The case for increasing control of tobacco to save more lives was further strengthened by a recent US study that showed that smoking is linked to most male deaths from all forms of cancer, not just lung cancer, reinforcing suggestions made by other studies.

The epidemiological study of men who died of cancer in Massachusetts over a 25 year period found that more than 70 per cent of the cancer death burden was linked to smoking. This is more than twice the 34 per cent estimate used since 2001. The study was the work of lead author Bruce Leistikow, a University of California (UC) Davis associate adjunct professor of public health sciences, and colleagues, and was published online in the journal BMC Cancer.

Leistikow, who specializes in researching premature deaths, said in a statement that the new findings support a growing scientific understanding that “smoking is a cause of many more cancer deaths besides lung cancer”.

He said that in the rush to link other factors like diet and pollution to cancer, we have perhaps overlooked the full impact that smoking, including breathing in second hand smoke, has had on cancer.

In their background information, Leistikow and colleagues cite various established ways of finding out, from an epidemiological point of view, how smoking is linked to deaths from cancer. However, their usefulness is limited because they can’t generalize to all subgroups of a population. But a new way is now available that can, hence the reason for this study.

Using the new method, which is based on the concept of “smoke load” to determine the population-specific smoking attributable fractions (SAFs), the researchers assessed cumulative lung cancer against non-lung cancer death rates among all Massachusetts men who died between 1979 and 2003. The data came from the National Center for Health Statistics.

The results showed that “lung and non-lung cancer death rates were tightly and steeply associated across years”.

A key finding was that the lung cancer/non-lung cancer associations suggested that 73 per cent of all cancer deaths in 2003 were smoking-related (ie linked to SAFs) for all ages and 74 per cent for those who died between the ages of 30 and 74.

The authors concluded that:

“The strong lung/non-lung cancer death rate associations suggest that tobacco smoke load may be responsible for most prematurely fatal cancers at both lung and non-lung sites.”

“The present method estimates are greater than the earlier estimates. Therefore, tobacco control may reduce cancer death rates more than previously noted,” they added.

Leistikow said:

“The fact that lung and non-lung cancer death rates are almost perfectly associated means that smokers and nonsmokers alike should do what they can to avoid tobacco smoke. It also suggests that increased attention should be paid to smoking prevention in health care reforms and health promotion campaigns.

The study was sponsored by UC Davis, the Health Research Board of Ireland and the US National Cancer Institute.

“Male tobacco smoke load and non-lung cancer mortality associations in Massachusetts.”
Leistikow BN, Kabir Z, Connolly GN, Clancy L, Alpert HR.
BMC Cancer 2008, 8:341

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Sources: Journal Article, University of California – Davis – Health System.

Written by: Catharine Paddock, PhD