Cancer means the presence of abnormal cells that are growing in an uncontrolled way. In breast cancer, cells can stay in the breast or spread throughout the body through blood or lymph vessels. Most of the time, the progression of breast cancer takes several months and even years.

Breast cancer is the most diagnosed cancer in women around the world, both before and after menopause. One in 9 women will develop breast cancer in her lifetime and 1 in 27 women will die from it.

Most often, breast cancer occurs after the age of 50. The 5-year survival rate after diagnosis ranges from 80% to 90%, depending on the age and type of cancer.

The number of people affected has increased slightly but steadily over the past 3 decades. However, the death rate has steadily declined over the same period, thanks to advances in screening, diagnosis and treatment.

Note that men can also be affected; they represent 1% of all cases.

On the breast

The breast is made up of fat, glands and ducts. The glands, arranged in lobules, produce the milk, and the ducts (lactation ducts or milk ducts) are used to transport the milk to the nipple. Breast tissues are influenced by hormones produced by women in variable quantities throughout their lives (puberty, pregnancy, breastfeeding). These hormones are estrogen and progesterone.

Types of breast cancer

There are different types of breast cancer classified into two categories: non-invasive and invasive cancers. The most frequent are glandular cancers or adenoarcinomas (95%) which develop from the cells of the ducts (ductal cancer) and lobules (lobular cancer). Eight out of ten cancers are ductal cancers.

Non-invasive cancers

Ductal carcinoma in situ. It is the most common type of non-invasive breast cancer in women. As the name suggests, it forms inside the lactation ducts of the breast. This type of cancer has been diagnosed much more frequently with the more widespread use of mammography. Treatment for this cancer leads to a cure in almost all cases. Normally it does not spread. In exceptional cases, without treatment, it may continue to grow and become “invasive” and therefore spread outside the lactation ducts.

Invasive or infiltrative cancers

These forms of cancer invade the tissues around the lactation ducts, but remain inside the breast. However, if the tumor is left untreated, it can spread to other parts of the body (for example, bones, lungs or liver) causing metastases.

  • Ductal carcinoma. It forms in the lactation ducts. Cancer cells pass through the wall of the ducts;
  • Lobular carcinoma. Cancer cells appear in lobules grouped together in the lobes. Then, they cross the wall of the lobules and disseminate in the surrounding tissues;
  • Inflammatory carcinoma. A rare cancer that is primarily characterized by a breast that can become red, swollen, and hot. The skin of the breast may also take on the appearance of orange peel. This type of cancer progresses faster and is more difficult to treat;
  • Other carcinomas (medullary, colloid or mucinous, tubular, papillary). These types of breast cancer are rarer. The main differences between these types of cancer are based on the type of cells affected;
  • Paget’s disease of the Breast. A rare cancer that manifests as a small sore on the nipple that does not heal.

Causes of breast cancer

There are several known risk factors for breast cancer. However, in most cases, it is impossible to explain the reasons for its occurrence in a particular person.

Mutations in genes, passed on from generation to generation or acquired over the course of life (exposure to radiation or certain toxic chemicals, for example, can change genes) can cause cancer breast. The BRCA1 and BRCA2 genes, for example, are genes for susceptibility to breast and ovarian cancer. Women who carry mutations in these genes have a very high risk of cancer.

The chances of recovery depend on the type of cancer and how far it has progressed when the treatment is started. Various factors influence how quickly a tumor will grow.

Symptoms of breast cancer

  • A breast lump, whether fixed or mobile. This is the most common symptom, for both women and men. Most lumps found in the breast, however, are not cancerous;
  • Spontaneous discharge from the nipple;
  • Nipple retraction (the nipple is turned inward);
  • A change in the appearance of the skin on a breast: thickening or hardening (“orange peel”), unusual redness, warmth, change (peeling) of the skin around the nipple;
  • An unusual change in the size or shape of a breast.

keep in mind that several factors can influence breast tissue and change the appearance of breasts: pregnancy, the menstrual cycle, a cyst in the breast, an infection, etc.

People at risk

There are a number of things that cannot be changed that increase your risk of developing breast cancer. These elements of risk allow physicians to determine who could benefit the most from screening and preventive measures.

Main risk elements:

  • Female gender. Less than 1% of breast cancer cases affect men and they are usually over 60 years old;
  • Age. The disease very rarely affects women under 30. About 85% of cases occur at age 50 or older;
  • Family history. Having a mother, sister or daughter with breast cancer or ovarian cancer increases your risk of getting it. Between 5% and 10% of breast cancers are thought to be caused by an abnormality transmitted genetically. The main genes predisposing to breast (and ovarian) cancer are called BRCA1 and BRCA2. Normally, these genes protect against cancer. When they are defective, they can no longer perform their functions. There are tests to see if a woman from a family at risk is herself a carrier of a mutation in one of these genes;
  • Personal history. Having cancer in one breast increases the risk of a second cancer forming;
  • Have a risky lesion in the breast (diagnosed during a biopsy). Women who have a risky lesion, such as atypical intracanal epithelial hyperplasia or lobular carcinoma in situ, are more likely to develop breast cancer one day. Note that a cyst in the breast is not a risky lesion. It does not increase the risk of breast cancer;
  • Nulliparity or late pregnancy. Not having had a child or having given birth after the age of 35 increase the risk of breast cancer.

Other risk factors:

  • Increased exposure to natural estrogens. Early onset of first menstrual period (before the age of 12) or late menopause (after age 55);
  • Radiotherapy treatments. It is known that women who have received high doses of radiation to the chest (high intensity x-rays) have a higher risk of developing breast cancer, especially if the radiation therapy was given before age 30 years old.

Risk factors

In studies, the following modifiable factors have been associated with an increased risk of breast cancer. Note, however, that breast cancer can form in the absence of all of these risk factors.

Main risk factors:

  • Overweight or obesity after menopause. A weight gain of 20 kg or more doubles the risk of breast cancer. Thus, for every 1,000 overweight women, there will be 45 more cases of breast cancer;
  • Physical inactivity. Those who exercise less than 4 hours per week are at greater risk of breast cancer, regardless of their weight. In 1,000 women, there will then be 27 more cases of breast cancer;
  • Alcohol consumption. The more alcohol you drink, the greater the risk of breast cancer. The effect of consuming 2 glasses of alcohol per day is as powerful as that of being inactive. In 1,000 women, there will also be 27 more cases of breast cancer;
  • Taking hormone replacement therapy during menopause. Replacing sex hormones during menopause can increase the risk of breast cancer. This increase translates into 2 more cases in 1,000 women.

The American WHI study (Women’s Health Initiative Study), the first results of which were published in 2002, revealed that women who take a combination of estrogen and progesterone at menopause for more than 5 years slightly increase their risk of breast cancer. Five years after stopping hormone therapy, this increased risk is hardly visible. If hormone therapy is used for less than 5 years, the risk of breast cancer is not changed.

  • In the WHI study, the women took either conjugated equine estrogens and synthetic progestin orally, or conjugated equine estrogens alone (for those who had the uterus removed) or a placebo;
  • Those who took hormone therapy consisting only of estrogen were not at greater risk of breast cancer;
  • According to a cohort study conducted in France and published in 200817, women who use micronized progesterone (for example, Prometrium®) instead of a synthetic progestogen (like Provera®) would not see their risk of breast cancer to increase. It will take further studies to verify this.

Other risk factors:

  • The use of the contraceptive pill. Some studies show that taking oral contraceptives (the contraceptive pill) slightly increases the risk of breast cancer in women who use them for more than 4 years. However, this risk is no longer observable 10 years after having stopped using the contraceptive pill. Other studies on the subject have not established a link between the contraceptive pill and breast cancer. However, carriers of a BRCA gene mutation reduce the risk of ovarian cancer by taking birth control drugs.
  • Exposure to carcinogenic chemicals. Coming into contact with chemicals in the environment (organochlorine pesticides (DDT), parabens, etc.) could contribute to the formation of breast cancer. The cause and effect link is however very difficult to establish.

Psychological factors

The role of psychological state in the development of cancer is controversial. Certain personality traits have been linked in studies to an increased risk of cancer. However, other studies have contradicted this hypothesis.

Prevention of breast cancer

Good lifestyle habits (physical exercise, a healthy diet including eating enough vegetables and fruits, stopping smoking, moderate alcohol consumption, etc.) and maintaining a healthy weight help reduce the risk of several types of cancer, including breast cancer.

Of course, the fight against cancer does not only require individual actions but also collective actions: reducing the presence of chemicals in household products, reducing the use of chemical pesticides, developing cities to promote physical activity, etc.

Other measures to prevent the onset of the disease:

  • Based on the results of various studies, experts recommend people at risk to take a vitamin D supplement of 25 µg (1000 IU) per day in the fall and winter. People at higher risk of vitamin D deficiency — this includes the elderly, people with dark skin pigmentation and people who rarely get in the sun — should also do the same during the whole year. According to some studies, such vitamin D intake reduces the risk of prostate cancer, breast cancer and colorectal cancer.
  • In people at a very high risk of breast cancer (such as carriers of a BRCA gene mutation) and only in these, certain drugs are sometimes given for prevention.

Screening measures

These measures aim to detect the cancer as early as possible in order to stop its progression and, if possible, to cure it.

  • Observation of any anomaly. Watch for any changes to the breast: lump, discharge, nipple retraction, pain, etc. To do this, feel and watch your breasts regularly.
  • Clinical breast examination by a healthcare professional. It can help detect a mass not seen by the woman or not visible on the mammogram.
  • Mammography. The CDC recommends screening mammography at least every 2 years for women aged 50 to 74. Outside of this age group, the need for screening varies from woman to woman, depending on her personal risk factors. It is best to discuss this with your doctor. Women aged 40 to 49 should talk to their doctor when deciding whether to begin getting mammograms according to the CDC.
  • Breast ultrasound. Doctors sometimes suggest this test in addition to a mammogram, for example in women with very dense breasts or when the mammogram has not been successful. Ultrasound can also be performed as the first line in women under 40 who are at very high risk of breast cancer, due to genetic predispositions. This exam does not expose you to any radiation.
  • Other tests are sometimes offered, as appropriate. Among the tests being studied is elastography, an imaging technique that uses ultrasound.

Note: Thermography — developed in the 1960s in hopes of improving screening for breast cancer — was approved by the Food and Drug Administration (FDA) in 1982 provided it was used in addition to another screening method. However, at the beginning of the 1980s, we did not yet have powerful tools available to detect breast tumors. Thermography is obsolete these days and most doctors no longer use it. In 2000, the American College of Radiology ruled that it was of no use, even as an adjunct to mammography.

Treatment of breast cancer

Treatment depends on the type of cancer and its stage of development. Surgery is an integral part of the treatment of the vast majority of breast cancers.


A biopsy involves taking a sample of the tumor for examination. The tests performed on it will influence the choice of treatment. First the doctor needs to know if the tumor is cancerous and then if it is, know the type of cancer. Tests done on the tumor sample also tell the doctor how advanced the cancer is and whether its growth can be stimulated by sex hormones (that is, whether the tumor is “hormone-dependent”).

Here are 3 of the tests performed:

  • Estrogen Receptor Test to find out if cancer growth can be stimulated by estrogen;
  • Progesterone Receptor Test to find out if cancer growth can be stimulated by progesterone
  • HER2 test. In cases of invasive cancer only, a genetic test is done to determine the degree of activation of the HER2 gene. When this gene is strongly activated, it indicates that the cancer is likely to grow faster. This is the case for about 10% of invasive cancers.

There are 5 categories of treatments:

  • surgery;
  • radiotherapy;
  • chemotherapy;
  • hormonal therapy;
  • targeted therapy.


Surgery is often the first treatment undertaken. It is used to remove the cancerous tumor. In breast cancer, it is called a mastectomy. The mastectomy is partial or segmental (part of the breast is removed) or total (the entire breast is removed). Almost always surgery is added to the lymph nodes in the armpit. The choice of the type of mastectomy depends among other things on the size of the tumor, its type and its location in the breast. The preference of the woman is also taken into account.

  • Partial mastectomy or lumpectomy. The surgeon removes the cancerous tissue (tumor) as well as some healthy tissue around the tumor. It is also called breast conserving surgery;
  • Total mastectomy. The breast is completely removed: mammary glands, fatty tissue, nipple and skin. It is chosen when it is not possible to do a partial mastectomy. This is done in about 20% to 25% of breast cancer cases. Depending on the case, breast reconstruction can be performed at the same time as the mastectomy or at a later time;
  • Lymph node surgery. In order to determine the stage of the disease and to choose the best treatment after surgery, it is almost always essential to know whether the cancer has reached the lymph nodes in the armpit on the affected side. These nodes drain the lymph that circulates in the breast. This can be done either by removing only the first nodes in this chain (this is called a sentinel node (s) biopsy) or by removing the entire chain. This removal sometimes causes complications, such as lymphedema in one arm (affected side). Lymphedema is an accumulation of lymph caused by disruption of the usual drainage pathways. It less common in cases where only the sentinel nodes are removed.


Partial mastectomy usually needs to be followed by radiation therapy to destroy any cancer cells that may have remained in the breast. It reduces the risk of a tumor coming back.

Radiation therapy is not always necessary with total mastectomy.


Chemotherapy uses a class of drugs, called antineoplastics, to treat cancer. For breast cancer, it is usually given after surgery. It destroys cancer cells that have escaped from the main tumor. Whether or not to start chemotherapy depends on the stage of the disease.

Hormonal therapy

Hormone therapy is, most of the time, combined with surgery, radiation therapy or chemotherapy.

If examination of the tumor shows that the cancer has hormone receptors, its development is therefore stimulated by sex hormones (estrogen and progesterone). Some medicines can slow or stop the progression of such cancer by blocking the action of the hormones.

There are 2 types of anti-hormonal drugs:

  • Anti-estrogens: such as tamoxifen, bind to the surface of cancer cells, to receptors normally occupied by estrogen. This medication is taken orally in tablet form;
  • Aromatase inhibitors: They prevent the production of estrogen by fatty tissue and the adrenal glands. These drugs are only used in postmenopausal women. These are also tablets taken by mouth.

Targeted therapy

Sometimes in women with invasive breast cancer, cancer cells overexpress the HER2 gene. This causes the tumor to grow faster. When this is the case, a medicine can be given, trastuzumab (Herceptin®) for example, which specifically blocks the action of the HER2 gene. This medication is given by intravenous injection.

Research is ongoing to find other biological therapies. This type of treatment usually causes fewer side effects than chemotherapy and hormonal therapy because it is more targeted.

How to prevent or treat lymphedema?

Lymphedema in the arm can occur after surgery to treat breast cancer. This complication affects no less than 1 in 44 women. Lymphedema is characterized by swelling of the arm (affected side). The arm becomes heavy and painful. The risk depends on the extent of the tissue removed during the surgery. Underarm lymph node dissection and radiation therapy near the armpits increase this risk. Lymphedema can develop a few days after treatment or months or even years later.

There are a number of things you can do to prevent lymphedema or to prevent it from getting worse.

  • Inform your doctor as soon as possible if a heaviness in the arm appears after the treatment;
  • Avoid lifting heavy objects in the days following surgery; use your arm and stretch gradually;
  • Take care to protect the skin of the arm at risk from cuts, burns and insect bites. Avoid all types of punctures on this arm (vaccination, blood tests, acupuncture needles, etc.), especially if lymphedema is already observed;
  • Wear gloves for manual tasks (cleaning, cooking, gardening, etc.);
  • Exercise at a moderate intensity on a regular basis. These exercises should involve arm movements and work well on the arm muscles. Your doctor can advise you on this;
  • Lose weight if you are obese as it can cause lymphedema to develop or worsen;
  • Avoid very hot temperatures (very hot water baths, steam rooms, hot climates) if they seem to cause heaviness in the arm.

There is no effective short-term treatment for lymphedema. However, some measures can relieve the symptoms:

  • Wearing a custom-made compression garment that hugs your entire arm 24 hours a day;
  • Practicing drainage and stretching exercises for the arm and shoulder;
  • Exercising (walking, swimming, doing yoga, etc.). Talk to your doctor concerning the intensity level of the exercises;
  • Receiving manual lymphatic drainage treatments, a gentle massage technique that stimulates the flow of lymph.

In conclusion

If you’ve just found out that you have breast cancer, you are probably worried and upset. Cancer is often scary. It is therefore very important to be well informed. Treatment for this cancer is much more precise than it used to be, better suited to each woman, and more effective.

The treatment is surely a great ordeal to go through but you must keep hope. Fewer and fewer women are dying from breast cancer the days.

Betsy Wilson

A true science nerd and pediatric nursing specialist, Betsy is passionate about all things pregnancy and baby-related. She contributes her expertise to the Scientific Origin.