May 17, 2005
Lifestyle Changes Can Prevent Cancer’s Return
Studies find low-fat diets fight breast cancer; aspirin does same against colon cancer
HealthDay News -- Simple lifestyle measures may reduce the risk of recurrence of certain types of cancer.
For the first time, evidence suggests that reducing dietary fat can reduce the risk of breast cancer recurrence in postmenopausal women.
And another study found that regular aspirin use may reduce the risk of colon cancer recurrence.
Both studies were presented at the American Society of Clinical Oncology annual meeting, in Orlando, Fla.
Women in the breast cancer study who followed a low-fat diet experienced a 24 percent improvement in relapse-free survival, compared with women in a control group who did not lower their fat intake.
"It's a demonstration that intervention programs that are resulting in lifestyle changes can be successful," said Dr. Robert Morgan Jr., a staff physician in medical oncology and therapeutics research at City of Hope Cancer Center, in Duarte, Calif. "A lot of doctors have been quite pessimistic in our ability to effect lifestyle changes in patient populations. These statistics are compelling and hypothesis-generating, although they clearly need a follow-up study."
"The role of dietary fat in breast cancer was raised about a quarter of a century ago, first by country differences in [breast cancer] incidence and in outcome after diagnosis," said study author Dr. Rowan T. Chlebowski, a medical oncologist at Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center. "But over the past 25 years, the precise role of dietary fat intake in breast cancer recurrence has remained an open question."
To address this open question, Chlebowski and his colleagues conducted a randomized, prospective trial involving several centers and 2,437 women aged 48 to 79, all diagnosed with early-stage breast cancer. All the participants had undergone surgery and, if indicated, radiation, chemotherapy and/or tamoxifen therapy.
Within one year of diagnosis participants were randomized either to a low-fat diet or to a control group. Women in the dietary group also attended regular sessions with a nutritionist. Although the eating plan was not designed for weight loss, women in the intervention arm lost an average of four pounds each, the researchers note.
The low-fat diet averaged 33.3 grams of fat daily -- a reduction of 50 percent from the standard diet, which averaged 51.3 grams of fat per day.
After about five years of follow-up, 9.8 percent of the women on the low-fat diet had had a recurrence compared with 12.4 percent of those on the standard diet. "There was a statistically significant difference in risk of about 3 percent at five years," Chlebowski said.
Even more striking were the results in women with estrogen receptor-negative cancer, who had a 42 percent lower risk of recurrence compared with women on a standard diet. "We had thought women with estrogen receptor-positive tumors would most benefit, with dietary fat influencing estrogen levels," Chlebowski said. "But the estrogen receptor-negative group had an 8 percent absolute difference."
The researchers plan to conduct more trials to try to confirm the findings.
A second study found that stage III colon cancer patients who used aspirin regularly after their surgery reduced their risk of a recurrence and death by about 50 percent compared with nonusers.
"Regular aspirin use has been associated with a reduced risk of developing colorectal cancer and polyps," said study co-author Dr. Jeffrey Meyerhardt, a gastrointestinal oncologist at Dana-Farber Cancer Institute in Boston. "The influence of aspirin use on the outcomes of patients with established colon cancer remains uncertain."
This trial looked at 830 stage III colon cancer patients who had undergone surgery and were getting chemotherapy. Each participant completed two questionnaires on diet, lifestyle and medication use, one after two months of chemotherapy and one six months after chemotherapy had ended.
Almost 9 percent of the total participants described themselves as consistent aspirin users (most of them taking 81 milligrams to 325 milligrams per day). After a median of 2.4 years of follow-up, this group had a 55 percent reduced risk of a recurrence and a 48 percent reduced risk of death.
Consistent users of Celebrex and Vioxx had similar risk reductions, but the overall numbers were smaller so this did not reach statistical significance. No benefit was seen with regular acetaminophen use.
Again, the findings require more confirmatory studies.
For more on life after cancer, visit the American Society of Clinical Oncology's People Living With Cancer (www.plwc.org ).