Obesity may shorten colon cancer survival

(HealthDay)—Colon cancer patients who were obese before their diagnosis may have an increased risk of dying from their cancer and other causes, a new study finds.

"Our data provide further evidence that maintaining a healthy body weight throughout life is very important," said study author Peter Campbell, director of the tumor repository in the American Cancer Society's epidemiology research program. "They also suggest that prediagnosis BMI may be something that clinicians should consider when managing patient care."

BMI, or body mass index, is a measurement of body fat based on height and weight. A BMI of 30 or more is considered obese.

The study included more than 6,700 colon cancer patients whose BMI two years before diagnosis was calculated based on self-reports. The patients were followed for an average of just over five years.

A higher BMI before diagnosis was associated with increased risk of death from colon cancer and all other causes. The association seen in the study does not prove a cause-and-effect relationship.

However, for every 5-point increase in BMI, there was a 7 percent higher risk of death from colon cancer and a 10 percent higher risk of death from all causes, the researchers said.

An increased risk of death among obese patients was seen even in those whose tumors carried an indicator that is typically associated with better results. This indicator is called "microsatellite instability," or MSI. Every 5-point increase in BMI boosted the risk of all-cause death by 19 percent in patients with MSI-high tumors and by 8 percent in those with MSI-stable/MSI-low tumors, the study found.

The study was scheduled for presentation Wednesday at the annual meeting of the American Association for Cancer Research in San Diego.

"Now that we have seen that obesity attenuates the survival advantage observed for patients with MSI-high tumors, we are looking at how it affects other tumor markers that have relevance for colorectal cancer survival," Campbell said in an association news release.

Data and conclusions presented at meetings are typically considered preliminary until published in a peer-reviewed medical journal.

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