
a belief that it provides a reliable and authoritative assessments of many
facets of cancer information valued by scientists, governments, nongovernmental
organizations and the general public, globally.
The
evaluations of carcinogenic risk are made by international working groups of independent
scientists. A detailed account of the procedures involved, research papers
referred and methodology followed for analysing the data etc. are given in the
monograph. Sufficient evidences are provided by IARC that complete transparency
in the process of monograph preparation is followed. The monographs are
prepared based on the examination of all relevant information (research papers
published in reputed journals) in order to assess the strength of the available
evidence that certain exposures could alter the incidence of cancer in humans. Based
on thorough study, the agents/substances are classified as follows.
i. Group 1: The agent is carcinogenic to humans. Ex.:
Lindane, soot, tobacco smoke, Benzene.
ii. Group 2A: The agent is probably carcinogenic to
humans. Ex.: Malathion, Glyphosate (a popular weedicide).
iii. Group 2B: The agent is possibly carcinogenic to
humans. Ex.: Chloroform Chlorophenoxy herbicides, DDT, Aloe vera whole leaf extract.
iv. Group 3: The agent is not classifiable as to its
carcinogenicity to humans. Ex.: Ampicillin, Caffeine, Eugenol, Tea.
v.
Group 4: The agent is probably not carcinogenic to
humans.
So far, IARC has published four reports on the carcinogenicity of areca nut and its components, chewing of tobacco with or without betel quid (Tambula/Pan), with or without areca nut, as follows.
1. Evaluation of the Carcinogenic risk of tobacco, Betel
quid and areca nut chewing. Published in 1985, Vol. 37.
2. Evaluation of carcinogenic risks to humans from betel-quid and areca-nut chewing and some areca-nut-derived nitrosamines. Published in 2004, Vol. 85.
3. Evaluation of Carcinogenic Risks to Humans from Smokeless
Tobacco and Some Tobacco-specific N-Nitrosamines. Published in 2007, Vol. 89.
4.
Identification of carcinogenic hazards from arecoline.
Published in 2021, Vol.128
A detailed
commentary along with critical comments shall be provided on each report in my future
Blogs.
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