Cancer is a group of diseases caused when genetic mutation at a cellular level leads to uncontrolled growth of certain cells which then have the potential to invade or spread in other parts of the body. In women, breast cancer is the most common type of invasive cancer and the second most fatal type of cancer, after lung cancer. However, advances in screening and treatment have meant that breast cancer now has a very promising survival rate, with a mortality rate of approximately 2.6%.
Risk Factors for Breast Cancer
Several factors can increase the likelihood of getting breast cancer, but having multiple risk factors does not necessarily mean that one will have breast cancer. Cases of people who have none of the risk factors developing breast cancer are prevalent as well cases of people with multiple risk factors not developing breast cancer. However, an understanding of the risk factors is useful in assessing how often screening is necessary. Risk factors include:
- Being female
- Aging
- Hormonal replacement therapy post-menopause
- Personal medical history of breast cancer, or other breast conditions
- Genetic history of breast cancer
- Obesity
- Onset of first menstruation at an earlier age than usual
- Having children at an older age, or never having children
- Radiation exposure
- Drinking alcohol
- Lack of exercise
Clinical Features of Breast Cancer
In the early stages, breast cancer may not present any symptoms. Most patients first discover breast cancer through a new lump on the breast or the armpit that feels different from the rest of the breast tissue and that did not exist before. This can coincide with other symptoms such as:
- Breast pain, or pain around the breast, such as the armpits
- Change in the size, shape, or appearance of the breast
- Strange discharge from the breast, possibly including blood
- Newly inverted nipple
- Rashes on the breast or surrounding the nipple
- Red pitting on the skin of the breast
- Flaking, peeling, or scaling of skin on the breast and/or surrounding the nipple
Diagnosing Breast Cancer
In its early stages, a cancerous tumor on the breast may be too small to be felt but may be screened during mammograms. However, mammograms are not always accurate, as studies have shown that a large number of women without breast cancer may also test positive during a mammogram. Apart from a mammogram, the most common method of screening for breast cancer is through a physical exam by a health practitioner. These methods do not necessarily lead to a diagnosis but help health practitioners determine whether further tests are needed. If required, the following further tests may be ordered by the doctor to diagnose for breast cancer:
- Breast ultrasound; in which sound waves are used to examine sonograms of the insides of the breast.
- Diagnostic mammogram; which is a more detailed x-ray of the breast than a screening mammogram.
- Magnetic resonance imaging (MRI); which is a body scan that uses magnets to produce detailed pictures of the insides of the breast.
- Biopsy; in which part of the breast tissue or fluid is removed and examined under a microscope, or sent for further testing.
Treatment and Management of Breast Cancer
Treatment of breast cancer depends on the type, stage, grade (i.e likelihood of the cancer growing and spreading), and the age and general health of the patient. The most common method of treatment is surgery, in which the cancerous tissues and some surrounding tissues are removed through an operation. Surgery may be a mastectomy (removal of the entire breast), quadrantectomy (removal of one-fourth of the breast), or lumpectomy (removal of a small part of the breast). This is based on the extent of spread of the cancer. Surgery may then be followed by additional treatments such as chemotherapy, radiation, and hormone therapy.
Treatment Modalities currently undergoing Clinical Trials
Fluoroglutamine [18F] F-GLN: Glutamine is one of two primary nutrients that support survival, biosynthesis, and cellular homeostasis in mammalian cells. In many aggressive cancer cells, the glutamynolytic pathway is found to be highly active. A clinical trial to investigate the possibility of using fluoroglutamine [18F] F-GLN as a diagnostic tool for primary or metastatic breast cancer is underway. This is not a treatment trial, and treatment decisions for the cancer will be made by the patient’s primary health provider.
Topical calcipotriene ointment: A study to determine the effects of a topical calcipotriene ointment on abnormal breast lesions that may be benign, premalignant, or malignant is underway. The researchers are trying to determine whether this topical ointment can stimulate the immune cells against the breast lesion such that it would prevent its recurrence after surgical removal.
Talazoparib, Sacituzumab Govitecan: A clinical trial to test whether the combination of drugs talazoparib and sacituzumab govitecan can stop the growth and spread of cancerous cells in patients with metastatic triple-negative breast cancer is ongoing. While neither of the drugs has been approved by the FDA for the treatment of this specific disease, talazoparib has been approved for other uses in breast cancer.
Ipatasertib, fulvestrant, aromatase inhibitor, palbociclib: The development of resistance to the standard course of treatment in metastatic breast cancer is common. A clinical trial to test whether the use of ipatasertib can prevent the cancerous cells from developing a resistance to the standard course of treatment is underway. Ipatasertib is not as of yet an FDA approved treatment for this disease, while fulvestrant, aromatase inhibitor, and palbociclib are FDA approved methods of treatment for metastatic breast cancer.
Prosigna PAM-50 assay: Prosigna PAM-50 assay is an FDA-approved drug used for patients with ER-positive breast cancer in order to develop a more individually-tailored treatment method based on the patient’s unique genetic make-up after surgery. Currently, prosigna assay is only approved for use post-surgery; a clinical trial to test whether prosigna assay can help patients pre-surgery is underway. Researchers hope that this test will provide patients and their health care providers with more information before surgery as well in order to make more effective treatment decisions.
References:
World Cancer Report 2014. World Health Organization. 2014. pp. Chapter 5.2.
Runowicz CD, Leach CR, Henry NL, Henry KS, Mackey HT, Cowens-Alvarado RL, et al. (January 2016).
"American Cancer Society/American Society of Clinical Oncology Breast Cancer Survivorship Care Guideline"
Bray F, Ferlay J, Soerjomataram I, Siegel RL, Torre LA, Jemal A (November 2018).
"Global cancer statistics 2018: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 countries"
Nelson HD, Tyne K, Naik A, Bougatsos C, Chan B, Nygren P, Humphrey L (November 2009). "Screening for Breast Cancer: Systematic Evidence Review Update for the US Preventive Services Task Force". U.S. Preventive Services Task Force Evidence Syntheses. Rockville, MD: Agency for Healthcare Research and Quality.
Nelson HD, Smith ME, Griffin JC, Fu R (April 2013).
"Use of medications to reduce risk for primary breast cancer: a systematic review for the U.S. Preventive Services Task Force"
Merck Manual of Diagnosis and Therapy (February 2003).
"Breast Disorders: Breast Cancer"
Lacroix M (December 2006).
"Significance, detection and markers of disseminated breast cancer cells"
Early Breast Cancer Trialists' Collaborative Group (EBCTCG) (October 2015).
"Aromatase inhibitors versus tamoxifen in early breast cancer: patient-level meta-analysis of the randomised trials"
Mazzucco A, Santoro E, DeSoto, M, Hong Lee J (February 2009).
"Hormone Therapy and Menopause"
