by Walter I Sussman

Osteoarthritis (OA) is one of the most common causes of joint pain and disability worldwide. If you’re dealing with persistent knee, hip, or hand pain, you may have come across low-dose radiation therapy (LDRT) as a potential treatment option.

While LDRT has been used in parts of Europe for decades, it remains controversial, especially in the United States. Why? Because although it may reduce pain, it raises important questions about long-term safety, cancer risk, and whether it actually treats the underlying disease.

What Is Low-Dose Radiation Therapy (LDRT)?

Low-dose radiation therapy uses low doses of ionizing radiation (typically 3.0-6.0 Gy total, delivered in 0.5-1.0 Gy fractions over 2-3 weeks) to target painful joints, but the evidence for its efficacy remains highly controversial and inconsistent (Hammedeh et a, 2025; Mahler et al, 2019; Schalmann et al, 2026).

Current consensus suggests low-dose radiation therapy should remain investigational, reserved for research settings or highly selected refractory cases where conventional treatments have failed, particularly in elderly patients unsuitable for surgery (Hammedeh et a, 2025; Schalmann et al, 2026). It is minimally used in the United States but more common in parts of Europe, particularly Germany (Dove et al, 2022).

Does LDRT Work for Osteoarthritis?

The clinical evidence for low-dose radiation therapy in osteoarthritis is inconsistent. While retrospective studies and some observational trials report response rates of 70-80% with sustained pain relief, the highest-quality randomized controlled trials show no significant benefit over sham treatment (Koneru et al, 2025; Weissmann et al, 2022).

• A 2019 Dutch RCT found no difference between low-dose radiation therapy and sham for knee osteoarthritis (44% vs 43% responders) (Mahler et al, 2019)
• A 2025 meta-analysis of 1,750 patients concluded that low-dose radiation therapy showed no significant benefit for pain (SMD: -0.92; P=0.13) or function (SMD: 0.22; P=0.22) compared to sham. The meta-analysis also found more adverse events with LDRT (RR: 1.44), particularly nail reactions (Hammedeh et a, 2025)

Understanding the Risks: The Biggest Concern

Cancer Risk (Primary Concern)

Radiation exposure, no matter how small, carries some level of cancer risk. The linear no-threshold (LNT) model assumes that cancer risk increases linearly with dose without a lower threshold, meaning theoretically even a single photon could induce cancer (Hirshfeld et al, 2018).

This model is based primarily on data from atomic bomb survivors (Life Span Study) and other high-dose exposures, then extrapolated downward to low doses (Hirshfeld et al, 2018). Excess cancer incidence becomes statistically detectable at doses around 100 mSv in adults and lower in children, substantially higher than typical low-dose radiation therapy doses of 3-6 Gy (3,000-6,000 mSv) total, though low-dose radiation therapy is localized rather than whole-body (Hirshfeld et al, 2018).

Recent systematic reviews support continued use of the LNT model for radiation protection, though acknowledge that risks at very low doses remain uncertain and may never be definitively proven or disproven epidemiologically.

Quantifying Cancer Risk from Low-Dose Radiation Therapy

For low-dose radiation therapy specifically, the absolute cancer risk maybe negligible in elderly populations, who comprise the typical osteoarthritis patient demographic (Nakamura, 2026; Schalmann et al, 2026)

Key risk-modifying factors may include:

• Age: Younger patients have higher radiation sensitivity and longer life expectancy for cancers to manifest; elderly patients may not survive long enough for radiation-induced cancers to develop

• Localized exposure: LDRT targets specific joints, not whole-body exposure

• Dose magnitude: 3-6 Gy total is relatively low compared to cancer radiotherapy (50-70 Gy)

• Cumulative exposure: Repeated treatments to the same site increase concern

• Genetic susceptibility: Patients with germline DNA repair mutations face higher risk

A 2015 review concluded that "risks of cancer following RT for benign disease for currently advised protocols are small, especially in older patients," though emphasized careful risk-benefit consideration in younger adults (McKeown et al, 2015).

Reference

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Hammadeh BM, Aldalati AY, Al Matairi A, Elshabrawi MN, Qtaishat FA, Al-Qunbar AM, Alzibdeh A, Abuodeh Y, Abuhijla F. Efficacy, safety, and pain management of low-dose radiation therapy in osteoarthritis: a comprehensive systematic review and meta-analysis. Rheumatol Int. 2025 Sep 1;45(9):210. doi: 10.1007/s00296-025-05942-z. PMID: 40888940.

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McKeown SR, Hatfield P, Prestwich RJ, Shaffer RE, Taylor RE. Radiotherapy for benign disease; assessing the risk of radiation-induced cancer following exposure to intermediate dose radiation. Br J Radiol. 2015;88(1056):20150405. doi: 10.1259/bjr.20150405. Epub 2015 Oct 14. PMID: 26462717; PMCID: PMC4984935.

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Schlamann A, Yu JB, Rühle A. Low-Dose Radiotherapy for Osteoarthritis: Current Evidence, Practical Recommendations and Future Perspectives. Semin Radiat Oncol. 2026 Jan;36:39-47. doi: 10.1016/j.semradonc.2025.07.001. PMID: 41391897.

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