Cigarette tar yields in relation to mortality from lung cancer in the cancer prevention study II prospective cohort, 1982-8
BMJ 2004; 328 doi: https://doi.org/10.1136/bmj.328.7431.72 (Published 09 January 2004) Cite this as: BMJ 2004;328:72All rapid responses
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Dear Sir,
An excellent paper you recently published (1) demonstrates similar
cancer risk in people who smoke medium, low and very low tar cigarettes.
This raises questions about smoking-related cancer causes that are
additional to tar components.
Nitrosamine-DNA adducts have certainly been shown in smokers. Many
important papers on this topic can be found in references (2) and (3). In
a recent study (4) we were able to confirm this in 13/14 smokers. However,
8/14 of the smokers also had nickel-DNA adducts and 11/14 had cadmium-DNA
adducts. Both nickel and cadmium are concentrated by the tobacco plant and
nickel is a known carcinogen.
I am unable to find any data to show reduced nickel and/or cadmium in
low tar cigarettes. The toxic metal DNA burden and especially the nickel
adducts may be additional risk factors for lung cancer in smokers.
Another concern from the results of our study is that 11/74 non-
smokers with no specific history of toxic metal exposure had nickel-DNA
adducts and 9/74 had cadmium-DNA adducts. A larger study is needed to
explore this area of cancer risk that may well offer an explanation for
similar lung cancer rates in smokers of medium and low tar cigarettes.
1) Harris JE, Thun MJ, Mondul AM, Calle EE. Cigarette tar yields in
relation to mortality from lung cancer in the cancer prevention study II
prospective cohort, 1982-8. BMJ 2004; 328: 72-6.
2) Hemminki K, Dipple A, Shuker DEG, Kadlubar FF, Segerback D,
Bartsch H. DNA Adducts: Identification and Biological Significance. IARC
Scientific Publications no. 125. Lyon, France: International Agency for
Research on Cancer, 1994.
3) Singer B, Bartsch H. Exocyclic DNA Adducts in Mutagenesis and
Carciogenesis. IARC Scientific Publications no. 150. Lyon, France:
International Agency for Research on Cancer, 1999.
4) McLaren Howard J. The Detection of DNA Adducts (Risk Factors for
DNA Damage). A Method for Genomic DNA, the Results and Some Effects of
Nutritional Intervention. Journal of Nutritional and Environmental
Medicine 2002; 12: 19-31
Competing interests:
None declared
Competing interests: No competing interests
The answer to a quandary?
Despite being an ex-smoker myself I am one of those who remain less
than convinced about some dangers of passive smoking in support of which
little good science appears to exist and am concerned that the current
raft of proposals to restrict the activities and civil liberties of
smokers is a ‘bridge too far’.
I read this article with great interest as
I believe that it may suggest the answer to a long-standing quandary which
the authors did not highlight.
The authors’ suggestion that compensatory smoking was the reason for no
difference in risk being demonstrated between those who smoked medium, low
or very low tar cigarettes is only one possible explanation for the
findings.
The consistent observation of the many examples of ‘Uncle Fred’ who smoked
heavily all his life and was fit as a flea until he passed on in his sleep
aged 90 should make us ask why did he neither get carcinoma of the lung,
despite the wholesale application of carcinogenic paint, nor elsewhere to
kill him; in other words, was he simply good at immunosurveillance?
Should the range of tars in cigarettes be equated with an equivalent range
of risk or are some individuals simply at risk for the development of any
sort of carcinoma due to poor defence mechanisms when the threshold of
carcinogen load is exceeded for example in very low tar brands, perhaps
through passive smoking or even diet? What about the incidence other
cancers in these and other patients?
Carcinoma of the lung with its smoking connection is very emotive but
perhaps rather than attempt to eradicate all passive smoking we should get
real and look more closely at the immune surveillance systems of ‘Uncle
Fred’ and his kind to the future benefit of all.
Competing interests:
None declared
Competing interests: No competing interests