'Western' Diet Tied to Colon Cancer

Higher Death Risk and Recurrence Link Must Be Confirmed, Researchers Say

By Salynn Boyles
WebMD Health News

Reviewed By Louise Chang, MD

Aug. 14, 2007 -- The typical Western diet may be more than just hazardous to the health of patients treated for colon cancer. New research suggests it may be deadly.

Former patients in the study who ate the most red and processed meats, refined grains, fats, and sugars were about three times as likely to die or have their cancers recur as patients who ate these foods the least.

While there is no shortage of evidence linking the so-called Western diet to an increased risk for developing colon cancer, the study is among the first to examine the impact of such a diet on survival among patients treated for the disease.

The findings must be confirmed, but Dana-Farber Cancer Center oncologist Jeffrey Meyerhardt, MD, a researcher on the team, says they cannot be ignored by colon cancer patients or their physicians.

The study appears in the Aug. 15 issue of the Journal of the American Medical Association.

"Doctors who treat colon cancer patients need to have the conversation about diet," he tells WebMD. "From my own experience I know that patients ask about this a lot. They want to know what they should be eating and whether they should be exercising. But it is hard to give recommendations without firm data."

Diet and Death From Colon Cancer

The study included 1,009 patients treated with both surgery and chemotherapy for colon cancer that had spread to the lymph nodes but not to distant sites, such as the liver or lungs (stage III disease), between April of 1999 and May of 2001.

Patients were asked to fill out standardized questionnaires designed to identify their food preferences and dietary intake during and six months after undergoing chemotherapy.

Based on these findings, Meyerhardt and colleagues identified two major dietary patterns: the "Western" diet, characterized by high intakes of red and processed meats, sweets, refined grains, and desserts, and a diet defined by the researchers as "prudent," which was high in fruits, vegetables, poultry, and fish.

Patients were followed for roughly five years, during which time 324 experienced recurrences of their colon cancer and 223 deaths occurred among these relapsed patients. Just 28 deaths were recorded among patients with no evidence of cancer recurrence.

Colon cancer recurrences or death were nearly 3.5 times more common among patients who most closely followed a Western diet than among patients who followed it the least.

When they looked at the prudent dietary pattern, no relationship was found between the prudent diet and colon cancer recurrence or death.

"Because this was an observational study, causality cannot and should not be drawn from these data," Meyerhardt and colleagues wrote. "Nonetheless, [they] suggest that a diet characterized by higher intakes of red and processed meats, sweets, and desserts, french fries, and refined grains increases the risk of cancer recurrence and decreases survival."

More Study Needed

In addition to confirming the findings, further research is needed to understand exactly what components of the two diets are harmful and beneficial to colon cancer patients and former patients, Meyerhardt says.

In an interview with WebMD, American Cancer Society spokesman Michael Thun, MD, called the study provocative. But he agreed that they must be confirmed.

"We test many, many different drug combinations to treat cancer, but researchers are only now beginning to concentrate on diet and other lifestyle changes that can potentially affect the prognosis and survival of cancer patients," he says.

Thun points out there are many good reasons for eating a diet rich in fruits vegetables and whole grains and limiting red and processed meats, refined grains, fats, and sugars.

"We can't say with certainty that improving [colon cancer] survival is one of them, but it is worth finding out," he says.

SOURCES: Meyerhardt, J.A. Journal of the American Medical Association, Aug. 15, 2007; vol 298: pp 754-764. Jeffrey A. Meyerhardt, MD, MPH, gastrointestinal oncologist, Dana-Farber Cancer Institute, Boston. Michael Thun, MD, vice president for epidemiology and surveillance, American Cancer Society, Atlanta.

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