FACTORS ASSOCIATED WITH GREATER BREAST CANCER RISK

1.Increasing age —

• Birth to age 49 – 2.1 percent4
• Age 50 to 59 – 2.4 percent
• Age 60 to 69 – 3.5 percent
• Age 70 and older – 7 percent
• Birth to death – 12.9 percent

2. Female sex — Breast cancer occurs 100 times more frequently in females than in males.

3.Weight and body fat in postmenopausal females —

• Postmenopausal females – A higher BMI and/or perimenopausal weight gain have been consistently associated with a higher risk of breast cancer among postmenopausal females
• Inverse relationship in premenopausal females – Unlike postmenopausal females, an increased BMI is associated with a lower risk of breast cancer in premenopausal females,

4. Tall stature — Increased height is associated with a higher risk of breast cancer in both premenopausal and postmenopausal females

5. Alcohol

6. Smoking

7. Insulin resistance – Type II DM has higher incidence of breast cancer.

8. Hormonal factors-A higher incidence in –

• Menopausal hormone therapy.
• Oral Contraceptives.

9.Bone mineral density – females with higher bone density have a higher breast cancer risk.

10.Benign breast disease -associated with an increased risk of breast cancer.

11. Dense breast tissue – Females with mammographically dense breast tissue, have a higher breast cancer risk.

12. Reproductive factors-

• Earlier menarche
• Later menopause
• Nulliparity
• Increasing age at first pregnancy.

13. Exposure to therapeutic ionizing radiation.

14.Personal and family history of breast cancer-increases the risk of developing an invasive breast cancer in the contralateral breast.Approximately 6 percent of all breast cancers are directly attributable to inheritance of a BRCA1/2 pathogenic variant.

FACTORS ASSOCIATED WITH DECREASED BREAST CANCER-

1. Physical activity.

2. Fiber intake – dietary fiber intake was associated with a 12 percent relative risk reduction in breast cancer incidence.

3. Low-fat dietary pattern in postmenopausal females —has been associated with reducing deaths following breast cancer diagnosis.

4. Weight loss in postmenopausal females — may reduce breast cancer risk

5. Calcium/vitamin D — higher plasma 25-hydroxyvitamin D levels may be associated with lower breast cancer risk in postmenopausal (but not premenopausal) females.

6. Association with folic acid  – Folic acid intake may attenuate the effect of alcohol consumption on breast cancer.

7. Breastfeeding

8. Chemoprevention ( endocrine therapy)with Aromatase inhibitors(AI) in postmenopausal females, or Estrogen receptor modulators (ERM) in pre- or postmenopausal females, reduces breast cancer risks.

Selection criteria for endocrine therapy include-

Age of 35 years or older with a life expectancy of at least 10 years and one of the following:

• A history of thoracic radiation administered prior to 30 years of age.
• A history of lobular carcinoma in situ.
• A ≥1.7 percent five-year risk for breast cancer. (Breast cancer risk assessment by Gail model2018)
• Atypical hyperplasia.

1.  Post menopausal women-
   For postmenopausal women at increased risk are  administered endocrine therapy for a total of five years.
   For postmenopausal women with baseline osteopenia/osteoporosis, we suggest a ERM rather than an AI.
   For postmenopausal women who are not candidates for a ERM (eg, personal history of thromboembolic event), an AI is appropriate.
2. Premenopausal women-Tamoxifen —
   Tamoxifen for five years for premenopausal women at high risk for breast cancer.

9. Mastectomy –
Recommended in –

• Women with a pathogenic genetic mutation conferring a high risk for breast cancer.
• Compelling family history.
• Prior thoracic radiation at <30 years of age.