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17 February 2013

Bone health

Bone Health and Bone Loss

Keeping your bones healthy throughout your life is important. Women are about twice as likely as men to develop osteoporosis (a disease that means your bones are weak and more likely to fracture) after age 50. If you’re a woman who’s been diagnosed with Breast Cancer, bone health is especially important for you. Research shows that some Breast Cancer treatments can lead to bone loss.

Your bones need calcium, vitamin D, and weight-bearing physical activity to stay healthy and strong.  Smoking, heavy alcohol use, and being underweight can also increase your risk for bone loss.

During your childhood and teenage years, your body generates new bone faster than it gets rid of old bone. After about age 30, you can start to lose bone faster than your body generates bone, which makes your bones weaker and more fragile. Some bone loss is natural as both men and women age. Still, it is important to take steps to make sure you don’t lose too much bone and put yourself at risk of easily breaking a bone by falling or tripping.

You may hear your doctor talk about “bone density” or “bone mineral density.” Both terms describe a measurement of how strong your bones are. The higher the density, the stronger and healthier your bones are.

Women are at higher risk of bone loss than men. When a woman goes through menopause, whether as a natural part of the aging process or because of Breast Cancer treatment, her levels of oestrogen and other hormones drop sharply. Oestrogen helps maintain bone density and a drop in oestrogen can lead to significant bone loss.

You may hear your doctors use two different words to talk about low bone density:

  • Osteopenia means you have lower-than-normal bone density. Osteopenia is not a disease, but it can mean that you’re at higher risk for fracturing a bone.
  • Osteoporosis is a disease and means that your bone density is so low that your bones are brittle and can fracture easily. White and Asian women are at highest risk for osteoporosis, but all women and men older than 50 are at risk for the disease.

Measuring Bone Health

There are a number of tools that your doctor can use to check your bone health, including a physical exam and blood and urine tests to measure your calcium levels.

In general, your doctor may order a bone mineral density test if you’re older than 45 and have had any of the following:

  • a fracture
  • height loss
  • change in posture
  • back pain

Bone density tests use x-rays or sound waves to measure how strong your bones are. Bone density tests are used to definitively diagnose bone loss and osteoporosis.

The most widely recognized bone mineral density test is dual-energy x-ray absorptiometry, commonly known as a DEXA scan. A DEXA scan uses low levels of x-rays and is quick and painless. A scanner passes over your whole body while you’re lying on a cushioned table. A DEXA scan can measure the bone mineral density of your whole skeleton, as well as specific points that are more likely to fracture, such as the hip, spine and wrist. Using a DEXA scan to measure bone mineral density at the hip and spine is considered the most reliable way to diagnose osteoporosis and predict the risk of fracture.

Your DEXA scan results are in the form of two scores:

  • T-score: Your T-score is the difference between your bone density and the average bone density of young, healthy woman. A score above -1 is considered normal. A score between -1 and -2.5 is classified as osteopenia and a score below -2.5 is classified as osteoporosis. Your T-score is used to estimate your risk of fracture.

Your doctor will interpret the results and understand what it means for your unique situation.

In general, doctors recommend that women 50 and older get a DEXA scan or other osteoporosis screening each year. But women may need to start screening earlier if they:

  • are underweight
  • smoke
  • have lost height or developed stooped or hunched posture
  • have sudden back pain with no apparent cause
  • are older than 45 and fracture a bone
  • have a chronic illness

No matter your age, if you’ve been diagnosed with Breast Cancer, your doctor will probably recommend a baseline DEXA scan before you start treatment and then regular DEXA scans as you move through treatment. This will allow you to make sure your bones are staying strong and take protective measures if you do start to lose some bone mass.

At a Glance

DEXA scan basics

  • The DEXA scan evaluates bone mineral density, or BMD.
  • The results predict the likelihood of fracture.
  • BMD is generally measured in the spine and hip.
  • The DEXA scan calculates bone density based on the amount of radiation absorbed by the bone, and compares your bone strength with that of young premenopausal women and other women in your age group.
  • The diagnosis of osteoporosis means that your bone density has fallen below the range expected in premenopausal women (often called a T-score below -2.5).
  • The results are kept in your medical chart for comparison with future DEXA scans.
  • A single measurement tells the doctor how strong your bones are at the time of the measurement, but  cannot accurately predict future bone loss.
  • If you have osteoporosis (a T-score below -2.5) your doctor may assume that you were in the normal range in your younger years, and that you have lost bone, There is no way of predicting whether your osteoporosis will get worse from this single measurement.
  • If your bone mass is in the lowest part of the young normal range (16%), your doctor may tell you that you have “osteopenia.” This only means that you are at greater risk of getting osteoporosis in the future. If you are postmenopausal and have osteopenia, you are also at increased risk of fracture. But your risk of fracture would be higher if you had osteoporosis.

Breast Cancer Treatment and Bone Loss

Certain breast cancer treatments can speed up bone loss or cause you to lose more bone than you normally would:

Chemotherapy: Some chemotherapy medicines can have a direct effect on your bone health. In other situations, some women who are close to menopause and get chemotherapy may have significant bone loss because the chemotherapy causes early menopause. If chemotherapy pushes your body into menopause, bone loss may begin while you’re still having treatment and continue after treatment is done.

Aromatase inhibitors (a type of hormonal therapy):

  • Arimidex (chemical name: anastrozole)
  • Aromasin (chemical name: exemestane)
  • Femara (chemical name: letrozole)

Aromatase inhibitors work by preventing the formation of estrogen. The loss of estrogen can lead to bone loss during treatment. Aromatase inhibitors are used most often in postmenopausal women diagnosed with hormone-receptor-positive early breast cancer.

Ovarian shutdown using medication or surgically removing the ovaries: Ovarian removal causes irreversible menopause. Your bone density may drop suddenly after ovaries are removed. Ovarian shutdown using medicine temporarily stops your ovaries from producing estrogen.

Other hormonal therapy medicines known as SERMs (selective estrogen receptor modulators) can actually help protect your bones by slowing bone loss. SERMs are:

  • tamoxifen
  • Evista (chemical name: raloxifene)
  • Fareston (chemical name: toremifene)

If an aromatase inhibitor or chemotherapy would have benefits for you, talk to your doctor about ways to protect your bones during treatment. This is especially important if you have any of the risk factors for bone loss:

  • being older
  • being postmenopausal
  • being small and thin
  • a family history of osteoporosis or broken bones
  • having low bone mass (osteopenia)
  • smoking
  • not getting enough calcium or vitamin D
  • not exercising
  • having more than 2 alcoholic drinks several times a week
  • having one of the following medical conditions:
    • hyperthyroidism or hyperparathyroidism
    • chronic lung disease
    • inflammatory bowel disease
    • Cushing’s disease
    • multiple sclerosis
    • arthritis

Different hormonal therapy and chemotherapy medicines can be used in your treatment plan, depending on your unique situation. And your treatment plan can change over time based on your needs, the benefits you’re getting, and any side effects you may have.

You’ll probably have a baseline DEXA scan before you start treatment with hormonal therapy or chemotherapy. If you don’t, talk to your doctor to see if having one makes sense for you. During follow-up visits during treatment, ask your doctor about your bone health and whether protective measures are right for you.

If you’re at high risk for osteoporosis and your bone mineral density declines during treatment, there are treatments to reduce the risk of or treat osteoporosis. In addition, there are lifestyle changes you can make to help keep your bones as strong as they can be.

Bisphosphonates for Osteoporosis and Bone Protection

Bisphosphonates limit the activity of certain bone cells, called osteoclasts, which help cause the bone weakening and breakdown that leads to osteoporosis.

These are available as daily or weekly or monthly doses or can be injected once every 3 months or once a year. Together, you and your doctor can decide if which one of these treatments is right for you.

Research has shown that bisphosphonates can increase the risk of atypical femur fractions when taken for 5 years or longer. The femur is the large leg bone that runs from your hip to your knee. An atypical fracture means that the bone is broken in an unusual spot. Still, atypical femur fractures are rare — only about 0.22% of women taking a bisphosphonate for more than 5 years will have an atypical femur fracture.

It is therefore necessary to review your bisphosphonate therapy after 5 years.

The bisphosphonates can sometimes cause a rare but serious side effect, osteonecrosis of the jaw, a condition in which the cells in the jawbone start to die. Researchers think that osteonecrosis of the jaw may develop because bisphosphonates stop the body from repairing microscopic damage to the jawbone that can happen during routine dental procedures or from everyday wear and tear. But it’s still not clear why this happens in some people and not in others. If you’re taking a bisphosphonate, tell your dentist right away. Together, you and your dentist can work out a dental treatment schedule that keeps your teeth healthy and minimizes your risk of osteonecrosis of the jaw.

Bisphosphonates must be taken in a specific way to avoid serious complications:

  • You take bisphosphonates with a full glass of plain (not seltzer) water only, on an empty stomach.
  • You must wait 30 minutes after taking a bisphosphonate before you eat or take other medicine.
  • You can’t lie down for at least 30 minutes after taking a bisphosphonate. This is to avoid irritating your esophagus (the tube from your mouth to your stomach), as well as other gastrointestinal side effects and heartburn. These side effects aren’t common, but if you already have them or develop them after starting bisphosphonate treatment, ask your doctor if you can get a bisphosphonate injection or another type of medicine.

Lifestyle Changes for Bone Health

There are several lifestyle changes you can make to keep your bones as strong as they can be:

  • Get enough calcium.People older than 50 should get 1,200 milligrams of calcium each day. Make foods that are high in calcium part of your diet:
    • dairy products such as low-fat milk, yogurt, and cheese
    • calcium-fortified orange juice
    • dark green leafy vegetables such as broccoli, spinach, collard greens, and bok choy
    • tofu
    • almonds
    • vitamin-fortified cereal
    • calcium supplements
  • Get enough vitamin D.Vitamin D helps your body absorb calcium. The current recommendation is that people younger than 50 get 200 international units (I.U.) of vitamin D per day. 400 international units per day is recommended for people aged 50-70, and 600 international units per day is recommended for people older than 70. The typical multivitamin contains 400 international units of vitamin D.Your body makes vitamin D when you’re in sunlight, but if you’re indoors most of the time or live in areas where sunlight is limited, add foods rich in vitamin D to your diet:
    • vitamin D-fortified milk
    • herring, salmon, and tuna
    • vitamin-fortified cereal
    • If you’re going to take a vitamin D supplement, most experts recommend taking the D3 form of the vitamin, not the D2 form.
  • Do weight-bearing exercise.Exercise makes your bones and muscles stronger and helps slow bone loss. Do 30 minutes of weight-bearing exercise 3-4 times a week for maximum bone health benefits:
    • walking
    • jogging
    • stair climbing
    • playing tennis, racquetball, or squash
    • dancing
    • lifting weights

You can do your 30 minutes of exercise 10 minutes at a time during the day to make it easier.

  • Limit or avoid alcohol. Heavy drinking increases the risk of bone loss.
  • Quit smoking. Smoking weakens bones and can lead to osteoporosis.

 

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