Do I need a colonoscopy at 45?

Why the screening age moved

The Australian National Bowel Cancer Screening Program now starts at 45 (down from 50). The change reflects a real and worrying trend: bowel cancer rates in adults aged 45–49 have been rising for two decades, and earlier screening saves lives.

The MJA (Medical Journal of Australia) and the Cancer Council have both publicly endorsed the shift. The new lower age applies to average-risk people with no symptoms and no family history. If you have either, your starting age is usually earlier — and your starting test is often colonoscopy, not FOBT.

FOBT first — for most people at 45

If you are 45, have no symptoms, and have no family history of bowel cancer or significant polyps, your starting point is the free FOBT/iFOBT kit posted to you every 2 years by the National Bowel Cancer Screening Program.

The test is simple — a small stool sample collected at home and posted to the lab. It detects microscopic blood that you can’t see. A negative result means another FOBT in 2 years. A positive result means a follow-up colonoscopy.

FOBT is not a perfect test. It misses some cancers and most polyps. But across the whole population it catches the cases that matter most and is much more affordable than putting every 45-year-old through a colonoscopy.

When colonoscopy should be your starting test

Colonoscopy is the right starting test rather than FOBT if you have:

• Any rectal bleeding — even “just on the paper” — that you don’t have a clear explanation for.
• A persistent change in bowel habit lasting more than 4 weeks.
• Unexplained iron-deficiency anaemia on a blood test.
• A first-degree relative (parent, sibling, child) with bowel cancer diagnosed at any age, or with advanced polyps.
• Two or more close relatives with bowel cancer.
• A known genetic condition such as Lynch syndrome or familial adenomatous polyposis.
• A history of inflammatory bowel disease (ulcerative colitis or Crohn’s affecting the colon) of more than 8 years’ duration.

If any of these apply to you, talk to your GP about a specialist referral rather than waiting for the FOBT mailout.

Family history — how to know if yours counts

Bowel cancer is the second-leading cause of cancer death in Australia. Roughly 1 in 5 cases occur in people with a family history.

The risk depends on the relationship and the age at diagnosis. A parent diagnosed at 75 is a different risk picture from a sibling diagnosed at 45. As a rough guide: one first-degree relative diagnosed under 55, or two close relatives at any age, often shifts you into a higher-risk category that warrants earlier and more frequent colonoscopy.

If you’re not sure where your family history puts you, a brief specialist consultation will tell you in 30 minutes — and may be reassuring rather than alarming.

If your FOBT is positive, what next?

A positive FOBT does not mean you have cancer. Most positive FOBTs are caused by haemorrhoids, polyps or minor mucosal bleeding. But every positive FOBT in Australia is followed up with a colonoscopy, because that is the only way to know.

If you’ve had a positive FOBT and are now looking at a private colonoscopy to avoid the public-system wait, see our cost guide for what to expect financially.

About your specialist — Dr Goutham Sivasuthan

Dr Goutham Sivasuthan is an Australian-trained specialist surgeon, with conjoint accreditation by the Gastroenterological Society of Australia (GESA) in both upper GI endoscopy and colonoscopy. He completed his medical degree at the University of Queensland and his advanced training across Brisbane’s tertiary hospitals.

Dr Goutham consults and operates exclusively at Brisbane-region day-surgery and hospital facilities, and is the only clinician you’ll meet through your care — from your first consultation, through your procedure, to your follow-up. He is committed to no-gap care for insured patients and transparent pricing for everyone else.

Frequently asked questions

When does the new screening age take effect?

The National Bowel Cancer Screening Program is rolling out the 45-start age progressively. Australians aged 45–49 are being added to the mailout list over multiple years. If you are 45 or older and haven’t had a kit yet, you can request one via the Department of Health website or speak to your GP.

What if I’m under 45 and have symptoms?

Symptoms — bleeding, change in bowel habit, anaemia — always warrant investigation regardless of age. Bowel cancer is rare under 45 but not impossible, and many other treatable conditions present the same way.

Do I need a colonoscopy if my parent had bowel cancer at 70?

A single first-degree relative diagnosed at 70 places you at moderately increased risk. The current guideline is colonoscopy from age 50 (or 10 years younger than the relative’s age at diagnosis, whichever is earlier) and then every 5 years. Your specialist will confirm the right schedule for your family history.

Is FOBT or colonoscopy more accurate?

Colonoscopy is more accurate — it directly visualises the entire colon and detects almost all cancers and the majority of significant polyps. FOBT is a screening test, designed to triage millions of people cheaply; it catches important cases but misses some.

What if I’m 45 with no symptoms and no family history?

Start with the FOBT/iFOBT. It’s the right first test for average-risk Australians at this age. Colonoscopy only becomes the starting test if your FOBT is positive or your situation changes.

This article is part of our specialist series on bowel and gut health. For the full overview, see our main service page.