Unfortunately, treatments for breast cancer can have a significant impact on bone density.
As 80% of breast cancers are hormone receptor positive most treatments will centre around reducing oestrogen levels. Oestrogen is integral for growth and maintenance of healthy bone.
Breast cancer treatments, such as aromatase inhibitors, chemotherapy-induced ovarian failure and gonadotropin-releasing hormone antagonists all decrease oestrogen levels, which in turn causes net bone resorption and bone loss.
This loss of bone density can be significant enough to cause some women to fall into the osteopenia (low bone density with moderate risk of fracture) or osteoporosis categories (very low bone density with significant risk of fracture).
Bone responds to two forms of regulation. One of them is hormones with oestrogen playing a large role. The other is mechanical forces imposed by gravity.
Peak bone mass occurs at around 30 years old for women. From this point onwards, unless there is significant loading, women will lose bone density at about ½ a percent to 2 percent per year.
During and particularly post menopause, as osestrogen is reduced in the body, the rate of bone density decline increases. For some women it can be as much as 10% a year.
Other risk factors play a role – genetics, smoking, excessive alcohol consumption, low body mass, rheumatoid arthritis, diabetes, coeliac disease, chronic use of steroids for other conditions and treatments for cancers such as breast cancer.
Hormone therapies commonly used to treat breast cancer include: aromatase inhibitors (anastrozole (Arimidex), letrozole (Femara), exemestane (Aromasin) and tamoxifen (Tamoxifen, Genox, Tamoxen, Tamosin, Nolvadex).
Aromatase inhibitors can all cause bone density loss and are used to treat postmenopausal women.
Tamoxifen can be used to treat pre and postmenopausal women. It will have a bone density lowering effect on premenopausal women but seems to have a protective effect for bones in postmenopausal patients.
Chemotherapy and oophorectomy (removal of ovaries) can also impact on bone density and cause younger women to experience premature menopause.
There is some research to suggest that radiotherapy can also reduce bone density.
Practitioners will generally guide their patients towards medication for treating low bone density. These are proven to be effective but can include complicated side effects for some patients and on-going, long-term treatment is required.
The other treatment for bone density is mechanical forces imposed by gravity.
As you may know by now more than a century ago, Wolff’s Law taught us that when enough pressure is placed on bones, they will reform themselves and, over time, become stronger naturally. In 2012, a large-scale study determined that triggering bone growth (for the hip and femur) required pressure 4.2 times the participants’ body weight — an amount far beyond what is possible through most exercise or natural movement alone.
For those who have or have had breast cancer there may be two limiting factors regarding participating in activities impactful enough to generate such force (such as tennis or gymnastics).
Their bones may already be at higher risk of fracture and significant fatigue is a common side effect of cancer treatment.
According to Cancer Australia the fatigue that is experienced isn’t a type of tiredness that can be helped by rest or a nap. It can be caused by chemotherapy and radiotherapy treatments and also from the emotional impact of diagnosis and treatment.
It recommends women do not push themselves – that they allow for time and rest so energy levels may gradually improve. It also recommends exercise stating that ‘’research shows that exercise is effective in reducing cancer related fatigue’’.
OsteoStrong Australia’s osteogenic loading system is only generating forces on the body for such a short amount of time that most clients find it doesn’t have the same stress effect on the body as regular exercise, allowing for the endorphin release and energy boosting effects of exercise without the soreness and fatigue that can follow – while also being effective at generating forces that will trigger bone density remodeling in the body.