# Epigenetic age after cancer treatment

Source: https://onco.cc/technologies/rejuv-age-epigenetic-clocks/  
OnCo record `rejuv-age-epigenetic-clocks` (Technology). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

An epigenetic clock reads chemical marks on DNA and estimates how old the body looks, which is not always the age on a birth certificate. In survivors of childhood cancer the clock runs ahead of chronological age, and the gap is larger after radiotherapy and after certain chemotherapy drugs. What the gap means for any one person is not yet known, and the clocks do not agree with each other.

## Summary

Epigenetic clocks estimate biological age from DNA methylation at a few hundred sites. In the St Jude Lifetime Cohort, methylation was measured in blood from 2,139 adult survivors of childhood cancer and 282 matched controls. Epigenetic age acceleration, the residual of epigenetic age regressed on chronological age using Levine's clock, was higher in survivors than in controls: adjusted least-square mean 0.63 years (95% CI 0.26 to 1.01) in survivors against -3.61 in controls. Within survivors, acceleration was significantly higher after chest radiotherapy, abdominal or pelvic radiotherapy, alkylating agents, glucocorticoids or epipodophyllotoxins, and it tracked health behaviour: 0.26 years with favourable behaviours, 1.07 with intermediate, 1.45 with unfavourable.

The acute picture is less tidy, and this is where cohorts disagree. In 94 women with early breast cancer sampled before and after adjuvant treatment, extrinsic, phenotypic and GrimAge acceleration and the estimated proportion of senescent T lymphocytes all rose; but when the groups were separated, most of those rises were significant only in the women who had radiotherapy alone, not in those who had chemotherapy and radiotherapy. A clock can also move because the mix of blood cells changed rather than because tissue aged, which is why intrinsic and extrinsic measures diverge.

In 1,413 long-term survivors of childhood cancer, higher acceleration on the PCGrimAge and DunedinPACE clocks was associated with worse attention, processing speed and executive function; mean leukocyte telomere length was not associated with neurocognition in the same study. No clock is validated as a clinical test, none is used to make a treatment decision, and no trial has shown that moving a clock changes what happens to a person. Clocks sold direct to consumers are not these clocks and are not interpretable against this literature.

## Fields

- Kind: Technology
- Status: emerging
- Last checked: 2026-10-02
- Tags: rejuvenation; survivorship; biological-ageing; epigenetics; biomarker
- Principle: DNA methylation at CpG sites changes with age in a sufficiently regular way that a penalised regression can predict chronological age from it; the residual, how much older or younger the methylation looks than the calendar says, is called epigenetic age acceleration. Later clocks (PhenoAge, GrimAge, DunedinPACE) are trained on mortality, clinical biomarkers or rate of change rather than on calendar age, which is why they behave differently from the first-generation clocks in the same blood sample.
- Strengths: Measurable in a routine blood sample; Large cohorts with clinical follow-up, so the association with later chronic conditions can be tested; Treatment exposures that raise it are identifiable, which points research at specific agents
- Limitations: Clocks disagree with each other on the same sample; Shifts in blood cell composition can move a clock without tissue ageing; No clock is a validated clinical test and none guides a treatment decision; Whether moving a clock changes outcomes has never been tested

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Epigenetic_clock
- Qin et al., Epigenetic age acceleration and chronic health conditions among adult survivors of childhood cancer (JNCI 2021): https://doi.org/10.1093/jnci/djaa147
- Sehl et al., The acute effects of adjuvant radiation and chemotherapy on peripheral blood epigenetic age in early stage breast cancer patients (npj Breast Cancer 2020): https://doi.org/10.1038/s41523-020-0161-3
- Dong et al., Epigenetic age acceleration, telomere length, and neurocognitive function in long-term survivors of childhood cancer (Nat Commun 2025): https://doi.org/10.1038/s41467-025-65664-5
- Epigenetic age acceleration in hematopoietic stem cell transplantation (Haematologica 2025): https://doi.org/10.3324/haematol.2024.285291
- Dynamics of epigenetic age following hematopoietic stem cell transplantation (Haematologica 2017): https://doi.org/10.3324/haematol.2016.160481

## Connected records

- technologies: [Clonal haematopoiesis after cancer treatment](https://onco.cc/technologies/rejuv-age-clonal-haematopoiesis-after-therapy/), [Frailty and late effects in survivors](https://onco.cc/technologies/rejuv-age-frailty-and-late-effects/), [Senescent cells and p16 after chemotherapy](https://onco.cc/technologies/rejuv-age-senescent-cells-after-treatment/), [Survivorship care and late-effects surveillance](https://onco.cc/technologies/survivorship-care-plan/), [Telomere length after treatment](https://onco.cc/technologies/rejuv-age-telomere-length/), [What actually works after treatment](https://onco.cc/technologies/rejuv-frontier-what-works/)
- fronts: [Recovery & Rejuvenation](https://onco.cc/fronts/rejuvenation/), [Supportive Care & Survivorship](https://onco.cc/fronts/supportive-care/)
- pathways: [Cellular senescence](https://onco.cc/pathways/senescence/), [Telomere maintenance & replicative immortality](https://onco.cc/pathways/telomere-maintenance/)
- terms: [Late effects and survivorship toxicity](https://onco.cc/terms/late-effects/), [Quality of life](https://onco.cc/terms/quality-of-life/)
- bottlenecks: [Survivorship and late effects are neglected](https://onco.cc/bottlenecks/b-survivorship/)

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