Catherine, Princess of Wales, is undergoing treatment for cancer. In a video thanking followers for their messages of support after her major abdominal surgery, the Princess of Wales explained, “tests after the operation found cancer had been present.”

“My medical team therefore advised that I should undergo a course of preventative chemotherapy and I am now in the early stages of that treatment,” she said in the two-minute video.

No further details have been released about the Princess of Wales’ treatment.

But many have been asking what preventive chemotherapy is and how effective it can be. Here’s what we know about this type of treatment.

It’s not the same as preventing cancer

To prevent cancer developing, lifestyle changes such as diet, exercise and sun protection are recommended.

Tamoxifen, a hormone therapy drug can be used to reduce the risk of cancer for some patients at high risk of breast cancer.

Aspirin can also be used for those at high risk of bowel and other cancers.

How can chemotherapy be used as preventive therapy?

In terms of treating cancer, prevention refers to giving chemotherapy after the cancer has been removed, to prevent the cancer from returning.

If a cancer is localised (limited to a certain part of the body) with no evidence on scans of it spreading to distant sites, local treatments such as surgery or radiotherapy can remove all of the cancer.

If, however, cancer is first detected after it has spread to distant parts of the body at diagnosis, clinicians use treatments such as chemotherapy (anti-cancer drugs), hormones or immunotherapy, which circulate around the body .

The other use for chemotherapy is to add it before or after surgery or radiotherapy, to prevent the primary cancer coming back. The surgery may have cured the cancer. However, in some cases, undetectable microscopic cells may have spread into the bloodstream to distant sites. This will result in the cancer returning, months or years later.

With some cancers, treatment with chemotherapy, given before or after the local surgery or radiotherapy, can kill those cells and prevent the cancer coming back.

If we can’t see these cells, how do we know that giving additional chemotherapy to prevent recurrence is effective? We’ve learnt this from clinical trials. Researchers have compared patients who had surgery only with those whose surgery was followed by additional (or often called adjuvant) chemotherapy. The additional therapy resulted in patients not relapsing and surviving longer.

How effective is preventive therapy?

The effectiveness of preventive therapy depends on the type of cancer and the type of chemotherapy.

Let’s consider the common example of bowel cancer, which is at high risk of returning after surgery because of its size or spread to local lymph glands. The first chemotherapy tested improved survival by 15%. With more intense chemotherapy, the chance of surviving six years is approaching 80%.

Preventive chemotherapy is usually given for three to six months.

How does chemotherapy work?

Many of the chemotherapy drugs stop cancer cells dividing by disrupting the DNA (genetic material) in the centre of the cells. To improve efficacy, drugs which work at different sites in the cell are given in combinations.

Chemotherapy is not selective for cancer cells. It kills any dividing cells.

But cancers consist of a higher proportion of dividing cells than the normal body cells. A greater proportion of the cancer is killed with each course of chemotherapy.

Normal cells can recover between courses, which are usually given three to four weeks apart.

What are the side effects?

The side effects of chemotherapy are usually reversible and are seen in parts of the body where there is normally a high turnover of cells.

The production of blood cells, for example, is temporarily disrupted. When your white blood cell count is low, there is an increased risk of infection.

Cell death in the lining of the gut leads to mouth ulcers, nausea and vomiting and bowel disturbance.

Certain drugs sometimes given during chemotherapy can attack other organs, such as causing numbness in the hands and feet.

There are also generalised symptoms such as fatigue.

Given that preventive chemotherapy given after surgery starts when there is no evidence of any cancer remaining after local surgery, patients can usually resume normal activities within weeks of completing the courses of chemotherapy.

Ian Olver, Adjunct Professsor, School of Psychology, Faculty of Health and Medical Sciences, University of Adelaide

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Former tennis star Monica Seles recently revealed she is living with the rare disease myasthenia gravis, which affects 12 in 100,000 people globally.

Seles explained her first symptoms appeared suddenly around three years ago. She began experiencing double vision and weakness in her arms and legs. This made everyday activities, such as drying her hair, a challenge.

So what is this condition?

Myasthenia gravis is a chronic autoimmune disorder, where your own immune system disrupts the communication between nerves and skeletal muscle.

In healthy people, nerve cells send a chemical messenger called acetylcholine. This tells muscles to contract by binding to its receptor.

In myasthenia gravis, antibodies block or destroy these receptors, so the signal is weakened or lost.

The result is muscle weakness that worsens with activity and improves with rest. This is called “fatigueability”.

What are the symptoms?

Muscle weakness can affect everyday functions such as walking, speaking, breathing and swallowing.

Symptoms, which can appear suddenly, may also affect the eyes, causing drooping eyelids and double vision.

In some cases, weakness of the muscles makes it difficult to breathe or can result in choking on food or water. This is called a “myasthenic crisis” and requires hospitalisation and sometimes life support.

In our research interviews, a young woman in her 30s living with myasthenia gravis described what it feels like to experience a crisis:

My speech slows, and I sound like I’m drunk, even though I’m fighting to breathe. Sometimes I can’t talk at all. Having my mum there to advocate for me has been life-saving, because I can’t explain what’s happening. Staying calm helps me cope.

Another man in his 70s explained just how suddenly the disease can appear:

It came on at my 70th birthday party. I developed ocular MG [a form of myasthenia gravis affecting the eyes] in the middle of my speech, and my grown children thought I was having a stroke. They rushed me to hospital – and that’s how it all began.

What causes it and who does it affect?

It’s unclear what causes the disease but it’s not thought to be hereditary.

There is some evidence it is more likely to occur with other autoimmune conditions such as autoimmune thyroid disease, lupus and rheumatoid arthritis but the evidence remains incomplete.

Myasthenia gravis can appear at any age. Early onset is more common in women (often before 40), while men are more likely to develop myasthenia gravis later in life.

How is it diagnosed?

Despite its serious impact, myasthenia gravis remains under-recognised and is difficult to diagnose. The diagnosis is “clinical”, which requires a doctor with experience in myasthenia gravis to make a judgement, based on the information available.

A handful of tests are available to support the diagnosis: blood tests for antibodies, nerve conduction studies and needle electromyography, which record the electrical activity of nerves and muscles. But these are far from perfect in establishing the diagnosis.

How is it treated?

There is currently no cure for myasthenia gravis, but a range of treatments can help manage symptoms. These include:

• oral medicines called anticholinesterase inhibitors, which temporarily improve communication between nerves and muscles
• immunosuppressant medications, which are generally taken by mouth. These dampen the immune system and reduce its attack
• plasma exchange and intravenous immunoglobulin (IVIg), which is a blood product. These are resource-intensive therapies that remove or block the harmful antibodies. These treatments require hospital admission for at least half a day to administer via an intravenous drip
• in some patients, surgery is performed to remove the thymus gland, which is located in the chest between the lungs. This plays a key role in the abnormal immune response in people with myasthenia gravis.

While most treatments are subsidised through the health system, access remains a challenge for some people. Plasma exchange and IVIg are not available in all hospitals, for example, meaning patients in regional areas may face long travel distances or delays in receiving urgent care.

What is the long-term outlook?

While myasthenic crises are life-threatening, the evidence so far suggests the disease won’t have a significant impact on life expectancy for most people. Treatments aim to reduce disease activity rather than offering a complete cure.

People with myasthenia gravis can have very different journeys with their disease. Some may need frequent hospital admissions, and around 10% have a form of disease which is difficult to treat.

Others may experience minimal symptoms requiring little to no treatment.

Many find their symptoms are unpredictable. As a woman in her 60s, who has had myasthenia gravis for ten years, told us:

I think you just get used to managing – to finding your own rhythm in all the uncertainty.

Gozde Aydin, Research Fellow, Centre for Health Economics, Monash University and Yong Lin Wang, Neurologist and Phd Candidate, Monash University

This article is republished from The Conversation under a Creative Commons license. Read the original article.