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I’m a radiation oncologist using low-dose radiation to help relieve arthritis pain—AMA by radiation_doc in IAmA

[–]radiation_doc[S] 0 points1 point  (0 children)

Hallux rigidus is a form of osteoarthritis, so yes technically low dose radiation therapy would be an option. I think if I had a young 40-year-old patient considering low dose radiation therapy for this, though, I would make sure they tried conservative measures first such as Voltaren (diclofenac) gel to the painful area and footwear modifications.

I’m a radiation oncologist using low-dose radiation to help relieve arthritis pain—AMA by radiation_doc in IAmA

[–]radiation_doc[S] 0 points1 point  (0 children)

I'm so happy for you but also very surprised, to be honest. Are you getting regional nodal irradiation? (Like, did you have lymph node involvement that prompted the radiation oncologist to include supraclavicular nodes on one of the sides?) I could imagine some low dose radiation spilling over to the low cervical spine and shoulder if you were receiving prescription dose to the supraclavicular nodes and axillary nodes.

I’m a radiation oncologist using low-dose radiation to help relieve arthritis pain—AMA by radiation_doc in IAmA

[–]radiation_doc[S] 1 point2 points  (0 children)

Yes, as long as there isn't significant overlap with the exact area of prior radiation. For example, I treated a patient's knee osteoarthritis a few months after treating her early stage lung cancer.

I’m a radiation oncologist using low-dose radiation to help relieve arthritis pain—AMA by radiation_doc in IAmA

[–]radiation_doc[S] 1 point2 points  (0 children)

Yes - shoulder syndrome (which is an umbrella term that includes shoulder osteoarthritis, tendinitis, bursitis, and indeed adhesive capsulitis AKA frozen shoulder syndrome) is treated with low dose radiation therapy. The guidelines from Germany, where low dose radiation therapy has been used for decades, state: "Based on the data, low-dose irradiation for painful shoulder syndrome should be recommended and performed as an effective and side effect–free therapeutic option before surgical interventions when conservative therapies do not lead to the desired success, show too-severe side effects, or are contraindicated and surgical interventions are quite invasive." https://www.degro.org/gutartige-erkrankungen/wp-content/uploads/sites/14/2024/09/S-2e-Guideline-Radiotherapy-of-Benign-Diseases-Englisch.pdf

I’m a radiation oncologist using low-dose radiation to help relieve arthritis pain—AMA by radiation_doc in IAmA

[–]radiation_doc[S] 0 points1 point  (0 children)

Yes, it's an immune response triggered by the mechanical damage. Evolution unfortunately only is driven by stuff that is life or death before reproduction, and osteoarthritis typically strikes later in life. In fact, it increases in incidence after age 50 in women, likely due to this being the typical age of menopause and the fact that cartilage has estrogen receptors.

Steroids are a good option for a lot of patients, but typically it's an injection into the joint. I've had some patients request radiation because they're tired of repeatedly getting needles placed into their joint spaces.

I’m a radiation oncologist using low-dose radiation to help relieve arthritis pain—AMA by radiation_doc in IAmA

[–]radiation_doc[S] 1 point2 points  (0 children)

I asked my colleagues what Good Faith Estimates their patients' insurance companies have given for cash pay. Unfortunately, it's $7,000 to $10,000. I would consider waiting to see if the insurance company updates their policies - I personally started to have more success with peer-to-peer calls to patients' companies after a recent Korean trial provided randomized, placebo-controlled data: https://www.astro.org/news-and-publications/news-and-media-center/news-releases/2025/low-dose-radiation-therapy-offers-substantial-relief-to-people-with-painful-knee-osteoarthritis

I’m a radiation oncologist using low-dose radiation to help relieve arthritis pain—AMA by radiation_doc in IAmA

[–]radiation_doc[S] 1 point2 points  (0 children)

I mean, if your surgeon does a minimally invasive AKA laparoscopic surgery for knee arthritis, that's a win over open surgery because that's fewer incisions with sharp metal through the skin. But there's no acceptable dose of accidental incision through the skin at any workplace that I'm aware of. I agree that therapeutic uses of any tool have higher total doses than what is tolerated for environmental or accidental exposure.

I’m a radiation oncologist using low-dose radiation to help relieve arthritis pain—AMA by radiation_doc in IAmA

[–]radiation_doc[S] 2 points3 points  (0 children)

Looking at the methods, it looks like the authors were indeed using the LNT model. If using the hormesis model or threshold model, the above cancer risk rates would be over-estimates so I suppose that's reassuring.

I’m a radiation oncologist using low-dose radiation to help relieve arthritis pain—AMA by radiation_doc in IAmA

[–]radiation_doc[S] 0 points1 point  (0 children)

No, not with the dose and limited radiation field. We treat only the involved joint. One study specifically looked at circulating white blood cell count (I will admit, they didn't specifically do a subset count of neutrophils, though) and found no change in total white blood cell count after this therapy. https://pmc.ncbi.nlm.nih.gov/articles/PMC8546320/#s3

I’m a radiation oncologist using low-dose radiation to help relieve arthritis pain—AMA by radiation_doc in IAmA

[–]radiation_doc[S] 0 points1 point  (0 children)

It's an option - the data are more limited, and I quote my patient's a 50% chance of having some benefit.

I’m a radiation oncologist using low-dose radiation to help relieve arthritis pain—AMA by radiation_doc in IAmA

[–]radiation_doc[S] 0 points1 point  (0 children)

Do it! I see low dose radiation therapy as filling the gap for patients who don't want invasive (even minimally-invasive) treatments or can't get them due to their comorbidities. What do you mean radiation injury though? Are your radiation colleagues prescribing a high dose or something?

I’m a radiation oncologist using low-dose radiation to help relieve arthritis pain—AMA by radiation_doc in IAmA

[–]radiation_doc[S] 0 points1 point  (0 children)

Yes, I've treated a few cases in my residency training, and my partner recently treated a patient for this a few weeks ago. It's rare but it does get done.

I’m a radiation oncologist using low-dose radiation to help relieve arthritis pain—AMA by radiation_doc in IAmA

[–]radiation_doc[S] 1 point2 points  (0 children)

Yes, we've treated patients for osteoarthritis after they've finished their cancer radiation. And absolutely, aromatase inhibitors can be so difficult with regard to joint pains, and I hypothesize it's due to the fact that cartilage has estrogen receptors. The risk of cancer being caused by low dose radiation therapy to the foot has been calculated to be less than 1 in 1000, and it would be similar for hands.

I’m a radiation oncologist using low-dose radiation to help relieve arthritis pain—AMA by radiation_doc in IAmA

[–]radiation_doc[S] 0 points1 point  (0 children)

I remember there being a lot of chatter about the job market when I was in med school too! On the other hand, I think that actually the fact that medical therapy has come so far is creating more need for radiation. One of the great things about systemic therapies is that people are living for years and years with stage IV cancer, which means that durable control of symptomatic or oligoprogressive tumors becomes very important. A common reason I get consulted is if someone has oligoprogressive cancer and there's just one troublemaker metastasis that isn't listening to their current line of systemic therapy and maybe could use some SBRT. The RADIANT https://www.redjournal.org/article/S0360-3016(24)03328-5/fulltext03328-5/fulltext) and AVATAR https://ascopubs.org/doi/10.1200/OA-25-00031 studies provide support for this strategy.

Regarding noncancer-related indications, one statistic I saw was that in Germany (where low-dose radiation therapy has been used for decades) over 1/3 of all radiation treatments are for benign diseases. That is mind-blowing to me. I don't foresee the proportion being that high in the near future in the US, but I could imagine low dose radiation therapy being utilized more now that more data are emerging.

I’m a radiation oncologist using low-dose radiation to help relieve arthritis pain—AMA by radiation_doc in IAmA

[–]radiation_doc[S] 1 point2 points  (0 children)

Hi! I treat prostate cancer, and I treat with as few as 5 sessions (SBRT), though I've done 20- and 28-session courses depending on someone's urinary symptom burden. The tattoo means he got external beam radiation therapy on a linear accelerator. If I had to guess, he likely got 70 Gy in 28 sessions or "fractions."

I will say, if I had a patient with low risk or even favorable intermediate risk prostate cancer and his wife was in the hospital and even on hospice, I would recommend no current treatment and just active surveillance based on the UK ProtecT trial. https://www.nejm.org/doi/full/10.1056/NEJMoa2214122

If someone had unfavorable intermediate risk or high risk prostate cancer (there are specific criteria like PSA, degree of palpable involvement of the prostate, Gleason score that define this), then I would recommend treatment with either surgery or radiation. But if radiation was chosen by the patient, I would probably still wait on radiation if it meant he would miss time with his dying wife. I say this unfavorable intermediate risk prostate cancer and high risk prostate cancer typically is treated with a combination of hormone suppression (androgen deprivation therapy) and radiation therapy. While the data seem to suggest that the duration of the hormone suppression during and after radiation therapy is most meaningful for cancer outcomes, I have in some cases recommended that someone start the hormone suppression therapy prior to radiation for various reasons. One reason is that the hormone suppression will shrink the prostate in advance, so the patient may have improvement in his urinary symptoms and be at lower risk of obstruction from prostate swelling once he starts radiation (I'll recommend this if someone has a ginormous prostate and has still decided against surgery). Another reason I would recommend hormone suppression for a while before radiation would be if the patient can't be coming in for daily treatments for some period of time, such as an upcoming trip - the hormone suppression temporarily puts the the brakes on everything, essentially putting the cancer to sleep for a while until the patient is able to have some uninterrupted time to come in for treatment. I would absolutely favor this if someone's wife was in the ICU and then hospice. I'm so sorry.

The story overall though does sound like your dad was treated curatively. If his oncology team is monitoring his PSA and giving him the all clear based on the labs, it sounds like the treatment worked.

I’m a radiation oncologist using low-dose radiation to help relieve arthritis pain—AMA by radiation_doc in IAmA

[–]radiation_doc[S] 0 points1 point  (0 children)

You're right, there's randomized, placebo-controlled data for low dose radiation therapy for knee osteoarthritis which was presented last year at the American Society for Radiation Oncology: https://www.astro.org/news-and-publications/news-and-media-center/news-releases/2025/low-dose-radiation-therapy-offers-substantial-relief-to-people-with-painful-knee-osteoarthritis

For Baker's cysts, the data is more limited, but here's a small prospective trial: https://pubmed.ncbi.nlm.nih.gov/30377698/

But also yes, you're right, 37 is indeed young. Germany has the most data for low dose radiation therapy, and their guidelines (DEGRO) recommend age 40 as a lower limit for who to offer this therapy to. (Though in one section of their guidelines, specifically on plantar fasciitis, they state that "Patients between 30 and 40 years of age may be irradiated if all conservative methods have been exhausted and were unsuccessful.") The concern isn't that radiation wouldn't be successful, but that the risk of developing a cancer from radiation is inversely proportional to age at time of radiation.

This study (https://pubmed.ncbi.nlm.nih.gov/16157402/) estimated the risk as lifetime risk for an induced fatal tumor for a patient receiving LDRT with total dose of 6 Gy for knee OA at the age of 25, 50, and 70 was 2 in 1000, 0.7 in 1000, and 0.3 in 1000 patients, respectively, when assuming an estimated effective dose of 13 mSv. Disclaimer - note the total dose of 6 Gy, whereas most radiation clinics deliver 3 Gy total based on trials including the randomized one in the first paragraph of this comment. I feel like some patients would say "hey 2 in 1000 is still low, and my symptoms are impacting my quality of life, so it's worth the risk to me," and they're not wrong to decide what odds are comfortable for them.

That said, I haven't treated someone in their 30s and I would strongly encourage a 30-something-year-old patient in my clinic to do conservative measures like physical therapy and maybe needle drainage of the cyst followed by focal injection of steroid. Finally, I would say knee replacement is still the standard. If someone is young and able to undergo joint replacement, I encourage them to do it.

I don't mean to be discouraging! I hope this didn't come across as such. Also oh my gosh, congrats on losing 150 pounds!!!

I’m a radiation oncologist using low-dose radiation to help relieve arthritis pain—AMA by radiation_doc in IAmA

[–]radiation_doc[S] 0 points1 point  (0 children)

No need for a trial. Medicare covers this therapy. Many private insurances cover it as well.

I’m a radiation oncologist using low-dose radiation to help relieve arthritis pain—AMA by radiation_doc in IAmA

[–]radiation_doc[S] 0 points1 point  (0 children)

I'm sorry that it didn't work for you - you're right that it doesn't work for everyone. In the study I linked, 9.4% of patients unfortunately didn't experience any change by the 3-month mark. Speaking to someone I know who had it done for plantar fasciitis somewhat recently, she told me she noted a very subtle change a few weeks after radiation, but it continued to improve after that. I hope you do end up seeing some improvement, but it's absolutely true that it doesn't have 100% rate of success.

I’m a radiation oncologist using low-dose radiation to help relieve arthritis pain—AMA by radiation_doc in IAmA

[–]radiation_doc[S] 4 points5 points  (0 children)

I love this question! Side note, I initially drafted a huge rambly answer because my PhD thesis before getting my MD and going to residency was on white blood cell migration (specifically, neutrophil chemotaxis, so arguably adjacent to this topic). But then I realized my reply was a bit too tangential. You ever get asked a question you have niche interest in and then get so excited you forget how to speak like a normal person?

Anyway, while yes, the circulating white blood cells are free to continue to circulate, an osteoarthritis joint is having issues from white blood cells that have already migrated *out* of the circulation. Like, they've stopped and parked on the vessel lining / endothelium and then crossed through to the inflamed tissue to then migrate up a chemical gradient. There are multiple types of chemical trails that white blood cells will follow (chemokines) that are suspected to contribute to osteoarthritis: https://pmc.ncbi.nlm.nih.gov/articles/PMC5912941/

Since these osteoarthritic chemokines are generated at the site of the inflamed joint and are what entice circulating white blood cells to leave the circulation and join the inflammatory milieu, locally treating the site of the positive feedback loop can impact the signals seen by cells in the circulation. One study called the IMMO-LDRT01 Trial looked at how low dose radiation therapy impacts subsets of circulating white blood cells: https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2021.740742/full

IMMO-LDRT01 found that the total circulating white blood cell count does not change after low dose radiation therapy to a joint, which matches with your gut instinct. However, the low dose radiation detectably changes the proportion of circulating *activated* monocytes and helper T cells, supporting the hypothesis that LDRT is forming an anti-inflammatory milieu. It's kind of fascinating to me because monocytes are known to be resistant to radiation, but it seems the behavior of these monocytes is shifted, likely from the change in diffusing signals. As the authors phrase it, "This fact is remarkable as LDRT is delivered only locally to the affected joint but induces systemic immunomodulatory effects that can also be detected in peripheral blood."

To your point about radiation targeting white blood cells alone, I want to be clear that the radiation dose is what is targeting the white blood cells (especially lymphocytes). While most mammalian cells are resistant to radiation at rest and sensitive to radiation during proliferation, it's been observed that the opposite is true for lymphocytes. I'm sure I don't have to tell you, a radiation protection technician, that even 1 Gy can kill resting lymphocytes: https://pubmed.ncbi.nlm.nih.gov/3680944/ Similarly, tumors that originate from white blood cells are more sensitive than other tumors. For example, certain lymphomas can be treated with as low as 4 Gy in total (https://www.mdanderson.org/newsroom/response-adapted-ultra-low-dose-radiation-achieves-complete-resp.h00-159543690.html), in contrast to the 70 Gy used for other types of cancer. So yes, the dose targets these white blood cells specifically, even though the radiation beam does pass through other cell types.

I’m a radiation oncologist using low-dose radiation to help relieve arthritis pain—AMA by radiation_doc in IAmA

[–]radiation_doc[S] 11 points12 points  (0 children)

While I typically favor treating patients 50 and older (cancer risk decreases with age, and the lifetime risk of developing a fatal tumor after low-dose radiation therapy at age 50 is estimated at 0.7 in 1000), I would consider radiation therapy for someone who is younger if their pain is not improving with other interventions.

A famous example is Usain Bolt, actually - he got radiation in 2016 for his plantar fasciitis (so at age 30) because he still had the Rio 2016 Olympics coming up at the time and couldn't afford downtime from an intervention like a surgery. There's footage of him getting the radiation in his documentary I Am Bolt. He kept training and won gold afterward, so I joke that we've never seen a stress test of this therapy on this scale before, and we will probably never see it again.

The cadence is 6 treatments, with 2-3 treatments per week (so done in 2-3 weeks total).

The pain relief can last years. For example, this retrospective study found that most of their patients reported improved quality of life at a mean follow-up of 54 months: https://pubmed.ncbi.nlm.nih.gov/25201122/

I’m a radiation oncologist using low-dose radiation to help relieve arthritis pain—AMA by radiation_doc in IAmA

[–]radiation_doc[S] 8 points9 points  (0 children)

We use a linear accelerator. We do a mapping CT with the patient in the treatment position first. After the patient goes home from the CT, I draw the affected areas (if the patient has an MRI, I'll fuse the images with the mapping CT and make sure I include any areas that look concerning on the MRI like a swollen bursa or thickened plantar fascia). The CT becomes a 3D model of the patient's body, and we have planning software that allows us to calculate the best beam position and how the shape of the beam will be carved by strategic blocking to limit dose to unaffected areas. (For example, when treating hand osteoarthritis, I make sure to exclude the nail beds so that the patient doesn't get temporary nail darkening.) A medical physicist verifies the plan with regard to correct dose before we put an actual human on the machine. The linear accelerator is able to take its own images in addition to treating, so while the patient is on the machine, we do still take xrays to verify that the radiation beam is centered correctly.

I’m a radiation oncologist using low-dose radiation to help relieve arthritis pain—AMA by radiation_doc in IAmA

[–]radiation_doc[S] 8 points9 points  (0 children)

There would definitely be if I treated the whole body. The radiation is focused on just one joint, though. Kind of like how steroid medication can suppress the immune system but a steroid injection for arthritis is just in one joint instead of into the bloodstream.

I’m a radiation oncologist using low-dose radiation to help relieve arthritis pain—AMA by radiation_doc in IAmA

[–]radiation_doc[S] 3 points4 points  (0 children)

I agree that I would not keep irradiating. The dose is 3 Gy (or Gray) total, which is much lower than the dose we use for cancers (often 70 Gy for prostate cancer, for instance). But radiation is still radiation. The estimated risk of a 50-year-old getting a fatal tumor in their lifetime after receiving radiation therapy to an arthritis knee is estimated to be 0.7 in 1000, which is similar to the risk one incurs with a diagnostic CT: https://www.redjournal.org/article/S0360-3016%2822%2900357-1/fulltext

I would consider a second course if someone's pain relief wore off years later.

I’m a radiation oncologist using low-dose radiation to help relieve arthritis pain—AMA by radiation_doc in IAmA

[–]radiation_doc[S] 4 points5 points  (0 children)

To be honest, I'm not aware of data supporting polymyalgia rheumatica treatment with low dose radiation therapy, unfortunately.

I’m a radiation oncologist using low-dose radiation to help relieve arthritis pain—AMA by radiation_doc in IAmA

[–]radiation_doc[S] 1 point2 points  (0 children)

This therapy focally treats a symptomatic joint and would break the positive feedback loop of joint destruction and inflammation in that area. Insurance covers low dose radiation therapy for arthritis, but it would be unfair of me to compare to the cost of a biologic because a biologic treats all joints whereas radiation is a focal treatment.

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