Osteoporosis and Cancer: What Is the Relationship?

Thinning bones in osteoporosis may become brittle and break. In cancer, uncontrolled cell growth, inflammation, and some types of cancer treatment can also adversely affect bones, leaving them more vulnerable to fractures. What does this mean for bone health?

This article explores the connection between osteoporosis and cancer and what this means when undergoing certain cancer treatments. You'll also find out how to most effectively manage both simultaneously.

Connection Between Osteoporosis and Cancer

If you have osteoporosis, your healthcare provider monitors your bone health and checks your bone mineral density for any signs of weakening.

One connection between osteoporosis and cancer is aging in general. Aging is undoubtedly connected to osteoporosis. Cancer also is more likely to occur in older individuals.

As people of any sex age, sex hormone levels tend to decline. The sex hormone estrogen protects against bone loss.

For people who menstruate, estrogen levels drop as they near menopause (when the monthly ovulation cycle stops). Estrogen levels can drop by up to 90% at menopause. This drop in estrogen levels leads to bone thinning.

Some studies have shown that bone density in people assigned male at birth is also related to the declining availability of sex hormones. They are increasingly bound to a protein that keeps them from being active. This reduction is an average of 47% for estrogen and 64% for testosterone. Less active estrogen means reduced bone mineral density.

Cancer can also cause bone loss. In cancer that has not metastasized (spread beyond its original site), increased inflammation both at the cancer site and throughout the body can lead to bone loss. The bones are also a common site of metastasis, affecting the skeleton.

Some forms of cancer treatment can also weaken bones, although they can improve survival. Cancer treatments may aim to reduce estrogen or testosterone to slow cancer growth (particularly when treating breast or prostate cancer). The blocking of these protective hormones can lead to bone weakening.

Cancer treatments that can increase the risk of osteoporosis include:

• Aromatase inhibitors, such as Femara (letrozole), Arimidex (anastrozole), Aromasin (exemestane)
• Gonadotropin-releasing hormone agonists, such as Zoladex (goserelin) and Lupron (leuprolide)
• Surgical removal of the ovaries or testes
  
• Androgen deprivation therapy, such as Casodex (bicalutamide), Eulexin (flutamide), Nilandron (nilutamide)
• Steroids, such as prednisone and cortisone
• Some chemotherapy medications
  
• Medications that suppress the immune system, such as methotrexate

Risks

Those who have cancer may find that they not only have an increased risk of osteoporosis from cancer itself. Types of cancer that may lead to bone loss include the following:

• Bone cancer
• Breast cancer
• Prostate cancer
• Lung cancer
• Multiple myeloma (cancer of the plasma cells)

In particular, those with bone and breast cancer are at increased risk.

The specific treatment you need to undergo to manage your cancer can also be a factor. When bone loss occurs due to cancer therapy, it can be more than seven times that of traditional aging. It is typically more rapid and severe.

Cancer treatment can further exacerbate osteoporosis if this condition is already affecting your bones. It is yet another risk factor that you need to weigh.

Treatment and Management of Osteoporosis With Cancer

Having either an increased risk for osteoporosis or osteoporosis outright can affect how your cancer is managed. Your oncologist (a doctor who specializes in treating cancer) will want to assess the chances that your bones will weaken and potentially develop fractures.

Some non-cancer-related risk factors they will weigh include the following:

• Your age
• If you are postmenopausal
• Whether you're a cigarette smoker
• Whether you consume alcohol
• If you've had other fractures as an adult
• Whether your body is producing sufficient sex hormones
• If you are thin
• If your parents had a history of hip fractures

If you have a cancer diagnosis and have at least one other risk factor for osteoporosis, you will likely be asked to take a bone mineral density test. For cases in which your oncologist has prescribed an anti-cancer medication known to cause bone loss, this test should be repeated at least every two years, if not sooner.

You may be given bone-modifying medication to help lower the risk of fractures if you have osteoporosis or are at a high risk of developing it. These include bisphosphonates, such as Zometa (zoledronic acid).

As a rule, hormone replacement therapies known to be protective of bone (such as estrogen replacement therapy), will be avoided if you have hormone-responsive cancer because it would stimulate cancer growth.

Prevention

Having a diagnosis of cancer does not necessarily mean that you are destined to also develop osteoporosis. To help keep osteoporosis from occurring in conjunction with any cancer diagnosis, you will likely be advised to do the following:

• Ramp up the amount of calcium and vitamin D that you consume. It will likely be recommended that you consume at least 1,000–1,200 milligrams per day of calcium and 800–1,000 international units (IU) per day of vitamin D.
• Quit smoking because it can affect bone quality and can otherwise heighten fracture risk.
• Give up drinking alcohol, which can affect your balance and otherwise lead to falls.
• Exercise to improve balance, strength, and flexibility and help reduce the chance of falls.

Summary

Osteoporosis occurs with age naturally but can also be brought on by cancer. Cancer can thin the bones, as can the treatment meant to kill the cancerous cells.

A decline in estrogen levels can lead to bone thinning in people of any sex, whether this occurs naturally or not. This hormone is often blocked to keep tumors that are sensitive to estrogen from spreading.

Your bone density will be monitored during cancer treatment. There are lifestyle measures that may help to keep you from losing bone and also medication that can help.

A Word From Verywell

If you have osteoporosis and are worried about what a cancer diagnosis will mean, keep in mind that there are measures that you can take, as well as medications that can make a difference. Monitoring and treatment for osteoporosis will be part of your care plan.