Cancer treatment side effect: Involuntary weight loss

Whether it’s due to pain from a growing tumor, swallowing difficulties caused by radiation therapy, or the nausea, loss of appetite or mouth sores that are sometimes caused by chemotherapy, involuntary weight loss is a serious side effect of cancer and its treatment for many patients.

But there are other reasons why cancer patients could be losing weight without trying.

We spoke with internal medicine and palliative care specialist Rony Dev, D.O., to learn more about involuntary weight loss and what patients can do to counteract this common side effect. Here’s what he had to say.

What are the most common causes of involuntary weight loss in cancer patients?

The simplest answer is “decreased caloric intake.” They just aren’t eating as much. And when you don’t take in enough calories for your body to maintain itself, weight loss is the result. There are quite a few things that contribute to weight loss in addition to the underlying cancer.

For one thing, the body secretes inflammatory proteins, including “tumor necrosis factor” (TNF), which make people feel bad and typically experience a significant decrease in their appetite.

Trying to control cancer requires a lot of energy, too, and cancer patients’ metabolism is often elevated to accommodate for the increased inflammatory response. That combination alone is enough to cause weight loss, but when you combine it with the appetite-suppressing qualities of pain, changes in the taste of food (often described as being metallic) due to chemotherapy, and the discomfort caused by constipation and reflux issues, the issue of weight loss is often compounded.

Mood disorders, depression and anxiety can also contribute to weight loss. In addition, there are endocrine factors, such as low testosterone, that can cause changes in body composition and a decrease in weight in male patients with certain cancers or on chronic opioid therapy.

What can doctors do to help patients counteract involuntary weight loss?

Fortunately, there are treatments especially for symptoms that can contribute to weight loss. We can use beta-blockers to treat hypermetabolism; antiemetics for combatting nausea; counseling, anxiolytics (drugs used to treat anxiety) and antidepressants for stress and mood disorders; anti-inflammatories to reduce inflammation, and hormonal supplements to replace testosterone in male patients.

What can patients do to manage involuntary weight loss?

Most interventions require a health care provider, so it’s important to communicate with your care team as soon as you notice a problem. They can enlist the help of any specialists you might need, such as a dentist for tooth pain or chewing problems, and a gastroenterologist for help with bowel issues.

Why is it important for cancer patients to get unwanted weight loss under control quickly?

Patients tolerate cancer treatment better and have better responses to it if they can maintain a healthy weight. So, adequate caloric intake is critical to preventing chronic undernourishment.

Unwanted weight loss can also lead to fatigue, which means patients aren’t able to do all of the things they want to do. That causes a lot of distress — not only in patients, but also in their caregivers.

That’s why it’s so important to catch this problem early. If someone loses 5% or more of their total body weight without trying, that’s a big red flag. And we need to start addressing some of those underlying factors right away, before it snowballs.

Is involuntary weight loss more common in patients with certain types of cancers?

Yes. More than 80% of patients with pancreatic cancer will experience unwanted weight loss. It’s fairly common in other gastrointestinal cancers, too. And we’re also more likely to see it in advanced cancers, regardless of the type.

Are there any clinical trials underway related to involuntary weight loss?

Yes. One clinical trial is assessing psychological factors associated with weight loss. It deals with the frequency of cancer-induced anorexia (loss of appetite) and cachexia (wasting disease) in patients with anxiety and depression, and assesses body composition and takes other mitigating factors into account.

A second clinical trial is studying whether a drug called anamorelin can spur weight gain by manipulating the appetite hormone, ghrelin.

What’s the one thing you want cancer patients to know about involuntary weight loss?

Once dramatic weight loss has occurred, it’s very hard to change course. So, seek help as soon as you notice it happening.

Request an appointment at MD Anderson online or by calling 1-877-632-6789.