GI cancer

For colorectal cancer, 45 is the new 50 for screening


The US Preventive Services Task Force (USPSTF) has recommended dropping the start age for colorectal cancer screening from 50 to 45 years.

The policy change, foreshadowed late last year in draft recommendations and previously reported in the limbic, acknowledges the increasing incidence of colorectal cancer in younger adults.

The USPSTF recommendations, published in JAMA, are now in line with the American Cancer Society which went early on the age change in a 2018 guideline update and the American College of Gastroenterology in their 2021 guideline update.

The USPSTF found in asymptomatic adults at average risk of colorectal cancer:

  • Screening in 50-75 year-olds has substantial net benefit.
  • Screening for 45-49 year-olds has moderate net benefit and should be recommended.
  • Screening in adults 76-85 years has small net benefit, and should be an individual decision based on a patient’s health status.
  • Competing causes of mortality in people from 86 years precludes any survival benefits that might outweigh the harms of screening.

The update to the 2016 USPSTF recommendation follows a systematic review of the evidence for harms and benefits of screening in adults from 40 years.

“Direct evidence on the benefits of colorectal cancer screening to decrease colorectal cancer mortality are available from randomised clinical trials on gFOBT and flexible sigmoidoscopy as well as cohort studies on FIT and colonoscopy.”

Modelling found that screening from the new start age of 45 to 75 years would result in 286-337 life-years gained per 1,000 individuals screened, 42-61 cancers averted per 1,000 individual screened and 24-29 CRC deaths averted per 1,000 individuals screened.

An editorial in JAMA said most young-onset colorectal cancer deaths occur in 45-49 year-olds.

“Although the effectiveness of screening remains unknown for the population aged 40-49 years, the lower rates of young-onset colorectal cancer in countries such as Austria that initiate colorectal cancer screening at age 40 also support the USPSTF policy change.”

But they questioned whether starting screening at age 45 years was early enough?

“Ultimately, optimal prevention and early detection of colorectal cancer among individuals younger than 45 years will require further research into the underlying aetiology and risk factors of young-onset colorectal cancer, which thus far remain elusive but are suspected to possibly be related to environmental exposures during early life.”

They said achieving increased uptake of colorectal cancer screening required “bold steps” beyond guidelines and public awareness campaigns such as bundling the provision of FIT kits with annual ‘flu shots.

“Moreover, physician accountability for prevention and outreach to patients’ families is also important.”

“Gastroenterologists who diagnose polyps and surgeons and oncologists who treat patients with colorectal cancer must identify mechanisms to communicate the importance of screening to at-risk relatives.”

Australian perspective 

However Australia is unlikely to follow suit in a hurry.

Sydney gastroenterologist Dr Cameron Bell told the limbic that the situation might be different if there were unlimited resources.

“The modelling done for the 2017 guidelines wasn’t in favour of reducing the age of commencement,” he said

“There are 60% of people in the 50-60 age group who don’t take up the National Bowel Cancer Screening Program (NBCSP) so energy would be well spent encouraging them to participate.”

“The other thing is evidence in the NBCSP is that the older age groups have much higher participation rates than those in their 50s so there would be a concern that you are sending out a lot of test kits and an even higher proportion of younger people are not going to do the test. That’s a lot of potentially wasted resource.”

Dr Bell said the decision makers were well aware of the increasing incidence of colorectal cancer in younger adults, which ensured the issue keeps getting reviewed on a regular basis.

“So it could change. I get the argument [from the USPSTF], and there is the added multiplier benefit of potential years-of-life gained because you are talking about people who are by definition five years younger if you find a cancer.”

However the numbers didn’t as yet stack up.

“Even though the age 40-45 or 45-50 or the 40-50 numbers have gone up, they are still nowhere near what the age 50-60 numbers were when the bowel cancer screening program was initiated.”

“You are not going to find as many cancers as you are in the 50-54 year old age group but the number of cancers you find is higher than you would have found 15 years ago.”

He said individuals who felt strongly about screening before age 50 could source kits outside the NBCSP.

“There is nothing stopping anybody going to their chemist and for under $40 doing a FOBT. That’s what is recommended for anyone with a significant family history from either 45 or 40 years of age, depending on the strength of the family history.”

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