New guidance for GPs highlights the best tools and interventions to help women.
Prevention strategies such as assessing risk factors, chemoprevention and surgery are vital in the fight to reduce the rising incidence of breast cancer, says an Australian expert.
GPs are on the frontline when it comes to initiating these strategies, outlined in new guidance in the AJGP.
“Over 21,000 new breast cancer cases [were] predicted in 2024, with a growing incidence, including a 10% rise in people aged under 50 in the last 20 years,” wrote Dr Sandy Minck, GP and member of BreastScreen Queensland’s Clinical Standards and Excellence Committee.
“These statistics highlight the urgent need for prevention strategies.”
Prevention required both population and individual approaches, and GPs would play a key role in helping women with risk assessment and interventions, Dr Minck said.
“Lifestyle changes, medication and surgical interventions can reduce breast cancer risk. These include maintaining a healthy weight, avoiding or limiting alcohol and getting regular exercise,” she told media.
“Risk-reducing medication can decrease breast cancer risk by 30–60%. There are two main categories of medication, selective estrogen receptor modulators and aromatase inhibitors. These are an effective risk-reducing strategy for patients who do not want to undergo, or want to postpone, mastectomy.
“Risk-reducing surgery is an option for those at very high risk of developing breast cancer. This can be overwhelming, and GPs can support women to make their own informed decision based on their individual risk, values, circumstances, and the potential benefits and risks of surgery.”
The first step was awareness, so Dr Minck encouraged conversations about family history and for patients to get familiar with the look and feel of their breasts so that they would be better able to spot changes.
“While this has no impact on prevention, it provides an opportunity for GPs to educate women about risk factors for breast cancer and encourage risk assessment,” she wrote.
Some risk factors, such as the genetic and demographic risk factors like BRCA1 and BRCA2 mutations, increasing age and history of radiation exposure, couldn’t be changed.
But women did have power over some risk factors.
Obesity accounted for up to 13% of breast cancers, alcohol up to 16%, physical inactivity up to 10%, not breastfeeding accounted for around 5%, MHT around 2% and hormonal contraceptives almost 1%.
“The first step in personalised breast cancer prevention is risk assessment. Proactive risk assessments beginning at age 25–30 years are required to facilitate identification of, and preventive interventions for, those who are at high risk of early-onset breast cancer,” Dr Minck wrote.
But these assessments should happen at regular intervals in a woman’s life, such as every 10 years, she said.
“A potential time point for a comprehensive risk assessment could be at age 40 years, or when an individual has decided that they do not want any or more children, in which case risk-reducing medication such as tamoxifen could be considered,” Dr Minck wrote.
Risk assessment tools included iPrevent, CanRisk and IBIS. The Australian-developed iPrevent tool was the only one to tailor screening and prevention options to the woman’s estimated risk, Dr Minck said.
Surgery is usually only recommended for women at high risk, which is defined as at least three times higher than the population average, or at least a 30% lifetime risk. Doctors could discuss bilateral risk-reducing mastectomy.
Women at a high risk or moderate risk of breast cancer, defined as at least 1.5-3 times the population risk or at least a 17% lifetime risk, could also consider medications such as tamoxifen if they were at least age 35 years and premenopausal, or raloxifene and aromatase inhibitors too if they were post-menopausal.
While chemoprevention was effective in high-risk women who wanted to avoid surgery, Dr Minck said that only 1.4% of at-risk women in a 2021 Australian study used it.
“These medications only reduce the risk of hormone receptor-positive breast cancer, but this is the most common breast cancer phenotype and the one that is increasing in incidence,” she wrote.
“Tamoxifen and, to a lesser extent, raloxifene, increase the risk of thromboembolic disease. Tamoxifen increases the risk of endometrial cancer. Common side effects of tamoxifen are vasomotor symptoms, and vaginal discharge and dryness. Common side effects with raloxifene are leg cramps and vasomotor symptoms.
To manage side effects, GPs could swap to a different medication – if the patient was post-menopausal – or modify the dose of tamoxifen.
“Ten-year data shows tamoxifen 5mg once daily for three years significantly prevents recurrence from non-invasive breast cancer after seven years from treatment cessation, without long-term adverse events,” Dr Minck wrote.
“Referral to a specialised service, such as the Preventing Cancer with Medications (PCMed) Service at the Peter MacCallum Cancer Centre is an option.”
Lifestyle interventions were appropriate at all risk levels.
“Women who followed the American Cancer Society’s recommendations [on lifestyle] saw a 22–31% lower risk of developing breast cancer compared to those who were less adherent,” Dr Minck wrote.
