(05-04-11) Colon cancer a risk for desk-bound workers

?ACTIVE couch potatoes? who have been in a sedentary job for more than 10
years have a risk of distal colon cancer two times higher than those in a more
active job, according to Australian research. (1)

Researchers from the Western Australian Institute for Medical Research at the
University of WA found the positive association between sedentary work and
colorectal cancer was independent of recreational physical activity and was
seen among the most recreationally active participants.

They said the finding fits with the ?active couch potato? phenomenon where
high amounts of sedentary behaviour and physical activity coexist.

The WA Bowel Health Study, a case?control, population-based study, took place
between 2005 and 2007 and involved men and women aged 40 to 79 years who lived
in WA. Self-administered questionnaires on lifestyle, diet, occupation and
medication use were completed by 918 patients recruited from the WA Cancer
Registry and 1021 age- and sex-matched controls.

Participants were asked to complete a lifetime occupation history. Jobs were
classified into five categories ranging from sedentary (eg, bookkeepers,
computing professionals), light (teachers, hairdressers), medium (mechanics,
nurses), heavy (plumbers, farmers) and very heavy (miners, fire fighters). More
than half of the participants were in the ?light? category.

Those who had spent 10 or more years in sedentary work had almost twice the
risk of distal colon cancer and nearly 1.5 times the risk of rectal cancer
compared with those who had never had a sedentary job.

The risk of both cancers increased with the length of time spent in sedentary
work among those who were the most recreationally active and the least
recreationally active participants.

The researchers said there were several plausible biological mechanisms to
explain why sedentary work and behaviour in general increased the risk of
colorectal cancer, including the fact it increased blood glucose levels and
decreased insulin resistance, which were both thought to promote colorectal
cancer carcinogenesis.

?Our finding that sedentary work is associated with the risk of distal colon
cancer but not proximal colon cancer adds to the evidence suggesting that
lifestyle factors may play a larger role in distal colon carcinogenesis than in
proximal colon carcinogenesis,? the researchers said.

?There is no clear mechanistic explanation, however, for why sedentary
behaviour would increase the risk of distal colon and rectal cancers, but not
proximal colon cancer.

?The findings of this study have occupational health implications, especially
given that advances in technology have led to increasing amounts of sedentary
behaviours at work and in other settings,? they said.

The authors said that as sedentary work was unlikely to be eliminated from
modern life, strategies to minimise the time spent sitting, especially in long
bouts, were needed.

An increasing level of sedentary behaviour had been linked to an increased
risk of several other chronic diseases, as well as increased mortality.

?Sedentary behaviour appears to be a novel and important risk factor for many
chronic diseases,? the researchers said.

- Source:
Kath Ryan
1. Am J Epidemiol, advance access March 2011

News

---

In evidenza

"L'informazione presente nel sito serve a migliorare, e non a sostituire, il rapporto medico-paziente."

Per coloro che hanno problemi di salute si consiglia di consultare sempre il proprio medico curante.