Alcohol is a double-edged sword. In moderate quantities - up to two drinks a day - it helps guard against heart disease. Yet moderate drinking also increases the risk of many cancers.
Now, a study reported in the Journal of Clinical Oncology has linked moderate drinking with a greater risk of breast cancer recurrence, particularly among older women and those who are overweight.
While research has found that alcohol intake increases a woman's chances of developing breast cancer, the evidence has been conflicting for breast cancer survival.
In the study, researchers followed 1,897 women treated for early stage breast cancer. After seven years, 293 women had their cancer return and 273 died as a result of breast cancer or other causes.
When the researchers factored in other variables such as age and body weight at time of treatment, regular drinkers - three to four alcoholic beverages a week - were 35 per cent more likely to have a recurrence than non-drinkers. Regular drinkers also had a 51 per cent greater chance of dying from the disease.
Moderate drinking was associated with poorer breast health for the entire study group, but the bulk of the risk fell upon postmenopausal and obese women. It's possible that these women may be more susceptible to the detrimental effects of alcohol.
These findings cannot be generalized to women treated for more advanced breast cancer because these patients were not included in the study.
Alcohol may contribute to breast cancer in a number of ways. One of its metabolic byproducts, acetaldehyde, is thought to be carcinogenic. Alcohol may also boost blood estrogen levels, which can feed cancer growth.
As well, alcohol may inhibit the ability of cells to repair faulty genes and make breast cells more vulnerable to carcinogens.
Surprisingly, the majority of previous studies of drinking habits and breast cancer recurrence have turned up mixed results with many showing no association. Yet, many of these studies looked at deaths from all causes.
The current findings suggest that alcohol intake may not increase the risk of all-cause mortality, only breast cancer deaths.
In other words, moderate drinking may increase a woman's risk of dying from breast cancer while protecting against death from heart disease, the No. 1 cause of death among North American women.
This raises an important question: Should women who have survived early stage breast cancer - the vast majority who will live long enough to be vulnerable to dying from heart disease - abstain from moderate drinking?
I'm afraid there's no clear-cut answer. Whether to consume alcohol is a personal decision based on a woman's health risks and her comfort level with those risks.
While one drink a day may benefit the heart by increasing HDL (good) cholesterol, reducing the likelihood of blood clots and suppressing inflammation, there are plenty of other ways to protect from heart disease.
It's well established that not smoking, healthy eating, regular exercise and managing heart risk factors such as diabetes, high blood pressure and elevated cholesterol guard against the disease.
There are also dietary measures breast cancer survivors can employ to reduce the risk of recurrence. According to the Canadian Cancer Society, 23,200 women will be diagnosed with breast cancer this year. The following strategies may prevent future breast cancer and improve your overall health.
Curb - or avoid - alcohol
If you decide to continue consuming alcohol, do so in moderation. That means no more than one drink a day (no more than two drinks a day for men). One drink is the equivalent of 12 ounces of beer, five ounces of wine or 1.5 ounces of spirits.
Drinking more than this can increase the risk of heart disease and stroke by increasing blood pressure, raising blood triglycerides and promoting weight gain.
Keep in mind, however, that even one drink a day may slightly increase the risk of developing breast cancer in the first place.
Increase vegetables and fruit
A number of studies have revealed that a diet high in vegetables and fruit reduces the likelihood of breast cancer recurrence. These foods contain nutrients and antioxidants that may prevent tumour formation and growth.
Aim for five servings of vegetables and three servings of fruit each day. One serving is equivalent to ½ cup cooked or raw vegetables, one cup salad greens, one medium-sized fruit, one cup chopped fruit and ½ cup 100-per-cent juice.
Studies suggest that cruciferous vegetables including broccoli, bok choy, Brussels sprouts, cabbage, cauliflower and kale are especially protective from breast cancer, particularly when eaten raw or lightly cooked. (When eaten raw, cruciferous vegetables provide more biologically active anti-cancer compounds.)
The Women's Intervention Nutrition Study (WINS), a trial that enrolled 2,437 postmenopausal women within one year of diagnosis of early stage breast cancer, found significant improvement in survival among women assigned to a low-fat diet (15 per cent of total calories or 33 grams of fat a day), especially among women with estrogen-negative breast cancer. (Estrogen-negative breast cancer does not respond to the hormone estrogen.)
Choose lean meats, poultry breast, legumes and non-fat dairy products. Use cooking oils, higher fat spreads and salad dressings sparingly.
Control body weight
Breast cancer survivors who are overweight or obese are more likely to have their cancer recur than normal weight survivors. Women who are overweight and sedentary have an even greater risk.
If your body mass index (BMI) is over 25, it is advised to reduce weight after breast cancer treatment to a BMI of 18.5 to 25. To determine your body mass index, use your Web browser to search for a BMI calculator.
Add daily exercise
Moderate exercise has been shown to improve breast cancer survival. In one study, walking 30 minutes six days a week - combined with a diet high in fruits and vegetables - reduced breast cancer death by 46 per cent.
Regular exercise lowers levels of circulating estrogen and helps maintain a healthy weight.
Leslie Beck, a Toronto-based dietitian at the Medcan Clinic, is on CTV's Canada AM every Wednesday. Her website is lesliebeck.com.