How Safe Is Low-Dose Radiotherapy for Osteoarthritis and Joint Pain

Does Low-Dose Radiotherapy Increase the Risk of Cancer?

For many patients considering low-dose radiotherapy for osteoarthritis or plantar fasciitis, the main concern is not the treatment itself. It is whether receiving radiation for a non-cancer condition could increase the risk of developing cancer later in life.

This is an important question and one that should be discussed openly.

Low-dose radiotherapy uses much smaller radiation doses than those generally used to treat cancer. For osteoarthritis, the aim is not to destroy tissue but to influence the inflammatory processes contributing to pain and stiffness.

The lower dose is reassuring, but it does not mean the long-term risk is zero. Any exposure to ionising radiation has the potential to damage DNA, and in theory this can contribute to the development of a malignancy many years later.

The more useful question is therefore not whether there is any theoretical risk, but how large that risk appears to be in the patients and body regions we actually treat.

What Does the Long-Term Evidence Show?

Until recently, one of the limitations when discussing low-dose radiotherapy was the lack of large contemporary studies specifically examining secondary cancer risk.

A major study published in 2026 provides some of the most useful evidence we now have.

Researchers followed 4,699 patients who received 5,614 courses of low-dose radiotherapy for non-cancerous musculoskeletal conditions. The average age at treatment was approximately 64 years, and most treatments involved peripheral joints.

Across the entire cohort, only three solid cancers were subsequently identified within previously irradiated treatment areas, equivalent to 0.064% of patients.

This is a reassuring finding, particularly because the study included long-term follow-up and patients had an estimated life expectancy of approximately 21 years after treatment.

The study also looked separately at blood cancers. This matters because some bones contain substantial amounts of active bone marrow, where blood cells are produced.

At 12.5 years, freedom from haematological malignancy was 99.0% after treatment away from marrow-rich regions compared with 97.7% after treatment closer to active bone marrow.

This does not mean that low-dose radiotherapy caused blood cancer in 1.3% of patients. The study was retrospective and did not include a matched group of untreated patients, and the patients receiving treatment to different parts of the body were not necessarily otherwise identical.

What it does demonstrate is that the location being treated is important when considering long-term radiation risk.

Peripheral Joints Are Different From Central Treatment Areas

Radiation risk is not determined by dose alone.

It also depends on how much normal tissue is exposed and which organs or tissues are within the treatment area.

Treating a knee, hand, foot or ankle exposes a relatively small peripheral part of the body. This is very different from treating a large region of the chest, abdomen or pelvis, where more bone marrow and internal organs may be exposed.

In the 2026 safety study, approximately 62% of treatments involved distal joints and another 37% involved proximal joints. The authors concluded that contemporary low-dose radiotherapy appeared reassuringly safe for peripheral musculoskeletal conditions, while recommending greater caution for central or marrow-rich treatment regions.

This distinction is particularly relevant to the conditions most commonly considered for treatment at Pinpoint Radiotherapy, including osteoarthritis of peripheral joints and plantar fasciitis affecting the foot, where the treatment area is small and located well away from most internal organs.

Why Age Matters

Radiation-induced cancers, when they occur, generally take many years to develop. A younger person therefore has a longer period during which a radiation-related malignancy could potentially emerge.

For an older adult with persistent osteoarthritis, the lifetime radiation risk is correspondingly lower.

This is one reason low-dose radiotherapy should not simply be offered to everyone with joint pain. Age, the joint being treated, symptom severity, previous treatment and other available options should all form part of the decision.

Current multidisciplinary guidance similarly emphasises appropriate patient selection rather than treating low-dose radiotherapy as a routine first treatment for osteoarthritis.

What About Immediate Side Effects?

The long-term cancer question tends to dominate discussions about safety because acute side effects from low-dose radiotherapy are generally limited.

The radiation dose is far below that commonly used in cancer treatment, so significant skin reactions or damage to the joint and surrounding tissues would not ordinarily be expected.

The treatment itself cannot be felt and patients do not become radioactive. There is generally no recovery period required after each treatment session.

Occasional temporary changes in symptoms can occur, and any unexpected problem should be discussed with the treating radiation oncologist, but for most patients the immediate treatment burden is relatively small.

The more important consideration remains whether the potential improvement in joint symptoms justifies accepting a very small but not completely absent long-term radiation risk.

Putting Secondary Cancer Risk Into Perspective

It would be misleading to say that low-dose radiotherapy carries no possibility of a radiation-related cancer.

Equally, the available evidence does not suggest that appropriately delivered low-dose radiotherapy to peripheral joints produces a large secondary cancer risk.

The largest contemporary long-term study found three solid cancers within the previously irradiated regions among 4,699 treated patients, while also highlighting that treatment close to active bone marrow deserves greater caution.

For the older patients most commonly being considered for low-dose radiotherapy to the knee, hand, foot, ankle or other peripheral sites, these results are reassuring.

The decision nevertheless remains individual. Radiation should be used because the expected benefit is reasonable for that patient, not simply because the dose is low.

Pinpoint Radiotherapy

At Pinpoint Radiotherapy, the potential long-term radiation risk is considered as part of every assessment for low-dose radiotherapy.

Particular attention is paid to age, the anatomical area being treated, the amount of normal tissue exposed and whether reasonable conservative treatment options have already been explored.

For appropriately selected older patients with persistent osteoarthritis or other peripheral musculoskeletal conditions, current long-term evidence provides considerable reassurance regarding secondary cancer risk.

The aim is not to describe low-dose radiotherapy as risk-free, but to place that risk in its proper context so patients can make an informed decision about whether treatment is appropriate for them.