Colorectal Cancer Rose in 2023 After 20 Years of Decline, Across Nearly All Ages

For two decades the line went one way. Picture a long slide drawn across a page: colorectal cancer in the United States, 55.2 new cases for every 100,000 people in 2000, easing down year after year to 36.7 by 2022. Then, at the very end, the line tips up. We read the new paper behind that turn the day it was published, checked its three numbers against the abstract, and set them beside the screening rules and the earlier research on who is getting this cancer.

Three things come out of it. The 2023 rise is small in size but new in kind: it is the first increase in the overall rate in the registry’s history. It is not confined to people in their 20s and 30s, the group most coverage has focused on; it runs up to age 69. And part of it is good news in disguise, because one age group is rising mostly because more of its members are now being screened.

The paper: A two-decade decline in colorectal cancer ended with a 2023 uptick

The study, “Colorectal Cancer among U.S. Adults, 2000–2023,” was published online in NEJM Evidence on October 27, 2026, by Caitlin C. Murphy of the University of Chicago with colleagues at UCLA, Emory, the VA and UC San Diego (PubMed 42937424; DOI). It uses the National Cancer Institute’s SEER 21 cancer registries, which the authors say cover 45.8% of the U.S. population.

According to the abstract, the age-adjusted colorectal cancer incidence rate was 55.2 per 100,000 in 2000, 36.7 per 100,000 in 2022 and 38.3 per 100,000 in 2023. The confidence intervals for 2022 (36.4 to 37.0) and 2023 (38.0 to 38.6) do not overlap. In our arithmetic, that is a 4.4% rise in one year, after a 33.5% fall over the 22 years before it. The authors call the 2023 increase “the first since the inception of SEER 21” and say it “warrants additional surveillance and investigation.”

One year is one year. A single data point can move back, and the authors frame it as a signal to watch rather than a settled trend. What makes it worth reading closely is where the rise is coming from.

The ages: The rise in colorectal cancer runs from young adults to the late 60s

Most of the attention on colorectal cancer in recent years has gone to adults under 50. That remains true: the University of Chicago release cites American Cancer Society figures showing incidence among adults aged 20 to 49 rose 3% a year from 2013 to 2022, and notes that colorectal cancer now ranks first among cancer deaths in adults younger than 50 (University of Chicago Medical Center release, October 27, 2026).

The new analysis widens the picture. According to the release, rates are now rising in every age group up to 65 to 69, and have plateaued among people aged 70 to 74. That older group matters because, as the release puts it, people of those ages are about 80% up to date with screening, the group where the system works best. A rise there is harder to explain by screening alone.

The authors also checked whether the pandemic created the jump. Screening dropped in 2020 and 2021, and a backlog of delayed diagnoses could in theory have landed in 2023. According to the release, the increase persisted even when 2020 and 2021 were left out, and screening had largely returned to pre-pandemic levels by January 2021, which makes COVID an unlikely explanation.

The good-news part: Screening at 45 explains the steepest line in the colorectal cancer data

The sharpest increase in the paper is among people aged 45 to 49: 12.76% a year from 2019 to 2023, according to the University of Chicago release. Held steady for four years, that compounds to roughly 62% (our arithmetic).

That number has a known cause. In May 2021 the U.S. Preventive Services Task Force lowered the recommended start of colorectal cancer screening from 50 to 45, giving 45 to 49 a grade B and 50 to 75 a grade A (USPSTF final recommendation). More people in their late 40s started getting checked, and checking finds cancers that were already there. Murphy put it plainly in the release: “That means that screening is doing as we intend it to do — it’s catching cancer earlier.”

Our reading: a rise driven by earlier detection is not the same as more people getting sick. Cancers found earlier are, in general, easier to treat. The open question in the paper is everything else, the rise in younger adults who are not yet screened and in the 65 to 69 group who largely already are.

The why: Generation, not just age, shapes colorectal cancer risk

Murphy describes the pattern in the release as a birth cohort effect, “the interaction of age and time”: people born around the same time carry their risk with them as they age. Earlier registry work points the same way. A 2017 American Cancer Society and National Cancer Institute analysis of SEER data from 1974 to 2013 found that, compared with adults born around 1950, those born around 1990 had about double the risk of colon cancer and about four times the risk of rectal cancer (Siegel et al., JNCI 2017, PMID 28376186).

If the generations born from the 1960s on carry a higher risk, the rise would be expected to reach older age groups as those generations get older, which is what the 2023 data now show up to 69. What drives the cohort effect is not settled. The release says the team plans laboratory work on environmental chemical exposures using colon organoids, small lab-grown models of colon tissue, and Sonia Kupfer of UChicago Medicine said the results “motivate us to understand reasons for this rise, so risk factors can be identified and possibly reduced.”

Diet is one of the long-studied threads. A 2011 BMJ meta-analysis of 25 prospective studies found that each additional 10 grams of dietary fiber a day was associated with a 10% lower risk of colorectal cancer, with cereal fiber and whole grains showing the clearest link (Aune et al., BMJ 2011, PMID 22074852). That is an association in observational data, not proof that fiber prevents the disease, and it does not explain the 2023 turn on its own.

The everyday version: What the new colorectal cancer numbers mean at home

For adults at average risk, the Task Force recommends screening from 45 through 75, and lists several ways to do it: a stool test (FIT or high-sensitivity guaiac) every year, a stool DNA-FIT test every one to three years, CT colonography or flexible sigmoidoscopy every five years, or colonoscopy every ten. Kupfer said in the release that there are several ways to screen that should be discussed with a clinician; for people younger than 45 or older than 75, the decision is individual.

For people under 45, screening is not routine, so symptoms do the work. The CDC lists a change in bowel habits; blood in or on the stool; diarrhea, constipation or a feeling that the bowel does not empty all the way; abdominal pain or cramps that do not go away; weight loss without a known reason; and low iron levels (CDC). It also notes that polyps and early colorectal cancer do not always cause symptoms, which is the whole case for screening. Any of those changes that sticks around is a reason to see a doctor, at any age. Our guide to blood in stool covers the common, harmless causes too.

And the everyday habit with the longest research record is the dull one: more fiber, from whole grains, beans, fruit and vegetables. Our piece on probiotics versus fiber sets out how much most people are missing.

How we checked this: Sources and method

We read the study’s abstract on PubMed (PMID 42937424) and its Crossref record on October 27, 2026; the journal’s own page was not reachable to us, so the age-group figures (the 12.76% a year for 45 to 49, the plateau at 70 to 74, the 80% screening figure, the pandemic check) are as stated in the University of Chicago Medical Center release of the same day, read as carried in full by Mirage News and Medical Xpress. The 3% a year figure for ages 20 to 49 is American Cancer Society data as cited in that release. Screening rules are from the USPSTF final recommendation of May 18, 2021; symptoms from the CDC. Earlier studies were matched by PMID and title before citing. Percentages marked as our arithmetic are ours. This article is educational, describes what the cited sources say, and is not medical advice.