Cancer is rarely triggered by a single factor. It
usually results from an interplay between environmental factors - such
as carcinogens or viruses - on one hand, and factors within the body -
such as hormones and inherited genes - on the other. Among numerous
carcinogens, tobacco towers over the rest as the biggest killer. In the
US, for example, it is responsible for 30% of all cancer deaths and 87%
of lung cancer deaths. Researchers estimate that a further one-third of
cancer deaths can be blamed on other "lifestyle" factors, such as diet
and obesity.
Viruses can cause cancer by
interfering with the genetic instructions in cells. The worst culprits
for this are the hepatitis B virus, which can cause liver cancer, and
the human papilloma virus, which can cause cervical cancer. The risk of
developing cancer increases with age, simply because cancerous changes
in cells usually take years to occur. Two of every three people
diagnosed with cancer in the UK each year are over the age of 65
No comments:
Post a Comment