Hormonal therapy and side effects

Hormone therapy is one of the most effective treatments for certain breast and prostate cancers that are fuelled by hormones. These cancers are called hormone receptor–positive, meaning the cancer cells rely on hormones, such as oestrogen or testosterone, to fuel their growth.

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Breast cancer

In women, oestrogen is mainly produced by the ovaries before menopause and after menopause by other body tissues that convert hormones from the adrenal glands. 

Adjuvant hormone therapy (AHT) helps slow or stop the growth of oestrogen-dependent cancer by either blocking the effects of oestrogen or reducing its production. The most commonly used agents include:

Tamoxifen, a selective oestrogen receptor modulator (SERM) that blocks oestrogen receptors in breast tissue.

Aromatase inhibitors (AIs), such as anastrozole, letrozole, and exemestane, which inhibit oestrogen production in post-menopausal women.

Ovarian suppression therapy, which reduces oestrogen levels in premenopausal women, sometimes combined with AIs for enhanced effect.

Prostate cancer

In men, androgen deprivation therapy (ADT) remains the foundation of treatment for prostate cancer, which depends on testosterone for growth. The goal of ADT is to reduce or block testosterone activity in the body. Current medications used are:

Gonadotropin-releasing hormone (GnRH) agonists, such as leuprolide, which suppress testosterone production.

Second-generation non-steroidal androgen receptor (AR) antagonists, including enzalutamide, apalutamide, and darolutamide, which prevents testosterone from binding to its receptor.

Androgen biosynthesis inhibitors, such as abiraterone, which blocks the enzyme CYP17 and reduces androgen synthesis.

Hormone therapy can be given before surgery or radiation to shrink tumours or after treatment to reduce recurrence risk. It’s also used in advanced disease to control progression and symptoms. 

Side effects

While hormone therapy is generally well tolerated and highly effective, long-term suppression of sex hormones can cause physical, cognitive, and emotional side effects. Awareness and proactive management of these effects are essential to maintaining quality of life and treatment adherence.

Physical side effects

Musculoskeletal symptoms: Joint pain, stiffness, and muscle aches are common, especially with aromatase inhibitors in women and ADT in men. Severe stiffness or pain can interfere with daily activities and reduce independence.

Vasomotor symptoms: Hot flashes and night sweats affect both men and women, often disturbing sleep and leading to fatigue. Fatigue is known to be the most common side effect in any cancer treatment and can last long after treatment has stopped.

Sleep disturbance: Difficulty falling or staying asleep is a prevalent side effect, contributing to daytime tiredness, impaired concentration, and reduced mood.

Cognitive impairment: Also known as brain fog, people with cancer may experience memory lapses, difficulty concentrating, and slower thinking, affecting work, social life, and daily tasks.

Weight gain and body composition changes: Loss of muscle mass, increased fat, and changes in body shape can impact self-esteem. Men on ADT are particularly at risk of central adiposity (accumulation of excess fat in the abdominal area) and insulin resistance.

Bone health: Long-term hormone suppression accelerates bone loss, increasing the risk of osteoporosis that can lead to fractures. Preventive measures, such as bisphosphonates or denosumab, are recommended for high-risk people with cancer.

Emotional and psychosocial side effects

Mood changes and feeling low: Fatigue, sleep disruption, and hormonal changes contribute to persistent low mood, irritability, and emotional distress, sometimes reducing motivation to adhere to therapy.

Body image and self-perception: Weight gain, bloating, joint stiffness, and hair thinning can alter self-esteem and confidence. You may not feel yourself or feel older than your age.

Social impacts: Pain, fatigue, and emotional distress often reduce participation in social activities, potentially leading to isolation and decreased quality of life.

Sexual health and fertility: Women may experience low libido, vaginal dryness, or painful intercourse. Men may have reduced libido or erectile difficulties. Younger women face challenges from treatment-induced menopause and fertility loss, which can cause significant emotional distress often undermined by the healthcare team. 

Most side effects can be linked to the physical side effects, thus management plays a vital role for physical as well as emotional recovery. 

Managing side effects

Effective management involves a multimodal approach:

• Pharmacologic treatments (SSRIs for hot flashes, bisphosphonates for bone health).
• Exercise and physical therapy to maintain strength and mobility.
• Cognitive and behavioural support for brain fog and fatigue.
• Psychosocial support to address mood changes and improve adherence.

Open communication with healthcare providers is essential. You should report side effects honestly, as underreporting may lead to premature discontinuation of therapy. There is also a need for more research into personalised side effect management, ensuring each patient receives strategies tailored to their needs.

Using food to help manage side effects

Nutrition plays an important role in reducing the physical and emotional side effects of hormone therapy and supporting recovery. While no single food can reverse the impact of hormone suppression, a balanced diet can help maintain strength, stabilise energy, and protect long-term health.

DID YOU KNOW? Exposing mushrooms to sunlight for 15–20 minutes with their stems facing up significantly increases their vitamin D levels, making them one of the few plant-based foods that can help support healthy vitamin D status giving you a delicious, sun-powered nutrient lift when you eat them.

Fatigue and muscle loss

Aim to include a good source of protein at every meal, such as eggs, fish, lean chicken, lentils, beans, or yoghurt. Pairing these with slow-release carbohydrates like oats, quinoa, or brown rice helps sustain energy levels. Including small protein-rich snacks (boiled egg, handful of nuts, or cottage cheese with fruit) can also reduce afternoon fatigue and preserve muscle mass.

Bone health

Calcium and vitamin D are essential. Choose calcium-rich foods, such as dairy or fortified plant milks, sardines, almonds, and leafy greens. Regular sunlight exposure and foods, such as salmon, egg yolks, or fortified cereals help maintain vitamin D levels. Magnesium from nuts, seeds, and whole grains also supports bone strength. 

DID YOU KNOW? Staying hydrated, eating regular balanced meals, and maintaining a healthy relationship with food are key to supporting both physical and emotional well-being during treatment. Working with a registered dietitian can help tailor nutrition goals to your treatment and recovery stage.

Joint stiffness and inflammation

Focus on an anti-inflammatory eating pattern which includes plenty of colourful fruit and vegetables, olive oil, nuts, seeds, and oily fish. These foods provide antioxidants and omega-3 fats that help reduce inflammation and support joint mobility.

Weight and metabolic changes

Limit refined carbohydrates, sugary drinks, and processed snacks. Replace these with high-fibre foods, such as vegetables, legumes, and whole grains, to improve insulin sensitivity, and promote satiety.

Hot flushes and mood swings

Reducing caffeine, avoiding alcohol and spicy foods can ease symptoms. Including soya foods like tofu, edamame, or soya milk (if tolerated) may help balance mild hormonal symptoms in women.

Meagan Atcheson is a clinical dietitian, specialising in oncology nutrition and complex clinical care. She focuses on quality of life, managing treatment-related symptoms, and empowering patients through every phase of cancer care with structured yet gentle nutrition guidance.

Sindi-marie Hall is a registered dietitian with a passion for imparting positive transformations through the realm of nutrition. She is committed to fostering well-being among those grappling with chronic or life-changing conditions, such as cancer, and the elderly.