Healthy 80 year olds need FIT tests

There is a trade-off in cancer screening. On the one hand, older people are more likely to get cancer - as the chart shows, colorectal cancer incidence rates rise with age. On the other hand, the number of years one can expect to live decreases as one gets older. If a cancer is slow growing - as colorectal cancer often is - an older person might die of a heart attack or another illness before the cancer becomes life threatening. In this case, putting a person through an unpleasant and possibly dangerous regime of colonoscopies and surgeries will create harm with very few benefits. 

But how do we make that trade-off? And where do we draw the line?

Ontario, BC, and most other provinces recommend that people at average risk of colon cancer get a fecal immunochemical test, or FIT, every two years between the ages of 50 and 74. This is in line with the American Cancer Society recommendations published here. 

But why stop at age 75? In Canada the average 75 year old man can expect to live 12 more years (based in 2017-19, pre-COVID, mortality rates), an average 75 year old woman has 14 years ahead of her. That's plenty of years for a cancer to get established and make a person's life miserable. If one multiplies the life expectancy numbers shown above with the cancer incidence rates, it turns out that the number doesn't change much over the life cycle - older people lose fewer life years when they get cancer, but they are much more likely to get it. 

So why aren't we doing FIT tests on older adults?

The American Cancer Society article on colorectal cancer screening (here) notes, "On the basis of data from gFOBT randomized trials, the lag time to CRC screening benefit has been estimated to be 10 years", which means screening is not worthwhile for people with less than 10 years life expectancy. But an average 78 year old man can still expect to life 10 years or more. A 78 year old in good health can expect to live even longer. Women still have 10 years of life expectancy at 80 (again, based on pre-COVID 2017-19 mortality rates). If you're a healthy 80 year old, you will meet that 10 year cut-off.

So, again, why the lack of clear recommendations on FIT screening for older adults?  

It's partly that very few studies are done on old folks: "Given the paucity of evidence to inform screening decisions in this age group, patient preference should weigh heavily in the decision" (source).

It's also that no one wants to talk about life expectancy; to tell patients that it's not worth screening them because they're likely to die within the next 10 years. So the American Cancer Society recommends simply avoiding these conversations: "patients may be receptive to a discussion with a clinician of screening cessation based on age and health status, but not emphasizing limited life expectancy" (source).  In this spirit, the Ontario government's colorectal cancer screening guidelines say "You can do an easy-to-use at-home test if you’re at average risk for colon cancer. You are at average risk if you are ages 50 to 74." That makes it sound like your risk goes down after age 74. It doesn't. It's just that historically many 74 year olds couldn't expect to live 10 years or more, so it wasn't worth screening them. 

But no one wants to tell you that. And people may die because of this systematic refusal to have difficult conversations.

Politics also come into play. Jacques and Noël (here) draw a distinction between "loud" policies and "quiet" policies.  Loud policies generate headlines like BC woman fighting cancer denied immunotherapy drug or Autistic kids 'falling through the cracks'. According to Jacques and Noël, loud policies   "impose visible costs and offer definite benefits". The payoff for spending money on a loud policy is immediate, and the people who benefit from the policy know about it. Consequently, loud policies "mobilize voters, groups, and parties"  - and thus help governments get (re) elected. 

Most preventative medicine, however, is "quiet" policy. It is "characterized by low levels of spending, an uncertain distribution of costs and benefits, or appear technical and difficult for the public to comprehend" (Jacques and Noël, above source).

There is no single, well-organized interest group that benefits from investments in FIT tests. There are so many different manufacturers of FIT tests (see a list here) - the market is too competitive to be ultra-profitable. And it's hard for your average 20, 40 or 60 year old to get worked up about cancer screening for 80 year olds - that's so far in the future - who cares?

Until someone you know is diagnosed with colon cancer, and you find out it could have been detected earlier if only they had access to preventative screening. That's when colorectal cancer screening becomes a LOUD policy issue, and you start shouting to anyone who will listen:

IF YOU'RE 80 YEARS OLD, HEALTHY AND ENJOYING LIFE, GET A FIT TEST.

(Available for $75 here if your doctor won't order one for you)

Comments

[Gavin Moodie]

Thanx for this.

Mightn't one conduct a cost-utility analysis: the cost per quality-adjusted life years.

Public Health Agency of Canada. (2024). Interpretation Guide – Health Economics

https://www.canada.ca/en/public-health/services/immunization/national-advisory-committee-on-immunization-naci/methods-process/interpretation-guide-health-economics.html