Definition:
It is defined as a disease in which life-threatening cells or cancer cells develop in the tissues of the breast. It is lumpy in the breast tissues and develops a dimpling in the skin, changing the shape of the breast.
Symptoms:
The symptoms include changes in the skin, pain, thickening or lump, changes in the nipple and breast shape or size change.Changes in the skin:
Breast skin irritation, puckering, dimpling and redness signifies the cancer in the breast.
Thickening or lump:
A thickening or lump in the underarm or breast is the most often happening symptom in breast cancer.
Changes in the nipple:
The retracted nipple, discharge, pain or some other uncommon changes occur in breast cancer.
Breast shape or size change:
The change in the shape or size of either one or both of the breasts are noticed here.
Factors influencing breast cancer:
The reasons for the majority of breast cancers are not known but, the most common causes include hormonal factors, environmental factors, genetic mutations in certain genes and lifestyle choices.Hormonal factors:
The hormonal factors involve hormone replacement therapy, childbearing, breastfeeding, early menstruation, oral contraceptives and late menopause.
Hormone Replacement Therapy (HRT):
Longtime processing of HRT, particularly, combinations of progesterone and estrogen may elevate breast cancer occurrence.
Childbearing:
Geriatric pregnancy or women who do not have kids are prone to breast cancer compared to the other women.
Note:
Geriatric pregnancy is defined as the pregnancy in a woman who is 35 or above 35 years of old.
Breastfeeding:
Women who are not involved in breastfeeding are prone to breast cancer.
Early menstruation:
Girls whose body starts the menstrual cycle before the age of 12 are likely to have breast cancer.
Oral Contraceptives:
Women who were under medication but recently paused the intake of pills are prone to breast cancer.
Late menopause:
The continuation of the menstrual cycle even after the age of 55 in women is at a greater risk for breast cancer.
Environmental factors:
The environmental factors include some chemicals, radiation exposure and pollution of air.
Some chemicals:
The contact of certain chemicals such as sunscreen and contaminated water increase the occurrence rate of breast cancer.
Radiation exposure:
The exposure of women to radiation particularly during the days of adolescence may increase the risk for breast cancer.
Pollution of air:
The inhalation of the contaminated air by the women can increase the rate of occurrence of breast cancer.
Genetic mutations:
The genetic mutations in the p53, oncogenes, HER2/neu, BRCA1 and BRCA2 gene result in cancer. The BRCA1 and BRCA2 genes are also responsible for DNA repair. The types of mutations that occur in breast cancer include loss of heterozygosity (LOH), epigenetic silencing and point mutations.
Genetic mutations in p53, oncogenes and HER2/neu:
The mutation in p53 enhances the tumor formation as its original function is to inhibit the tumor development. So, it is called a tumor suppressor gene (before mutation). The oncogenes are genes that promote tumor growth. One such example is HER2/neu as its overexpression induces the growth of the tumor.
Genetic mutations in BRCA1 and BRCA2 gene:
The mutations in either one or both the genes elevates the risk for breast cancer in women.
DNA repair:
The BRCA1 gene recruits the BRCA2 gene which in turn results in the interaction of RAD51 protein that is essential for HR (in strand invasion). It is also involved in the processing of the damaged site prior to the recruitment of the BRCA2 gene.
Types of genetic mutations:
The loss of heterozygosity (LOH) involves the mutation of a single copy of a gene either due to chromosomal rearrangement or deletion that indirectly suppresses the tumor suppressor genes. The epigenetic silencing involves the silencing of the genes by altering the gene expression such as DNA methylation, but not the DNA sequences. The point mutations include single nucleotide mutations that either result in the inactivation of the tumor suppressor genes or activation of the oncogenes.Lifestyle choices:
The lifestyle choices include lack of physical activity, consumption of alcohol, obesity and diet.
Lack of physical activity:
The lack of physical activities like running, exercise could lead to breast cancer.
Consumption of alcohol:
The intake of alcohol even at a moderate level elevates the risk for cancer.
Obesity:
The women who are obese are with high levels of estrogens in them which in turn is a greater risk for breast cancer.
Diet:
The diet with more levels of processed foods and the intake of the eatables with high fat levels are at a greater risk for breast cancer.
Mechanisms and cell biology:
The mechanisms involved in the development of cancer include apoptosis evasion, metastasis and angiogenesis.
Apoptosis evasion:
It is the process where the cancer cells escape from the apoptosis which is nothing but programmed cell death. It happens when there is nutrient deprivation, hypoxia etc.,
Metastasis:
It involves the spread of cancer cells to distant sites from the primary tumor in the body of the affected person.
Angiogenesis:
It is the process of formation of new blood vessels that deliver nutrients and oxygen to the tumor cells for their growth and proliferation ultimately leading to apoptotic evasion and metastasis.
Types of breast cancer:
The major types of the breast cancer include Invasive Lobular Carcinoma (ILC), Inflammatory Breast Cancer (IBC), Angiosarcoma, Lobular Carcinoma In-Situ (LCIS), Invasive Ductal Carcinoma (IDC), mixed tumors, Metastatic Breast Cancer, HER-2 Positive Breast cancer, Paget's Disease of the nipple, Triple Negative Breast cancer and Ductal Carcinoma In-Situ (DCIS).
Invasive Lobular Carcinoma (ILC):
It forms first in the glands which produce milk and then spread to the surrounding breast tissues. It is the second most common type of cancer.
Inflammatory Breast Cancer (IBC):
It is noticed by the swelling of the breast which appears inflamed and red as they block the pathway of the lymph vessels. It is diagnosed only at a later stage and is a rare breast cancer type.
Angiosarcoma:
It also blocks the pathway of the blood and the lymph vessels. It is also a rare type of breast cancer.
Lobular Carcinoma In-Situ (LCIS):
It is not a disease but a disorder which can increase the occurrence of breast cancer.
Invasive Ductal Carcinoma (IDC):
It is the first most common breast cancer type. It can potentially spread to the surrounding tissues of the breast and initiates in the milk producing glands
Mixed tumors:
It has the properties of both the IDC and ILC.
Metastatic breast cancer:
It is the fourth stage of the breast cancer in which the cancer cells spread to all the body parts of the women including liver, bones, lungs etc.,
HER-2 Positive Breast Cancer:
It has more of the HER-2 protein in promoting the growth of the cell and is mostly aggressive.
Paget's disease of the nipple:
It is a rare breast cancer type and it targets and damages the areola and nipple skin.
Triple Negative Breast Cancer:
It is not a main type but a subtype which does not possess the receptors for progesterone and estrogen the HER2 protein is not overexpressed.
Ductal Carcinoma In-Situ (DCIS):
It remains within the milk ducts and does not spread to the other body parts. It is easily treatable.
Diagnosis:
Several biomarkers are used for the detection of breast cancer. They are circulating biomarkers, protein biomarkers and others. The reoccurrence of Breast cancer can be diagnosed by gene expression profiling such as the Oncotype DX test. It predicts breast cancer in its early stage which is called hormone receptor positive, HER2 negative breast cancer. Some of the common techniques used for the diagnosis of breast cancer include Fluorescence in situ hybridization (FISH), biopsy, PCR, mammography and immunohistochemistry (IHC). A few of them are molecular imaging and diagnostic techniques.
Circulating biomarkers:
CfDNA (Circulating cell free DNA), CTC (Circulating Tumor Cells) and miRNAs are the circulating biomarkers in the human blood and are used for the detection of breast cancer.
Protein biomarkers:
CA 27.29, CA 15-3 and CEA (Carcinoembryonic antigen) are the protein biomarkers used for the detection of breast cancer.
FISH:
The fluorescent probes are used to diagnose breast cancer here. The amplification of HER2 gene takes place for conformation of breast cancer.
Biopsy:
A few breast tissue samples are extracted from the patient and are examined using some of the techniques like PCR, IHC and FISH.
PCR:
This molecular technique is used to amplify particular DNA sequences especially, HER2 gene.
Mammography:
The use of X-Ray is done to detect breast cancer. For the women who are below age 35, ultrasound is an additional method to diagnose breast cancer as they have breasts which are much denser.
IHC:
In this method, the antibodies are utilized to diagnose specific tissue samples. It is used to diagnose estrogen receptor, progesterone receptor and HER2.
Treatment and Prevention:
The treatment methods include chemotherapy, gene therapy, surgery, targeted therapy, radiation therapy, and hormone therapy. Mostly, the targeted therapy plays a major role in personalized medicine in the treatment of breast cancer.
Gene therapy:
The RNAi and CRISPR techniques enable for the silencing and editing of the genes responsible for breast cancer respectively.
Surgery:
Prophylactic mastectomy is a surgical procedure which involves the removal of one or two breasts from the affected patient.
Targeted therapy:
It involves the targeting of CDK (Cyclin Dependent Kinases) and cyclins which bind to CDK proteins and proliferate cell division and uncontrolled tumour growth. The CDK4/6 inhibitors target the CDK proteins and prevent the proliferation of cancer cells . It also includes the use of monoclonal antibodies like Herceptin which is utilized by the HER2 positive breast cancer affected person to target the HER2 protein. The monoclonal antibodies such as Trastuzumab which are also known as Herceptin are bound to the HER2 protein which is more overexpressed in the breast tissues of the affected patients. This specific targeted binding of Herceptin to HER2 inhibits the tumour growth.
The preventive measures include following a healthy lifestyle by properly exercising, eating healthy food, breastfeeding and a very low level of alcohol consumption. The screening programs and genetic counseling involves the predictive measures taken by the children of the carrier patients who carry the genes for the development of breast cancer.
