Bone Thinning (Osteoporosis)
What causes it: Long-term hormone therapy (ADT) can lead to bone thinning. Testosterone is important for maintaining bone density – it signals bone cells to keep bone strong. When ADT lowers your testosterone to very low levels, your bones may gradually lose minerals and become less dense. Essentially, you can develop treatment-induced osteoporosis, similar to how postmenopausal women lose bone mass when estrogen drops. This side effect becomes more significant the longer you remain on hormone therapy. LHRH agonists/antagonists and surgical castration all have this effect. Anti-androgen pills alone have a smaller impact on bone density, but they are often used in combination with other therapies. Additionally, if you already are older or have risk factors for osteoporosis (such as a family history, smoking, long-term steroid use, or lack of calcium/vitamin D), ADT will compound those. In advanced prostate cancer, sometimes the cancer itself can spread to bones and weaken them, but that’s a different mechanism (bone metastases). Here we are focusing on the generalized bone loss throughout the skeleton caused by hormone deprivation.
How it affects daily life: In the early stages, bone thinning has no symptoms. You won’t “feel” your bones getting weaker. The danger is that over time, weakened bones can lead to fractures (broken bones). These fractures might occur with minimal trauma – for example, something as simple as twisting to lift a heavy object or a minor fall from standing height could cause a bone to break if it’s very osteoporotic. Common sites of fracture are the spine, hips, and wrists. Spinal fractures can cause back pain, loss of height, or a stooped posture if multiple vertebrae collapse. A hip fracture is a serious event that can greatly affect mobility. So, while you might not notice bone loss day to day, the risk manifests in these potential injuries. Also, bone thinning can cause bones to be more achy or tender in some people (though outright bone pain is more likely from cancer metastases than osteoporosis). It’s worth noting that men starting ADT don’t suddenly become osteoporotic overnight – it’s a gradual process over years. So, this is more of a long-term side effect to be aware of, especially if you’re on hormone therapy indefinitely. Regular bone density scans (DEXA scans) might be done to monitor your bone health if you’re on ADT for a long duration.
Ways to manage or reduce it: Preventing and managing osteoporosis is very important for your overall health. Lifestyle measures: Ensure you get enough calcium and vitamin D – these are the building blocks for healthy bones. Calcium-rich foods include dairy products (milk, yogurt, cheese) and leafy green vegetables. Vitamin D is made in the skin with sunlight exposure and also comes from foods like fatty fish and fortified dairy; often doctors will recommend a daily vitamin D supplement, especially if levels are low or you have limited sun exposure. The typical target is around 1200 mg of calcium and 800-1000 IU of vitamin D daily (from combined diet and supplements), but follow your doctor’s advice.
Exercise: Regular exercise, particularly weight-bearing and resistance exercise, can help maintain bone density. This means activities like walking, jogging, climbing stairs, and lifting weights or using resistance bands. Even moderate exercise like brisk walking several times a week can signal your bones to stay strong. Exercise also improves balance and strength, which reduces the risk of falls (thus preventing fractures). If you’re new to exercise, start gently and maybe consult a physical therapist for a safe routine. Avoid smoking and excessive alcohol, as both can accelerate bone loss. Also, be cautious about fall risks in your home – remove loose rugs, install grab bars if needed, ensure good lighting – to protect your bones from injury. Medical interventions: Doctors have specific medications to counteract bone loss from ADT. One common class is bisphosphonates (such as alendronate or zoledronic acid). These drugs slow down bone breakdown and are often used in osteoporosis treatment. They can be given as a weekly pill or a periodic IV infusion depending on the drug. Another medication is denosumab (Xgeva/Prolia), an injection every 6 months that also strengthens bones and is shown to prevent fractures in men on ADT.
Denosumab is often used if bisphosphonates aren’t suitable. Your doctor will decide if and when you need these medications, possibly after checking your bone density via a DEXA scan. These medications have their own considerations (for example, maintaining good dental hygiene is important because of a rare jaw side effect of these drugs), but they are effective at preserving bone mass. If you are starting long-term ADT, ask your doctor about a baseline bone density test and whether you should start any bone-protective therapy. Often, if you’re expected to be on ADT for many years, they might start a bone medication proactively. Monitoring: Keep up with any recommended bone density scans to track your bone health. If a scan shows osteoporosis or a downward trend, that’s a signal to intensify treatment or preventive measures. In summary, while bone thinning is a silent side effect, it’s one that can be managed by a combination of lifestyle (calcium/vitamin D, exercise) and medications. By addressing it, you greatly reduce the risk of fractures and ensure your skeleton stays as strong as possible during your cancer treatment journey.