# Familial risk and heritability of cancer among twins in Nordic countries (NorTwinCan)

Source: https://onco.cc/key-papers/paper-mucci-nortwincan-heritability-jama-2016/  
OnCo record `paper-mucci-nortwincan-heritability-jama-2016` (Key paper). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Following more than 200,000 twins in Denmark, Finland, Norway and Sweden for a median of 32 years, this study estimated that about a third of the variation in cancer risk is inherited, with higher shares for melanoma and prostate cancer.

## Summary

A prospective cohort of 80,309 identical and 123,382 same-sex fraternal twin individuals in the population-based twin registers of Denmark, Finland, Norway and Sweden, followed through the cancer registers between 1943 and 2010. Time-to-event models estimated familial risk, the risk of cancer given that a co-twin developed it, and heritability, adjusting for age and follow-up and accounting for censoring and the competing risk of death. Karolinska Institutet's Department of Medical Epidemiology and Biostatistics was among the collaborating centres.

## Fields

- Kind: Key paper
- Last checked: 2026-11-03
- Journal: JAMA
- Year: 2016
- DOI: 10.1001/jama.2015.17703
- Authors: Mucci LA, Hjelmborg JB, Harris JR, Czene K, Havelick DJ, Scheike T, Graff RE, Holst K, et al.; Nordic Twin Study of Cancer (NorTwinCan) Collaboration
- Findings: 27,156 incident cancers were diagnosed in 23,980 people, a cumulative incidence of 32 per cent.; Cumulative cancer risk was 46 per cent (95 per cent CI 44 to 48) in identical twins and 37 per cent (36 to 38) in fraternal twins whose co-twin developed cancer, against 32 per cent overall.; Heritability of cancer overall was 33 per cent (95 per cent CI 30 to 37); significant heritability was found for skin melanoma (58 per cent), prostate (57 per cent), non-melanoma skin (43 per cent), ovary (39 per cent), kidney (38 per cent), breast (31 per cent) and corpus uteri (27 per cent).
- What it means: It gives patients and counsellors population figures for how much a twin's or close relative's cancer raises one's own risk, cancer by cancer, and it shows that for prostate cancer and melanoma inherited risk is substantial.
- Caveats: Twin heritability is a population estimate under model assumptions, not a measure of any individual's genetic risk.; An erratum was published (JAMA 2016;315(8):822).

## Sources

- JAMA 2016: https://doi.org/10.1001/jama.2015.17703
- PubMed: https://pubmed.ncbi.nlm.nih.gov/26746459/

## Connected records

- key papers: [Environmental and heritable factors in the causation of cancer: analyses of cohorts of twins from Sweden, Denmark, and Finland](https://onco.cc/key-papers/paper-lichtenstein-twins-cancer-heritability-nejm-2000/)
- cancers: [Melanoma](https://onco.cc/cancers/melanoma/), [Prostate cancer](https://onco.cc/cancers/prostate/)
- fronts: [Prevention & Risk](https://onco.cc/fronts/prevention/)
- institutions: [Karolinska University Hospital](https://onco.cc/institutions/karolinska/)
- bottlenecks: [Inherited risk is mostly unidentified](https://onco.cc/bottlenecks/b-hereditary-risk/)
- journals: [JAMA](https://onco.cc/journals/jama/)

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