Eating cruciferous vegetables lowers death risk from breast cancer and recurrence, study shows
Higher consumption of cruciferous vegetables — broccoli, cauliflower, Brussels sprouts, kale and cabbage — reduced breast cancer death rates, a large Chinese study found, suggesting that women diagnosed with breast cancer are more likely to survive if they ate more of these vegetables.
Researchers from the Vanderbilt-Ingram Cancer Center and Shanghai Center for Disease Control and Prevention adjusted for other factors that might influence women’s outcomes — including demographics, exercise, clinical characteristics and additional dietary behaviors. They still found that women who ate cruciferous vegetables during the first 36 months after they were diagnosed with breast cancer gained a reduced risk for death — either from breast cancer or from other causes. They also had a reduced risk for cancer recurrence.
The investigators followed the progress of almost 5,000 women for around five years after they were diagnosed with breast cancer. The women were participants in the Shanghai Breast Cancer Survival Study, which investigated Chinese breast cancer survivors who had been diagnosed between 2002 and 2006 with different grades of tumor.
The study participants filled out detailed dietary questionnaires at the start of the study, 18 months into the study and 36 months later. Then, depending on how much cruciferous vegetables they ate, the researchers classified them into five groups.
What the Vanderbilt University and Chinese researchers found was this:
• During the study period, 587 women died, 496 of these from breast cancer. In 615 women, cancer recurred.
• As consumption of the cruciferous vegetables increased, the chances of dying from breast cancer fell by 22 percent to 62 percent and from all causes by 27 percent to 62 percent.
• Breast cancer recurrence risk also decreased, by between 21 percent and 35 percent
• By about five years after diagnosis, women in the top fifth group — who ate an average of about 150 grams of cruciferous vegetables a day — were 42 percent less likely to have died from breast cancer and 58 percent less likely to die from any cause compared to women in the bottom fifth — who ate less than 54 grams a day
• Women in the top fifth were also 19 percent less likely to have their breast cancer recur.
• Survival rates were influenced by vegetable consumption in a dose-response pattern. The more cruciferous vegetables women ate during the first three years after diagnosis, the lower the risk of death or cancer recurrence.
Compared with women who ate less than 54 grams of cruciferous vegetables a day, those who ate 150 grams of cruciferous vegetables a day:
• Had a 62 percent reduced risk of total mortality
• A 62 percent reduced risk of breast cancer mortality
• A 35 percent reduced risk of breast cancer recurrence
The findings, presented on April 3 at the annual meeting of the American Association for Cancer Research in Chicago, Illinois, may help about 1.5 million women who have breast cancer.
Breast cancer is the most common cancer in women worldwide and a leading cause of death in women.
The United States and United Kingdome have the highest incidence rates worldwide — together with the rest of North America and Australia/New Zealand. In these countries, breast cancer affects one in eight women during their lives. According to the American Cancer Society, in 2012, about 290,000 women in the U.S. will be diagnosed with breast cancer.
“Cruciferous vegetables, such as cauliflower, cabbage, bok choy, turnips and broccoli, contain high amounts of glucosinolates, which are hydrolyzed to bioactive compounds including isothiocyanates (ITCs) and indoles,” says Sarah Nechuta, a research fellow in Vanderbilt University’s epidemiology center and a researcher on the new study.