Some women are more likely to get breast cancer as it runs in their family, they are at risk of familial breast cancer. There are medications, called chemoprevention, which may lower their risk of developing breast cancer by a third. However chemoprevention can also cause serious side effects, like womb cancer and blood clots. This makes decision to start them difficult. Researchers found that not all women who can have these medications are on them.

The investigators want to ask familial breast cancer specialists whether they recommend general practitioners (GP) to prescribe chemoprevention, by sending them a short survey. These specialists look after women where breast cancer runs in the family. The specialists assess a women's chance of getting breast cancer and advice those with increased risk what can be done to prevent breast cancer.

The investigators will then look at whether specialist recommendation makes a difference to whether GPs prescribe chemoprevention medication. This will be done by linking the specialists' survey response to information on GP prescribing that the government regularly publishes. This may help the investigators understand why chemoprevention is not used as often as it potentially can be.

Phase I: Short survey of lead clinicians of familial cancer services, descriptive analysis of recommendations by areas of the country

Phase II: Prescribing data analysis (using OpenPrescribing) comprising:

1. t-test to compare the chemoprevention prescribing rate in general practices where chemoprevention is recommended versus not recommended;
2. interrupted times series analysis to assess the change in the chemoprevention prescribing after recommendation from specialist compared with changes occurring in practices where chemoprevention is not recommended and
3. panel regression across all practices, in order to distinguish the relative impacts of national versus local recommendation, and the change over time.

Inclusion Criteria:

• Lead clinicians of NHS familial cancer services across England
• Standard general practices (classed as type 4 by NHS Digital, to exclude walk-in centres, prisons, care homes, etc.) with prescribing data for chemoprevention available on OpenPrescribing

Exclusion Criteria:

• General practices with less than 10 female patients aged 35 to 44 registered
• General practices which cannot be linked to any familial cancer service from survey responses

NHS familial cancer services and general practices in England

Prescribing analysis code and raw data (of publicly available, anonymised, primary care prescribing data) will be made freely available alongside publication of results.