Obese Breast Cancer Patients May Be Undertreated

Adjusting drug dose for weight may leave them more vulnerable

TUESDAY, June 14, 2005 (HealthDay News) -- A woman's weight may influence the dosage of chemotherapy drugs she receives, according to a new study.

Researchers found that obese or overweight patients are much more likely to get a reduced dose of the potentially lifesaving drugs as other as slimmer patients.

Researchers analyzed data from 901 practices on nearly 9,700 early-stage breast cancer patients treated with adjuvant chemotherapy between 1990 and 2001.

Adjuvant chemotherapy is given to breast cancer patients with no measurable spread of cancer beyond the primary tumor. This treatment is meant to improve the chances of disease-free and overall survival in these patients. In some cases, doctors decide to reduce doses of adjuvant chemotherapy, which are calculated based on body weight, given to heavier women because the doctors are concerned about possible toxic effects from the treatment.

Of the women in the study, 62 percent were above a healthy weight, 31 percent were overweight, 17 percent were obese and 14 percent were severely obese.

Among the severely obese patients, 37 percent had a first-cycle chemotherapy dose reduction of at least 10 percent, compared with 20 percent of obese patients, 11 percent of overweight women and 9 percent of women with a healthy weight.

There was wide variation in the practices' use of first-cycle chemotherapy dose reductions in their overweight and obese breast cancer patients. About 60 percent of the practices reduced the doses in more than 10 percent of their overweight and obese patients, while 33 percent did not reduce doses for any of their overweight and obese patients.

"However, given the evidence that maintaining dose intensity improves the likelihood of overall and disease-free survival and the lack of data supporting dose reductions in overweight and obese women, it is likely that the practice variations we have observed represent 'unwarranted variation' in the adjuvant treatment of patients with breast cancer," the study authors wrote.

The findings are published in the June 13 issue of the Archives of Internal Medicine.

More information

The UpToDate educational program has more about adjuvant therapy.

SOURCE: American Medical Association, news release, June 13, 2005
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