Immunotherapy has transformed melanoma treatment, helping many patients achieve long-term control of their disease. While these treatments can be highly effective, they can also cause side effects when the immune system becomes overactive and begins to affect healthy organs. Some of the most important side effects involve the endocrine system, which produces hormones that regulate essential functions throughout the body.
In a recent webinar hosted by Melanoma Patients Australia (MPA) and Melanoma Institute Australia (MIA), melanoma specialists explored how immunotherapy can affect hormone-producing glands, how these side effects are managed, and what patients need to know to stay safe.
Immunotherapy works by releasing the “brakes” on the immune system, enabling it to recognise and attack cancer cells more effectively. Unlike chemotherapy, which directly targets cancer cells, immunotherapy stimulates the body’s own immune defences.
However, in some cases the activated immune system can mistakenly attack healthy tissues. These are known as immune-related adverse events, or immune-related side effects.
Because the immune system is active throughout the body, these side effects can affect many organs. The endocrine organs are among the most commonly affected.
The four endocrine organs most commonly impacted by immunotherapy are:
Unlike many other immunotherapy side effects, endocrine side effects are often permanent. The good news is that they are usually very manageable with appropriate hormone replacement therapy and ongoing monitoring.
Changes in thyroid function affect approximately 10-20% of patients receiving immunotherapy.
The thyroid often becomes inflamed initially, causing an overactive thyroid (hyperthyroidism). Over time, the gland may stop working properly, leading to an underactive thyroid (hypothyroidism).
Symptoms of an Overactive Thyroid
Symptoms of an Underactive Thyroid
If hypothyroidism develops, it is typically treated with a daily thyroid hormone replacement tablet known as levothyroxine.
Pituitary and Adrenal Gland Side Effects
The pituitary gland, often called the body’s “master gland”, helps regulate many hormones, including cortisol, the body’s natural stress hormone.
Inflammation of the pituitary gland (hypophysitis) occurs in around 1-10% of patients receiving immunotherapy. Adrenal gland inflammation is less common but can also occur.
When these glands are affected, cortisol levels can fall dangerously low.
Common Symptoms Include:
These symptoms can be vague and easily mistaken for other conditions. Patients are encouraged to report any new or worsening symptoms early, particularly during the first months of treatment.
Why Cortisol Matters
Cortisol is essential for life. If levels become critically low, patients can experience an adrenal crisis, which requires urgent medical attention.
Patients diagnosed with adrenal insufficiency are typically prescribed cortisol replacement medication, such as hydrocortisone or prednisone, and receive education about “sick day management”, including when to increase their medication during illness and when emergency treatment may be required.
Many patients also carry a medical alert bracelet and an emergency steroid injection.
Diabetes Caused by Immunotherapy
Although rare, immunotherapy can sometimes damage the insulin-producing cells in the pancreas, resulting in immune-related Type 1 diabetes.
This affects approximately 1% of patients and most commonly occurs after the first few treatment cycles.
Symptoms of High Blood Sugar Include:
Routine blood tests often identify rising glucose levels before significant symptoms develop.
Treatment involves insulin replacement and education from diabetes specialists to help manage blood sugar levels safely.
Your treatment team closely monitors for endocrine side effects through:
Blood tests commonly include:
Most endocrine side effects occur within the first few months of treatment, making early monitoring especially important.
Melanoma nurses and specialist oncology nurses play a critical role in helping patients recognise side effects early.
Nurses can:
Early reporting of symptoms can make a significant difference in diagnosis, treatment and outcomes.
Melanoma patient Carmel Finnegan shared her experience of developing endocrine side effects during immunotherapy treatment.
After treatment began, Carmel experienced persistent headaches, extreme fatigue, light sensitivity and severe sugar cravings. It took time to identify that low cortisol levels were contributing to her symptoms.
Today, with hormone replacement therapy, specialist support and education, Carmel manages her condition successfully.
Reflecting on her experience, she emphasised the importance of self-advocacy, seeking support, understanding sick day management and connecting with others who have shared experiences.
While endocrine side effects of immunotherapy are often lifelong, they are highly treatable and should not discourage patients from seeking or continuing potentially life-saving treatment.
If you are receiving immunotherapy:
Most importantly, remember that you are not alone. Your healthcare team, melanoma nurse, endocrinologist and support organisations are there to help you navigate treatment and manage any side effects that arise.
For support and information, contact Melanoma Patients Australia or speak with your treating healthcare team.
Whether you’re newly diagnosed, undergoing treatment, recovering from surgery, managing side effects, or adjusting to life after treatment, support is available.Â
Melanoma Nurses work alongside healthcare teams to ensure patients receive not only expert clinical care but also the emotional, practical, and informational support needed to navigate the challenges of melanoma.Â
If you or a person you care for has been affected by melanoma, consider speaking with your healthcare team about available nursing support or contacting Melanoma Patients Australia to learn more about its free specialist Telehealth Nurse Service.Â
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