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Many women who've had chemotherapy for breast cancer report gaining weight during the treatment, though the reasons for an expanding waistline are not yet well understood. The phenomenon is not seen in patients who have surgery alone, or surgery followed by radiation.

Should women care? And what can they do safely to re-establish a healthy body weight? This article suggests some answers and surveys women's feelings — through the voices of health experts and breast cancer survivors themselves.

After battling breast cancer, the battle of the bulge may seem unimportant to many women. For others, the extra pounds may be distressing. For good or ill, popular American culture places a premium on being slender. And for a women adjusting to the loss of a breast or other physical changes, weight gain can come as yet another blow to her body image and self-confidence.

An average 5-8 pound weight gain has been documented over a year's time for women undergoing chemotherapy. Some women gain less than the average; some more — climbing as high as 25 pounds over their pre-treatment body weight (Journal of Clinical Oncology. 2001; Vol.19, No. 9:2381-2389).

Beyond any concerns about appearance, we now know that carrying too many extra pounds is a risk for several types of cancer, including breast cancer in women past menopause.

And in a cruel twist of fate, research has found that breast cancer survivors who were overweight or obese were more likely to have their cancer recur than thinner survivors. So pounds packed on inadvertently during chemotherapy could raise a woman's risk for recurrence. (Journal of Clinical Oncology. 2002. Vol. 20, No. 15: 3302-3316)

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Fat cells in the body make small amounts of estrogen. The more fat cells there are, the more estrogen is present. And estrogen nourishes some types of breast cancer. But the relationship between weight and breast cancer is complex. For example, excess fat around the belly seems to increase risk more than the same amount of fat around the hips and thighs.

More important than a woman’s weight is her body mass index (BMI) — the relationship between her height and weight. BMI is one of the most accurate ways to determine when extra pounds translate into health risks. A BMI calculator can help determine whether a woman’s weight is healthy — or whether extra weight might increase her risk for health problems.

"I'm not doing anything different. I eat the same and am still exercising, but I'm still gaining weight!" – Maggie, CSN member

Many factors, not just one, affect a woman’s body weight — diet, medications, exercise, changes in metabolism. Often, taking a closer look uncovers what's contributing to the weight gain.

Diet

“My problem was not content but quantity! The chemotherapy boosted my appetite and I found it all too easy to give in.” — Liza, CSN member

Although nausea is a widely-known side effect of chemotherapy, some women experience intense food cravings at other times.

Patients often reach for sweets or carbohydrate-rich foods, such as pasta, breads, and rice, which can quickly pack on the pounds, especially when the portion size is increased.

Body composition changes

Unlike the typical weight gain, which involves lean and fatty tissue, chemotherapy, induced weight gain involves only fat. In fact, evidence shows there may even be a loss of lean body mass.

Dr. Wendy Demark-Wahnefried, RD, an associate research professor at Duke University Medical Center said, “It’s not necessarily the weight gain, but the change in body composition that is worrisome.” The change in body composition is characteristic of the normal aging process. “If you look at these women in the year after diagnosis, the chemotherapy patient ages 10 years over the course of a year. Although you might think a change in body fat of 2% is not much, indeed it is. The time clock is sped up.”

Menopause

“I found that during chemo I had to eat what I could and that posed some small gain but now post-chemo my metabolism is so slow because of menopause brought on by chemo.” – Karen, CSN member

Another possible culprit is premature menopause, brought on by chemotherapy. Whether it occurs naturally or is chemically induced, the end results are the same. Changes in the lean muscle/body fat balance and a slowing of metabolism (the rate at which the body burns calories in order to sustain life) make gaining weight easier. This doesn’t mean that it’s inevitable a woman will gain weight. However, the activity level and eating habits that kept extra weight off in the past may no longer do so.

Decrease in physical activity

“I just couldn't do anything. The fatigue is something that’s hard for others to comprehend. It would last for days and I was so tired I had to hold on to furniture to walk.” – Christine, CSN Member

A drop in physical activity during treatment seems to be another factor. Studies have shown that women with breast cancer tend to exercise less after diagnosis. This will certainly come as no surprise to women going through the fatigue, nausea, and pain associated with treatment. All of that makes them feel less inclined to exercise. But women often cut back even on light activity like housework. Interestingly, researchers have found that exercise, not rest, helps lessen fatigue.

Tamoxifen

“I know it’s the tamoxifen! I didn’t gain weight until I started taking it.” – Patricia, CSN member

Many women who have taken tamoxifen after initial treatment believe their weight gain is due to the hormone. But while there have been occasional reports of tamoxifen making women pack on extra pounds, but there is not much scientific evidence to support it. American Cancer Society medical editor, Rick Alteri, MD, notes that most large clinical studies have not found a solid link between the two. Though he acknowledges, “It’s hard to get a handle on this issue, since many women may be getting tamoxifen at an age when they may be going through menopause (or are going through menopause early as a result of the chemotherapy), at which time they normally gain some weight.”

But there may be a changing of the guard on the horizon. A recent report indicates that most newly diagnosed women now are being given an aromatase inhibitor (anastrozole, letrozole, and exemestane), instead of tamoxifen. Research has found that women who took an aromatase inhibitor instead of or after tamoxifen had a slightly lower risk of recurrence than women who took tamoxifen alone for 5 years.

Dietary changes

To slim down after chemotherapy, Colleen Doyle, MS, RD, director of nutrition for the Society, advises women to carefully monitor what they eat. "Try to stick to a diet that's high in fruits, vegetables, and whole grains, and low in total fat and saturated fat," she said. This type of diet has been clearly shown to lower the risk of heart disease, and now there's evidence that a low-fat diet may lower the risk of breast cancer recurrence, too.

Women also might try increasing their protein intake. A recent clinical study revealed that a carbohydrate-heavy, lower-protein diet based on the old USDA food pyramid actually reduced the effectiveness of exercise. On the other hand, a University of Indiana study (Journal of Nutrition. 2005, Vol.135: 1903-1910) found that when a protein-rich eating plan was combined with exercise, the two worked together: When participants lost weight, they lost fat, not muscle.

Exercise

Exercise is critical for weight loss, according to Doyle — and it helps people maintain good health overall, boosts physical energy for a higher quality of life, builds a better body-image, and lessens fatigue.

Beyond those well-documented benefits, for women recovering from chemotherapy for breast cancer, evidence of the benefits of exercise continues to mount. One study, conducted at Penn Sate University, found that exercise after chemotherapy for breast cancer may increase the activity of infection-fighting T cells. While this was a small study that will need further confirmation, it is promising.

The good news is that even moderate activity has been shown to improve breast cancer survival. A few hours of walking or other physical activity weekly may help survivors live longer. According to a recent study (Journal of the American Medical Association. 2005; Vol. 293, No. 20:2749-2486), women who exercised 3-5 hours a week at a 2-3 mile-per-hour pace were less likely to die of their breast cancer than those women who exercised less than an hour a week. And it doesn’t matter whether the activity is done all at once or spaced throughout the day. These findings are in step with what the American Cancer Society recommends for cancer survivors.

A woman should, of course, check with her cancer care team before starting an exercise routine, but there's a good chance that she can do some type of physical activity during or after chemotherapy. Be sure to talk with your health care team first about activities that use your arms, like weight lifting.

Breast cancer survivors can develop lymphedema (arm swelling) after surgery to remove lymph nodes or radiation treatment.Debbie Saslow, PhD, director of breast and cervical cancer for the American Cancer Society, warns, “We really don’t know a lot about what brings on lymphedema, so we caution women about lifting weights – especially heavy weights on the upper body.”

Support groups

“About a year after my last treatments, I joined Weight Watchers. Even though the topic was weight, it always covered life's issues and our dealing with them (even met some other breast cancer survivors).” – Patty, CSN member.

Some women find that support groups, like those found at Weight Watchers, help them adopt healthier eating habits, which in turn lead to weight loss. There are also exercise programs designed specifically for cancer patients. A woman’s health care team, local hospital Wellness Center, or theYWCA are good resources for finding a safe, high quality activity program.

Although weight gain after chemotherapy can be a real concern for some survivors, it's probably lower on the priority list than treating and beating breast cancer. And more women are conquering the disease today than ever before. Since 1991, the death rate has fallen 20%, thanks to chemotherapy, other modern treatments, and better early detection.

“I just remember that I’m a survivor, an accomplishment in itself. I just do my best, unless the weight becomes a health issue. As long as I am happy and healthy the world is mine” – Sue, CSN member