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Causes of Breast Cancer by Your Healthy Life

It is another amazing day to you all as Your Healthy Life Website hits a modest visit to the world of Oncology, the branch of medicine that deals with cancer. In this article, we shall pay more attention to the causes of breast cancer, the risk factors associated with this form of cancer without ignoring a brief overview of the breast anatomy.

Breast cancer also called breast carcinoma is the uncontrollable growth of cells found in the breast. Cancer of the breast is the second most common cancer in women and the second most fatal cause of cancer deaths in ladies after cancer of the lungs.

According to the American Cancer Society (ACS), carcinoma describes cancer that arises in the lining layer (epithelial cells) of organs e.g. the breast.



Breasts are milk-producing glands located on the chest wall each on one side of the breastbone. The breast is made up of three parts:


  • It functions in the production of milk.
  • Consists of 12-20 sections called lobes.
  • Each lobe is divided into smaller lobules. The lobule is the gland that produces milk.
  • The lobule also contains a grape-like structure called the alveoli, which are modified sweat glands.
  • In the alveoli lies the alveolar cells that secrete breast milk into the lumen, a space found in the centre of the alveoli. The alveoli possess unique cells called myoepithelial cells that squeeze and push the milk out of the lumen.
  • This milk moves down through special ducts called lactiferous duct and then through one of the pores found in the nipples.
  • The milk duct connects the lobe and lobules and acts as a tube delivering milk to the nipple.


  • This surrounds the glandular tissue.
  • It contains adipose or fat tissue and makes up most of the breast.
  • There are also suspensory, or Cooper’s ligaments located in the stroma which keep it in position.
    Breast anatomy by Your Healthy Life


  • They lie beneath the skin covering the breast and drain the lymph.
  • The lymph is a fluid that makes up the white blood cells and cellular waste products.
  • Draining of the lymphatic vessels forms the lymph nodes that usually find themselves in the armpit or axilla.


Them main causes of breast cancer are a bit complicated and quite challenging for physicians and experts. Oncologists can’t properly explain why a lady may have breast cancer and another woman may not.

Breast carcinoma usually begins in the breast cells where cancer or malignant cells invade the surrounding breast tissues which then later spread or metastasize to other regions of the body.

Generally, the cells that constitute the glandular tissue have binding sites or receptors for hormones like estrogen and progesterone secreted by the ovaries, and prolactin released by the pituitary gland. All these hormones (estrogen, progesterone, and prolactin) trigger the alveolar (milk-producing glands) cells to divide and increase in number. Consequently, the lobule increases in size. Thus, the presence of estrogen and progesterone create a risky atmosphere for the alveolar cells which often undergo programmed cell death, a condition medically known as apoptosis.

Then production of estrogen ceases after menopause causing the alveolar cells to die. As a result, the breast tissues, after some time, become replaced by fat tissues. Moreover, the production of estrogen and progesterone from the ovaries increases during a lady’s menstrual cycle but slows down after menstruation. This makes the alveolar cells to divide and apoptosize (die).

Specific breast carcinoma also has mutations in the ERBB2 gene that may rocket human epidermal growth factor receptors (organs or cells that respond to heat, light, or some external stimulus which may cause growth in this case, and transmit signals to sensory nerves), or HER-2, which when activated promote the growth of cells.

Once these mutations causing cancer do occur, the affected cell which is likely an epithelial cell that lines the lobules and ducts begin to grow uncontrollably arising to a tumour. Initially, this tumour is called in-situ carcinoma and is located within the alveolar basement membrane.

Tumour may consist of the following types:

  • Ductal carcinoma In-Situ (DCIS) where the tumour cells grow from the walls of the ducts into the lumen. Failure to treat DCIS over some time, these tumour cells can bypass the alveolar basement membrane transforming to Invasive Ductal Carcinoma IDC. Moreover, DCIS can proceed along the lactiferous (milk) duct and through the pore onto the skin over the nipple. This condition is termed Paget’s disease of the breast. Note that In-Situ means in its original place (or localised)
  • Lobular Carcinoma In-Situ (LCIS) where several tumour cells grow within the lobules or milk-producing glands. They do not invade the ducts but cause the affected alveolar to increase in size. Unlike DCIS, LCIS doesn’t cross the basement membrane over time to form Invasive Lobular Carcinoma (ILC). For this reason, the American Cancer Society terms Lobular Carcinoma In-Situ as Lobular neoplasia.

However Invasive Lobular Carcinoma, ILC can arise when tumour cells invade one of the breasts lobules and later metastasize or spread to other parts of the breasts. This condition maybe found in both breasts, unlike in the other types of Breast Cancer.

Other types of breast carcinoma include:

  • Inflammatory breast cancer.
  • Angiosarcoma.
  • Recurrent breast cancer.


As earlier said, oncologists find it challenging to explain why some ladies develop breast cancer and some don’t. There are, however, risk factors that are known and capable of affecting a woman’s likelihood of being affected with cancer of the breast. A risk factor is any circumstance that can improve your chances of getting an infection. Some of these factors can be managed or controlled as some remain uncontrollable.

i) Uncontrollable Risk Factors for Breast Carcinoma.

a) Family History and Inherited Genes.

Ladies whose close relatives have had cancer of the breast are likely at risk of acquiring it as some cancer cases do run in their families.

The National Cancer Institute reports that breast carcinoma is also linked to specific inherited mutations in tumour suppressor genes. These genes include BRCA-1, BRCA-2, and TP53. These genes slow cell division and cause cells to undergo apoptosis (programmed cell death) if they divide uncontrollably. Mutations in BRCA-1 and BRCA-2 are both autosomal mutations (that is, if a girl gets the gene from a single parent, she may have the mutation) which can be inherited and later generate to familial breast cancer as well as ovarian cancer. A mutation is a process whereby the DNA sequence is altered or changed due to a mistake that occurred during DNA replication(copying) or due to environmental factors like UV light and cigarette smoking.

b) Menstrual Cycle:

The Cell Theory proposed by Schleiden and Schwann states that, cells are the fundamental unit of structure and function of all living organisms and that cells arise from preexisting cells by cell division. Each moment of cell division may lead to genetic mutation and mutation further generates to tumour formation. The more menstrual cycles that take place in a woman’s lifetime, the more tumour formation that lady is bound to encounter, and hence the likely increase in risks of breast cancer she may be exposed to. Examples of cases that may warrant a lady to experience more menstrual cycles include early age menarche (that is early first menstrual bleeding, usually below 12) and late age of menopause.

c) Dense Breast Tissue:

Breast density is the amount of breast tissue with respect to fat tissue found in a woman’s breast. Those with an increased quantity of breast tissue possess a higher amount of breast density and are more prone to cancer of the breast. Breast density is usually measured using a mammogram. It’s important to note that physicians find it quite challenging scanning breasts having denser tissues as this proves difficult to read using the mammogram due to the blurred areas of abnormal tissue.

d) Age:

Being one of the highly ranked risk factors for breast cancer in women, the older a lady becomes, her risk of developing cancer amplifies. This is absolutely true for women above 50 and those embracing menopause as many researchers report that about 8 out of 10 cases of breast carcinoma come from women above 50.

e) Non-Cancerous Breast Implications:

Benign or non-cancerous breast conditions rarely increase the risk of breast carcinoma. Examples of these cases include Hyperplasia with little or no symptoms of lump and pain, Atypical (not typical) hyperplasia where cells lining the ducts or lobules rapidly divide forming an unusual shape and pattern., Lobular neoplasia which is a benign condition where the lobular cells rapidly divide.

f) Earlier Breast Cancer or Lump:

Ladies who have been affected with breast in the past or have had early non-invasive cancer cell changes in their breast ducts may have a high risk of acquiring cancer of the breast either in the other or the same breast.

g) Gender:

The Harvard Medical School ranks this among the strongest risk factors for breast carcinoma. Though men can acquire breast cancer, it is rarely common since they have some breast tissue but lack secreting alveoli. In males, breast carcinoma is caused by inherited mutations in the BRCA-1 and BRCA-2 genes. Women are more prone to breast cancer because their breasts are more liable to estrogen and progesterone that triggers abnormal growth of cells.

ii) Risk Factors You Can Control:

This can be made up of two types.

1. The lifestyle of women.

Ladies who decide to control and manage the way they live and how they expose themselves to their environment will be less likely prone to the risks of getting cancer of the breast. However, we aren’t saying the lady will not develop cancer. Some of these factors here include:

a) Radiation:

Ladies who have been exposed to environmental factors like ionizing radiations from X-rays or CT (computerised tomography) scans, probably during radiotherapy on their chest, may slightly have an increased risk of developing cancer of the breast.

b) Smoking:

Smoking has been reported to cause several illnesses that are connected to a higher risk of breast carcinoma in younger, premenopausal, and postmenopausal females. This risk factor greatly rises in females with a family history of breast cancer.

c) Alcohol:

Women who drink a lot of alcohol and those who drink little alcohol on regular bases may likely be exposed to breast cancer. The higher the amount of alcohol a woman consumes, the more likely she is at risk of having breast carcinoma.

d) Obese Ladies:

Those with overweight or obese females are likely at greater risk of been visited by cancer of the breast compared to women with less weight. This is especially true after menopause where the production of estrogen is ceased by the ovaries and most estrogen is gotten from fat tissues. So obese ladies or females with more fat tissue release more estrogen subjecting themselves with a higher risk of breast carcinoma. Obese women are also affirmed to have higher insulin levels which are associated with some breast cancer.

e) Exercise:

Lack of exercise makes a lady less active and may be overweight. This makes her more liable to suffer from breast carcinoma. Nonetheless, women who keep it active for about 20-30minutes per day are less likely to develop cancer of the breast.

f) Pregnancy and Breastfeeding:

Pregnancy in the long run and breastfeeding are reported to slightly reduce the risk of breast cancer. Many pregnancies and early pregnancies also reduce the risk of ladies having breast carcinoma since estrogen production has been interrupted. Having a child at a later age like early 30s or never having a baby, subjects a lady at a higher risk of developing breast carcinoma. Breastfeeding reduces the total number of a lady’s menstrual cycles.

2. Hormones Risk Factors and Breast Carcinoma:

a) Estrogen And Progesterone.

The higher the levels of endogenous (made by the ovaries) estrogen and progesterone in a woman’s blood, the greater the risk she faces of having breast carcinoma. The ovaries make most of the estrogen before menopause or during puberty to regulate periods. High levels of estrogen are usually due to early menarche (first menstrual bleeding), late menopause, childlessness, and late pregnancy.

b) Hormone Therapy.

This is a form of treatment that relieves symptoms caused by menopause. Two main types here include combined hormone therapy (HT) and Estrogen replacement (or Estrogen) therapy (ET). Combined HT involves estrogen plus progestin, a synthetic version of progesterone, and when used as a treatment after menopause, usually in a period of about four years, makes ladies more exposed to risks of developing cancer of the breast. Dr. Wendy Chen from Harvard Medical School states that the risk continues over time and does not plateau. Progesterone is added here because estrogen-alone may increase the risk of uterine cancer.

Estrogen therapy (ET) is often recommended for ladies who have had their uterus removed (hysterectomy), otherwise estrogen will increase the woman’s risk of cancer of the uterus. Nonetheless, ET slightly increases the risk of breast cancer and not as compared to combined HT. The estrogen-only therapy (ET) tends to be higher in normal-weight females with respect to obese women since overweight ladies are already at higher risk of breast cancer due to their peak amount of estrogen in their blood.

It is worth noting that vaginal estrogen poses no risk of breast cancer.

c) Diethylstilbestrol (DES).

This is a form of estrogen that was given to some pregnant ladies between 1940-1971 in the US to prevent miscarriages, premature labour, and other pregnancy-related problems. Women who took DES were at a higher risk of getting cancer of the breast, so were females whose mothers took these drugs while pregnant for them.

For more insights into the risk factors associated with breast carcinoma, kindly visit the American Cancer Society here.


None Risk Factors of Breast Carcinoma.

The following do not cause breast cancer: Deodorant, cell phones, contact with someone with breast cancer, multiple pregnancies, caffeine, hair dye, wearing underwear bras, having an abortion or miscarriage, using breast implants.


To make this long carcinogenic story short, as the causes of breast cancer prove a tough one for many physicians, the risk factors outlined above tend to play a significant role in the numerous types of breast carcinoma. And when women and their health care providers do their very best to quell the aggressiveness of these risk factors, so will be the occurrence of these breast tumours.

Your Healthy Life will be most elevated as you contribute your opinion concerning this work and for any doubts, kindly drop your worries in the comment box below.


Medically reviewed by Dr. Emmanuel Sako and Dr. Mbam Leonard.