Healthy Diet May Lower Prostate Cancer Progression Risk finds JAMA study

Prostate cancer grade reclassification is a term describing changes in cancer grade after follow-up, indicating that the disease is progressing. This study provides critical information regarding whether diet might alter the severity of cancer and whether healthier patterns of eating might reduce the risk of progression among men under surveillance.

This was a prospective cohort study of 886 men diagnosed with GG1 prostate cancer between January 2005 and February 2017. The participants were 50 years or older and chose active surveillance and completed a validated food frequency questionnaire at enrollment. Their dietary patterns were assessed based on guidelines and the inflammatory potential of diet. The analyses were done from 29 October 2023 through 17 June 2024.

The two primary dietary measurements that were used in this research included the Healthy Eating Index 1999-2000 (HEI), and an energy-adjusted HEI (E-HEI), which measures diet consistency with the Dietary Guidelines for Americans. Two more parameters evaluated were Dietary Inflammatory Index (DII), and the energy-adjusted DII (E-DII).

Competing risk regression models were applied to assess whether baseline HEI, E-HEI, DII, and E-DII scores could predict grade reclassification to GG2 or higher or to GG3 or higher (extreme grade reclassification) at any point in time after follow-up. The analyses controlled for the prognostic factors associated with active surveillance and smoking history to minimize confounding.

After a median of 6.5 years of follow-up, that is an interquartile range of 4.0-9.1 years, the results of this study in their main results were summarized below:

Absolute Reclassification Rates

• A total of 187 men (21%) experienced grade reclassification to GG2 or higher and 55 men (6%) experienced extreme reclassification to GG3 or higher.

Cumulative Incidence of Grade Reclassification

• 3 years: 7% (95% CI, 5%-9%)

• 5 years: 15% (95% CI, 12%-17%)

• 10 years: 33% (95% CI, 29%-37%)

Cumulative Incidence of Extreme Grade Reclassification:

• 3 years: 2% (95% CI, 1%-4%)

• 5 years: 4% (95% CI, 3%-5%)

• 10 years: 10% (95% CI, 7%-13%)

Higher HEI scores were associated with reduced risk for both types of reclassification:

• For reclassification to GG2 or higher, the SHR was 0.85 (95% CI, 0.73-0.98) per 1-SD increase in HEI, and 0.86 (95% CI, 0.74-1.00) per 1-SD increase in E-HEI score.

• For extreme reclassification to GG3 or higher, higher HEI scores were associated with SHR of 0.72 (95% CI, 0.57-0.93) per 1-SD increase and with SHR of 0.73 (95% CI, 0.57-0.94) for E-HEI scores.

• Neither DII nor E-DII scores were significantly associated with the risk of reclassification. For grade reclassification to GG2 or greater, SHR was 1.08 (95% CI, 0.93-1.26) per 1-SD increase in DII and 1.02 (95% CI, 0.86-1.21) for E-DII.

In conclusion, adherence to American dietary guidelines as measured by the HEI was associated with a reduced risk of prostate cancer grade reclassification among men on active surveillance for GG1 prostate cancer. These findings support the idea that diet quality could be a modifiable risk factor in prostate cancer management, especially among men who are at risk for disease progression to more aggressive cancer requiring curative therapy.

Reference:

Su, Z. T., Mamawala, M., Landis, P. K., de la Calle, C. M., Shivappa, N., Wirth, M., Hébert, J. R., Pavlovich, C. P., & Trock, B. J. (2024). Diet quality, dietary inflammatory potential, and risk of prostate cancer grade reclassification. JAMA Oncology. https://doi.org/10.1001/jamaoncol.2024.4406