Australians aged 50-74 are being encouraged to use the bowel cancer screening test as soon as they receive it in the mail.

People are too busy to participate in the national bowel screening program even though the three-minute test could save their life.

Data released on Monday shows 40 per cent of respondents who received the free and potentially life-saving bowel cancer screening kits in 2017 did not use it.

Many said they ignored the test because they did not have the time.

Professor David Currow, Chief Officer and CEO of the Cancer Institute NSW says its critical older Australians take the test because bowel cancer can be successfully treated in 90 per cent of cases if detected early.

"So please don't leave these kits in your drawer or wait until you are experiencing symptoms," said Professor Currow.

A survey conducted by the Cancer Institute of New South Wales found 40 per cent of the respondents said they did not have time to do the three minute do-it-yourself test, while 15 per cent said they simply forgot.

Three per cent said embarrassment prevented them from taking it.

Christopher Horn, Bowel Cancer Screening Manager at Cancer Institute NSW says the test is "clean" and very quick.

Mr Horn warned having had a recent colonoscopy is not a safeguard and that screening is still essential.

The other important message, he says, is that people can have no symptoms and still have bowel cancer.

More than 16,000 Australians will be diagnosed with bowel cancer every year.

Data from the NSW Cancer Registry shows that about 60 per cent of people with bowel cancer find out it has already spread to other organs like the liver or lungs by the time they are diagnosed, reducing the chances of successfully treating it.

To improve bowel cancer survival, early detection is critical and people aged 50 to 74 are encouraged to use the test kit as soon they receive it in the mail.

"A couple of minutes spent doing the test could save months of invasive treatment later on and chemotherapy," said Mr Horn.

Reasons For Not Taking Bowel Screen Test:

* Don't have time (40 per cent);

* Forgot (15 per cent);

* Already had a colonoscopy (10 per cent);

* Too embarrassing (3 per cent);

* No symptoms (1 per cent).

(Source: Cancer Institute NSW)