Breast Cancer and Osteoporosis

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Q: My wife is a recent breast cancer survivor. She’s had bone density tests every four months during this past year and they were all fine. But I am concerned, because now she’s one inch shorter than she was at her last doctor visit four months ago. I realize this may be a mistake from one measurement to the other, but if it isn't, what could be the cause of this loss in height?

A: Congratulations on your wife being a survivor and may she continue to do well. As far as her change in height, a one-inch loss would be unusual in just four months. My initial impression is that it’s a mistake and she should get her height checked again. She should be measured in her bare feet (no shoes) and around the same time of day at each appointment. The reason for this is that a person may be a little shorter at the end of the day (gravity and standing may slightly compress the discs between the vertebrae) compared to earlier in the morning. However, you are certainly right to be concerned about your wife’s height loss because there is a link between breast cancer and osteoporosis. This is the reason your wife’s doctor routinely checks her bone density and measures her height.

Osteoporosis is a disease that results from a decreasing bone mass, which leads to thinning, porous and weak bones. As the bones lose strength, they also lose bone density, which may lead to a loss in height. A further consequence and one which causes much pain and disability is the higher likelihood of bone fractures, especially in the spine, hip, pelvis or wrist. Unfortunately, the bone weakening leading to osteoporosis is often silent and without symptoms. That is why it is especially important to screen for this disease in high-risk individuals by conducting bone density studies (or DEXA scans). These tests not only screen for the development of osteoporosis before a fracture occurs, but they can predict one's chances of fractures in the future.

The Link Between Breast Cancer and Osteoporosis

Fortunately, most women affected by breast cancer will live long after their treatment plan ends. However, breast cancer as well as some of the treatments used against this disease may increase the risk for osteoporosis. And this risk may be even higher if the person had low bone mass (osteopenia) before the breast cancer was diagnosed. But there are a number of reasons for the link between breast cancer and osteoporosis, such as:

Breast cancer itself. This disease can increase the bone dissolving process of cells known as osteoclasts. The result is a weakening of the bones.
Early menopause. Some types of chemotherapy (cyclophosphamide, methotrexate and fluorouracil) may stop the ovaries from producing estrogen, which in turn brings on menopause. Without the bone protective effects of estrogen, bone loss may occur.
Steroids. These are often given to help people cope with the side effects of chemotherapy. A potential side effect of their continuous use is bone loss.
Surgically induced menopause from removal of the ovaries (oophorectomy) or radiation-induced menopause resulting from irradiation to the ovaries. While these procedures are done to slow breast cancer growth (some breast cancers are stimulated by estrogen), they can also lead to a sudden lowering of estrogen levels, as well as a rapid loss of bone mass.
Hormonal therapies using aromatase inhibitors (letrozole, anastrozole, others). These are newer types of treatment used for postmenopausal women with breast cancer. Early research suggests these have the potential to lead to a loss of bone density, but further study is ongoing. Other hormonal treatments such as leuprolide and goserelin can shut down the ovaries in premenopausal women, leading to a lack of estrogen production and consequently, bone loss.

Even though bone cannot be totally replaced once it has been lost, there are measures available to prevent osteoporosis and to treat the condition after onset. Our first approach is through lifestyle adjustments. These can be very beneficial and include:

Adequate daily calcium in the diet (1,000 milligrams for premenopausal and 1,500 milligrams for postmenopausal women), as well as a daily dose of vitamin D between 400-800 international units.
Regular weight bearing exercise such as dancing, climbing stairs, walking, as well as strength exercises for the arms and upper body.
Stop smoking as it weakens the bones.
Decrease alcohol intake.
Maintain good posture. Yoga, Pilates and tai chi may also help with overall body health and flexibility.

We also have medications available (bisphosphonates, raloxifene and others) to prevent and treat osteoporosis. These are very useful, especially for a patient with breast cancer.

As you mentioned, your wife’s bone density studies have been normal, so we know her bone health is OK. That’s very good news. However, she will still need to be monitored, most likely on a yearly basis rather than every four months. Please ask your wife if you can have a meeting with her health-care team to discuss the best ways for staying cancer free, while at the same time keeping her bones healthy and strong. Best of health to the both of you.

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Robert Danoff, D.O., M.S., is a family physician and program director of The Family Practice Residency, as well as the combined Family Practice/Emergency Medicine Residency programs at Frankford Hospitals, Jefferson Health System, Philadelphia, Pa. He is the medical correspondent for CN8, The Comcast Network, a regular contributor to Discovery Health Online and a contributing writer to The New York Times Special Features. (Read his full bio.)