Colorectal Cancer Rose 1.6 Per 100,000 in 2023; Screening Is Only Part

Subtract 36.7 from 38.3 and you have the whole headline in one small number: 1.6. That is how much the U.S. colorectal cancer rate rose in 2023, from 36.7 new cases per 100,000 people to 38.3, the first rise in the SEER 21 registry data since they began in 2000.

The finding comes from a short Public Health Alert published Oct. 27, 2026 in the NEJM Evidence report by Caitlin Murphy of the University of Chicago and four co-authors. SEER 21 is a National Cancer Institute registry set covering 45.8% of the U.S. population. The authors tracked age-adjusted incidence from 2000 to 2023. (Incidence is new diagnoses per year; age-adjusted means the rate is corrected for the ageing of the population, so different years can be compared fairly.) It fell from 55.2 per 100,000 in 2000 to 36.7 in 2022, then ticked up. The authors themselves call the 2023 increase "apparent" and "modest."

Put in plain numbers, 1.6 more per 100,000 is a 4.4% rise from 2022, or roughly one extra diagnosis for every 62,500 people. The 2023 rate is still about 31% below the 2000 rate. None of that makes the disease minor: the National Cancer Institute's SEER program puts the lifetime chance of a diagnosis at about 3.9%, roughly 1 in 26, and overall five-year relative survival at 65.4%. But a reader who saw "colon cancer is rising in nearly every age group" deserves the scale first, and then the more useful question: which part of this rise is screening working, and which part is not?

At 45 to 49, the biggest jump is mostly screening doing its job

The sharpest increase in the alert was at ages 45 to 49: 12.76% a year from 2019 to 2023. Percentages hide their base. The per-person rate for this age group is not in the material reviewed here, and the group sits well below older adults in risk (the chart below shows the gradient).

The timing points to screening. National guidance moved the recommended start age from 50 to 45, and the U.S. Preventive Services Task Force finalized its version on May 18, 2021, giving ages 45 to 49 a Grade B. The authors say the jump is likely driven by more people being tested after that change. Murphy put the implication this way:

"That means that screening is doing as we intend it to do — it's catching cancer earlier."

Caitlin Murphy, professor, University of Chicago, lead author

A separate analysis gives the mechanism some numbers. In a 2025 American Cancer Society analysis in JAMA of SEER 21 data for 2004 to 2022, incidence at ages 45 to 49 rose 1.1% a year until 2019, then 12.0% a year from 2019 to 2022, "driven by the detection of local-stage tumors." Local-stage means the cancer has not spread beyond where it started. That rate went from 11.7 to 17.5 per 100,000 between 2021 and 2022, a 50% relative increase that works out to 5.8 more cases per 100,000. A companion JAMA study found screening in this age group rose 62% from 2019 to 2023. (These are the society's figures from a different analysis, not the new paper's.)

That is the signature of a test finding cancers sooner. It is also the point of screening: SEER figures show localized colorectal cancer has a 91.3% five-year relative survival, yet only 33.8% of cases are diagnosed that early. For a different prevention story, see our report that the HPV jab cuts cervical cancer deaths in young women to near zero. Only 37% of adults 45 to 49 were up to date in 2023, so this effect has room to continue.

At 50 to 69, screening does not explain the rise

Older ages are where the story turns. CIDRAP's summary says age-specific rates "seemed to increase in all age-groups up to age 65 to 69," with a plateau at 70 to 74. Those older groups were historically the biggest beneficiaries of screening, and about 80% of people in them are up to date, according to the University of Chicago release. The authors conclude that more testing cannot explain a rise there, and suggest unknown risk factors may be offsetting the gains screening has made.

Here is a method point that the coverage skipped. Screening produces a bump in local-stage diagnoses, because it finds small cancers that would otherwise surface later. A real rise in risk shows up differently: as growth in advanced-stage disease, which testing does not create. The American Cancer Society's Colorectal Cancer Statistics 2026 report found exactly that at ages 50 to 64. During 2013 to 2022 incidence rose 0.4% a year, and the increase was "confined to advanced disease," regional and distant stage by about 1% a year each.

So the age groups look different under this lens. Ages 45 to 49 look like earlier detection. Ages 50 to 64 look like something else. Ages 65 to 74, at 82% up to date in 2023 per the American Cancer Society, are unexplained, but they are also one year of data. This is a framework drawn from separate American Cancer Society studies. The new paper's own age and stage tables were not available for review, so none of this is that paper's finding. In fact, CIDRAP's summary says the alert's overall trend was similar across diagnostic stage, which the framework alone would not predict.

The chart is the reason percentages mislead here. The group with the biggest percentage jump, 45 to 49, is not where per-person risk is highest. Adults 65 and older have a rate of 153.1 per 100,000, about 2.25 times the 50 to 64 rate and 11.7 times the rate for ages 20 to 49. Of the 158,850 new cases the society expects in 2026, 86,610 (55%) are in people 65 and older and 24,640 (16%) are under 50. Still, 45% of diagnoses now come before 65, up from 27% in 1995.

Why is it happening? Nobody knows. The authors' working idea is a birth cohort effect, which Murphy describes this way:

"I think of a birth cohort effect as the interaction of age and time. As people born around the same time move through time and age together, we're going to see more colorectal cancers being diagnosed."

Caitlin Murphy, professor, University of Chicago

In that reading, people born in the 1960s and later carry higher risk as they age. Murphy added that whatever is causing colorectal cancer in younger people "is now also causing it to increase in older people as well." Her team, working with toxicologist Xin Hu of Emory, is measuring thousands of environmental exposures in a small blood sample and plans organoid tests (lab-grown miniature tissue). No link has been established. The American Cancer Society also reports that rectal cancer incidence has risen 1% a year since 2018 and now accounts for about one in three diagnoses (32%).

One year of registry data is a signal, not a verdict

The limits are worth stating plainly. This is an observational study of registry data, so it can count cancers but cannot say what causes them. SEER 21 covers 45.8% of the country, not all of it. The 2023 rise is a single year, which is why the authors say it "warrants additional surveillance and investigation" and why Medical Daily's summary calls it an early signal. And the alert is short; the full tables were not reviewed for this article.

Two checks cut against dismissing it. The increase persisted when 2020 and 2021 were excluded, and screening had largely returned to pre-pandemic levels by January 2021. The authors write:

"Although postpandemic catch-up in diagnoses cannot be excluded, it seems unlikely to explain the increase in 2023."

Authors, via CIDRAP

Checks against over-reading it are just as plain. For adults 65 and older, the American Cancer Society found incidence fell 2.5% a year during 2013 to 2022, in contrast to increases of 3% a year at ages 20 to 49 and 0.4% a year at 50 to 64. A one-year uptick at 65 to 69 sits against a long decline. It could be the start of a reversal, or noise.

What to do at each age, and which test to choose

Know your start age, finish the test you choose, and do not wait on symptoms.

The American Cancer Society updated its guideline in May, keeping 45 as the start age. The menu is wider than colonoscopy. A FIT (a stool test done at home) or high-sensitivity stool blood test is repeated every year. The updated multitarget stool DNA test and a new stool RNA test run every three years. Colonoscopy is every 10 years; flexible sigmoidoscopy or CT colonography every five. A new blood test taken in a doctor's office is recommended only for people who decline or do not complete preferred tests, because it is less sensitive for advanced precancerous lesions and stage I cancers than stool tests.

The release stresses that the most effective test is the one the patient completes. Sonia Kupfer, MD, who directs the Gastrointestinal Cancer Risk and Prevention Clinic at UChicago Medicine, adds that "there are several ways to do screening that should be discussed with a clinician, so people know what the different screening tests are intended for and how often these need to be repeated." About 20 million eligible Americans, roughly 1 in 3 adults, have not been tested as recommended.

A positive stool or blood test is not a diagnosis, but it does need a colonoscopy, preferably within six months. Follow-up colonoscopy is the step that completes screening, and it is where the cost catch lives. Most private plans and Medicare cover recommended screening without a deductible or copay, but some costs can still apply, such as when a polyp is removed or when a private plan bills a follow-up colonoscopy as diagnostic.

Under 45, with no risk factors, there is no routine test. Kupfer says to watch for symptoms such as blood in the stool, changes in bowel habits or unexplained weight loss and see a doctor; ongoing abdominal pain is another warning sign listed by Medical Daily. The American Cancer Society says three in four colorectal cancers in adults younger than 50 are found at an advanced stage, which is the argument against waiting. People with inflammatory bowel disease, an inherited condition such as Lynch syndrome, or a personal or family history of colorectal cancer or polyps may need to start earlier or be screened more often.

Whether 2024 repeats 2023 will be clear when the registry updates, and the exposure studies will take longer. The guidance has not changed in the meantime, and the number worth checking tonight is the date of your last test.