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The Science Nook on Diet Quality and Mortality Risk in Colorectal Cancer

by Jenna Koroly, MS, RD, CSOWM, CDN

The American Cancer Society predicts an estimated 145,600 new colorectal cancer cases in the United States in 2019. However, there have been improved survival rates over the past 30 years, likely due to increased screening as well as improvements in risk factors and treatment options [i]. In honor of Colorectal Cancer Awareness Month, this month’s Science Nook features the below study on diet quality before and after diagnosis as related to mortality risk. 



Associations of Pre- and Postdiagnosis Diet Quality with Risk of Mortality Among Men and Women with Colorectal Cancer

Journal: Journal of Clinical Oncology

This prospective study used data from the 184,185 individuals enrolled in the Cancer Prevention Study II (CPS-II) Nutrition Cohort, which began in 1992/1993. 2671 individuals for the pre-diagnosis cohort and 1321 individuals for the post-diagnosis cohort were identified. The CPS-II Nutrition Cohort involved participants self-reporting via Food Frequency Questionnaires (FFQs) at baseline, 1999, and 2003.

The current study looked at four different dietary patterns before and after colorectal cancer diagnosis as related to mortality risk. The dietary patterns and scoring included:

  • The DASH Diet: high score indicates high intake of fruits, vegetables, whole grains, legumes/seeds, and low-fat dairy products; and low intake of saturated fat, sodium, and added sugars.
  • The American Cancer Society Guidelines on Nutrition and Physical Activity for Cancer Prevention (ACS-score): high score indicates consumption of at least five servings per day of fruits and vegetable, variety of fruits and vegetables, higher intake of whole grains than refined, and low intake of red/processed meats.
  • Prudent Pattern (data driven): high score indicates high intake of fruits and vegetables, whole grains, legumes, and fish.
  • The Western Pattern (data driven): high score indicates high intake of refined grains, solid fats, salty snacks, red and processed meats, and eggs. 


The authors found for diet quality pre-diagnosis:

1. Highest ACS-scores were associated with a 22% lower risk of all-cause mortality compared to lowest ACS-scores
2. Significant inverse trends for ACS-score and all-cause and colorectal cancer specific mortality
3. The highest quartile of Western dietary pattern had a 30% higher risk of death compared to the lowest quartile

The authors found for diet quality post-diagnosis:

1. Higher DASH, ACS, and prudent dietary pattern scores were significantly associated with lower all-cause mortality
2. Inverse associations of DASH and ACS-scores and colorectal cancer specific mortality risk, and a significant trend with increasing Western diet quartiles
3. No association between the prudent diet and colorectal cancer specific mortality, although there was a significant inverse trend with all other remaining causes

 The authors found for change in diet quality from pre- to post-diagnosis:

1. Those with high Western diet scores before or after diagnosis were at increased risk of colorectal cancer specific mortality and total mortality compared with those with low scores
2. In those with low diet quality pre-diagnosis, improved DASH and prudent scores from pre- to post-diagnosis were inversely associated with colorectal cancer specific mortality [ii]

For the Patient and Caregiver

The features of the dietary patterns looked at in this study that were associated with decreased risk of mortality overall have in common: increased consumption of plant-based foods and fiber and decreased consumption of red and processed meat and added sugars. Depending on your starting dietary pattern, a transition to more plant-based eating is a great first step. Try Meatless Mondays (eating vegetarian for at least one day out of the week!) and plant-based meal preparation including grain bowls with quinoa, chickpeas, green vegetables of choice, sweet potato, and seeds.   

For the Healthcare Team

When working with patients on colorectal cancer prevention or recurrence prevention, encourage plant-based and high fiber foods including chickpeas, lentils, edamame, quinoa, nuts, seeds, fruits, and vegetables. Discussing simple and delicious plant-based recipes can provide excitement and encouragement, rather than putting a greater focus on what foods to avoid. Aim to educate patients on additional research around colon cancer prevention as well, including maintaining a healthy body weight, partaking in regular physical activity, limiting alcoholic beverages, and smoking cessation [i]


[i] Anselmo C. (2019). Colorectal cancer: understanding risks, new screening guidelines and lifestyle recommendations. Food & Nutrition Magazine. Retrieved from https://foodandnutrition.org/from-the-magazine/colorectal-cancer-understanding-risks-new-screening-guidelines-and-lifestyle-recommendations/  

[ii] Guinter MA, McCullough ML, Gapstur SM, Campbell PT. (2018). Associations of pre- and postdiagnosis diet quality with risk of mortality among men and women with colorectal cancer. J Clin Oncol;36:3404-3410. doi: 10.1200/JCO.18.00714

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