Aug 28 Among women who have been treated for
breast cancer, heavier women are more likely to have their
disease come back and more likely to die of cancer, according to
a U.S. study.
Previous studies have tied obesity to a higher chance of
getting breast cancer and a worse outcome in women who have
already been diagnosed.
But the current study - which appeared in the journal Cancer
- makes the post-diagnosis picture clearer, said lead researcher
Joseph Sparano, associate chairman of medical oncology at the
Montefiore Einstein Center for Cancer Care in the Bronx, New
"Obesity seemed to carry a higher risk of breast cancer
recurrence and death, even in women who were healthy at the time
that they were diagnosed, and despite the fact that they
received the best available chemotherapy and hormone therapy,"
The relationship with weight may be because certain hormones
that are linked to body weight may also fuel tumor growth in the
most common form of the disease, known as estrogen
Data for the study came from trials sponsored by the U.S.
National Cancer Institute of women with stage I, II and III
breast cancer who were given standardized treatment, with drug
doses adjusted based on weight.
Out of close to 5,000 women treated for cancer, about
one-third were obese and another one-third were overweight.
Over the next eight years, one in four women had their
cancer come back and 891 died - including 695 from breast
Sparano and his colleagues found that compared to women of
normal weight, obese women were 40 percent more likely to have a
breast cancer recurrence over the study period and 69 percent
more likely to die from breast cancer or any other cause.
Even among overweight but not obese women, there was also a
general trend toward a higher risk of recurrence and death with
The link was especially strong for women with estrogen
receptor-positive cancer, which accounts for two-thirds of
Although the new study can't prove that extra weight and fat
have a direct impact on certain breast cancers, Sparano said it
was "biologically plausible."
Women carrying extra fat have been shown to make more
estrogen, meaning that this may fuel the growth of the estrogen
receptor-positive tumors, he said.
"Insulin levels are known to be higher in patients who are
obese because they develop insulin resistance... (and) insulin
can stimulate the growth of breast cancer cells," he added.
Whether women with the disease can improve their long-term
outlook by losing weight hasn't been proven, researchers said.
"The highest priority is just getting through the
chemotherapy if chemotherapy is necessary and taking their
endocrine therapies," Sparano said.
"But for those who are obese or overweight, there may be
additional benefits that one can achieve through diet and
through weight reduction that may produce a reduction in the
risk of recurrence that's just as significant as the reduction
that they get from the standard therapies," he added.
(Reporting from New York by Genevra Pittman at Reuters Health;
editing by Elaine Lies and Bob Tourtellotte)