After curative surgery and adjuvant chemotherapy for stage III colon cancer, patients who ate a high-fat diet were more likely to have a recurrence than those who ate a so-called prudent diet, found researchers here.
Those with a higher recurrence risk ate more meat, fat, French fries, refined grains, and desserts. Jeffrey A. Meyerhardt, M.D., M.P.H., of the Dana-Farber Cancer Institute, and colleagues, reported in the Aug. 15 issue of the Journal of the American Medical Association.
By contrast, a "prudent diet," high in fruits, vegetables, poultry, and fish, had no effect on cancer recurrence or death.
The findings came from a prospective observational study of 1,009 patients with stage III disease enrolled in a randomized adjuvant chemotherapy trial from April 1999 through May 2001. The NCI-sponsored Cancer and Leukemia Group B (CALGB) trial compared with weekly fluorouracil and leucovorin with weekly irinotecan, fluorouracil, and leucovorin.
Previous epidemiological studies have indicated that dietary factors are associated with the risk of developing colon cancer, the researchers wrote. "However, the influence of diet and other lifestyle factors on the outcome of patients with established colon cancer is largely unknown," they added.
It is possible, they said, that after resection of stage III colon cancer, increasing intake of the high-fat and processed foods in the Western diet may facilitate a milieu that allows residual microscopic disease to proliferate and spread.
Also, they said, patients rated high for consumption of foods in the Western diet after diagnosis may have had a similar diet before diagnosis and consequently may have had more biologically aggressive tumors. Nonetheless, there was no significant association between dietary pattern and tumor-related characteristics, the researchers said.
Patients filled out a semiquantitative food frequency questionnaire during and six months after adjuvant chemotherapy. Using factor analysis, the researchers identified two major dietary patterns, the fat-heavy Western diet and the prudent diet. Patients were then followed up for cancer recurrence or death.
During a median follow-up of 5.3 years for the overall cohort, 324 patients had a cancer recurrence, 223 died as a result, and 28 died without documented cancer recurrence.
Compared with patients in the lowest quintile of the Western pattern, those in the highest quintile had a more than three-fold higher risk of cancer recurrence or death (adjusted hazard ratio hazard ratio for disease-free survival, 3.25, 95% confidence interval 2.04-5.19; P for trend <0.001).
Patients in the highest quintile were also 2.9 times more likely to have a recurrence than those in the lowest quintile (adjusted HR, 2.85; CI, 1.75-4.63, P for trend <0.001).
Similarly, a significantly higher overall risk of death was observed compared with the lowest quintile (adjusted HR, 2.32; CI, 1.36-3.96, P for trend <0.001).
The reduction in disease-free survival with the Western diet was not significantly modified by sex, age, nodal stage, body mass index, physical activity level, baseline performance status, or treatment group.
No relationship was seen for recurrence-free survival (P for trend =0.84) or overall survival (P for trend =0.54) across various intakes of the prudent dietary pattern.
The adjusted hazard ratio comparing the highest and lowest quintiles of the prudent diet was 1.20 (CI, 0.83 -1.75) for disease-free survival (P for trend 0.78).
Similarly, no relationship was seen for recurrence-free or overall survival across the various intakes for those who ate a prudent diet.
Higher prudent diet scores were found for patients who were physically active, had a lower BMI six months after adjuvant therapy, and were less likely to be smokers.
Higher undesirable Western scores were seen among men, whites, and past or current smokers.
In contrast, other characteristics, particularly tumor types known to predict prognosis, did not vary significantly among the quintiles of either dietary pattern, the researchers reported.
The researchers pointed out that they could not completely exclude the possibility that a higher intake of the Western pattern may have reflected other predictors of poor prognosis.
Nevertheless no significant association between diet and predictors associated with cancer recurrence (extent of invasion into bowel wall, number of positive lymph nodes) was observed.
Because the study was observational, causality cannot and should not be drawn from these data, Dr. Meyerhardt wrote. Nonetheless, the data suggest that eating more red and processed meat, sweets and desserts, French fries, and refined grains increases the risk of recurrence and decreases survival.
"Further analyses are under way to better delineate specific nutrients or food groupings that may have the strongest association," the authors concluded.
Eric Jacobs, Ph.D., a senior epidemiologist at the American Cancer Society, called the study by Dr. Meyerhardt and colleagues well-designed and addressing "an important question that has not been studied so far."
He pointed out that diet and the risk of colon cancer studies have not been consistent, but there has been almost nothing about the risk of recurrence. "The effect of diet on recurrence may be biologically different from the original risk," he noted. "Other studies will have to attempt to duplicate the results and then see where it leads."
As to why the prudent diet showed no benefit beyond not stimulating recurrence is an important question, he added. "Stay tuned," Dr. Jacobs said. "It's a really important question and needs more research."
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The findings came from a prospective observational study of 1,009 patients with stage III disease enrolled in a randomized adjuvant chemotherapy trial from April 1999 through May 2001. The NCI-sponsored Cancer and Leukemia Group B (CALGB) trial compared with weekly fluorouracil and leucovorin with weekly irinotecan, fluorouracil, and leucovorin.
Previous epidemiological studies have indicated that dietary factors are associated with the risk of developing colon cancer, the researchers wrote. "However, the influence of diet and other lifestyle factors on the outcome of patients with established colon cancer is largely unknown," they added.
It is possible, they said, that after resection of stage III colon cancer, increasing intake of the high-fat and processed foods in the Western diet may facilitate a milieu that allows residual microscopic disease to proliferate and spread.
Also, they said, patients rated high for consumption of foods in the Western diet after diagnosis may have had a similar diet before diagnosis and consequently may have had more biologically aggressive tumors. Nonetheless, there was no significant association between dietary pattern and tumor-related characteristics, the researchers said.
Patients filled out a semiquantitative food frequency questionnaire during and six months after adjuvant chemotherapy. Using factor analysis, the researchers identified two major dietary patterns, the fat-heavy Western diet and the prudent diet. Patients were then followed up for cancer recurrence or death.
During a median follow-up of 5.3 years for the overall cohort, 324 patients had a cancer recurrence, 223 died as a result, and 28 died without documented cancer recurrence.
Compared with patients in the lowest quintile of the Western pattern, those in the highest quintile had a more than three-fold higher risk of cancer recurrence or death (adjusted hazard ratio hazard ratio for disease-free survival, 3.25, 95% confidence interval 2.04-5.19; P for trend <0.001).
Patients in the highest quintile were also 2.9 times more likely to have a recurrence than those in the lowest quintile (adjusted HR, 2.85; CI, 1.75-4.63, P for trend <0.001).
Similarly, a significantly higher overall risk of death was observed compared with the lowest quintile (adjusted HR, 2.32; CI, 1.36-3.96, P for trend <0.001).
The reduction in disease-free survival with the Western diet was not significantly modified by sex, age, nodal stage, body mass index, physical activity level, baseline performance status, or treatment group.
No relationship was seen for recurrence-free survival (P for trend =0.84) or overall survival (P for trend =0.54) across various intakes of the prudent dietary pattern.
The adjusted hazard ratio comparing the highest and lowest quintiles of the prudent diet was 1.20 (CI, 0.83 -1.75) for disease-free survival (P for trend 0.78).
Similarly, no relationship was seen for recurrence-free or overall survival across the various intakes for those who ate a prudent diet.
Higher prudent diet scores were found for patients who were physically active, had a lower BMI six months after adjuvant therapy, and were less likely to be smokers.
Higher undesirable Western scores were seen among men, whites, and past or current smokers.
In contrast, other characteristics, particularly tumor types known to predict prognosis, did not vary significantly among the quintiles of either dietary pattern, the researchers reported.
The researchers pointed out that they could not completely exclude the possibility that a higher intake of the Western pattern may have reflected other predictors of poor prognosis.
Nevertheless no significant association between diet and predictors associated with cancer recurrence (extent of invasion into bowel wall, number of positive lymph nodes) was observed.
Because the study was observational, causality cannot and should not be drawn from these data, Dr. Meyerhardt wrote. Nonetheless, the data suggest that eating more red and processed meat, sweets and desserts, French fries, and refined grains increases the risk of recurrence and decreases survival.
"Further analyses are under way to better delineate specific nutrients or food groupings that may have the strongest association," the authors concluded.
Eric Jacobs, Ph.D., a senior epidemiologist at the American Cancer Society, called the study by Dr. Meyerhardt and colleagues well-designed and addressing "an important question that has not been studied so far."
He pointed out that diet and the risk of colon cancer studies have not been consistent, but there has been almost nothing about the risk of recurrence. "The effect of diet on recurrence may be biologically different from the original risk," he noted. "Other studies will have to attempt to duplicate the results and then see where it leads."
As to why the prudent diet showed no benefit beyond not stimulating recurrence is an important question, he added. "Stay tuned," Dr. Jacobs said. "It's a really important question and needs more research."
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