Cancer Cachexia & Muscle Wasting Prevention

Some people during cancer treatment lose weight because they are eating less. Others lose muscle while still eating reasonably well — the stairs get harder, a full grocery bag feels heavy, standing up from a low chair takes a push off the armrest. The second pattern is not simply the first one with more effort required, and understanding the difference changes what you should expect from the advice you are given.

The National Cancer Institute describes cancer cachexia in its patient materials as a wasting syndrome that can cause weakness, weight loss, and fat and muscle loss. The detail that surprises most people is in the next line: it can occur even when you are eating well.

NCI's clinical version is more precise. It defines cachexia as a multifactorial syndrome defined by an ongoing loss of skeletal muscle mass that cannot be fully reversed by conventional nutrition support and leads to progressive functional impairment. Every part of that sentence is doing work. It is multifactorial, so there is no single cause to correct. Conventional nutrition support does not fully reverse it. And the endpoint measured is function — what you can do — not a number on a scale.

NCI describes three stages: precachexia, where early metabolic signs appear before substantial weight loss; cachexia, with significant weight loss or sarcopenia that is not simple starvation; and refractory cachexia, which is clinically resistant and typically seen in advanced-stage cancer.

A related term you may hear is sarcopenia, which NCI defines as the condition of severe muscle depletion. It is reported to occur in 50% of patients with advanced cancer, and a meta-analysis cited by NCI found that low skeletal muscle index at cancer diagnosis was associated with worse survival in patients with solid tumors.

This is the part worth saying plainly, because well-meaning family members often push food harder as weight falls. NCI states that increased caloric intake, whether by the oral route or by supplementation with total parenteral nutrition, has failed to counteract the wasting process. It also notes that although anorexia may also be present, the energy deficit alone does not explain the pathogenesis of cachexia.

The reason is that inflammatory signalling is driving the muscle loss. NCI identifies products of host tissues — tumor necrosis factor-alpha, interleukin-1, interleukin-6, interferon-gamma, and leukemia inhibitor factor — as mediators of this complex syndrome.

There is no treatment in the NCI material reviewed here that reliably reverses established cachexia. NCI's patient page mentions that you may also take medicines that increase appetite, but appetite medicines target intake, not the muscle loss itself, and NCI does not present them as a cure for the syndrome. If someone offers you a supplement or protocol that promises to rebuild lost muscle during active cancer, treat that promise with suspicion.

What that does not mean is that nothing is worth doing. Poor intake makes everything worse, and it is fixable. NCI states that the goal of nutrition screening is to rapidly identify patients who are at risk of developing malnutrition and refer them to a health care professional, ideally a registered dietitian — and notes research finding the median time from cancer diagnosis to dietitian referral was 61 days. You do not have to wait for that referral to be offered.

NCI's appetite guidance is specific: eat small meals every 2 to 3 hours, about 5 or 6 meals per day; eat within 1 hour of waking up; eat foods high in protein and calories; eat high-protein foods first in your meal when your appetite is strongest; drink milkshakes, smoothies, juices, or soups if you do not feel like eating solid foods; and sip on nutrition supplement drinks between meals, such as Ensure and Boost.

If nausea is the barrier to eating, that is a treatable problem in its own right and is covered on our nausea and appetite loss page. Weakness also has causes other than muscle loss — NCI lists weak or achy muscles and muscle wasting among the effects of motor nerve damage from treatment, which is a different problem with different management.

• Weight loss. NCI says to speak with them right away if you start to lose weight, and to report weight loss of more than 3 to 5 pounds in one week to your doctor.
• The American Cancer Society suggests paying attention if you lose more than 5% of your body weight in a year without trying, and contacting your team about rapid loss of more than 3 pounds in a week.
• Severe fatigue that leaves you unable to do your usual activities.
• Any symptom that is keeping you from eating — pain, nausea, mouth problems, feeling full quickly.

Ask directly for a referral to a registered dietitian. It is a standard oncology service and does not require a crisis first.

• National Cancer Institute — Nutrition in Cancer Care (PDQ), Health Professional Version: https://www.cancer.gov/about-cancer/treatment/side-effects/appetite-loss/nutrition-hp-pdq
• National Cancer Institute — Nutrition in Cancer Care (PDQ), Patient Version: https://www.cancer.gov/about-cancer/treatment/side-effects/appetite-loss/nutrition-pdq
• National Cancer Institute — Appetite Loss and Cancer Treatment: https://www.cancer.gov/about-cancer/treatment/side-effects/appetite-loss
• National Cancer Institute — Nerve Problems (Peripheral Neuropathy) and Cancer Treatment: https://www.cancer.gov/about-cancer/treatment/side-effects/nerve-problems
• American Cancer Society — Weight Changes: https://www.cancer.org/cancer/side-effects/eating-problems/weight-changes.html