Breast cancer

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Research in breast cancer

We are always learning more about cancer. Researchers and healthcare professionals use what they learn from research studies to develop better practices that will help prevent, find and treat breast cancer. They are also looking for ways to improve the quality of life of people with breast cancer.

The following is a selection of research showing promise for breast cancer. We’ve included information from PubMed, which is the research database of the National Library of Medicine. Each research article in PubMed has an identity number (called a PMID) that links to a brief overview (called an abstract). We have also included links to abstracts of the research presented at meetings of the American Society of Clinical Oncology (ASCO), which are held throughout the year. You can find information about ongoing clinical trials in Canada from or Clinical trials are given an identifier called a national clinical trial (NCT) number. The NCT number links to information about the clinical trial.

Reducing the risk of breast cancer and breast cancer recurrence

Some substances or behaviours may lower your risk of developing breast cancer or reducing the risk of breast cancer coming back after treatment. The following is noteworthy research into ways to lower your risk.

Diet may help make breast tissue less dense. Research shows that women who limit the amount of meat and high-calorie foods (such as fat or oils) and eat large amounts of plant foods (such as vegetables and fruit) had lower density breast tissue. This was especially true in post-menopausal women and non-smokers (PLoS One, PMID 26208331). This is important because dense breasts have more connective tissue, glands and milk ducts than fatty tissue, which can make it harder to find cancer on a mammogram. Having dense breasts is an important breast cancer risk factor so lowering breast density by changing one’s diet may also reduce the risk of developing breast cancer. However, much longer follow-up is needed to find out if this is a way to reduce breast cancer risk.

Metformin(Glucophage) is a drug that helps control diabetes. Some studies suggest that women who take metformin have lower rates of breast cancer (Current Pharmacological Reports, PMID 26405648). A review of several studies found that metformin did not lower the risk for breast cancer, but it may improve survival in women diagnosed with the disease (Journal of Breast Cancer, PMID 26472977). A Canadian clinical trial is currently looking at the role of metformin in lowering the risk of breast cancer recurrence (NCT 01101438).

Anti-estrogen drugs such as tamoxifen (Nolvadex, Tamofen) or exemestane (Aromasin) may be offered to women who have a high risk of developing breast cancer to lower their chances of developing the disease. But many women choose not to take these drugs because they worry about their side effects and long-term effects. Researchers are trying to find ways to give these drugs so they cause fewer or less severe side effects. They are looking at lowering the dose of the drug or giving the drug for a short period of time with breaks in between (intermittent administration). Researchers hope that reducing the side effects might encourage more women at high risk for breast cancer to take these drugs (Seminars in Oncology, PMID 2690130).

Physical activity may improve survival after breast cancer. An analysis of physical activity reported by women found that brisk walking or other types of moderate exercise for 2.5 hours a week or more may lower the chance of dying from breast cancer by as much as 32%. More research is needed to understand how physical activity can help improve survival (European Journal of Cancer, PMID 27529756).

Find out more about research in reducing the risk of cancer.


Screening tests help find breast cancer before any signs or symptoms develop. When cancer is found and treated early, the chances of successful treatment are better.

The TMIST screening trial is looking at digital breast tomosynthesis combined with digital mammography, compared to digital mammography alone. Digital breast tomosynthesis is a type of mammography that takes many x-rays of the breast from many different angles. A computer puts the images together to make a 3-D picture of the breast. Digital mammography uses an electronic image of the breast instead of x-ray film. It is sometimes called full-field digital mammography. The study wants to find out if using both digital breast tomosynthesis and digital mammography is a more accurate way of screening for breast cancer. There are several Canadian centres participating in the study (NCT 02616432).

Diagnosis and prognosis

A key area of research looks at better ways to diagnose and stage breast cancer. Researchers are also trying to find ways to help doctors predict a prognosis (the probability that the cancer can be successfully treated or that it will come back after treatment). The following is noteworthy research into diagnosis and prognosis.


Digital breast tomosynthesis can help doctors find cancer more easily in dense breasts. It can also help a radiologist see more clearly if an abnormal area is non-cancerous or cancerous. This type of imaging may help lower the number of false positives (the test results suggest that a woman has breast cancer when she actually doesn’t). It may also lower the number of women who have to come back for more testing. One disadvantage of this test is that it also exposes the breast tissues to more radiation than standard mammography (Diagnostic Interventional Imaging, PMID 26275829; European Journal of Radiology, PMID 26499000; Radiology, PMID 26458206, PMID 25961633). However, Canadian researchers have recently come up with techniques to lower the amount of radiation needed for this technique.

Radioactive seed localization may help doctors better target abnormal areas or tissue that can’t be felt in the breast. A radiologist places the radioactive seeds in the suspicious area during a breast x-ray or CT scan. The surgeon can use these seeds to find the abnormal area or tissue more easily during surgery. Radioactive seed localization may be an alternative to wire localization biopsy (Journal of Surgical Oncology, PMID 25195916). One study showed that using radioactive seeds help the surgeon remove only the abnormal tissue and less normal tissue (British Journal of Surgery, PMID 26503897).

Circulating tumour cells are cancer cells found in the bloodstream of some women diagnosed with breast cancer. The CellSearch circulating tumor cell (CTC) test can find these cells. Research shows that having CTCs is a negative prognostic factor for breast cancer, especially when the number of tumour cells does not drop after chemotherapy (Journal of the National Cancer Institute, PMID 24832787). Other research found that women with HER2-positive breast cancer are more likely to have CTCs (Clinical and Translational Oncology, PMID 26260915). CTCs may also mean that inflammatory breast cancer is likely to come back (recur) and has a poorer prognosis (Journal of the National Cancer Institute, PMID 26374427).

Gene-based tests

Gene-based tests find differences between normal genes and genes that are changed (mutated) in cancer cells. Microarray analysis is a type of gene-based test that allows researchers to look at many genes together to see which ones are turned on and which ones are turned off. Analyzing many genes at the same time to see which are turned on and which are turned off is called gene expression profiling. Researchers hope that developing more gene-based tests will help doctors identify the best treatments for certain cancers, including breast cancer. Gene-based tests will also help doctors tailor more treatments to each person’s cancer based on their unique genetic makeup.

The TAILORx Breast Cancer Trial is using a test called Oncotype DX to determine the risk that breast cancer will come back (recur). The test identifies a Recurrence Score, which is the level of risk for recurrence. The trial confirmed that women with a Recurrence Score of 10 or less have such good outcomes that it is very unlikely chemotherapy would improve their survival. In the same trial, women with a Recurrence Score between 11 and 25 were randomly assigned to receive hormonal therapy alone or hormonal therapy and chemotherapy to determine whether chemotherapy is necessary in this group of women. Results are not yet available from this part of the study (New England Journal of Medicine, PMID 26412349).

MammaPrint is a test that looks at the activity of 70 genes in breast cancers. A recent study found that this test can identify early stage breast cancer that has a low genetic (or genomic) risk of recurrence, even if there appears to be a high risk of recurrence after surgery and additional treatments based on standard clinical factors. Women with breast cancer that has a low genomic risk of recurring might not need chemotherapy and so can avoid the side effects of this treatment (New England Journal of Medicine, PMID 27557300).


Biomarkers are substances, such as proteins, genes or pieces of genetic material like DNA and RNA, that are found naturally in the body. They can be measured in body fluids like blood and urine or tumour tissue that has been removed from the body. Researchers are looking at the following biomarkers to see if they can help doctors predict a prognosis for and find out which treatments will benefit women with breast cancer:

Find out more about research in diagnosis and prognosis.


Researchers are looking for new ways to improve treatment for breast cancer. Advances in cancer treatment and new ways to manage the side effects from treatment have improved the outlook and quality of life for many people with cancer. The following is noteworthy research into treatment for breast cancer.

Radiation therapy

Researchers are looking for new ways to use radiation therapy to treat breast cancer.

Radiation therapy to axillary lymph nodes may be an alternative to surgery to remove them. An ongoing clinical trial is comparing radiation therapy to removing the lymph nodes under the arm in women who had chemotherapy and then breast surgery. The trial is looking for any differences in the length of time before breast cancer recurs and overall survival in women who receive each treatment. It is also trying to find out if lymphedema develops less often with one of the treatments and how large an area should be treated with radiation therapy (NCT 01901094).

Radiation therapy to regional lymph nodes may lower the chance that breast cancer will recur. A Canadian study looked at women who had breast cancer in the lymph nodes or who didn’t have cancer in the lymph nodes but had a high risk of recurrence. These women were assigned to 2 groups. One group was given radiation therapy to the whole breast and the regional lymph nodes, which are under the arm, in the chest and around the collarbone. The other group was given radiation only to the breast. The results of the study show that adding radiation to the regional lymph nodes did not improve survival compared to radiation only to the breast. But breast cancer recurred less often in women who had radiation to the regional lymph nodes as well as the breast (New England Journal of Medicine, PMID 26200977).

Accelerated partial breast radiation directs radiation only to the area of the breast where a tumour is instead of to the whole breast. It is considered accelerated because the radiation is given in larger doses over a shorter period of time than standard radiation therapy. One study gave accelerated partial breast radiation to the area of a small breast tumour before doing surgery to remove the tumour and some healthy tissue around it (called wide local excision). The results suggest that accelerated partial breast radiation may reduce the amount of breast tissue that has to be removed (Radiotherapy and Oncology, PMID 25701298). Another study compared giving accelerated partial breast radiation by intensity-modulated radiation therapy (IMRT) to radiation to the whole breast. IMRT is a type of conformal radiation therapy, which uses special equipment to target and shape the radiation beams to the area of the tumour while protecting surrounding tissues. Results showed that the accelerated partial radiation given by IMRT had fewer side effects than and offered the same survival as radiation to the whole breast (European Journal of Cancer, PMID 25605582).

Radiation after a mastectomy is not a standard treatment. A recent study looked at giving radiation therapy after surgery to women with tumours larger than 5 cm but whose cancer had not spread to lymph nodes or other parts of the body. They found that these women survived longer than women who did not have radiation therapy after mastectomy (ASCO, Abstract 1018).

Heart damage can be caused by radiation therapy, especially when it is used to treat the left breast. One study taught a group of women to hold their breath while having radiation treatment, and then measured the amount of radiation that reached the heart muscle. Researchers compared the amount of radiation to another group of women who breathed normally during the treatment. They found that holding the breath lowered the amount of radiation absorbed by the heart. Experts hope that holding your breath during radiation therapy could help reduce the amount of heart damage (Clinical Oncology, PMID 27890346).

Find out more about research in radiation therapy.


The following is noteworthy research in chemotherapy for breast cancer.

Early stage breast cancer

Early stage breast cancer means that the tumour is smaller than 5 cm and the cancer has not spread to more than 3 lymph nodes. It includes stages IA, IB and IIA. Researchers are looking for new and more effective drugs, combinations of drugs and ways to give chemotherapy for early stage breast cancer.


Neratinib (HKI-272) is a type of targeted therapy drug. It is a tyrosine-kinase inhibitor that blocks certain proteins that help cancer cells grow. A recent study looked at giving neratinib to women with early stage HER2-positive breast cancer. They were treated with chemotherapy (doxorubicin and cyclophosphamide), followed by paclitaxel, and then trastuzumab.When they finished these treatments, one group of women was given neratinib for 12 months, while another group was given a placebo. Results of the study show that women who were given neratinib had better disease-free survival than women who were not given the drug (The Lancet Oncology, PMID 26874901),but there hasn’t been enough time since the study ended to determine whether survival was significantly longer when women receive neratinib.


Bisphosphonates are drugs that help strengthen bone by stopping the body from breaking it down. A recent review of a large number of studies (called a meta-analysis) showed that bisphosphonates lower the rate of breast cancer recurrence in the bone and improve overall survival for women with early stage breast cancer. This benefit was only seen in women who had already reached menopause when they started treatment (The Lancet, PMID 26211824).

Triple-negative breast cancer

Triple-negative breast cancer means that the cancer cells don’t have receptors for estrogen and progesterone and they don’t have extra copies of the HER2 gene. Standard treatments for breast cancer, such as hormonal therapy or targeted therapy, can’t be used with this type of breast cancer. Researchers are looking for better ways to treat and improve survival for women with triple-negative breast cancer.

Cisplatin (Platinol AQ) and gemcitabine (Gemzar) were compared to paclitaxel (Taxol) and gemcitabine in women who had triple-negative breast cancer that had spread to other parts of the body. The results show that the cisplatin and gemcitabine combination improved survival and had fewer side effects. Researchers suggest that it could be the first combination chemotherapy used for metastatic triple-negative breast cancer (Lancet Oncology, PMID 25795409).

The TNT trial that randomized women with metastatic triple-negative breast cancer to carboplatin or to docetaxel showed that women with an inherited BRCA1 or BRCA2 gene mutation responded better and longer to treatment with carboplatin (Paraplatin, Paraplatin AQ). Results of this trial also showed that women who didn’t have a BRCA gene mutation were no more likely to respond to carboplatin than to docetaxel. Researchers note that knowing the BRCA status of women with triple-negative breast cancer is an important factor in deciding which chemotherapy drugs to offer (San Antonio Breast Cancer Symposium, Abstract S3-01).

Metronomic maintenance chemotherapy means that the drugs are given in small daily doses over a long period of time after the main chemotherapy treatment is finished to prevent recurrence. It can also reduce side effects so the treatment is easier to take than getting high doses of drugs every few weeks. Doctors think that metronomic maintenance chemotherapy might be effective against triple-negative breast cancer because it often recurs after chemotherapy is finished. A recent study gave maintenance metronomic chemotherapy with methotrexate and cyclophosphamide (Cytoxan, Procytox) to women with triple-negative breast cancer for a year after they had finished chemotherapy with carboplatin. The results showed that women who received maintenance metronomic chemotherapy had higher survival rates than women who did not receive this treatment (ASCO, Abstract e12087).

Find out more about research in chemotherapy.

Hormonal therapy

Researchers are looking for new ways of treating hormone receptor–positive breast cancer, especially in premenopausal women.

The SOFT study looked at the role of ovarian suppression in premenopausal women with hormone receptor–positive breast cancer. Ovarian suppression uses drugs to stop the functioning of the ovaries. The study compared 3 groups. One group was given just tamoxifen (Nolvadex, Tamofen), the second group was given tamoxifen and ovarian suppression, and the third group was given exemestane (Aromasin) with ovarian suppression. Results of the trial found that while ovarian suppression with either drug improved disease-free survival, ovarian suppression with exemestane was more effective. However, this result was found only in women who were still premenopausal at the end of treatment. No significant benefit was found in women who became menopausal at the end of treatment (New England Journal of Medicine, PMID 25495490).

Having hormonal therapy alone, rather than hormone therapy and radiation therapy, may be a treatment option for women over the age of 60 with slow-growing breast cancer. Early results of a Canadian trial show that women in this group had a low risk of recurrence with hormonal therapy alone. The trial is still accepting participants, and researchers hope that results will confirm these early findings (Journal of Clinical Oncology, PMID 25964246; NCT 01791829).

Fulvestrant (Faslodex) was compared to anastrozole (Arimidex) in post-menopausal women with advanced hormone receptor–positive breast cancer who had not been treated with hormonal therapy. The study showed that women who were given fulvestrant had a longer progression-free survival compared to women who had been given anastrozole (The Lancet, PMID 27908454).

Anastrozole (Arimidex) was compared to tamoxifen in post-menopausal women with hormone receptor–positive ductal carcinoma in situ (DCIS). Tamoxifen is sometimes given after surgery and radiation therapy to lower the risk that DCIS will come back in women treated with lumpectomy. The study results show that the women taking anastrozole had a lower risk of recurrence compared to the women taking tamoxifen. This effect was especially strong in women younger than 60 years of age (The Lancet, PMID 26686957).

Breast reconstruction surgery

Researchers are looking for ways to improve reconstructive surgery. One challenge is to find the best way to successfully insert an implant at the time of mastectomy (when there is no natural tissue to hold the implant in place), rather than doing further surgeries in the future to insert a tissue expander and later the implant.

SERI surgical scaffold is a material made out of natural silk, which the body can gradually break down and absorb. A recent study looked at using SERI surgical scaffold to make a pocket in the area where the breast was removed during surgery. Then the surgeon placed an implant into the pocket to form a breast. Results from the study showed that women who had the SERI surgical scaffold were very satisfied with the cosmetic results. It also found that the SERI surgical scaffold material did not cause any more complications than other breast reconstruction techniques, such as tissue transfer (Plastic and Reconstructive Surgery, PMID 25502862).

Acellular dermal matrix (AlloDerm, DermaMatrix) is a type of implant that uses special donated human skin tissue. To prevent rejection, the cells are removed from the donated tissue so just the connective tissues made of collagen (a type of protein) are left. The BREASTrial is looking at the advantages, disadvantages and safety of using acellular dermal matrix for one-step reconstruction after mastectomy. (Plastic and Reconstructive Surgery, PMID 25539330).

Find out more about research in cancer surgery.

Supportive care

Living with cancer can be challenging in many different ways. Supportive care can help people cope with cancer, its treatment and possible side effects. The following is noteworthy research into supportive care for breast cancer.

Luteinizing hormone–releasing hormone (LHRH) agonists may help preserve ovarian function in young women diagnosed with breast cancer. A recent meta-analysis found that using the LHRH agonists goserelin (Zoladex) or triptorelin (Trelstar) during chemotherapy may lower the amount of damage to the ovaries from the chemotherapy drugs used to treat breast cancer and seems to decrease the risk of premature menopause. More research is needed to find out whether giving LHRH agonists in addition to chemotherapy can help keep a woman’s ability to get pregnant after treatment is finished and whether this approach is safe in women with hormone receptor–positive breast cancer (ASCO, Abstract 1050). Find out more about research in fertility options.

Skin changes caused by radiation therapy to the breast include redness, dry skin and peeling. Researchers used a skin cream containing steroids to find out if it could reduce the severity of skin reactions. One group of women was given a steroid cream, while the other was given a moisturizing cream. Both groups used the cream during radiation treatment and for 2 weeks after radiation therapy had finished. Results showed that women who used the steroid cream had significantly fewer skin changes during radiation therapy (Radiotherapy and Oncology, PMID 27913066).

Learn more about cancer research

Researchers continue to try to find out more about breast cancer. Clinical trials are research studies that test new ways to prevent, detect, treat or manage breast cancer. Clinical trials provide information about the safety and effectiveness of new approaches to see if they should become widely available. Most of the standard treatments for breast cancer were first shown to be effective through clinical trials.

Find out more about cancer research and clinical trials.

disease-free survival

The percentage of people with a given disease who are alive without any detectable disease (are disease-free) for a defined period of time.

For example, if cancer treatment results in a 70% disease-free survival over 5 years, then 7 out of every 10 people did not have any detectable disease for 5 years after treatment.

disease-free survival

The percentage of people with a given disease who are alive without any detectable disease (are disease-free) for a defined period of time.

For example, if cancer treatment results in a 70% disease-free survival over 5 years, then 7 out of every 10 people did not have any detectable disease for 5 years after treatment.

luteinizing hormone–releasing hormone (LHRH) agonist

A drug that stimulates the pituitary gland to produce more luteinizing hormone (LH).

The pituitary gland produces luteinizing hormone (LH), which in turn stimulates the testicles to produce testosterone. A LHRH agonist causes the pituitary gland to overproduce LH until it eventually stops responding to the drug. When the pituitary gland stops producing LH, the testicles stop producing testosterone.

Also called LHRH agonist.


A teenaged girl sitting on her bed I was in total shock when I heard the diagnosis of cancer. Cancer to me was an adult’s disease. Being a 13-year-old teenager, it certainly wasn’t even on my radar.

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