When Tracy Smith was diagnosed with breast cancer, her doctors knew they had to provide more than just the standard treatment.
"You hear chemo, and you don't know what's going to happen," Smith said.
Studies show people who are obese are less likely to survive cancer when given chemotherapy. Now, doctors may know one reason why obese cancer patients die at a higher rate than thinner ones.
There is a surprising inequality in the care they receive.
"A substantial proportion of patients receiving chemotherapy who are overweight or obese are under-dosed, under-treated," said Dr. Gary Lyman, an oncologist at Duke University.
Studies suggest as many as 40 percent of obese patients get less than 85 percent of the full chemo dose.
Doctors often measure medication based on ideal, not actual, body weight - or cap the dose fearing heavy patients can't handle it.
"If you dose obese patients based on their actual body weight, they have no more side effects, in some studies, actually, less side effects, than healthy-weight patients," said Lyman.
The research prompted the American Society of Clinical Oncology to adopt guidelines for weight-based chemo dosing for the obese.
However, not all doctors are aware of the changes. Luckily, those at Duke University were aware when treating Smith, an obese breast cancer survivor.
"I'm sure they gave me the right amount for my body weight," Smith said.
She says cancer patients should ask questions if they're concerned.
"There are no stupid questions, especially when it comes to your health," Smith said.
There may no longer be a one-size-fits-all approach to chemo.
The dosing issue applies to all types of cancer treated with chemo, including breast, colon, lung and ovarian. Sixty percent of Americans are overweight and more than one-third of them are obese.