Nightly News | August 27, 2012
>>> as we've said there's a story in the news tonight about breast cancer , a new study that shows definitively weight is an important risk factor in determining if a woman will suffer a recurrence, and as many doctors have insisted, losing weight after diagnosis can lead to better outcomes all around. our report on all of it tonight from our chief medical editor, dr. nancy snyderman .
>> reporter: breast cancer strikes almost 300,000 women a year. while cure rates have improved over the last 20 years, increasingly doctors are focusing on a certain group of women who don't fare as well as others.
>> there's a clear connection between obesity at the time of a breast cancer diagnosis and an increased risk of occurrence of breast cancer .
>> reporter: dr. joseph sparano is an oncologist who specializes in breast cancer at montefior einstein center for cancer care in new york and is a lead researcher of today's study which focuses on the most common type of breast cancer .
>> we've known for a long time obesity is associated with an increased risk of breast cancer but what this study shows is that risk is there even if patients get optimal therapy.
>> reporter: even after ruling out problems like heart disease , diabetes, kidney and liver disease , being clinically obese with a body mass index over 30 is an independent risk factor . the fat causes changes with insulin,est row estrogen and inflammation and serve as fuel for cancer cells . the study looked at almost 7,000 women with stage one to three breast cancer who required chemotherapy as part of their treatment. women who were obese when diagnosed had a 30% higher risk of recurrence and almost a 50% higher risk of death than women of normal weight.
>> reducing weight could have an effect in terms of reducing the risk of recurrence.
>> reporter: experts say even a weight loss as little as six pounds can make a difference. in one study, leading to a 25% reduction in the risk of recurrence, which can be comparable to the treatment with chemotherapy. dr. nancy snyderman , nbc news, new york.