Bone density scan: why is it important and when to do it?

 Gabriella Kourie educates us on when and why a bone density scan is needed if you are diagnosed with breast cancer.

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If you’ve undergone or currently undergoing treatment for cancer, your doctor may have sent you for a bone density scan. There is a variety of reasons why you might be going for the scan and it’s important to know the role that the scan plays in both prevention and treatment when it comes to: bone lesions as well as secondary bone degeneration (osteopenia, osteoporosis and/or osteoarthritis).

What is a bone density scan?

It’s a special type of X-ray that looks at and measures the bone mineral density (BDM) at various sites of the skeleton. Simply, the scan looks at and gives readings of how strong your bones are and how good the quality of your bone-building blocks is. A high bone density, generally, indicates a lower risk of bone fracture.

The more scientific explanation: the scanner is a device that produces two types of X-ray beams: one which is higher energy and the other is lower energy. The number of X-rays passing through the bone from each beam is then measured and it produces a number that varies depending on the BMD.

What is the process?

The scan itself takes a short period of time, between 15-25 minutes. It’s non-invasive in the sense that no injections are given beforehand and no pain is felt during the procedure. The radiation exposure is lower compared to that of an MRI or CT scan and there is no tunnel involved. You’ll lie on an open table and flat panels move over the areas of the body that are being scanned.

When you receive your report, you’ll see that the spine and one or both of your hips have been scanned. These snapshots are enough to give a sufficient overview of the overall bone density of your skeleton. This has been shown to be the most effective way of predicting or indicating a person’s risk of bone fracture.

Understanding the results

The results of the bone density scan are given a numerical value in the form of a T-score. It compares your bone density to that of a healthy 30-year-old as this is a time where the human bones are at their strongest. A high score indicates strong bones and a low score indicates weaker bones.

Breakdown of the T-score ranges

1.0 or above  = normal bone density

Between -1.0 and -2.5  = low bone density, or osteopenia

-2.5 or lower = osteoporosis

The second value you’ll see on your report is the Z-score. This compares your bone density to the bone density of a typical person of your same sex, age and body size and weight.

Impact of cancer and treatment

Cancer and treating therapies stand as a major risk factor for patients developing osteoporosis due to bone loss and deterioration of the above-mentioned bone-building blocks. A loss of bone strength ultimately puts you at risk of bone fragility and increases risk of bone fracture.

By sending you for a bone density scan, your doctor is able to ensure optimal management of skeletal health. The bone density scan is essential when making decisions around reducing bone loss and fracture risk in patients who have received or are receiving treatment for cancer.

The occurrence of osteoporosis in the context of breast cancer is mainly linked to hormone positive breast cancer treatments; induced by chemotherapy as well as the hormone blocker therapy. Oestrogen plays a vital role in maintaining healthy bone density through a physiological process that results in decreased bone resorption and bone loss.

When should you have it?

The recommended time is either at the start of treatment or before taking hormone blockers. This gives your doctor your baseline bone density scores and gives them an indication of pre-existing conditions that may be there due to genetics, smoking and excessive weight. This helps your doctor to determine the type and strength of hormone blocker treatment they prescribe.

Your doctor will then explain the recommended time frame for when to have your next bone density scan. However, the general guideline is every one to two years as a breast cancer patient. 

Gabriella Kourie is a qualified occupational therapist. She further trained and qualified 
as a PORi oncology and breast cancer rehabilitation therapist and is currently qualifying in Lymphoedema Assessment 
and Treatment.

MEET THE EXPERT – Gabriella Kourie

Gabriella Kourie is a qualified occupational therapist. She further trained and qualified as a PORi oncology and breast cancer rehabilitation therapist and is currently qualifying in Lymphoedema Assessment and Treatment.

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