Aromatase inhibitor joint pain: can exercise help?

Aromatase inhibitors lower the amount of oestrogen in the body, and Macmillan says joint pain on these drugs "is probably caused by a decrease in oestrogen levels" [2]. Macmillan notes that joint pain is also a common symptom of the menopause [2].

Breast Cancer Now says painful joints are common on hormone therapy for breast cancer, "especially drugs like letrozole, anastrozole and exemestane" [1]. Breast Cancer Now describes the pain as mild and temporary for some people and "more long term and severe for others" [1].

Breast Cancer Now says you may feel pain in your hands, wrists and knees, but it can affect other joints too, like the hips or shoulders [1]. Stiffness is common and can be worse first thing in the morning [1]. Breast Cancer Now also lists carpal tunnel syndrome, trigger finger and tendonitis among the joint problems people may have [1].

Very common. Joint pain affects up to half of the women who take an aromatase inhibitor, often within six months of starting [3][4].

The HOPE trial report states that arthralgia (pain or stiffness in the joints) is "reported in up to 50% of patients with breast cancer within 6 months of starting AI therapy" [3]. A Cochrane review puts it the same way: "Nearly half of all women on AIs experience these side effects" [4].

Exercise may help. In the HOPE trial, a year of aerobic exercise and supervised strength training reduced joint pain in previously inactive women on aromatase inhibitors, with no exercise-related harms [3]. Breast Cancer Now also says strength and flexibility exercises "can help reduce joint and muscle pain" [1].

The HOPE trial randomly assigned 121 women who had been taking an aromatase inhibitor for at least six months and had joint pain [3]. To take part, the women had to be inactive: under 90 minutes of activity a week and no strength training in the past year [3]. Half were given 150 minutes a week of aerobic exercise, mostly brisk walking, plus supervised strength training twice a week. The other half had usual care [3].

After 12 months, worst joint pain scores had fallen by 1.6 points (29%) in the exercise group, compared with a 0.2-point (3%) increase in the usual care group [3]. The authors reported that "There were no adverse events associated with the exercise program" [3].

The evidence is promising but not settled. A 2020 Cochrane review of seven studies (400 women) found no clear evidence of benefit overall, called the pain evidence "very uncertain", and judged exercise "probably safe, with no harms reported" [4].

Cochrane reviews pool the suitable trials and grade how certain the results are. In this review of exercise for aromatase inhibitor joint and muscle symptoms in early breast cancer, the reviewers could not say whether exercise improves pain, quality of life or grip strength, or helps women keep taking their medication [4].

The reviewers still concluded that "exercise needs to be part of routine care for women with breast cancer" [4]. The HOPE trial itself only included women who were inactive at the start, and its authors note that the results "may only be generalizable to physically inactive breast cancer survivors" [3]. If you have secondary breast cancer, check with your treatment team before starting any new type of exercise [1].

UK charities recommend a mix of strength, flexibility and gentle aerobic exercise such as walking or swimming [1][9]. Breast Cancer Now recommends strength and flexibility exercises for joint pain, and suggests being active for 150 minutes a week, which you can break up, for example into 25-minute sessions [1].

Strength work matters for another reason. The NHS says letrozole and anastrozole can make your bones weaker and more likely to break [5][6], and Breast Cancer Now says "Regular weight-bearing exercises can help bones to grow and become stronger" [9]. Our guides to bone health after cancer and exercise for osteoporosis cover bone-friendly training in more detail.

The HOPE programme of 150 minutes a week plus two strength sessions [3] matches the UK Chief Medical Officers' advice for all adults: at least 150 minutes of moderate activity a week and muscle strengthening on at least two days [10].

Start small, choose activities that feel comfortable, and build up slowly over weeks. The UK Chief Medical Officers say "Any activity is better than none - and more is better still" [10], so a few minutes a day is a real start.

A practical way to begin, based on the advice above:

1. Pick a comfortable base. Breast Cancer Now says regular exercise such as walking or swimming may help to relieve pain and joint stiffness [9].
2. Loosen up in the morning. Morning stiffness is common [1], so gentle stretching or a short walk may suit you better than a hard session straight after waking.
3. Add strength twice a week. Resistance bands or body-weight exercises are a simple start [1]. HOPE used two supervised strength sessions a week [3].
4. Track your pain. Note how your joints feel the day after each session and take that record to your appointments.

For general advice on rebuilding fitness, see exercise after cancer treatment.

No, not on your own. The NHS says "Do not stop taking letrozole without talking to your doctor first" [7], and Breast Cancer Now says "It's important to speak to your treatment team before stopping any treatment" [1]. If you want to stop, the NHS says your doctor can discuss other options for treating your breast cancer or preventing it coming back [7].

Letrozole is usually taken for about five years, and sometimes for up to ten [7]. Joint pain is the most common reason people do not take aromatase inhibitors as prescribed [3], so it is worth raising early. Breast Cancer Now says your team may suggest a short break, switching to another type of treatment or trying another brand of the same treatment [1]. Only take a break if your specialist has agreed to it [7].

Painkillers, physiotherapy and some self-help measures can sit alongside exercise. Ask your pharmacist or doctor which painkiller and dose are right for you, and tell your team if the pain does not settle [1][5].

• Painkillers: simple pain relief such as paracetamol or ibuprofen can help; check the dose and possible side effects with a doctor or pharmacist first [1].
• Physiotherapy: your treatment team may be able to refer you to a physiotherapist, "who can suggest exercises to help your symptoms" [1].
• Acupuncture: Breast Cancer Now says there is "some evidence that acupuncture can help with joint and muscle pain" [1]. Breast Cancer Now says most complementary therapies are safe for people with breast cancer, but check with your treatment team or GP before taking any herbal medicine, as some may affect how certain cancer treatments work [1].
• Heat, ice and posture: Breast Cancer Now suggests heat or ice packs on sore areas and regular breaks from sitting for long periods [1].

Your treatment team may be able to refer you to a physiotherapist, who can suggest exercises to help your symptoms [1]. A clinical exercise physiologist (CEP) is another professional who prescribes and delivers exercise [11].

Clinical exercise physiologists are "responsible for prescribing and delivering evidence-based exercise", and NHS Health Careers lists their work in "oncology with patients with different types of cancer and at different stages of treatment" [11]. A CEP works alongside your oncology team, not instead of it. If you live in London, cancer rehab in London also covers NHS and charity options.

Request a match with a verified clinical exercise physiologist through The Health Nav.

• Cancer rehabilitation in the UK
• Exercise after breast cancer: surgery to recovery
• Bone health after cancer
• Exercise for osteoporosis
• Exercise after cancer treatment
• Cancer-related fatigue
• Exercise and prostate cancer (hormone therapy for prostate cancer)