Assessing risk of familial breast cancer

: effectiveness of current UK guidelines

  • Lucy Littlejohn

Student thesis: Master's ThesisMaster of Science

Abstract

Breast cancer risk is a common indication for referral to clinical genetics. National Institute of Health and Care Excellence (NICE) guidelines use family history to stratify patients by 10-year risk of breast cancer from the ages 40-49. Patients are divided into low (10-year risk <3%), moderate (3-8%) and high risk (>8%). Those with a BRCA mutation are considered to be very high risk. Women at moderate or high risk are offered screening from age 40. This study aimed to assess the effectiveness of NICE risk categorisation at identifying women at risk of early onset breast cancer.

Family history data was obtained for unaffected women with a family history of breast cancer, aged <50 years, referred to Tayside clinical genetics from 2000-2010. Patients were risk stratified de novo by NICE criteria. Those who went on to develop breast cancer were identified.

1,409 women were included in the cohort, with a total of 15,414 patient-years of follow up. Of these patients, 35.84% were NICE low risk, 37.04% moderate risk and 27.11% were high risk. 22 BRCA mutation carriers were identified.

30 invasive breast cancers developed, 13 in moderate and 13 in high risk women. Kaplan-Meier analysis demonstrated no significant difference in cancer rates between low and moderate risk women from ages 40-49 (Log rank p=0.431). There was a significant difference from 40-49 years between low and high risk women (p=0.036), but not on exclusion of BRCA carriers (p=0.136). The 10-year absolute risk from 40-49 years was 0.82% (95% CI, 0.72-0.94%) for low risk, 1.68% (1.53-1.83%) for moderate risk, and 3.56 (3.34-3.80%) for high risk women. NICE absolute 10-year risk thresholds for screening were not met in any group.

This study provides some evidence that screening prior to age 50 in those without a BRCA mutation may be unnecessary. In the study cohort, NICE family history criteria identify women at increased risk of breast cancer, but not at the absolute risk thresholds suggested for screening. There is a need for further evaluation of NICE criteria.
Date of Award2017
LanguageEnglish
Awarding Institution
  • University of Dundee
SupervisorJonathan Berg (Supervisor)

Cite this

Assessing risk of familial breast cancer: effectiveness of current UK guidelines
Littlejohn, L. (Author). 2017

Student thesis: Master's ThesisMaster of Science