A cancer signifies the presence of abnormal cells that multiply uncontrollably. In the case of breast cancer, cells can remain in the breast or spread through the body through the blood or lymphatic vessels. Most of the time, the progression of breast cancer takes several months and even a few years.
The breast cancer is the most diagnosed cancer in women worldwide, both before and after menopause. A woman in 9 will be diagnosed with breast cancer in her lifetime and one in 27 will die.
Most often, breast cancer occurs after 50 years. The 5-year survival rate after diagnosis ranges from 80% to 90%, depending on age and type of cancer.
The number of people affected has increased slightly but steadily over the last 3 decades. On the other hand, the mortality rate has steadily declined over the same period, thanks to advances in screening, diagnosis and treatment.
Note that the men may also be affected; they represent 1% of all cases.
The breast consists of fat, glands and canals (see diagram below). The glands, arranged in lobules, produce the milk and the channels (lactation ducts or galactophores) are used to transport the milk to the nipple. Breast tissues are influenced by hormones produced by women in varying amounts throughout their lives (puberty, pregnancy, breastfeeding …). These hormones are estrogen and progesterone .
Types of breast cancer
The various types of breast cancer evolve differently:
- In situ ductal carcinoma. It is the most common type of non-invasive breast cancer in women. As its name suggests, it is formed within the breast lactation channels. This type of cancer has been diagnosed much more frequently since the more widespread use of mammography. The treatment of this cancer leads to healing in almost all cases. Normally, it does not spread. In exceptional cases, without treatment, it continues to grow and can become “infiltrating” and spread outside the lactation channels.
Invasive or invasive cancers
These forms of cancer invade the tissues around the lactation channels, but remain inside the breast. On the other hand, if the tumor is not treated, it can spread to other parts of the body (eg, the bones, lungs or liver) by generating metastases .
- Ductal carcinoma. It is formed in the lactation channels. Cancer cells pass through the walls of the canals;
- Lobular carcinoma. The cancer cells appear in the lobules grouped in the lobes. Then, they cross the wall of the lobules and spread in the surrounding tissues;
- Inflammatory carcinoma. A rare cancer that is characterized mainly by a breast that can become red, swollen and hot. Breast skin can also look like an orange peel. This type of cancer progresses faster and is more difficult to treat;
- Other carcinomas (medullary, colloidal 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. A rare cancer that is manifested by a small wound in the nipple that does not heal.
Causes breast cancer
Several risk factors for breast cancer are known. However, in most cases, it is impossible to explain the reasons for its appearance in a particular person.
Of mutations in genes, passed from one generation to another or acquired during life (exposure to radiation or certain toxic chemicals, for example, alter the genes) can cause cancer breast. The BRCA1 and BRCA2 genes, for example, are susceptibility genes for breast and ovarian cancers. Women who carry mutations of these genes have a very high risk of cancer.
Evolution breast cancer
The chances of recovery depend on the type of cancer and its stage of evolution at the time of treatment. Various factors influence the speed at which a tumor will grow. To learn more about the stages of cancer evolution, see our Cancer fact sheet.
Symptoms breast cancer
- A lump in the breast, whether fixed or mobile. This is the most common symptom, for both women and men.Note. Most lumps detected in the breast, however, are not cancerous;
- Of flows spontaneously from the nipple;
- A retraction of the nipple (the nipple is turned inward);
- A change in the appearance of the skin of a breast: thickening or hardening (“orange peel”), unusual redness, heat, change (peeling) of the skin around the nipple;
- An unusual change in size or shape of a breast.
|Several factors can influence breast tissue and change the appearance of breasts: pregnancy, the menstrual cycle, a breast cyst, an infection, etc.|
People at risk
A number of non-modifiable elements increase the risk of breast cancer.
These risk factors allow physicians to determine which individuals would benefit most from screening and preventive measures.
Main risk elements:
- Female sex. Less than 1% of breast cancer cases are men, and men are usually over 60 years old;
- Age. The disease rarely affects women under 30 years old. 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 the risk of getting cancer. Between 5% and 10% of breast cancers are caused by an inherited disorder. The main susceptibility genes for breast (and ovarian) cancer are named BRCA1 and BRCA2. Normally, these genes protect against cancer. If they are defective, they can no longer perform their duties. There are tests to see if a woman from a high-risk family is herself carrying a mutation to one of these genes;
- Personal antecedent. Having ever had breast cancer increases the risk of a second cancer being formed;
- Having a risky breast lesion (diagnosed during a biopsy). Women who have an at-risk lesion , such as atypical intraductal epithelial hyperplasia or lobular carcinoma in situ, are more likely to develop breast cancer one day.
Note. Note that the breast cyst is not a risky lesion. It does not increase the risk of breast cancer;
- Null parity or late pregnancy. The fact of not having had a child or giving birth only after the age of 35.
Other risk elements:
- Increased exposure to natural estrogens. Early onset of first menstruation (before age 12) or late menopause (after age 55);
- Radiotherapy treatments. Women who have received high doses of thoracic radiation (high-intensity x-rays) are known to be at increased risk of developing breast cancer, especially if radiotherapy has occurred before age. 30 years old.
In studies, the following modifiable factors have been associated with a higher risk of breast cancer. Note, however, that breast cancer can develop 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, out of 1,000 overweight women, there will be 45 more cases of breast cancer;
- A sedentary lifestyle. Those who practice less than 4 hours of physical exercise a week are at greater risk of breast cancer, regardless of their weight 7. Out of 1,000 women, there will be 27 more cases of breast cancer;
- The consumption of alcohol. The higher the alcohol consumption, the more the risk of breast cancer increases . The effect of drinking 2 glasses of alcohol per day is as powerful as the sedentary lifestyle. Out of 1,000 women, there will also be 27 more cases of breast cancer;
- Taking hormone replacement therapy at menopause. The replacement of sex hormones at menopause may increase the risk of breast cancer. This increase is reflected in 2 more cases out of 1 000 women.
|Details about hormone therapy
The US Women’s Health Initiative Study (WHI), whose first results were published in 2002, found that women who take a combination of estrogen and progesterone during menopause for more than 5 years slightly increase their risk. Of breast cancer. Five years after stopping hormone therapy, this increase in risk is almost invisible. In the case of use of hormone therapy for less than 5 years, the risk of breast cancer is not changed.
Other risk elements:
- 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 stopping the use of the contraceptive pill. Other studies on the subject have not established a link between the contraceptive pill and breast cancer. On the other hand, carriers of a mutation in the BRCA gene reduce the risk of ovarian cancer by taking anovulants.Finally, a report from the Society of Obstetricians and Gynecologists of Canada states that “having ever used oral contraceptives does not increase the risk of breast cancer associated with hormone therapy”.
- Exposure to carcinogenic chemicals. Being in contact with chemicals in the environment (organochlorine pesticides (DDT), parabens, etc.) may contribute to the formation of breast cancer. The causal link is, however, very difficult to establish.
The role of the psychological state in the appearance of cancer is controversial. Certain personality traits have been associated in studies with an increased risk of cancer. However, other studies have come to contradict this hypothesis. For more information, see our Cancer fact sheet.
|Basic preventive measures|
|The lifestyle habits (exercise, healthy diet with plenty of fruits and vegetables, stopping smoking, moderate alcohol consumption, etc.) and maintaining a healthy weight helps reduce the risk of several types of cancer, including breast cancer. For more details on these measures, see our Cancer fact sheet.
See also the suggestions of nutritionist Hélène Baribeau in the Custom Diet: Cancer .
Of course, the fight against cancer does not only require individual actions but also collective actions: reduce the presence of chemicals in household products, reduce the use of chemical pesticides, develop cities to promote physical activity etc.
|Other measures to prevent the onset of the disease|
|These measures aim to detect cancer as early as possible in order to halt its progression and, if possible, heal it.
Observation of any anomaly. Be on the lookout for any changes within: bump, flow, nipple retraction, pain, etc. To do this, feel and watch your breasts regularly.
Clinical examination of breasts by a health professional. It can help detect a mass not perceived by the woman or not visible on mammography. The Canadian Cancer Society recommends that this exam be done at least every 2 years, starting at age 40.
Mammography. Health Canada recommends mammography screening at least every 2 years for women aged 50 to 69. Outside this age group, the need for screening varies from one woman to another, depending on her personal risk factors. It is better to discuss it with your doctor. The Canadian Task Force on Preventive Health Care does not recommend mammography for women aged 40 to 49 who are not at risk because of the lack of benefits and possible harms (radiation exposure, biopsies unnecessary).
Breast ultrasound. Physicians sometimes suggest this as an adjunct to mammography, for example, in women whose breasts are very dense or when mammography has not been conclusive. Ultrasound can also be performed on the front line of women under 40 who are at a very high risk of breast cancer due to genetic predisposition. This examination does not expose to any radiation. Current devices offer a resolution 2.5 times better than it was 15 years.
On the other tests are sometimes offered as appropriate. Among the examinations under study is elastography, an imaging technique that uses ultrasound.
Note . The thermography is not a breast cancer screening measure recognized in Canada. (See the box below.)
|What about thermography?
In the United States, the use of thermography to screen for breast cancer appears to be a trend in alternative settings. In her book Women’s Bodies, Women’s Wisdom , renowned American gynecologist Christiane Northrup says that this method can detect all kinds of breast conditions at a very early stage, even if there are no apparent symptoms. This imaging method uses infrared rays to detect temperature changes on the body surface. Thermography does not require any compression of the breast and does not expose to any ionizing radiation. According to Northrup, some tumors cancerous or even precancerous breast can be revealed because they cause inflammatory reactions that warm the skin.
However, all expert reports consulted (Canadian, American and others) and radiologists interviewed formally discourage thermography for breast tumor detection. According to them, this method is unreliable because it generates a significant proportion of false positive and false negative results.
Thermography was approved by the US Food and Drug Administration (FDA) in 1982 for breast cancer screening, as long as it is used in addition to another screening method. However, in the early 1980s, we did not yet have powerful tools to detect tumors in the breast.
Nowadays, thermography is obsolete and doctors no longer use it. In 2000, the American College of Radiology ruled that it is of no use, even in addition to mammography. Thermography was developed in medicine in the 1960s in hopes of improving breast cancer screening.
Treatment depends on the type of cancer and its stage of development . The surgery is part of the treatment of the vast majority of breast cancers.
The biopsy involves taking a sample of the tumor for examination. The tests performed on it will influence the choice of treatment. It is necessary to know if the tumor is cancerous then if it is the case, to know the type of cancer. The tests on the tumor sample also tell the doctor what is the stage of the cancer and whether its growth can be stimulated by the sex hormones (that is, if the tumor is “hormone-dependent”).
Here are 3 tests performed:
- Estrogen hormone receptor assay and progesterone receptor assay . To find out if cancer growth can be stimulated by estrogen or progesterone;
- HER2 test . In cases of invasive cancer only, a genetic test is performed to determine the degree of activation of the HER2 gene. When this gene is highly activated, it indicates that the cancer is likely to grow faster. This is the case for about 10% of invasive cancers.
Treatments breast cancer
There are 5 categories of treatments:
- hormonal therapy;
- Targeted therapy.
Surgery breast cancer
The surgery is often the first treatment undertaken. It serves to remove the cancerous tumor. In the case of breast cancer, it is called mastectomy . The mastectomy is partial or segmental (part of the breast is removed) or total (the entire breast is removed). One almost always adds a surgery to the lymph nodes of the armpit. The choice of type of mastectomy is based, among other things, on the size of the tumor , its type and 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 conservative surgery;
- Total mastectomy . The breast is fully removed: the mammary glands, the fatty tissue, the nipple and the skin. It is chosen when it is not possible to perform a partial mastectomy. This is done in about 20% to 25% of breast cancer cases. Depending on the case, a 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 the surgery, it is almost always essential to know if the cancer has reached the lymph nodes located in the armpit hollow on the affected side. These ganglia drain the lymph circulating in the breast. This can be done either by removing only the first ganglia of this chain (this is what is called the biopsy of the sentinel lymph node), or by removing the complete chain. This ablation sometimes causes complications, such as lymphedemain one arm (reached side). Lymphedema is a buildup of lymph. It is caused by the disruption of the usual drainage channels. It is rarer if only the sentinel lymph nodes are removed. To learn more about its prevention and treatment, see the box below.
Partial mastectomy should usually be followed by radiotherapy to destroy cancer cells that may have remained in the breast. It reduces the risk of a tumor reappearing.
In case of total mastectomy, radiotherapy is not always necessary. To learn more about this treatment, consult our Cancer fact sheet.
The chemotherapy uses a class of drugs called antineoplastic, to treat cancers. For breast cancer, it is usually given after surgery . It destroys cancer cells that have escaped from the main tumor. The choice of whether or not to start chemotherapy depends on the stage of the disease . To learn more about this treatment, consult our Cancer fact sheet.
The hormone therapy is most often combined with surgery, radiotherapy or chemotherapy.
If the examination of the tumor shows that the cancer has hormonal receptors, its development is stimulated by the sex hormones (estrogen and progesterone). Some medicines can slow or stop the progression of such a cancer by blocking the action of hormones .
There are 2 types of anti-hormonal drugs :
- The antiestrogens , such as tamoxifen (Nolvadex-D) which binds to the surface of cancer cells, receptors normally occupied by estrogens. This medicine is administered orally in tablet form;
- The aromatase inhibitors : anastrozole (Arimidex), letrozole (Femara) and exemestane (Aromasin). They prevent the production of estrogen by fatty tissues and adrenal glands. These drugs are used only in postmenopausal women. They are also tablets administered orally.
Sometimes, in women with invasive breast cancer, cancer cells overexpress the HER2 gene. This causes faster growth of the tumor. When this is the case, one can give a drug, trastuzumab (Herceptin), which specifically blocks the action of the HER2 gene. This medicine is given by intravenous injection .
Research continues 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?
A lymphedema in the arm can occur after surgery for breast cancer. This complication affects no less than 1 in 4 women . Lymphedema is characterized by swelling of the arm (affected side). The arm becomes heavy and painful . The risk depends on the extent of tissue removed during surgery. Underarm lymph nodes and underarm radiotherapy increase this risk. Lymphedema can occur a few days after treatment or months or even years later.
Various measures help to prevent lymphoedema or to prevent it from getting worse.
There is no effective treatment in the short term to overcome lymphoedema. Some measures can nevertheless relieve symptoms .