Breast Cancer Awareness : October 2024

Breast cancer occurs when cells in the breast tissue begin to grow and multiply in an abnormal and uncontrolled way to form a growth or tumour.  It is the most commonly diagnosed cancer among women, accounting for approximately one in four cases of cancers globally, with a higher rate in the MENA region, exceeding one in three. 

Only 5-10% of breast cancers are hereditary; in contrast, nearly 25% of breast cancers are preventable by adopting lifestyle measures.

What are the risk factors for breast cancer?

Risk factors include those which you cannot control, for example gender or age and those you can control, such as lifestyle habits like smoking.

Risk factors you cannot or may not be able to control

• Gender and age are the strongest risk factors for breast cancer.
• Being born female – 99% of breast cancers occur in women – it is important to note that men also have breast tissue and breast cancer in men accounts for 0.5-1% of all breast cancer diagnosis.
• Age – breast cancer becomes more common with increasing age, especially after the age of 40, with the likelihood increasing as we get older. 
• Hereditary – genetic risk only accounts for 5-10% of all cancer cases.  The most common genetic mutation is the BRCA 1 or BRCA 2 mutation.
  Knowing your family history is important to assess risk.  Having one first-degree relative with breast cancer doubles your risk, and having two first-degree relatives triples your risk. 
• Personal history of breast cancer – having a history of breast cancer in the past increases the risk of developing cancer in another part of the same breast or in the other breast.
• Radiation therapy to the chest – women previously treated with radiation therapy to the chest for another cancer when younger have an increased risk for breast cancer.  The risk is highest when radiation was given when the breasts are still developing, in teenagers and young adults.
• Starting menstrual periods early and/or having a late menopause – women who started menstruating early, especially before the age of 12, have a slightly higher risk of breast cancer, as do women who have a late menopause, usually after the age of 55 years.  This risk is due to the increased exposure to hormones from an increased number of menstrual cycles through their lifetime.
• Older age for first pregnancy – women who have their first pregnancy after the age of 35 years or who never become pregnant have an increased risk of breast cancer compared to women who have their first baby at an earlier age and have multiple pregnancies. 

Which lifestyle factors have been shown to reduce the risk of breast cancer?

There are several lifestyle related risk factors that can be controlled including diet, physical activity, alcohol reduction and maintaining a healthy weight.

1. Nutrition

• Fruits and vegetables have been shown to decrease the risk of breast cancer by about 10%.  Try to include a minimum of five portions of fruit and vegetables a day, aiming for a variety throughout the week.  Include the following:
  • Carotenoids - yellow/orange fruits and vegetables (e.g butternut squash, carrots, bell peppers, tomatoes and apricots).
  • Dark green leafy vegetables (e.g.spinach, bok choy, collard greens).
  • Cruciferous vegetables (e.g kale, cabbage, broccoli, cauliflower).
  • Berries
  • A variety of herbs and spices – curcumin in particular, in the form of turmeric has been shown to have anti-cancer properties.
• A diet high in fibre – in addition to a variety of fruits and vegetables, include wholegrains, legumes, nuts and seeds.
• Limit consumption of saturated fat – some studies have shown a positive link between saturated fat intake and breast cancer risk.  Processed and red meats in particular, have been linked to an increased risk of cancer, including breast cancer. 
• Avoid ultra-processed foods (e.g. packaged snacks such as crisps or biscuits, soda drinks and “fast foods”).  One study showed a 10% increase in the proportion of ultra-processed foods in the diet resulted in a 10% increased risk of overall and breast cancer.
• Include soya in the diet - breast cancer risk is lower in Asian countries where soya consumption is much higher than in Western populations.  One study showed swapping dairy milk for soya milk reduced the risk of breast cancer by up to 32%.  Whole or minimally processed soya foods should be consumed - choose edamame beans, tempeh, tofu, soya yoghurt and soya milk. 
  
  (Note: see FAQs for soya foods and hypothyroidism)

After the diagnosis of breast cancer, adopting a low-fat diet with the inclusion of fruits, vegetables and wholegrains has shown to reduce death from breast cancer by up to 21%.

1. Incorporate physical activity - regular physical activity reduces breast cancer risk by 25-30%, with greater levels of activity conferring a greater degree of protection.  Aim to incorporate about 30 minutes of moderate intensity activity e.g brisk walking, five times a week.
   After a diagnosis of cancer, incorporating regular physical activity can reduce the risk of death by nearly 40%.
2. Maintain a healthy weight – women who are overweight after menopause have a higher risk of breast cancer compared to women who are in the normal weight range.  Although weight management is influenced by multiple factors, a diet high in fibre that is predominantly plant-based, low in saturated fat and processed foods, alongside regular physical activity, will help with weight management.
3. Avoid alcohol – the link between alcohol and breast cancer is very strong.  Drinking three to six drinks per week increases the risk of breast cancer by 15% compared to women who do not drink.  There is no safe limit when it comes to alcohol and cancer – the less you drink, the more you lower your risk.
4. For mothers, breastfeed if possible – breastfeeding has shown to reduce the risk of breast cancer.
5. Quit smoking - tobacco contains many cancer-causing chemicals.  If you smoke, it is best to quit and not replace it with any other form of tobacco.  All forms of tobacco are harmful.   

Disclaimer:
The content in this article is for general informational purpose and is not meant to replace or substitute for professional medical advice, diagnosis or treatment.  Always consult a qualified healthcare professional with any questions or concerns about your health.

References :

• Global Cancer Observatory (who.int)
• Bray F, Laversanne M, Sung H, et al. Global cancer statistics 2022: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 countries. CA Cancer J Clin. 2024; 74(3): 229-263.
• https://www.cancer.org/cancer/types/breast-cancer
• Farvid MS, Chen WY, Rosner BA, Tamimi RM, Willett WC, Eliassen AH. Fruit and vegetable consumption and breast cancer incidence: Repeated measures over 30 years of follow-up. Int J Cancer. 2019;144(7):1496-1510.
• Gary E Fraser, Karen Jaceldo-Siegl, Michael Orlich, Andrew Mashchak, Rawiwan Sirirat, Synnove Knutsen, Dairy, soy, and risk of breast cancer: those confounded milks, International Journal of Epidemiology, Volume 49, Issue 5, October 2020, Pages 1526–1537
• Rowan T. Chlebowski et al., Dietary Modification and Breast Cancer Mortality: Long-Term Follow-Up of the Women’s Health Initiative Randomized Trial. JCO 38, 1419-1428(2020).
• Dietary Modification and Breast Cancer Mortality: Long-Term Follow-Up of the Women’s Health Initiative Randomized Trial. JCO 38, 1419-1428(2020).
• Lynch BM, Neilson HK, Friedenreich CM. Physical activity and breast cancer prevention. Recent Results Cancer Res. 2011;186:13-42.
• Breasts The Owner’s Manual, Dr Kristi Funk
• Chen WY, Rosner B, Hankinson SE, Colditz GA, Willett WC. Moderate Alcohol Consumption During Adult Life, Drinking Patterns, and Breast Cancer Risk. JAMA. 2011;306(17):1884–1890.
• IARC Monographs Volume 124: Night Shift Work – IARC (who.int)