# Colorectal cancer incidence patterns in the United States, 1974-2013

Source: https://onco.cc/key-papers/paper-siegel-colorectal-incidence-birth-cohort-jnci-2017/  
OnCo record `paper-siegel-colorectal-incidence-birth-cohort-jnci-2017` (Key paper). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

The analysis that showed the rise in bowel cancer in young adults is a birth-cohort effect: someone born in 1990 has twice the colon cancer risk and four times the rectal cancer risk of someone born in 1950 at the same age.

## Summary

Siegel, Fedewa, Anderson, Miller, Ma, Rosenberg and Jemal analysed colorectal cancer incidence trends in Surveillance, Epidemiology and End Results areas from 1974 to 2013, covering 490,305 cases, by five-year age group and birth cohort using incidence rate ratios and age-period-cohort modelling.

Age-specific relative risk by birth cohort declined from around 1890 until 1950 and then rose continuously through 1990, so that risk for contemporary birth cohorts has returned to the level of those born around 1890. The authors concluded that screening initiation before age 50 should be considered, an argument the United States Preventive Services Task Force accepted in 2021.

## Fields

- Kind: Key paper
- Last checked: 2026-09-24
- Tags: colorectal-evidence
- Journal: JNCI: Journal of the National Cancer Institute
- Year: 2017
- DOI: 10.1093/jnci/djw322
- Authors: Siegel RL, Fedewa SA, Anderson WF, et al.
- Findings: Colon cancer incidence rose 1.0 to 2.4 percent annually since the mid-1980s in adults aged 20 to 39, and 0.5 to 1.3 percent since the mid-1990s in adults aged 40 to 54.; Rectal cancer incidence rose 3.2 percent annually from 1974 to 2013 in adults aged 20 to 29.; The proportion of rectal cancers diagnosed under 55 doubled from 14.6 percent to 29.2 percent between 1989-1990 and 2012-2013.; Compared with those born around 1950, people born around 1990 have double the colon cancer risk (incidence rate ratio 2.40, 95 percent CI 1.11 to 5.19) and quadruple the rectal cancer risk (4.32, 2.19 to 8.51).
- What it means: The paper that turned early-onset colorectal cancer from an anecdote into a policy problem, and the direct evidence behind lowering the screening start age from 50 to 45 in the United States.
- Caveats: Registry incidence cannot say why the cohort effect exists; obesity, diet, antibiotics and the microbiome are all candidates and none is established.; Age-period-cohort models cannot separate the three effects without assumptions, and the youngest cohorts rest on few cases, hence the wide confidence intervals.; United States data; the European picture (Vuik 2019) is similar but not identical.

## Sources

- J Natl Cancer Inst 2017: https://doi.org/10.1093/jnci/djw322
- PubMed: https://pubmed.ncbi.nlm.nih.gov/28376186/
- Europe PMC full text (PMC6059239): https://europepmc.org/article/MED/28376186

## Connected records

- key papers: [Colorectal cancer statistics, 2023](https://onco.cc/key-papers/paper-siegel-colorectal-cancer-statistics-ca-2023/), [Geographic and age variations in mutational processes in colorectal cancer](https://onco.cc/key-papers/paper-diaz-gay-colibactin-geographic-age-mutational-processes-nature-2025/), [Increasing incidence of colorectal cancer in young adults in Europe over the last 25 years](https://onco.cc/key-papers/paper-vuik-early-onset-colorectal-europe-gut-2019/), [Sugar-sweetened beverage intake in adulthood and adolescence and risk of early-onset colorectal cancer among women](https://onco.cc/key-papers/paper-hur-sugar-sweetened-beverages-early-onset-colorectal-gut-2021/)
- cancers: [Colorectal cancer](https://onco.cc/cancers/colorectal/), [Early-onset colorectal cancer (under 50)](https://onco.cc/cancers/early-onset-colorectal/), [Rectal cancer](https://onco.cc/cancers/rectal-cancer/)
- fronts: [Early Detection & Screening](https://onco.cc/fronts/early-detection/), [Prevention & Risk](https://onco.cc/fronts/prevention/)
- technologies: [Colorectal cancer screening (colonoscopy, FIT, stool DNA, blood)](https://onco.cc/technologies/colorectal-screening/)
- bottlenecks: [Prevention we already have is not deployed](https://onco.cc/bottlenecks/b-prevention-adoption/), [The hardest cancers are found late](https://onco.cc/bottlenecks/b-early-detection/)
- journals: [JNCI: Journal of the National Cancer Institute](https://onco.cc/journals/jnci/)
- roadmaps: [Colorectal cancer roadmap: from the adenoma-carcinoma sequence and the first screening trials to total mesorectal excision, oxaliplatin, RAS testing, immunotherapy for mismatch repair-deficient disease, ctDNA-guided treatment and organ preservation](https://onco.cc/roadmaps/colorectal-roadmap/)
- ideas: [Find out what is driving early-onset bowel cancer, starting with colibactin, before extending screening any further](https://onco.cc/ideas/idea-crc-early-onset-cause-hunt/), [UK gap: shorten the route to diagnosis for patients below the screening age, where the rise in incidence is](https://onco.cc/ideas/idea-crc-uk-young-patient-referral-and-diagnostic-interval/)

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