The study is published in the Journal of the American Medical Association (JAMA) and is the work of Dr Jeffrey A. Meyerhardt, of the Dana-Farber Cancer Institute, Boston, and colleagues from various other research centres in the US.
Previous research has found links between lifestyle factors and cancer recurrence and mortality, but none has yet looked in detail at the composition of diets most closely linked to these outcomes.
Meyerhardt and colleagues analysed data from 1,009 patients with stage III colon cancer who were taking part in a randomized trial comparing 2 post operative chemotherapies between April 1999 and May 2001. They analysed their diet and compared it to rates of recurrence and survival.
The participants filled in questionnaires that asked about the types and quantities of food they were eating while they underwent chemotherapy and for six months afterwards.
Using a statistical method called "factor analysis" the researchers analysed the participants' eating patterns and found they clustered into two groups, one which they called "prudent" (high in fruit, vegetables, whole grains, poultry and fish) and a second which they called "Western" (high in meat, fat refined grains, and desserts).
Meyerhardt and colleagues found that the patients whose food intake was most like the Western diet had a significantly greater risk of cancer recurrence and death than those whose diet was least like the Western one.
However, no such associations were found when they looked at the prudent dietary pattern.
The detailed results showed that over the median follow up of 5.3 years, for all participants:
- The cancer recurred in 324 patients.
- 223 patients died with cancer recurrence.
- 28 died without documented cancer recurrence.
- A higher intake of a Western dietary pattern after cancer diagnosis was associated with a significantly worse disease-free survival (ie reccurence of colon cancer or death).
- The 20 per cent of patients whose diet was most like the Western pattern had over three times less chance of disease free survival compared to the 20 per cent of patients whose diet was least like the Western one (adjusted hazard ratio was 3.25 for top versus bottom quintile).
- Recurrence-free survival and overall survival risks followed a similar pattern.
- Adjusting for factors such as sex, age, nodal stage of cancer, body mass index (BMI), level of physical activity, and chemotherapy treatment group did not significantly alter the results for Western diet.
- The prudent dietary pattern had no significant associations with cancer recurrence or mortality.
"Higher intake of a Western dietary pattern may be associated with a higher risk of recurrence and mortality among patients with stage III colon cancer treated with surgery and adjuvant chemotherapy. Further studies are needed to delineate which components of such a diet show the strongest association."
Commenting on their findings the authors said that to their knowledge this was the first study to look into the effects of different diet on the recurrence and mortality rates of stage III colon cancer survivors.
However, they were keen to point out that this was an observational study and therefore it does not prove that the type of diet followed by the patients caused the results.
But they did say that:
"Nonetheless, the data 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."
They suggest further research is needed that looks in more detail at the links between particular types of food and recurrence and survival rates of colon cancer.
"Association of Dietary Patterns With Cancer Recurrence and Survival in Patients With Stage III Colon Cancer."
Jeffrey A. Meyerhardt; Donna Niedzwiecki; Donna Hollis; Leonard B. Saltz; Frank B. Hu; Robert J. Mayer; Heidi Nelson; Renaud Whittom; Alexander Hantel; James Thomas; Charles S. Fuchs.
JAMA 2007 298: 754-764.
Vol. 298 No. 7, August 15, 2007.
Click here for Abstract.
Click here for more information on Colon Cancer (National Cancer Institute, US, contains patient and practitioner information pages).