Bone health is majorly affected by breast cancer and the treatment thereof. Dr Dirk Steyn explains the risk of fractures that can occur later on in life.
The impact of breast cancer and treatment
Most patients that presents with breast cancer (BC) are postmenopausal and usually have a low bone density to start with. The majority of patients, pre- or postmenopausal, experience a shift in their hormonal status which causes accelerated bone loss and is associated with a higher risk for a bone fracture for the rest of their life.
BC survivors have a 15% increased risk for bone fracture compared with women who never had cancer. Treatment that can cause bone density decline is numerous and the cumulative affect can be detrimental. Chemotherapy, hormone ablation therapy, anti-oestrogen therapies, radiation and medication used, like cortisone, all have a negative effect on bone health.
How treatment affects bone health
Chemotherapy affects pre- and postmenopausal women. Premenopausal women more so, and chemotherapy usually causes a 10-year earlier menopause compared to the normal population. This is dependent on the chemotherapy regimen used and the age of the patient. This causes a decrease in the hormones needed to sustain bone health.
Premature menopause caused by medications causes a decrease in the overall oestrogen levels. This is the main reason for bone density decline. Bone fractures occurrence in premenopausal women is minor initially but bone fracture risk later in life is well-proven. Therefore, pre-emptive medical and modifying lifestyle choices in patients is pertinent to decrease the risk for bone fracture at a later stage in life.
Medication that decreases oestrogen, like tamoxifen, is often used to treat BC because the more oestrogen, the more the cancer grows. Tamoxifen in postmenopausal women protects in bone health and studies have shown that there is a significant reduction in bone fractures. In contrast to this, premenopausal women on tamoxifen have shown a decrease in bone density.
Another medication that decreases oestrogen levels is aromatase inhibitors. This works by decreasing oestrogen production in fat cells but has no effect on the production of oestrogen by the ovaria. Therefore, it’s mostly used in postmenopausal women in whom the ovaries are inactive.
In postmenopausal women, aromatase inhibitors are the preferred choice. This medication causes a significant decrease in bone density and increases the chance of bone fracture significantly.
Radiation interrupts the blood flow to bone and therefore affects bone health of the radiated area.
Make your bones strong
All women starting BC treatment should be assessed for bone health prior to starting treatment. Your treating doctor must take a detailed history to assess your risk of osteopenia (bone loss) and a dual-energy X-ray absorptiometry (DEXA) scan must be performed.
A healthy diet and normal weight are essential and a referral to a dietitian is mandatory.
- Adequate intake of dietary protein.
- Natural antioxidants found in fruit and vegetables.
- A healthy diet supersedes supplements.
- Avoid excessive carbohydrates because of the higher chance of diabetes in BC patients.
- Avoid smoking, excess caffeine, coloured carbonated beverages (even sugar free) and alcohol.
- Calcium intake (1000 – 1200 mg daily) preferably from food sources. Supplements may be added.
- Vitamin D intake (800 – 1000 units daily).
- Exercise is extremely important and resistance exercises has been proven to decrease the rate of declining bone density.
Bone strengthening drugs
The role of bisphosphonates (drugs that work by slowing bone loss) increasing bone density in postmenopausal women with BC has been clearly shown and studied extensively. It slows down the cells that breakdown bone and increases the activity of bone forming cells.
Furthermore, it’s come to light that postmenopausal women with BC who use bisphosphonates have a significant decreased risk of BC recurrence; at a distant site; in bone; and BC mortality.
A bisphosphonate that can be used to increase bone density is zoledronic acid, especially in postmenopausal women on aromatase inhibitors.
Denosumab has also been proven to increase bone density and to decrease the chance of a fracture in women on aromatase inhibitors.
MEET THE EXPERT – Dr Dirk Steyn
Dr Dirk Steyn is an orthopaedic surgeon practicing at Netcare Milpark Hospital. He specialises in shoulder, elbow, hands, and foot and ankle. A Bone Health Centre will open soon at Netcare Milpark Hospital with the main aim of preventing osteoporotic fractures and treating osteoporosis from a multi-disciplinary approach, which he will be part of.
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