The fat contained in the diet is one of the sources of estrogen, which may lead to shorter survival in breast cancer patients. Candyce H. Kroenke et al. from the Oakland Research Centre in Canada conducted a study to assess the effect of high-fat and low-fat dietary intake on breast cancer recurrence and mortality among patients diagnosed with breast cancer, and their findings were published in the March online issue of JNCI. The researchers included 1,893 women from the Epidemiologic Study of Life After Tumor Diagnosis who were diagnosed with early-stage invasive breast cancer between 1997 and 2000 and who completed the Fred Hutchinson Cancer Research Center Food Frequency Questionnaire. After 11.8 years (median follow-up time) of follow-up for these breast cancer patients, a total of 349 patients experienced recurrence and another 372 patients died, 189 of whom died from breast cancer. The investigators used a delayed entry Cox risk proportional regression model to assess the relationship between patients’ cumulative mean fat intake at enrollment, and their mean fat intake after 5-6 years of follow-up, and their prognosis. All statistical tests were performed bilaterally. The findings noted that overall dietary fat intake was not associated with breast cancer patient-specific outcomes in the adjusted multivariate analysis, but the investigators found that overall dietary fat intake did positively correlate with overall mortality. The investigators did not find an association between low-fat dietary intake and recurrence and death from breast cancer. However, high-fat dietary intake did positively correlate with clinical outcomes in breast cancer patients. Compared to the reference population (fat intake of 0-0.5 servings/day), mortality was higher in breast cancer patients with high fat dietary intake (fat intake of 0.5-1.0 servings/day) with a risk ratio of 1.20, 95% confidence interval 0.82-1.77, and in breast cancer patients with fat intake of 1.0 servings/day and above with a risk ratio of 1.49, 95% confidence interval The researchers also noted a positive association between high-fat dietary intake and breast cancer recurrence, but the difference did not reach statistical significance. Furthermore, the researchers noted that regardless of the diet consumed by the patients, their risk of recurrence and death was correspondingly higher if their fat content was high. The findings suggest that a high-fat diet increases mortality among patients diagnosed with breast cancer, but a low-fat diet does not reduce mortality.