Young Ju, Ph.D.

Breast Cancer Statistics (1-3)

Breast cancer is the most common cancer among women in the US, accounting for ~31% of newly diagnosed cancer. A female’s lifetime risk of breast cancer is about 1 in 8. Although male breast cancer is rare, it’s increasing, and a man’s lifetime risk is about 1 in 833. Breast cancer is also the second leading cause of cancer death among women in the US. In 2023, 297,790 women (2,800 men) were estimated to have been diagnosed with invasive breast cancer, and 43,700 women (530 men) were estimated to have died of their disease in the US.

The good news is that due to earlier detection and advances in treatment, the 5-year relative survival rate for most breast cancer types has improved from 75% (1975-1977) to 91% (2012-2018). Also there are lifestyle changes that you can make to reduce some risk factors.

Types and Subtypes of Breast Cancer (1-6)

There are two main types of invasive breast cancer: ductal carcinoma and lobular carcinoma. Breasts contain fatty, connective, and glandular tissues (Figure 1). About 65-85% of all breast cancers develop in the milk ducts of the breast; about 10%  develop in the milk-producing lobules or glands.

Figure 1. Structure of breast (6)

The three major subtypes of invasive breast cancer could be categorized by the presence or not of estrogen receptors (ER), progesterone receptors (PR), and/or human epithelial growth factor receptors 2 (HER2).

 Luminal (or hormone-sensitive) are  ER-positive and/or PR-positive, and HER2-negative:

•  ~38-51% of breast cancers

•  Higher survival rate

•  High response rate to hormone therapy

 HER2 are ER-negative, PR-negative, and HER2-positive:

•  ~10-15% of breast cancers

•  Higher translocation rate into bone

 Triple-negatives are ER-negative, PR-negative, and HER2-negative:

•  ~20% of breast cancers

•  Aggressive growth, difficult to treat

•  ~80% of breast cancers with BRCA1 and BRCA2 gene mutations

•  Most common among women under 40 years of age and in African-American women

Determining Stage (7)

The stage of a breast cancer is determined by three clinical characteristics: presence and size of the tumor (T), whether the cancer is in the lymph nodes (N), and whether the cancer has spread to other parts of the body (metastases) (M). Also the presence of ER, PR, or HER2 affects staging of breast cancer. Based on these characteristics, breast cancer is categorized into four (I, II, III, and IV) stages. The stage of the cancer helps patients and doctors to determine a prognosis, the best treatment options, and the likely outcome of selected treatments.

Symptoms and Signs (2-6)

Some warning signs and symptoms of breast cancer include:

•  New lump in the breast or armpit

•  Thickening or swelling of part of the breast

•  Irritation or dimpling of breast skin

• Redness or flaky skin in the nipple area or the breast

•  Pulling in of the nipple or pain in the nipple area

•  Nipple discharge

•  Any change in the size or the shape of the breast

• Pain in any area of the breast

Risk Factors We Cannot Control (2-6)

Several risk factors contributing to develop breast cancer have been identified that we cannot control:

•  Age: The risk for breast cancer increases with age. However, women of all ages can be diagnosed.

• Race & ethnicity: Caucasian women have higher risk than others

• Genetic mutations: e.g., BRCA1 & 2

•  Reproductive history: early menarche (before age 12) or late menopause (after age 55), first pregnancy after age 30 or never having given birth

•  Dense breasts: relatively high amounts of connective tissue

•  Personal history of BC or certain non-cancerous breast diseases

•  Family history of BC or ovarian cancer

•  Previous radiation therapy to the breast or chest

 Risk Factors We Can Control (2-6)

We can control several risk factors to lower risk of developing breast cancer:

•  Physical inactivity

• Overweight or obesity

•  Using hormones: Hormone replacement therapy used to be prescribed to relieve menopausal symptoms (> 5 years).

•  Not breastfeeding

•  Alcohol consumption

 Screening and Diagnosis (2-6)

Several ways to check changes in breasts or detect breast cancer include:

• Breast self-exam: Adult women of all ages are encouraged to check their breast at least once a month and look for changes, signs and symptoms of breast cancer

•  Clinical breast exam: A health care provider checks patients’ breasts to look for abnormalities and warning signs. It can be done during annual health check-ups.

• Imaging such as mammograms are used as a routine screening tool. Computed tomography, and MRIs are used for women at high risk and for those already diagnosed and treated with surgery.                 

o   Mammogram: a X-ray picture of the breast; annual (at least biannual) mammogram is recommended for women age 40 and older at average breast cancer risk.

o   Computed Tomography (CT): a X-ray 3-D picture of the breast

o   Magnetic Resonance Imaging (MRI): an advanced imaging method using magnets and radio waves; can detect small tumors

•  Genetic testing: Tissue samples or blood samples are used to detect mutations or abnormalities in genes that are associated with breast cancer (including BRCA 1 and 2), and help provide a patient’s prognosis and determine the most effective treatment options.

•  Biopsy: If breast symptoms or the results of imaging tests suggest breast cancer, a breast biopsy may be needed to confirm breast cancer.

Treatments (2-6)

Treatment for invasive breast cancer usually involves a combination of local and systemic treatment options. 

• Local

○       Surgery: Remove the entire breast that has cancerous tumor (mastectomy) or remove tumors and some of the normal tissue surrounding it and preserve the shape of the breast and the nipple area (breast-conserving)

○       Radiation: Destroy cancer cells with high-energy particles or rays

•  Systemic

○       Chemotherapy drugs (either by i.v. or mouth) kill breast cancer cells and can be used before and/or after surgery.

○       Hormone therapy blocks estrogen from binding to estrogen receptors and supplying estrogen to ER-positive breast cancer cells.

○       Targeted drug therapy kills or slows down breast cancer cells: Drugs are directed at target proteins and can be used to treat HER-2-positive breast cancer.

○       Immunotherapy boosts a patient’s immune system to recognize and destroy some types of breast cancer cells more effectively.

Prevention (2-6)

Since breast cancer is considered a lifestyle disease, lowering controllable risk factors can reduce the chance of getting breast cancer

• Know your risk. 

•  Maintain a healthy body weight.

•  Eat a healthy diet: limit consumption of processed meat and red meat, eat at least 2½ cups of vegetables and fruits each day, choose whole grains instead of refined-grain products, etc.

•  Be physically active.

•  Get screened.

•  Avoid drinking alcohol.

•  Breastfeed.

Conclusions

Breast cancer is still the most frequently diagnosed cancer, and the second leading cause of cancer death among women in the US. Generally, an annual mammogram is recommended at age 40 and older. Regular self-exams and mammograms can increase early detection rates. Early detection and treatment are still the best strategies for a better cancer outcome.

People with any breast health problems should talk to their healthcare providers. This information is provided for your reference and you use at your own risk; you should rely on your medical professional for medical advice.

References

1. American Cancer Society. Cancer Facts & Figures 2024. https://www.cancer.org/content/dam/cancer-org/research/cancer-facts-and-statistics/annual-cancer-facts-and-figures/2024/2024-cancer-facts-and-figures-acs.pdf

2. National Cancer Institute: http://www.cancer.gov/

3. American Cancer Society: http://www.cancer.org/

4. Centers for Disease Control and Prevention: http://www.cdc.gov/cancer/breast/

5. Surveillance, Epidemiology, and End Results Program:  http://www.seer.cancer.gov

6. American Institute for Cancer Research – http://www.aicr.org .

7. National Breast Cancer Foundation https://www.nationalbreastcancer.org/what-is-breast-cancer/

8. Breast Cancer Org. Breast Cancer Stages https://www.breastcancer.org/pathology-report/breast-cancer-stages

This information is provided for your reference and you use at your own risk; you should rely on your medical professional for medical advice.