New research is suggesting that consuming less dietary fat after being diagnosed with breast cancer may significantly improve a person’s survival rate. Estimates show that around one in eight women in the U.S. will be diagnosed with invasive breast cancer at some point in their lives.
If the cancer is found only in the breast and has not spread to other parts of the body, 99 per cent of the people who receive such a diagnosis go on to live cancer-free lives for a minimum of five years. If the cancer has spread to the surrounding lymph nodes, 85 per cent of patients with breast cancer have the same five-year survival rate. However, this rate drops to 27 per cent if the cancer has travelled to distant parts of the body.
There are some factors that can influence a survivor’s outlook though. Some studies have revealed that being obese, for example, raises the risk of breast cancer recurrence, even death, by 35 to 40 per cent. To determine whether or not a following a low-fat diet would impact a patient’s chance of cancer recurrence and overall survival, scientists led by Dr. Rowan T. Chlebowski, Ph.D. — of the City of Hope National Medical Center in Duarte, CA —investigated. Dr. Chlebowski and colleagues first re-examined the results from the Women’s Health Initiative (WHI) randomized clinical trial, which showed a preliminary association between better overall survival and low-fat diet following a breast cancer diagnosis.
The WHI trial then investigated 48,835 postmenopausal women who enrolled in the study between 1993 and 1998. At the time, however, the trial did not offer insights as to whether the improved outlook was due to the eating habits that the women had before developing breast cancer.
There was also the possibility that a low-fat diet improved other health outcomes that are unrelated to breast cancer. Therefore, the longer lifespans could have been due to these other outcomes. To clarify these uncertainties, Dr. Chlebowski and colleagues conducted the present study — which was also a randomized trial.
Researchers examined 19,541 women diagnosed with breast cancer who reduced their dietary fat intake by 20 per cent, and upped the amount of fruits and vegetables that they consumed. The researchers also examined a control group of 29,294 breast cancer patients who continued their usual diets. The dietary interventions lasted for 8.5 years, on average, while the analysis carried out by the researchers took place 11.5 years after their diagnosis, on average.
The study revealed that “breast cancer overall survival was significantly greater for women in the dietary intervention group than in the usual-diet comparison group.”
In fact, the 10-year survival rate for the women who consumed less fat was 82 per cent, compared with 78 per cent in the control group. Specifically, 120 women died in the control group, compared with only 68 in the intervention group.
“A dietary change may be able to influence breast cancer outcome,” explain the researchers, who conclude that “sustained dietary intervention is needed” to maintain this positive effect.
