From both cohorts, a total of 2440 cases of CRC were identified. Patients in the highest quintiles (Q5) in both the diet and lifestyle scores were considered the most adherent compared with those in the lowest quintile (Q1). In general, higher-quintile patients were more likely to undergo CRC screening and be nonsmokers.
When reviewing the data, the authors frequently compared patients in the highest quintile (Q5) with those in the lowest quintile (Q1). There was a stronger, statistically significant association between lower CRC risk and adherence to the WCRF/AICR criteria in men, but not the association was not statistically significant in women. In men, the multivariable adjusted hazard ratio (HR)Q5 vs Q1 was 0.64, (95% CI, 0.52-0.77) compared with women (HRQ5 vs Q1, 0.86; (95%CI: 0.72-1.02).
In male patients, stronger adherence was associated with a statistically significant decreased risk of distal colon cancer (HRQ5 vs Q1, 0.47; 95% CI, 0.33-0.68) but not proximal colon cancer (HRQ5 vs Q1, 0.82; 95% CI, 0.58-1.15). These differences in colon cancer location were not observed in women and there were no associations between the adherence scores and rectal cancer. When the authors looked solely at the impact of adherence to the dietary recommendations (diet score), they found a decreased risk of CRC only in men (HRQ5 vs Q1, 0.74; 95% CI, 0.61-0.90) and not women (HRQ5 vs Q1, 0.93; 0.77-1.12).
The authors concluded that greater adherence to the 2018 WCRF/AICR recommendations as measured by a multicomponent “lifestyle score” was associated with a statistically significant decreased risk of CRC in men (but not women), especially in distal colon cancer.
The strengths of this study include a robust patient population, prospective nature of the data collection, and the long-term follow-up. There are several limitations, however. The lifestyle score as derived from the 2018 WCRF/AICR guidelines was a relatively new score and has yet to be validated across multiple studies. Some of the recommendations in these guidelines were vague and hard to incorporate into objective numbers for analysis, especially in regard to the definition of “partial adherence.” Nonetheless, it is important to note that the recommendations made by the WCRF/AICR may impact the risk of CRC in a certain patient population. It will be interesting to review future data from these cohorts and see if the lifestyle score can also be validated in future studies.
- Petimar J et al. Adherence to the World Cancer Research Fund/American Institute for Cancer Research 2018 Recommendations for cancer prevention and risk of colorectal cancer. Cancer Epidemiol Biomarkers Prev. doi: 10.1158/1055-9965.EPI-19-0165.
- World Cancer Research Fund/American Institute for Cancer Research. Diet, nutrition, physical activity and cancer: a global perspective: A summary of the Third Expert Report. American Institute for Cancer Research; 2018: Washington, D.C.
- World Cancer Research Fund/American Institute for Cancer Research. Food, nutrition, physical activity, and the prevention of cancer: a global perspective. American Institute for Cancer Research; 2007: Washington, D.C.