In US, 4 in 10 cancers due to 'modifiable risk'

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A new look at cancer in the USA finds that almost half of cancer deaths are caused by smoking, poor diet and other unhealthy behaviours.

A large new study from the American Cancer Society lists risk factors for various types of cancer.

The study was published in the journal CA: A Cancer Journal for Clinicians.

Better education about cancer prevention and access to preventive health care should be key parts of the battle against cancer in America, the study concluded. "We've looked at one source of information about risk factors for one type of cancer and another source of information for a different type of cancer".

Breast cancer tops the chart for most new cancer cases, followed by prostate cancer and bronchus or lung cancer.

Many cancers are causally related to potentially modifiable risk factors, [4, 5] and contemporary estimates of this proportion in a population (ie, the population-attributable fraction [PAF]) are a valuable tool for setting priorities for cancer prevention and control.

Cancer specialists have long recognized causal associations between potentially modifiable risk factors and various types of cancer, Islami and co-authors noted in their introduction.

The study used 2014 data and was conducted by the American Cancer Society. The risk factors included in the analysis were: cigarette smoking; secondhand smoke; excess body weight; alcohol intake; consumption of red and processed meat; low consumption of fruits/vegetables, dietary fiber, and dietary calcium; physical inactivity; ultraviolet light; and six cancer-associated infections. Excess body weight was associated with more than twice as many potentially preventable cancers in women as in men, whether represented by PAF (10.9% versus 4.8%) or actual case volume (85,680 versus 37,670).

Researchers found an estimated 42% of the 1.57 million cancer cases in the USA three years ago were linked to preventable risk factors.

With regard to specific types of cancer, the proportion of cases attributable to potentially modifiable risk factors exceeded 15% for 15 of the 26 cancers.

With respect to cancer mortality, smoking accounted for nearly 30% (169,180) of all cancer deaths and more than half of cancer deaths attributable to potentially modifiable risk factors (265,150).

In 2014, the latest year with available incidence data, there were 1,596,486 new cases of cancer and 591,686 deaths from it. A similar sex disparity was observed for physical activity, which accounted for 4.4% of preventable cancers in women versus 1.5% in men.

Among all risk factors, cigarette smoking accounted for the highest proportion of cancer cases, the study found. Smoking accounted for more than 80% of lung cancer and 74% of all larynx cancers.

"This report underscores how important it is to focus on healthy behaviours and healthy public policies to reduce the number of people hearing the words "you have cancer" each year", Dr. Leah Smith, an epidemiologist at the Canadian Cancer Society, said in a statement.

- Excess body weight was associated with 60 percent of uterine cancers and about one-third of liver cancers.

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