Historia del Ocio

The relation between dietary fat intake and breast cancer survival has been

increasingly reported by a number of investigators. The majority of studies regarding dietary fat and survival showed an increased risk of dying with higher fat intake [134-137], with the exception of one study showing a risk reduction [138]. An early study examined the relation between dietary fat and breast cancer survival among both Caucasian and Japanese women with breast cancer diagnoses in Hawaii [139]. The study reported more than triple the risk of death for high versus low total fat intake for Caucasian women. In comparison, nearly 40% mortality risk reduction was reported among women of Japanese ancestry for high versus low total fat intake. Though both estimates were imprecise, this difference in the direction of the reported associations among Caucasian and Japanese women may highlight the importance of examining different types of fat on breast cancer, such as ω-3 and ω-6 PUFA.

fat intake. Two large randomized trials were conducted in the mid-1990s in order to examine the effect of reductions in dietary fat intake on prognosis among breast cancer survivors in the U.S. The Women’s Intervention Nutrition Study (WINS) was focused primarily on the efficacy of reduction in dietary fat intake [140]. The WINS study included approximately 2,400 postmenopausal women who had completed primary treatment and had been diagnosed with stage one breast cancer in the previous year. Study participants were randomized to receive an intervention targeted to reduce fat intake. The study reported slight reductions in the hazard for overall survival (HR = 0.89; 95% CI = 0.65, 1.21) [140]. In contrast, the Women’s Healthy Eating and Living (WHEL) trial focused on the efficacy of changes in dietary pattern, which included reduction in dietary fat intake [141]. The WHEL study included approximately 3,000 women, among whom nearly 80% were postmenopausal, and had been diagnosed with stage one breast cancer within the previous four years. The

intervention focused on implementing a dietary pattern with high fruit, vegetable, and fiber intake and low total fat intake. The WHEL study reported null associations for the dietary pattern intervention on overall survival (HR = 0.97; 95% CI = 0.78, 1.22) [142]. A modest reduction in the hazard for recurrence was reported in the WINS study (HR = 0.76; 95% CI = 0.60, 0.98), but not for the WHEL study (HR = 0.99; 95% CI = 0.83, 1.17).

It is important to note the differences in assessment methods used in these two trials. The focus of the WHEL study was on dietary pattern changes, which included reduction in dietary fat intake. Whereas, the WINS study’s primary focus was on reduction of dietary fat intake. Also, the studies differ with regards to the time between breast cancer diagnosis and enrollment. The WINS study enrolled women within one year of diagnosis, whereas the WHEL study enrolled women within four years of breast cancer diagnosis. Thus, the WINS

study would focus on more short-term prognosis, or women who could have a breast cancer event within five years of diagnosis. In contrast, the WHEL study under sampled women who had a breast cancer event within four years of the diagnosis, and therefore are unable to examine the effect of the intervention on early recurrence and death. This may explain the differences in the reported HRs for breast cancer recurrence in the two studies.

These previous studies on breast cancer progression and mortality focused on

reductions in total fat intake without any consideration given to the type of fat. It is possible that ω-3 and ω-6 PUFAs will have differential effects on survival, and that reduction in dietary intake of the unfavorable ω-6 fatty acids and increases in the more favorable ω-3 fatty acid could improve breast cancer survival. Therefore, examination of these different types of PUFAs and their relative balance could further elucidate the relation between dietary fat and breast cancer survival.

Non-steroidal anti-inflammatory drugs could also improve survival by reducing inflammatory metabolites resulting from metabolism of arachidonic acid via cyclooxygenase enzymes. However, only two studies on NSAID use in relation to survival from breast cancer have been reported to date, and results were conflicting [143, 144]. Thus, other avenues for improving breast cancer survival should be considered.

1.3.7 Summary

There are many established clinical indictors of breast cancer prognosis, including late age at diagnosis, low socioeconomic status, African American race, ER- tumor subtype including triple negative and basal-like breast cancer, and inadequate treatment, which have been demonstrated to worsen prognosis among breast cancer patients. Additionally, there is

growing evidence that lifestyle factors such as weight maintenance, increased physical activity, and reduced fat intake before and after diagnosis improve survival. The promising findings for nutritional factors underscore the hypothesis that some factors may be modified in an effort to improve survival, and support the examination of other possible nutritional factors that could influence breast cancer survival. One possibility is dietary PUFA intake, which may help to provide an opportunity for improving survival among women diagnosed with breast cancer.