A study by the University of Cambridge and the Institute of Cancer Research (ICR), London, has found that current GP referral rules miss up to 95% of women under 50 in England who go on to develop breast cancer within the next 10 years. The research was published in the British Journal of Cancer on 4 August 2026.

The rules come from NICE — the National Institute for Health and Care Excellence — which tells GPs in England when to send a patient for further breast cancer checks. These guidelines also miss up to 95% of women under 50 who have a higher-than-average risk of the disease.

The main reason is that the guidelines rely heavily on family history. If breast cancer does not run in your family, you are unlikely to be referred. But according to the study, 73% of women under 50 who develop breast cancer within 10 years have no family history of the disease (The Guardian).

The researchers compared the NICE rules with a newer system called Boadicea, developed by the University of Cambridge and funded by Cancer Research UK. Boadicea looks at a wider range of factors — reproductive history, lifestyle, and genetics — instead of family history alone. Think of it like a security checkpoint that searches your whole bag rather than just checking one pocket. The system identified eight times as many women under 50 who would develop breast cancer compared with the NICE criteria. The ICR published its own news release on the findings (ICR).

Dr Juliet Usher-Smith of the University of Cambridge, one of the study's authors, called for a review of the NICE criteria. She said the current rules used in general practice are missing up to 95% of women under 50 who will go on to develop breast cancer. Prof Montserrat García-Closas of the ICR, also a named author, pointed out a trade-off: the NICE rules are simple for GPs to use, while a full risk assessment including genetic testing takes more time and resources.

Breast Cancer Now, a charity that supported the study, said the research should feed into the current review of NICE's family history guidelines. Dr Simon Vincent, the charity's chief scientific officer, said new ways to identify women at increased risk could help prevent some breast cancers or catch them earlier.

What Else Is Happening

These findings come amid wider efforts to bring more thorough risk assessment into everyday GP visits. A 2025 study by F Stutzin Donoso and colleagues, called the CanRisk-GP protocol, is testing whether GPs can offer breast cancer risk assessment that includes polygenic scores. Polygenic scores add up the tiny effects of many genes to estimate a person's inherited risk. That study will show whether women find this kind of assessment acceptable in a routine GP setting.

Earlier research has already found problems in how referrals work. A 2024 study by JA Usher-Smith titled "Patterns of referrals to regional clinical genetics services" reviewed hospital records of GP referrals for women aged 18-49 suspected to be at above-average risk for breast cancer. A separate 2024 study by the same researcher found that in one trial, an intervention improved the proportion of genetic referrals that met guidelines, with an odds ratio of 4.5 and a 95% confidence interval of 1.6 to 13.1. Another 2024 study, by S Hindmarch, noted that NICE guidance recommends enhanced screening and prevention for women at increased risk, and aimed to map current risk assessment practice.

National guidelines recommend that English women aged 30-49 with moderate or high risk of breast cancer be offered screening and prevention, according to a 2026 study by R Dennison at the University of Cambridge titled "Priorities for breast cancer risk assessment in UK women." A 2018 study by LA Littlejohn found that UK NICE guidelines use family history to sort women by their 10-year risk of breast cancer from age 40.

The stakes are measurable. According to the Breast Cancer Research Foundation, a US woman aged 30 has a 0.49% risk of developing breast cancer over the next 10 years, while a woman aged 50 has a 2.40% risk over the same period. Earlier ICR research from 2014, in a news release titled "Genetic testing could improve breast cancer prevention," reported that screening women for a wide range of known genetic risk factors could improve prevention strategies.

The broader picture here is a slow shift toward personalised cancer risk assessment in routine care. The Boadicea findings, along with the upcoming CanRisk-GP results, could add pressure on NICE to move beyond family history as the main gateway for referral. The central question is whether busy GP surgeries can take on the extra work of fuller risk assessment — including genetic testing — without overwhelming the system. The trade-off between keeping things simple and catching more cases is likely to shape any future guideline change.