Obese patients are more likely to have a recurrence of colon cancer than their normal-weight counterparts and face an increased risk of dying from the disease, while it’s not clear that losing weight would improve their prognosis.
Dr. James J. Dignam of the University of Chicago and colleagues note, healthy lifestyle changes would probably have other beneficial effects for obese colon cancer patients.
There is strong evidence that being obese, defined as having a body mass index (BMI) of 30 or greater, both increases the likelihood of developing colon cancer and worsens prognosis for individuals diagnosed with the disease, Dignam and his team report in the Journal of the National Cancer Institute.
To better understand the relationship between a patient’s BMI and the outcome of chemotherapy for colon cancer, Dignam and his team looked at 4,288 colon cancer patients participating in two large nationwide clinical trials.
The patients underwent surgery following a diagnosis of Dukes B or C colon cancer and all of the patients were randomly assigned to a chemotherapy regimen.
Subjects with a BMI of 35 or greater (defined as very obese) had a 38-percent risk of a tumor recurrence, compared with normal weight individuals (those with a BMI of 18.5 to 24.9), the researchers found.
The very obese were also 28 per cent more likely to die during the 11.2-year follow-up period.
Underweight patients also had an elevated risk of death compared with those of normal weight, but most of their 49 per cent increased death risk was due to causes unrelated to colon cancer.
The increased risk among the very obese could be related to the interplay between insulin, insulin-like growth factors and proteins that bind to these growth factors, Dignam and his colleagues suggest.
While more research is needed to determine if obese colon cancer patients will do better if they lose weight, they add, ”physicians might use the frequent encounters they have with these patients to counsel them regarding the possibility of modifying this risk with lifestyle changes.”
In any case, the researchers note, helping obese colon cancer patients eat better and become more active will likely have other benefits.