Breast cancer is the malignant tumor (a tumor with the potential to invade other tissues or spread to other parts of the body) that starts in the cells of the breast. It occurs both in men and women. However male breast cancer is rare [1,2].
What is breast?
A woman’s breasts contain specialized glands that can produce milk. The breast structure consists of 15-20 lobes. Each lobe is made up of many smaller lobules which have groups of tiny glands that can produce milk. The milk travels through a network of tiny tubes (ducts) to a reservoir that lies just below the nipple. The dark round area of skin surrounding the nipple is called the areola. The breast also contains blood & lymph vessels and lymph nodes.
The Lymph System of the Breast
One of the main ways breast cancer spreads is through the lymphatic system. Lymph vessels carry a clear fluid called lymph which drains into lymph nodes. Lymph nodes are small bean-shaped structures which contain cells that fight infections (immune system cells). Lymph vessels from the breast drain into the axillary lymph nodes and supraclavicular lymph nodes.
Burden of the disease
Among Indian women, breast cancer is the commonest cancer in Indian women overall [3,4].
The information given here is for female breast cancers.
In 2018, 1,62,468 new cases and 87,090 deaths were reported for breast cancer in India .
Are you at risk?
A risk factor for breast cancer is anything that increases your chance of getting breast cancer.
Having a risk factor does not mean that you will definitely develop breast cancer.
Risk factors you cannot change (“non-modifiable”) 
Gender: If you are a woman, you are more likely to develop breast cancer than men. This may be due to more exposure to hormones which promote breast cell growth (such as estrogen and progesterone).
Age: Your risk of breast cancer increases as you age. A study in North India reported that the average age of the patient at presentation was between 45 and 50 years.
Family history of cancer: Your risk of breast cancer increases, if your mother, sister or daughter was diagnosed with breast cancer, particularly at a young age. Your risk also increases if your father or brother had breast cancer. However, the majority of people with breast cancer have no family history . Read More
Genetic Factors: If you have inherited certain rare gene mutations from parents, you are at an increased risk for breast cancer. The most common known gene mutations observed in people with breast cancers are in the BRCA1 and BRCA2 genes. Having these mutated genes does not necessarily mean that you will get breast cancer.
Breast cancers linked to BRCA1 and BRCA2 mutations occur more frequently in younger women and more often affect both breasts compared to cancers that are not linked to these mutations. Women with these inherited mutations also have an increased risk for developing ovarian cancers. Genetic tests are available to look for these mutant genes that are linked with breast cancer. Genetic tests are not recommended for everyone. You should discuss with your doctor if these genetic tests are helpful in your case.
Menstrual History:Having your first period at a younger age (before age 12) increases your risk of breast cancer. Likewise attaining menopause at an older age increases your risk .
Past history of breast cancer: If you have had breast cancer in one breast earlier, you have an increased risk of developing cancer in the other breast.
Risk factors you can modify (life style related)
Obesity: Being obese increases your risk of breast cancer . Read More
Pregnancy : Women who have never been pregnant have a greater risk of breast cancer than women who have had one or more pregnancies. Also, giving birth to a child after the age 35 may increase the risk of breast cancer compared to women who give birth earlier .
Lactation: Lack of or shorter duration of lactation increases the risk of breast cancer .
Drinking alcohol: Drinking excessive alcohol increases the risk of breast cancer.
Hormone intake: Women treated to get relief from menopausal symptoms with combined estrogen and progesterone hormone therapy medications (hormone replacement therapy) have an increased risk of breast cancer . The risk decreases when women stop taking these medications.
Radiation exposure: Moderate to high-doses of exposure to ionizing radiation exposure or receiving radiation treatment to your chest area as a child or young adult, increases the risk of breast cancer.
How can it be prevented?
Prevention by changing lifestyle-related risk factors 
Maintain ideal body weight
Quit smoking and excessive alcohol consumption
Breast-feed the baby
Avoid unnecessary radiation exposure.
Prevention By Genetic Testing 
If you have a history of breast cancer in the family (either mother, sister or daughter with breast cancer), you can have genetic testing for the presence of BRCA1 and BRCA2 gene mutations. However, having a copy of mutated gene does not mean that you will certainly get breast cancer. If the genetic tests are positive, you may require genetic counseling and advice by your attending surgeon.
When should you consult a doctor?
Breast Cancer Signs and Symptoms
The most common symptom of breast cancer is a new mass or lump in the breast. If you have a hard mass, it is more likely to be cancerous [14,15]
Any change in the breast or nipple appearance [16,17]
Unexplained change in shape or size of the breast
Unexplained shrinkage of breast
Unexplained swelling of the breast, especially on one side only
Recent unevenness of the breasts (It is normal for women to have one breast slightly smaller than the other, but if this asymmetry is a recent one, then consult your doctor)
Dimpling anywhere on the breast
Sunken or inverted nipple
Redness or scaling of the skin of the breast, nipple or areola
Uneven areas or pores on the skin that resemble an orange peel.
Clear or bloody discharge other than breast milk 
Swelling of lymph nodes/glands in armpits or around collar bone.
You can check for these signs of breast cancer by examining your own breast every month. If you find anything abnormal, consult your doctor and get yourself clinically examined .
Are there tests for early detection?
Early Detection [21,22]
Clinical breast examination (CBE)
CBE is recommended for all women once a year after 30 years of age.
A clinical breast exam (CBE) is an examination of your breasts by a health professional such as a doctor, a nurse or medical social worker.
The health professional will first look carefully at your breasts for abnormalities/changes in the nipple, skin, size or shape of the breasts.
Then, using his or her fingers, the examiner will feel (palpate) your breasts for the presence of any lumps. S/he will also examine the area under both arms for any swelling of your lymph nodes.
Breast self-examination (BSE)
You should have a clear knowledge of how your breasts look normally. Feel your breasts and seek medical advice promptly if any change in the breast is noticed.
BSE is a suggested option for women above age 20 years to look for early signs of breast cancer.
There are Five Steps of Breast Self-Exam (BSE).
Stand in front of the mirror with your shoulders straight and arms on hips and look at your breasts
Are they their usual size, shape, and colour?
Is this any visible distortion or swelling? Consult doctor if there is :
dimpling, puckering, or bulging of the skin
changed position or an inverted nipple (pushed inward instead of sticking out)
redness, rash, or swelling of the breasts
Now, raise your arms and look for the same changes.
Look for any dimpling of skin or in-drawing nipple.
While you’re at the mirror, gently squeeze each nipple between your finger and thumb
Consult doctor if nipple discharge is milky or yellow fluid or blood.
Lie down and use your right hand to feel your left breast and then your left hand to feel your right breast.
Use a firm, smooth touch with the pad of your 3 middle fingers, keeping the fingers flat and together.
Cover your entire breast from top to bottom, side to side; from your collar bone to the top of your abdomen and from your armpit to your cleavage.
Begin at the nipple, moving in larger and larger circles until
you reach the outer edge of the breast. Also move your fingers up and down vertically, in rows.
Begin examining each area with a very soft touch, and then increase pressure feel the deeper tissue.
Feel your breasts while you are standing or sitting.
It is easier to feel your breasts when their skin is wet and slippery (like while taking bath).
Cover your entire breast, using the same hand movements described in Step 4.
Do Monthly Breast Self Examination!
As recommended by clinician
How can it be diagnosed?
Breast Self Examination (BSE): It can be done at the comfort of your own home.
Women who are menstruating – Every month BSE should be done 7 days/ 1 week after the menses have stopped.
Post menopausal – On a fine day every month.
Breast Cancer Diagnosis 
Clinical Breast Examination: A doctor examines your breasts and under arm area for any lumps by palpation. Nipples are examined for any suspected discharge, skin changes and retraction.
Mammogram: A mammography machine uses low-dose x-rays to take images of your breast. First the machine compresses each breast and takes x-ray images on film. This is commonly used for early detection of breast cancer.
Breast Ultrasound: In this procedure, a device sends high frequency sound waves through your breast. The sound signals received from tissues are converted into pictures on computer screen. These images allow the doctor to look for any abnormality.
MRI Scan: In this procedure, a high-powered magnet and a computer is used to scan and to create detailed images of the breast and surrounding organs. Breast MRIs are recommended only in specific cases where mammogram information is insufficient.
Fine needle aspiration biopsy/cytology (FNAB/FNAC): After a positive physical examination/ ultrasound or mammogram, a small piece of tissue/fluid is taken from an abnormal finding area of the breast and examined for cancer cells using a thin needle and a syringe without using anesthesia.
Core needle breast biopsy: A larger, hollow needle is inserted into the breast lump and cylindrical piece of breast tissue (core) is taken out for histopathological examination to confirm cancer. A core biopsy provides more breast tissue for examination than FNA.
Surgical (open) biopsy: Occasionally, surgery may be recommended to remove a part or whole breast lump to check for cancer. This is performed under anesthesia.
Nipple discharge cytology (nipple discharge exam): A sample of fluid or discharge from the nipple is examined under the microscope to look for cancer cells. Even if the nipple discharge cytology result is negative, the surgeon may go in for other tests if there is a clinical suspicion.
Staging and Treatment
(i) Breast Cancer Staging 
Breast Cancer staging is based on following parameters:
The size of the lesion/lump/tumor
Whether the cancer is localized to breast only
Whether cancer has spread to the lymph nodes
Whether the cancer has spread to other parts of the body beyond the breast
TNM staging system
The TNM system takes in to account.
Tumor size (T stands for tumor)
Lymph node involvement (N stands for node)
Whether the cancer has metastasized (M stands for metastasis), or moved beyond the breast to other parts of the body.
(ii) Treatment of Breast Cancer
Different ways to treat breast cancer include
Your individual treatment is planned based on following factors:
Clinical stage of breast cancer
Histopathologic grade of cancer
Presence or absence of hormone receptors
Overall general health
Surgery for Breast Cancer
Different types of surgery are as follows:
Lumpectomy: Only the lump/tumor or area of cancer is removed
Quadrantectomy: About a quarter of the breast tissue involved by the tumor is removed
Simple mastectomy: Removal of the breast tissue (including the skin and the nipple) and the tissues that cover the chest muscles
Radical mastectomy: Removes the muscles of the chest wall along with the structures mentioned in mastectomy
Modified radical mastectomy: Removal of breast, nipple, lymph nodes in armpit but chest wall muscles are spared
Radiotherapy for Breast Cancer
Radiotherapy treatment uses ionizing radiation to destroy cancer cells. It is a common treatment for breast cancer after surgery. After breast-conserving surgery (lumpectomy or wide local excision), women usually have radiotherapy to the whole of the remaining breast tissue.
External beam radiation: This is the most commonly used type of radiotherapy for breast cancer. External beam radiation works by focusing a beam of radiation from a machine to its target, the area of the body affected by cancer.
Brachytherapy: This type of radiotherapy uses an implant to deliver radiation to the cancer site. For breast cancer, radioactive seeds or pellets are placed inside the breast near the cancer.
Chemotherapy for Breast Cancer
Chemotherapy refers to the use of anti-cancer drugs to kill breast cancer cells. Chemotherapy can be used for three major purposes:
Adjuvant therapy: The goal is to prevent or postpone cancer from coming back after the initial surgery and radiation.
Neo-adjuvant therapy: The chemotherapy drugs are given before the surgery to shrink the tumor to make the surgery easier.
Treatment of metastatic disease: Chemotherapy can be one of the main ways to kill cancer cells that have spread to other parts of the body. Read More>>
Hormone Therapy for Breast Cancer
Hormone therapy is used in women with certain types of breast cancer whose tumors are sensitive to estrogen or progesterone (hormones that cause the cancer to grow). Not all breast cancers are hormone-sensitive, so not all breast cancers will respond to a hormone-blocking treatment.
These drugs slow or stop the growth of cancer cells possessing hormone receptors. As an add-on therapy, endocrine therapy helps prevent the original breast cancer from returning and also helps reduce the risk of the development of new cancers in the other breast.
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 Collaborative Group on Hormonal Factors in Breast Cancer. Menarche, menopause, and breast cancer risk: individual participant meta-analysis, including 118,964 women with breast cancer from 117 epidemiological studies. Lancet Oncol 2012;13:1141-51
 Vrieling A, Buck K, Kaaks R, et al. Adult weight gain in relation to breast cancer risk by estrogen and progesterone receptor status: a meta-analysis. Breast Cancer Res Treat 2010;123:641-49
 Ewertz M, Duffy SW, Adami HO, et al. Age at first birth, parity and risk of breast cancer: a meta-analysis of 8 studies from the Nordic countries. Int J Cancer 1990;15;46:597-603
 Collaborative Group on Hormonal Factors in Breast Cancer. Breast cancer and breastfeeding: collaborative reanalysis of individual data from 47 epidemiological studies in 30 countries, including 50?302 women with breast cancer and 96,973 women without the disease. Lancet 2002;360:187-95
 Rinaldi S, Peeters PHM, Bezemer ID, et al. Relationship of alcohol intake and sex steroid concentrations in blood in pre- and post-menopausal women: the European Prospective Investigation into Cancer and Nutrition. Cancer Cause Control 2006;17:1033-43