Abstract P3-02-03: Breast cancer screening by women from BRCA1 & BRCA2 mutation positive families
Authors: Wuttke Melanie , Milne Roger , Weideman Prue , Picken Sandra , Smith Charmaine , Friedlander Michael ,   kConFab Investigators, McLachlan Sue-Anne , Hopper John L , Phillips Kelly-Anne 
Published: May 2015

Purpose: Breast screening may detect breast cancer (BC) at an early stage but optimal screening depends on a woman’s level of risk and age. This study estimates the contemporary prevalence of BC screening by Australian women from families with a BRCA1/2 mutation identified by Family Cancer Clinics.

Methods: Subjects were carriers and true non-carriers from families with a BRCA1/2 mutation enrolled in the nationwide kConFab cohort. They are followed up every 3 years with a questionnaire which includes use of breast ultrasound, mammography (MMG), magnetic resonance imaging (MRI) and clinical breast examination (CBE) over the previous 3 year period. Data from each woman’s most recent questionnaire (completed Oct 2009- March 2014) were used in the analysis. All knew their mutation result. Those who had risk-reducing mastectomy, previous cancer, were evaluated for benign breast disease, pregnant or breastfeeding or received their mutation result in the most recent follow-up round were excluded. Screening behaviour was categorized based on current national guidelines (see table). Associations with underscreening and overscreening were assessed using unconditional logistic regression to estimate odds ratios and 95% confidence intervals.

Definitions of overscreening and underscreening for carriers & true non-carriersGroupsOverscreening*Underscreening*CarriersBreast imaging (MMG +/- MRI) more often than annuallyBreast imaging less often than annually if age ≥30True non-carriersAge &lt;40: any screening MMG; age ≥40: MMG more often than every 2 years OR any MRI or ultrasound screeningAge 50-70: MMG less often than every 2 years*Definitions derived from Cancer Australia Guidelines which do not recommend for or against CBE in any group and differ from US guidelines.

Results: Of 372 eligible participants, there were 92 mutation carriers (42 BRCA1, 50 BRCA2) and 280 true non-carriers. 1% of carriers were overscreening, 86% were screening annually while 13% were underscreening. MRI, which is funded for mutation carriers aged 30-50 years, was used by only 52% (13/27) of carriers aged &lt;50 years and by 7 carriers aged &gt;50. Underscreening carriers were more likely to be single (OR=2.78, 95%CI=1.28-5.88, P=0.009) while those with a first degree cancer affected relative were less likely to underscreen (OR= 0.40, 0.19-0.85, P=0.017). CBE was undertaken by 79% of carriers at least yearly; 15% had no or irregular CBE.

115/280 (41%) non-carriers were overscreening, 55% were screening appropriately and 5% were underscreening. Underscreening non-carriers were more likely to be single (OR 3.85, 95%CI=1.00-14.9, P=0.05). Predictive of overscreening in non-carriers was having a cancer affected first degree relative (OR=2.92, 1.55-5.51, P=0.001). Non-carriers were less likely to utilise CBE (54%).

Conclusion: Most mutation carriers in kConFab are having regular screening MMG, but MRI is underutilised even when funded. The reasons for low usage of MRI requires further research and is concerning given its increased sensitivity over MMG. Overscreening is common in true non-carriers of BRCA mutations. Family cancer history and marital status may predict inappropriate screening behaviour.

Citation Format: Melanie Wuttke, Roger Milne, Prue Weideman, Sandra Picken, Charmaine Smith, Michael Friedlander, kConFab Investigators, Sue-Anne McLachlan, John L Hopper, Kelly-Anne Phillips. Breast cancer screening by women from BRCA1 & BRCA2 mutation positive families [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P3-02-03.