Chapter 2-4: Breast Cancer Screening

What is the burden of disease?

1. Second leading cause of cancer in women

2. In average-risk women, the cumulative lifetime risk of developing breast cancer is 12%.

3. The 10-year risk at age 40 is 1.5%; at age 50, it is 2.4%; at age 60, it is 3.5%.

4. In 2015, breast cancer was diagnosed in 232,000 women with 40,000 breast cancer–related deaths.

Is it possible to identify a high-risk group that might especially benefit from screening?

1. Women who have a BRCA1/BRCA2 mutation are a special high-risk group, with a relative risk of developing breast cancer of 10.0–32.0 and a cumulative lifetime risk of 45–70%.

2. Referral for genetic counseling and testing is recommended in patients with breast cancer and the following characteristics:

   1. A known mutation in the family

   2. Breast cancer diagnosed ≤ 50 years

   3. Triple-negative (estrogen receptor–negative, progesterone receptor–negative, human epidermal growth factor receptor 2–negative) breast cancer diagnosed in women aged ≤ 60 years

   4. Two breast cancers in a single patient

   5. Breast cancer diagnosed at any age plus ≥ 1 relative with breast cancer diagnosed ≤ 50 years; or ≥ 1 relative with ovarian cancer at any age; or ≥ 2 relatives with breast, pancreatic, or prostate cancer diagnosed at any age.

   6. Male sex

   7. Ashkenazi Jewish descent with breast, ovarian, or pancreatic cancer diagnosed at any age

   8. Personal history of ovarian cancer

3. Family members should be referred for genetic counseling if there is a known family mutation; ≥ 2 breast cancers in a single person; ≥ 2 individuals on the same side of the family with breast cancer with one diagnosed ≤ 50 years; ovarian cancer; male breast cancer; first- or second-degree relative with breast cancer diagnosed ≤ 45 years

4. Other very high-risk women, defined as having a cumulative lifetime risk of > 20%, include those with a history of chest radiation, personal history of breast cancer, strong family history (≥ 2 first-degree relatives with breast cancer, ≥ 1 relative with premenopausal breast cancer, ≥ 1 male relative with breast cancer), and biopsy confirmed atypical hyperplasia or lobular carcinoma in situ.

5. Breast density is a risk factor for breast cancer.

   1. Density is categorized as fatty (BiRads Density Category A), scattered fibroglandular density (Category B), heterogeneous density (Category C), or extremely dense (Category D).

   2. The relative risk of breast cancer in women with Category D density, compared to those with Category A density, is 2.4–4.5.

6. Age is a strong risk factor.

7. Other risk factors are listed in Table 2-7.

8. Protective factors include > 16 months of breastfeeding, 5 or more pregnancies, exercise, postmenopausal BMI < 23 kg/m², oophorectomy before age 35.

9. A Breast Cancer Risk Assessment Tool has been developed.

   1. Available at https://bcrisktool.cancer.gov/

   2. Uses statistical methods applied to data from the Breast Cancer Detection and Demonstration Project, a mammography screening project conducted in the 1970s, to assess breast cancer risk

   3. Does not include breast density

What is the quality of the screening test?

1. Mammograms, 95% of which are now done digitally, are more sensitive in older women and in women ...