Having More Muscle Mass May Mean Milder Chemotherapy Side Effects

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Chemotherapy destroys cancer cells because the medicines target cells that are rapidly dividing. But healthy cells in your blood, mouth, intestinal tract, nose, nails, vagina, and hair also divide rapidly. So chemotherapy affects them, too.

Some of the most common chemotherapy side effects are:

  • hair loss
  • diarrhea
  • fatigue
  • anemia/low red blood cell counts
  • low white blood cell counts
  • infection
  • memory loss
  • mouth and throat sores
  • neuropathy (tingling/pain in the hands and feet)
  • vaginal dryness
  • taste and smell changes
  • vomiting

The side effects you have from chemotherapy will depend on the regimen you’re on, the amount of medicine you’re getting, the length of treatment, and your general health. The side effects you have may be different from someone else who’s on the same chemotherapy regimen.

Two small, companion studies suggest that women with more muscle mass were likely to have milder chemotherapy side effects than women with less muscle mass.

The studies were published online on Jan. 31, 2017 and in the Feb. 1, 2017 issue of the journal Clinical Cancer Research. Read the abstracts of:

Metastatic breast cancer is breast cancer that has spread to a part of the body away from the breast, such as the bones or liver.

Taxane chemotherapy medicines are:

  • Taxol (chemical name: paclitaxel)
  • Taxotere (chemical name: docetaxel)
  • Abraxane (chemical name: albumin-bound or nab-paclitaxel)

Taxanes work by interfering with the ability of cancer cells to divide.

Anthracycline chemotherapy medicines are:

  • Adriamycin (chemical name: doxorubicin)
  • Ellence (chemical name: epirubicin)
  • Doxil (chemical name: doxorubicin)
  • daunorubicin (brand names: Cerubidine, DaunoXome)
  • mitoxantrone (brand name: Novantrone)

Anthracyclines work by damaging cancer cells’ genes and interfering with their reproduction.

In the first study, the researchers used CT (computerized tomography) scans to measure the muscle mass of 151 women diagnosed with early-stage breast cancer. The women ranged in age from 23 to 75. All the women were being treated with a chemotherapy regimen that included an anthracycline and a taxane.

Overall, 50 women (33%) developed severe or very severe side effects from chemotherapy. The researchers found that women with the lowest amount of muscle mass were much more likely to have severe or very severe side effects from chemotherapy, especially low red and white blood cell counts and stomach/intestinal problems.

In the second study, the researchers again used CT scans to measure the muscle mass of 40 women diagnosed with metastatic breast cancer. The women ranged in age from 34 to 80. All the women were being treated with a chemotherapy regimen that included a taxane.

About 58% of the women were classified as “sarcopenic,” which means they had lost muscle mass and function and also had lower muscle tissue quality.

The researchers found:

  • 57% of the sarcopenic women had severe or very severe side effects from chemotherapy
  • 18% of the non-sarcopenic women had severe or very severe side effects from chemotherapy
  • 39% of the sarcopenic women had to be hospitalized because of chemotherapy side effects
  • 0% of the non-sarcopenic women had to be hospitalized because of chemotherapy side effects

These differences were statistically significant, which means that they were likely due to the difference in muscle mass and not just because of chance.

"More and more studies are showing that muscle mass, especially loss of muscle and function, or so-called sarcopenia, is associated with poor outcomes, poor survival, and more toxicity with cancer treatment," said Hyman B. Muss, M.D., Mary Jones Hudson Distinguished Professor and director of the University of North Caroline Lineberger Geriatric Oncology Program and a coauthor of both studies. "It may be that muscle mass is related to the metabolism of chemotherapy in your body, as well as your general fitness. So people with a low muscle mass may simply be less fit, and their bodies don't tolerate chemotherapy treatments as well. These patients may be especially vulnerable to treatment effects."

This study reinforces the results of earlier research and adds more evidence to the idea that exercise, maintaining a healthy weight, and making healthy lifestyle choices can help make breast cancer treatment side effects less severe.

Besides fewer and less severe side effects from treatment and helping you have more muscle mass and strength, there are many other benefits to regular exercise if you’ve been diagnosed with breast cancer:

  • a lower risk of breast cancer coming back (recurrence)
  • easier to maintain a healthy weight
  • more energy
  • better mobility
  • healthy bones
  • better self-esteem and less stress
  • better sleep

“These studies highlight the benefits of keeping yourself healthy before, during, and after breast cancer treatment,” said Brian Wojciechowski, M.D., a medical oncologist and Breastcancer.org’s medical adviser.

If you’re busy with work, household chores, and family matters, finding time to exercise almost every day can be hard. Exercising also can be extremely difficult if you’re recovering from breast cancer treatment or having painful side effects. Still, it’s worth your while to make time to move.

It can help to break up your exercise into 20- or 30-minute sessions that add up to about 5 or more hours per week. Walking is a great way to start. Maybe you walk 30 minutes before going to work and 30 minutes on your lunch break. You can add a few more minutes by parking farther away from your building or taking mass transit. Or you can make plans to walk with a friend after work -- you’re more likely to stick with exercise if someone else is counting on you. Plus, you can socialize at the same time.

Visit the Breastcancer.org Exercise section for tips on exercising safely and how to stick to an exercise routine.



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