9.3 Breast cancer
Age 0-9 10-14 15-19 20-24 25-29 30-34 35-39 40-44 45-49 50-54 55-59 60-64 65-69 70-79 >80
Increasing age is a major risk factor for developing breast cancer. Other major risk factors include a personal history of atypical hyperplasia or lobular carcinoma in situ, a strong family history of the disease or mutation in a breast cancer predisposition gene, and previous radiotherapy (eg for previous cancer). Breast cancer risk factors that reflect hormonal exposures in the distant past, such as age at menarche or age at first birth, are less predictive of late-life breast cancer than factors indicating recent hormonal exposures such as high bone mass or obesity (refer to Cancer Australia for further information).
Breast cancer risk is not normally distributed: most women have a low (<4%) lifetime risk; and the remainder 4% to more than 80%.39,40
Prevention of breast cancer
Physical activity,41 adequate folate,42 a Mediterranean diet,43 normal BMI (in postmenopausal women only) and decreased alcohol consumption44 are associated with a decreased risk of breast cancer in observational studies. For women at moderate (ie 1.5–3 times the population risk) or high (ie >3 times the population risk) risk, additional interventions such as risk-reducing medication45 (moderate and high risk) and risk-reducing surgery46 (high risk) are available. Referral to specialist genetic assessment is available for women assessed at high risk.
The screening strategy employed for an individual woman depends on her individual degree of risk. Validated tools are available that can assess an individual woman’s breast cancer risk (eg International Breast Cancer Intervention Study (IBIS) tool, available here).47 For asymptomatic, low-risk women, BreastScreen Australia recommends screening mammograms every two years for women aged 50–74 years (B).48
The benefits of screening are obvious. However, the risks must not be forgotten: assuming that screening reduces breast cancer mortality by 15%, and that overdiagnosis and overtreatment is at 30%, then for every 2000 women invited for screening over 10 years, one will avoid dying of breast cancer and 10 healthy women, who would not have been diagnosed if there had not been screening, will be treated unnecessarily.49,50 An extra 200 women will experience important psychological distress including anxiety and uncertainty from false positive findings. The substantial advances in treatment, and greater breast cancer awareness since the trials were carried out, mean that presented breast cancers are detected earlier and survive better, so screening today is less effective than at the time of the trials. Recent observational studies show more overdiagnosis than in the trials and very little or no reduction in the incidence of advanced cancers with screening.51
The decision to start screening mammogram should be an individual one. This is especially for women aged <50 years, where the benefits–harms ratio is less favourable.48
- Screening mammogram in women aged 40–49 years may reduce the risk of dying of breast cancer, but the number of deaths averted is much smaller than in older women, and the number of false-positive tests and unnecessary biopsies are larger (C). Some women put a higher value on the potential benefit than the potential harms, and may choose to begin screening between the ages of 40–49 years (C).48
- For women at average risk (ie <1.5 times population risk) of breast cancer, most of the benefit of a mammogram will result from biennial screening during ages 50–74 years of age.48
- Of all age groups, women aged 60–69 years are most likely to avoid a breast cancer death through mammogram screening (C).48
- All women undergoing regular screening mammogram are at risk of overdiagnosis – the detection (and then treatment) of non-invasive and invasive breast cancer that would otherwise not have become a threat to their health, or even apparent, during her lifetime (C).48
- Women with a parent, sibling, or child with breast cancer may benefit more than average-risk women from beginning screening between 40 and 49 years of age (C).48
- Cancer Australia recommends considering annual mammograms from 40 years of age if the woman has a first-degree relative <50 years of age diagnosed with breast cancer (refer to Table 9.3.1).48
- There is insufficient evidence to assess the balance of benefits and harms of screening mammogram in women aged >75 years (I).48 Randomised trials of the benefits of screening mammogram did not include women >74 years of age. However observational studies favour extending screening mammogram to older women who have a life expectancy of not less than 10 years.52
- There is insufficient evidence to recommend that clinical breast examination offers any benefits to women, of any age (C).48 However, it is recommended that all women, whether or not they undergo mammogram screening, are aware of how their breasts normally look and feel, and promptly report any new or unusual changes (such as a lump, nipple changes, nipple discharge, change in skin colour, pain in a breast) to their GP. No one method for women to use when checking their breasts is recommended over another.
The recommended screening strategy for women at different individual degrees of risk is outlined in Table 9.3.1. Cancer Australia recommends that women at any age at increased risk (ie >1.5 times population risk) are offered an individualised surveillance program by their GP and/or specialist.53 This might include regular clinical breast examination and breast imaging with mammography and/or ultrasound and magnetic resonance imaging (MRI). There is government funding available for MRI screening for women <50 years of age at high risk of developing breast cancer.54
Implementation of breast cancer screening
A systematic review of strategies for increasing the participation of women in community breast cancer screening found five favourable active strategies: letter of invitation, mailed educational material, letter of invitation plus phone call, phone call, and training activities plus direct reminders.57
- Moyer on behalf of US Preventive Services Task Force. Screening for prostate cancer: US Preventive Services Task Force Recommendation Statement. Ann Intern Med 2012;157(2):120–34.
- Evans DG, Warwick J, Astley SM, et al. Assessing individual breast cancer risk within the U.K. National Health Service Breast Screening Program: A new paradigm for cancer prevention. Cancer Prev Res (Phila) 2012;5(7):943–51.
- Hopper JL. Disease-specific prospective family study cohorts enriched for familial risk. Epidemiol Perspect Innov 2011;8(1):2.
- Goncalves AK, Dantas Florencio GL, Maisonnette de Atayde Silva MJ, Cobucci RN, Giraldo PC, Cote NM. Effects of physical activity on breast cancer prevention: A systematic review. J Phys Act Health 2014;11(2):445–54.
- Chen P, Li C, Li X, Li J, Chu R, Wang H. Higher dietary folate intake reduces the breast cancer risk: A systematic review and meta-analysis. Br J Cancer 2014;110(9):2327–38.
- Albuquerque RC, Baltar VT, Marchioni DM. Breast cancer and dietary patterns: A systematic review. Nutr Rev 2014;72(1):1–17.
- Jayasekara H, MacInnis RJ, Room R, English DR. Long-term alcohol consumption and breast, upper aero-digestive tract and colorectal cancer risk: A systematic review and meta-analysis. Alcohol Alcohol 2016;51(3):315–30.
- Cuzick J, DeCensi A, Arun B, et al. Preventive therapy for breast cancer: A consensus statement. Lancet Oncol 2011;12(5):496–503.
- Nelson HD, Pappas M, Zakher B, Mitchell JP, Okinaka-Hu L, Fu R. Risk assessment, genetic counseling, and genetic testing for BRCA-related cancer in women: A systematic review to update the US Preventive Services Task Force recommendation. Ann Intern Med 2014;160(4):255–66.
- Antoniou AC, Hardy R, Walker L, et al. Predicting the likelihood of carrying a BRCA1 or BRCA2 mutation: Validation of BOADICEA, BRCAPRO, IBIS, Myriad and the Manchester scoring system using data from UK genetics clinics. J Med Genet 2008;45(7):425–31.
- US Preventive Services Task Force. Breast cancer: Screening. Rockville, MD: USPSTF, 2015. Available at [Accessed 15 November 2015].
- Marmot MG, Altman DG, Cameron DA, Dewar JA, Thompson SG, Wilcox M. The benefits and harms of breast cancer screening: an independent review. Br J Cancer 2013;108(11):2205–40.
- Pace LE, Keating NL. A systematic assessment of benefits and risks to guide breast cancer screening decisions. JAMA 2014;311(13):1327–35.
- Gotzsche PC, Jorgensen KJ. Screening for breast cancer with mammography. Cochrane Database Syst Rev 2013;6:Cd001877.
- Walter LC, Schonberg MA. Screening mammography in older women: A review. JAMA 2014;311(13):1336–47.
- Lauby-Secretan B, Scoccianti C, Loomis D, et al. Breast-cancer screening – Viewpoint of the IARC Working Group. N Engl J Med 2015;372(24):2353–58.
- Cancer Australia. MRI for high risk women. Sydney: Cancer Australia, 2015. Available at https://canceraustralia.gov.au/clinical-best-practice/breast-cancer/screening-and-early-detection/mri-high-risk-women [Accessed 15 November 2015].
- Cancer Australia. Advice about familial aspects of breast and epithelial ovarian cancer: A guide for health professionals. Sydney: Cancer Australia, 2015. Available at http://canceraustralia.gov.au/sites/default/files/publications/advice-about-familial-aspects-breast-cancer-and-epithelial-ovarian-cancer/pdf/2015_bog_familial_aspects_int.pdf [Accessed 15 November 2015].
- Pruthi S, Heisey RE, Bevers TB. Chemoprevention for breast cancer. Ann Surg Oncol 2015;22(10):3230–35.
- Bonfill X, Marzo M, Pladevall M, Marti J, Emparanza JI. Strategies for increasing the participation of women in community breast cancer screening. Cochrane Database Syst Rev 2001;1:CD002943.