Factors that modify breast cancer risk in women

Cancer prevention is action taken to lower the chance of getting cancer. Dr Nirasha Chiranjan lists the factors that modify breast cancer risk in women.

Breast cancer occurs in every country of the world in women at any age after puberty but with increasing rates in later life. It is a leading cause of mortality in women. In 2020, there were 2,3 million women diagnosed with breast cancer and 685 000 deaths globally.¹

As of the end of 2020, there were 7,8 million women alive who were diagnosed with breast cancer in the past five years, making it the world’s most prevalent cancer.

Approximately half of breast cancers can be explained by known risk factors, like reproductive factors and proliferative breast disease. An additional 10 percent are associated with family history and genetics.

In addition, risk may be modified by demographic, lifestyle, and environmental factors.

Risk factors^2-7

Increasing age
Female sex
Weight and body fat in post-menopausal women
Dense breast tissue
Benign breast disease
Hormone therapy
Early menarche and later menopause
Nulliparity
Tobacco and alcohol usage
Increasing age at first pregnancy
Family history of breast cancer
Genetic mutations
Previous exposure to ionizing radiation

Behavioural choices and related interventions that reduce the risk of breast cancer include:

Breastfeeding

The protective effect of breastfeeding has been shown in multiple studies. The magnitude of which depends on the duration of breastfeeding.

A large pooled analysis estimated that for every 12 months of breastfeeding, there was a 4,3% reduction in the relative risk of breast cancer.⁸ A postulated mechanism for the protective effect of breastfeeding is that it may delay the re-establishment of ovulatory cycles.

Regular physical activity and weight control

The risk of breast cancer is lower in physically active women compared to their least active counterparts. The reduction in breast cancer risk through physical activity may be from weight control and the effect that exercise plays on circulating hormonal influences.⁹

Diet

Low-fat dietary pattern in postmenopausal women. This pattern has been associated with reducing deaths following breast cancer diagnosis. The proposed mechanism is thought to be from a reduction in metabolic syndrome.
Diet rich in fruits and vegetables (Mediterranean diet) – plant based diets may decrease breast cancer risk.
Diet high in fibre – studies show that dietary fibre intake is associated with a risk reduction in breast cancer incidence.¹⁰

Medical and surgical risk reduction strategies

In women with a high-risk of breast cancer, chemoprevention with aromatase inhibitors in postmenopausal women, or tamoxifen in pre- or postmenopausal women, reduces breast cancer risks. Mastectomy also greatly decreases breast cancer risks and is an appropriate option for select patients at high-risk, for example BRCA carriers.

Protect our mothers, sisters and daughters

To ensure we protect ourselves, our mothers, our sisters, our daughters, and many others, it is extremely important to be aware and talk about the dietary and behavioural interventions that are safe and effective ways to reduce breast cancer risk.

Breast cancer is treated with a multi-disciplinary approach involving surgical oncology, radiation oncology, and medical oncology, which has been associated with a reduction in breast cancer mortality.

Cancer prevention is action taken to lower the chance of getting cancer. By preventing cancer, the number of new cases of cancer in a group or population is lowered. Hopefully, this will lower the number of deaths caused by cancer.