Prophylactic (Risk-reducing) Mastectomy Rates in the UK: Analysis of the Clinical Practice Research Datalink

Date of ISAC Approval: 
03/04/2017
Lay Summary: 
Familial breast cancer is defined as cancer related to breast occurring in persons with one or more family members who were also affected by cancer to the ovaries or breast. When such family history is present, women are referred to a physician specialized in genetic risk in oncology, to have a blood testing to sear for genetic predispositions that increase breast cancer risk. According to the current UK guidelines, having a mastectomy prior any breast cancer occurs can reduce the risk of cancer for these women with specific genetic predispositions. Our research hypothesis is that the number of mastectomy prior any breast cancer within the women population have increased since genetic testing are available (1994), and may also have in the following months after Angelina Jolie's mastectomy announcement in May 2013. This study will thus search how many women had had a mastectomy prior any breast cancer within the population of women living in the UK from 1987 to January 2017, and compare them according to women individual level of risk of breast cancer.
Technical Summary: 
Familial breast cancer is defined as occurring in people with one or more family members affected by breast, ovarian, or a related cancer such as primary peritoneal cancer. About 5% of breast cancers can be attributed to inherited mutations in specific high risk genes (BRCA1&2, and TP53). According to current NICE guidelines in the UK, preventive mastectomy is one of the breast cancer risk reduction strategies that can be proposed to BRCA1, BRCA2 and TP53 mutation carriers. This study will examine incidence rates (per 1000 women per month and per year) of prophylactic (risk-reducing) mastectomies in a representative cohort of women living in the UK from the Clinical Practice Research Datalink (CPRD) database since database conception in 1987 to the last available data point in January 2017. Incidences rates will be estimated on cohorts of (a) women until censoring event such breast and/or ovarian cancer, or in situ breast cancer, (b) women until censoring event such any type of cancer. Incidence rate will also be estimated depending on women age (with a direct standardization on the UK population) and if they belong to a high-risk group (BRCA1&2, and TP53, family history of breast of/and ovarian cancer).
Health Outcomes to be Measured: 
Preventive mastectomy (i.e. before any breast and/or ovarian cancer, or any type of cancer)
Collaborators: 

Alexander Liede - Chief Investigator - Amgen
Dafydd Gareth Richard Evans - Collaborator - Imperial College London
Justyna Amelio - Collaborator - GSK
Leroy Sandrine - Corresponding Applicant - Amgen