Reducing breast cancer risk

Almost everyone knows a relative, friend or co-worker, who has breast cancer. “Knowledge is Power” and so it is important to be informed. So, what is the best protection against breast cancer? 

There are certain factors that place one at risk of developing breast cancer. Some of these we cannot change  (race or age) but some of them, we can.  These factors are mainly lifestyle related,  and if we improve these we can significantly impact our lives.

Let’s focus on what I consider to be the top five risk-reducing lifestyle factors.

1. Alcohol

Studies have shown that consuming three to six alcoholic drinks per week carries a 15% increased risk of breast cancer. Higher consumption of seven to fourteen alcoholic drinks per week carries a 30-60% increased risk. In light of the above information, no more than one drink a day, or even less is recommended to reduce risk.  No alcohol consumption would minimise risk significantly.

2. Overweight and Obesity

Obesity is defined as when the body mass index (BMI), a measurement obtained by dividing a person’s weight in kilograms by the square of the person’s height in meters, exceeds 30kg/m². Being overweight, or obese increases the risk of many illnesses, including breast cancer. The reasons for increased breast cancer risk are two fold:

• More fatty tissue allows the presence of higher oestrogen levels which can stimulate the growth of breast cancer cells.

• More body fat is associated with higher insulin levels, which is a hormone that can trigger the growth of breast cancer cells.

Not only does obesity influence breast cancer risk but it can also have an impact on whether a cancer recurs and risks of dying from cancer.

A recent study published in a journal called “Cancer”, analysed over 6 000 postmenopausal women, diagnosed with cancer who received optimal treatment. The findings were that obesity at diagnosis, is associated with a 30% higher risk of cancer recurrence and a nearly 50% higher risk of death, despite the correct and best treatment. Even if a woman is overweight and not obese, the risks are still increased but not as high.

So then, the lesson is to stay within a good BMI range to prevent breast cancer, and if obese or overweight at diagnosis, to institute weight reduction measures as part of the treatment plan. (see table 1)

Below  18. 5 Underweight
18. 5 – 24. 9 Normal
25 – 29. 9 Overweight
30 – over Obese

There is definitely an association between increased physical activity and breast cancer risk. One study shows that as little as 10 – 19 hours of moderate physical activity per week was associated with a 30% reduced risk of developing breast cancer. This association was stronger for postmenopausal breast cancer that premenopausal cancer. In women who already have breast cancer there is no doubt that exercise results in better mood, body image and self-esteem. Women then have little to

loose and much to gain from regular physical activity.


There is emerging evidence that both smoking and exposure to secondhand smoke, has an increased associated breast cancer risk.  The longer a woman smokes, the higher her risk. Among women who began smoking at an early age and before their first pregnancy the risk is even higher. While quitting reduces the risk, researches are reporting that it can take up to twenty years before  the risk matches that of a woman who has never smoked.


Research suggests that women with low Vit D levels have a higher risk of breast cancer. Vit D is not only important for good bone health, it appears to help our immune and nervous systems to function properly as well. The mechanism for protection from good Vit D levels seems to be related to its function of controlling normal breast cell growth and stopping the growth of cancerous breast cells. Researchers have recommended an optimum serum level to be 40 – 60 mg/ml. This can be determined from a simple blood test and if levels are too low, supplements can be taken. Usually this can be done under the supervision of a doctor.


Dr Sumayya Ebrahim is a gynaecologist in private practice in Johannesburg. She is also a blogger. Check out her blog “vaginations by Dr E” on

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