Pre- and Postdiagnosis Diet and Risk of Mortality in Colorectal Cancer


Key Points

  • Better pre- and postdiagnosis dietary patterns were associated with reduced all-cause and colorectal cancer–specific mortality.
  • Improvement from poor prediagnosis diet to better postdiagnosis diet was associated with improved colorectal cancer–specific mortality.

In a study reported in the Journal of Clinical Oncology, Guinter et al found that better prediagnosis and postdiagnosis dietary patterns were associated with improved overall and colorectal cancer­–specific survival among patients diagnosed with colorectal cancer.

Study Details

The study involved 2,801 patients in the Cancer Prevention Study-II Nutrition Cohort who were cancer-free at baseline in 1992–1993 and subsequently diagnosed with invasive nonmetastatic colorectal cancer during follow-up through June 2013. Pre- and postdiagnosis diet data were available for 2,671 and 1,321 participants, respectively; of these, 1,414 and 722 died during follow-up. Dietary quality was assessed using Dietary Approaches to Stop Hypertension (DASH) score, American Cancer Society nutrition guidelines (ACS score), prudent pattern score, and Western dietary pattern score.

The DASH score is based on high sex-specific rankings of intakes for fruits, vegetables, whole grains, low-fat dairy products, and legumes/seeds, and low rankings for saturated fat, sodium, and added sugars. The ACS score is based on consumption of ≥ 5 servings per day of fruits and vegetables, a high variety of fruits and vegetables, more whole grains than refined grains, and limited red/processed meat. The prudent pattern is characterized by high intake of fruits and vegetables, whole grains, legumes, and fish. The Western pattern is characterized by high intake of refined grains, red and processed meats, eggs, solid fats, and salty snacks.

Associations With Dietary Patterns

Extreme scoring group comparisons (all high vs low scores) showed that higher prediagnosis ACS score was associated with reduced all-cause mortality (hazard ratio [HR] = 0.78, 95% confidence interval [CI] = 0.65–0.95) and colorectal cancer–specific mortality (HR = 0.74, 95% CI = 0.54–1.03). Higher prediagnosis Western diet score was associated with higher all-cause mortality (HR = 1.30, 95% CI = 1.03–1.64).

For postdiagnosis diet, higher ACS score was associated with reduced all-cause mortality (HR = 0.62, 95% CI = 0.47–0.83) and colorectal cancer–specific mortality (HR = 0.35, 95% CI = 0.17–0.73). Higher DASH score was associated with improved all-cause mortality (HR = 0.79, 95% CI = 0.62–0.99) and colorectal cancer–specific mortality (HR = 0.56, 95% CI = 0.35–0.89). The prudent pattern score was inversely associated with all-cause mortality (HR = 0.72, 95% CI = 0.56–0.93). Among participants with poor diet quality before diagnosis, improved DASH score (HR = 0.54, 95% CI = 0.31–0.92) and improved prudent pattern score (HR = 0.53, 95% CI = 0.29–0.95) from pre- to postdiagnosis were associated with reduced colorectal cancer–specific mortality.

The investigators concluded, “Dietary patterns reflective of high intakes of plant foods and low intakes of animal products before and after [colorectal cancer] diagnosis are associated with longer survival.”

The study was supported by the American Cancer Society.

Mark A. Guinter, PhD, MPH, of the American Cancer Society, is the corresponding author for the Journal of Clinical Oncology article.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.