We know that certain lifestyle choices can increase the risk of cancer, but a new study puts into perspective just how many cancer-related deaths could be stopped by exercising more, drinking less, cutting out smoking, or making other lifestyle changes.
Digging through official statistics for Australia in 2013, researchers found that 38 percent of cancer deaths – that's about 16,700 deaths in total – could potentially have been prevented by reducing risk factors.
Top of the list, unsurprisingly, was tobacco smoking, responsible for 23 percent of cancer-related deaths, while poor diet, obesity, and infections each accounted for 5 percent. The researchers hope to highlight just how many lives could be saved with preventative action.
"Cancer is the biggest cause of death in Australia," says one of the researchers, David Whiteman from the QIMR Berghofer Medical Research Institute in Australia. "It claimed 44,000 lives in 2013 and caused untold grief and heartache to many more."
"While in many cases cancer is tragically unavoidable, this study highlights what we've known for years: cancer isn't always a matter of genetics or bad luck."
Of the other "modifiable" risk factors – ones that we can do something about – UV radiation accounted for 3.2 percent of deaths (1,390 people), alcohol for 2.4 percent of deaths (1,037 people), insufficient physical activity for 0.8 percent of deaths (357 people), and reproductive or hormonal factors for 0.4 percent of deaths (172 people).
If you're wondering why all those percentages add up to more than 38, it's because some factors co-occur to cause cancer.
There was some variation by gender, with these eight factors responsible for 41 percent of cancer deaths among Australian men and 34 percent of cancer deaths in women.
"The proportions of potentially preventable cancer deaths are higher among men than women because, on average, men smoke and drink more, spend more time in the sun, and don't eat as well," says Whiteman.
The data also showed the most preventable types of cancer: lung, bowel, cutaneous (skin) melanoma, liver, and stomach.
Of course overdoing the booze, for instance, doesn't necessarily mean you will get cancer – the same as going teetotal doesn't guarantee you won't be hit by the disease. It's sometimes a complicated picture, but these factors can push the risk up or down by varying levels in each case.
To use the example of smoking, people who smoke are 15-30 times more likely to get lung cancer than those who don't. Meanwhile, those whose BMI is too high are up to twice as likely to develop kidney or liver cancer.
A lot of factors come into play, but the main point here is that managing modifiable risk factors can make a difference in a huge number of cases. The research backs up a 2014 study in the US that found up to 21 percent of annual cancer deaths were preventable.
And with a disease as widespread and devastating as cancer, we're talking about thousands and thousands of needless deaths each year. The QIMR Berghofer Medical Research Institute has produced a free guide on how to reduce your cancer risk.
"There is a lot people can do to reduce their risk of developing and dying from cancer," says Whiteman. "Even small improvements in these areas would substantially reduce the number of people who die prematurely from cancer each year."
The research has been published in the International Journal of Cancer.