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 York.
"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," he said.
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 receptor-positive cancer.
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 cancer.
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 increasing weight.
The link was especially strong for women with estrogen receptor-positive cancer, which accounts for two-thirds of breast cancers.
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. SOURCE: http://git.ly/qzl-lzeL
In the far-reaching health scandal, breast implants were later found to contain substandard, industrial-grade silicone gel that was seven times cheaper than medical-grade silicone.
Device eliminates risk of deadly blood clots; need for blood thinners
A new initiative will help transform readiness of countries against virus breakouts like those seen in Guinea, Liberia and Sierra Leone
Protest in Nairobi sees hundreds take to streets to back doctors' pay demands
The Arctic Council's recently released Arctic Resilience Report has shown how the Arctic is to specific abrupt environmental changes resulting from climate change and human activity: essentially, "tipping points".
Irrawaddy dolphins can be found in rivers, lakes and seas across southern Asia, from the northwest Bay of Bengal, in India, to the south of Indonesia but are now being killed by rogue gangs
Singaporean Seah Chiang Nee, a former newspaper editor, died aged 76 in a local hospital on Saturday, his wife Patricia Wong said. He was hospitalised in July.
Renault reacted with a statement saying that its cars "are not equipped with cheating software affecting anti-pollution systems."
Worldwide tobacco use causes loss of $1 trillion and six million lives annually, says World Health Organization
China now owns five of the six largest solar module manufacturing firms in the world, according to the report.
Some 7.7 million new cases of dementia are reported every year, with Alzheimer's disease being the most common cause and contributing to 60–70% of cases.
Funding is critical to support the humanitarian needs of the poorest country in the Americas, said Mourad Wahba, the deputy special representative for the UN's stabilization mission in Haiti.
Conservationists estimate that more than 20,000 elephants were killed for their ivory last year, with similar tolls in previous years. The WWF campaign group says 415,000 of the animals remain.
Spanish police enforce severe restrictions on traffic in the capital as health fears grow over air pollution
The outbreak erupted in December last year in the slums of the capital Luanda, spreading to 16 of Angola's 18 provinces and into neighbouring Democratic Republic of Congo.
Number of births expected to continue falling as population ages, number of women in their 20s and 30s declines.