A woman's breast cancer risk should be formally assessed using a validated risk prediction tool such as CanRisk, IBIS or iPrevent. These tools can be used to estimate 5- and 10-year breast cancer risks for women with a family history of breast cancer and can help guide decisions regarding commencing breast surveillance before age 40 years.
Based on the population evidence, there has been a shift towards breast awareness (vigilance towards own breast changes) in lieu of routine breast self-examination (BSE). A meta-analysis reported no reduction in mortality in women who detected their cancers during BSE, and no difference in mortality between women who received training for BSE compared with those who did not receive training.r In the same study, BSE was associated with considerably more women seeking medical advice and having biopsies.
Mammography has been shown to reduce breast cancer mortality for women. A large single-arm prospective study of moderate-risk women aged 40-49 years showed that annual mammography is both cost effective and clinically effective in reducing breast cancer predicted mortality.r This study also showed that the false-positive rates and associated radiation exposure were similar to those in the National Breast Screening Program.r For women with heterogeneous dense and dense breast tissue, supplemental screening should be considered as breast density limits the sensitivity of mammograms and breast density is independently associated with an increased risk of breast cancer.r
Digital breast tomosynthesis (DBT) plus mammography is associated with improved cancer detection rates and lower recall rates compared with mammography alone. These effects are significant for women of all breast densities, and women under age 60 years. The incremental additional radiation dose of DBT needs to be considered in women having frequent screening from a young age.r
MRI is not routinely recommended for women at moderate risk of breast cancer, but may be considered depending on individual risk factors, such as breast density. A randomised study of annual breast MRI and biannual mammography versus annual mammography in women with increased familial risk showed that MRI is associated with improved cancer detection (13.9 vs 4.9 screen-detected cancers per 1000 screens, p=0.00012). Statistically significant benefit was observed in the preliminary screen but not for subsequent screening rounds (10 vs 5.9 breast cancers per 1000 screens, p=0.72). Cancers in the MRI group were smaller and more likely to be node negative irrespective of screening round. Longer-term follow-up is required to understand whether this translates to a mortality benefit or represents over-diagnosis.r
Five years of treatment with selective oestrogen receptor modulators (SERM), such as tamoxifen and raloxifene, or aromatase inhibitors (AIs), such as anastrozole or exemestane, have been shown to reduce the risk of oestrogen receptor-positive breast cancer in women identified to be at increased risk. A meta-analysis showed that tamoxifen reduced breast cancer incidence by 32% (HR 0.62 with 95% CI, 0.62–0.76) compared with placebo in women at increased risk. Tamoxifen was more effective at reducing breast cancer risk than raloxifene but had greater toxicity. AIs reduced breast cancer risk by 53% (RR 0.47, 95% CI, 0.35-0.63) compared with placebo.r After cessation of therapy, persistent breast cancer risk reduction has been shown for tamoxifen and anastrazole.rr None of the medications have proven mortality benefit. See COSA - Medications to lower the risk of breast cancer: clinician guide.
Modifiable risk factors for breast cancer
For a summary of the evidence for modifiable lifestyle risk factors for breast cancer, see Cancer Australia “Risk factors for breast cancer: a review of the evidence.” These recommendations apply to the general population; there is no specific evidence for the moderate-risk group.