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breast cancer

health canada-approved treatments: breast cancer

this complete guide outlines all the treatments available for breast cancer in canada.

by karen hawthorne

oct 15 2024

23 minute read

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breast cancer can be a manageable disease for patients and their families with growing options, access to care and support. getty images

this article is for informational purposes only and is not intended to provide medical advice, diagnosis or treatment. always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.

finding a breast lump or noticing changes in breast skin is frightening. these are two symptoms of breast cancer, the most common cancer diagnosed in women in canada after skin cancer — and certainly a high-profile disease in the medical community. however, it doesn’t only affect women. everyone is born with breast tissue, so anyone can get breast cancer, although it’s rare in men.

breast cancer starts in the cells of the mammary gland. the breast tissue covers a larger area than most people realize – it goes from just below the collarbone, called the clavicle, to the armpit and across to the breastbone.

risk increases with age and most cases are in women over 50. public health efforts have focused on this age group with breast cancer screening guidelines starting at age 50. a mammogram every two years is recommended for women aged 50 to 75 who are at average risk.

however, rates of breast cancer are rising in women in their 20s and 30s, and often diagnosed at later stages when the cancer is more aggressive. now, cancer specialists, family doctors and patients with the coalition for responsible healthcare guidelines say the guidelines don’t reflect emerging research and there’s a need for more awareness of breast cancer for younger women and earlier screening.

there’s no single risk of breast cancer, but some factors that increase your risk include:

family history of breast cancer, especially in a mother, sister or daughter diagnosed before menopause, or if you have a mutation on the brca1 or brca2 genes
previous breast disorders with biopsies showing abnormal cells
no full-term pregnancies or having a full-term first pregnancy after age 30
in post-menopausal women, obesity and physical inactivity
beginning to menstruate at an early age
later than average menopause
taking hormone replacement therapy (estrogen plus progestin) for more than five years
alcohol consumption
obesity

sources:

public health agency of canada – breast cancer

cbc news, april 24, 2024 – canadian doctors are using ‘outdated’ guidelines to screen for cancer, experts warn

here’s a look at the treatment options available for canadians.

surgery

surgery is the main treatment for breast cancer to remove part or all of the cancerous tumour. the type of surgery recommended depends on a few things, including the size and location of the tumour, breast size, if the cancer has spread to the lymph nodes (under your arm, near your collarbone or near your breastbone at the front centre of your chest) and other treatments you have already undergone to treat breast cancer. patients may be given chemotherapy before surgery to shrink a large tumour so that it’s easier to remove, which is called neoadjuvant chemotherapy.

surgery is usually done to remove the tumour or to check if the cancer has spread to the lymph nodes. it’s also the main intervention to remove cancer that comes back in your breast (local recurrence) or for breast reconstruction to reshape your breast after the cancer has been removed.

chemotherapy drugs may be given before surgery (called neoadjuvant chemotherapy) to shrink a large tumour to make it easier to remove.

the following types of surgery treat breast cancer, based on factors like stage of cancer, location, patient health, age and concerns.

breast-conserving surgery (bcs)

bcs is also known as a lumpectomy where the aim is to keep as much of the breast intact as possible. most of these surgeries are followed by radiation therapy to kill cancer cells that may not have been removed by surgery, decreasing the risk of the cancer returning.

bcs is possible when the breast tumour and an area of tissue around the tumour, known as a margin of tissue, can be removed, so that there’s enough tissue left for the breast to look natural. after surgery, the breast is typically smaller, firmer and a bit different in shape, but changes are minimal. bcs treats ductal carcinoma in situ, or dcis, and early-stage breast cancer. some lymph nodes under your arm are usually removed as well during this surgery. removed breast tissue goes to a lab for a pathologist to examine. they can return one of two findings:

a negative, or clear, margin means there are no cancer cells on the edges of the removed tissue
a positive margin indicates there are cancer cells in the edges of the removed tissue, which requires an additional surgery to remove more tissue or all of the breast tissue to prevent cancer growth and spread

studies show that women who have bcs followed by radiation therapy have similar long-term survival rates as those who have a mastectomy, where the entire breast is removed.

sources:

canadian cancer society – surgery for breast cancer

university of rochester medical center – breast-conserving surgery

mastectomy

a mastectomy is the removal of an entire breast where the lymph nodes, nerves and muscles in your chest are left in place. the nipple may or may not be removed. there are options following the surgery to use a prosthetic to replace the breast that was removed or to have some form of reconstruction to replace the breast. some patients choose to “live flat” or asymmetrical, as long as the weight of one breast doesn’t impact the spine. other reasons to go ahead with a mastectomy include:

if reconstruction isn’t an option
if you have complications from reconstruction
if wearing a prosthetic is uncomfortable or unaffordable

mastectomy may be done:

to treat tumours that are large compared to your breast size
when the cancer is in more than one area of your breast
if there are positive margins after bcs
if you can’t have bcs or the radiation therapy that usually follows bcs
if the cancer recurs after bcs and radiation therapy
if you choose to have a mastectomy instead of bcs
to treat inflammatory breast cancer, an aggressive cancer that blocks the lymph vessels in your breast skin causing swelling and redness

there are modifications to mastectomy. a skin-sparing mastectomy doesn’t remove the skin that covers the breast, so if you plan to have breast reconstruction at the same time as the surgery, it can be done with reduced scarring.

a double mastectomy is a surgery that removes both breasts, sometimes done to prevent breast cancer in people who have a high risk of breast cancer, like people with brca gene mutations.

a modified radical mastectomy removes all of your breast, including the nipple and tissue that covers the chest muscles and the lymph nodes in the armpit. typically, nerves and muscles are left in place. this type of mastectomy is important for breast cancer that has spread to the lymph nodes or inflammatory breast cancer.

a rarer version, called a radical mastectomy, removes more muscle, lymph nodes and tissues than a modified radical mastectomy.

there are potential side effects of mastectomy, including:

infection
swelling where tissue was removed
buildup of blood or fluid in the wound
scarring
problems moving your arm or shoulder
numbness in your chest
nerve pain in the chest wall, armpit or arm that doesn’t go away, called post-mastectomy pain syndrome, or pmps
lymphedema, or swelling, if lymph nodes were removed
changes to body image and self-esteem

sources:

canadian breast cancer network – mastectomy

canadian cancer society – surgery for breast cancer

breast reconstruction

the aim of breast reconstruction is to make the breast look and feel as natural as possible. the surgery is done by a plastic surgeon who is specially trained. more than one operation may be needed. there are other considerations here: patients may choose to have surgery on the breast that didn’t have cancer to make both breasts look alike. it’s important to realize that the reconstructed breast will never feel exactly like a natural breast in sensation and firmness. it may feel numb because the nerves that run through the breast are removed during a mastectomy. your breast skin can regain some sensation in time.

research conducted by the canadian partnership against cancer (cpac) has looked at the complexity of surgical decision-making for healthcare providers and patients, identifying the variations, barriers and opportunities for better use of cpac’s national breast cancer surgery standards to improve care and outcomes. the study, published in 2021 in current oncology , surveyed surgeons across canada and identified opportunities to connect with community support organizations and physician networks. for example, many surgeons highlighted breast cancer patients as strong advocates for breast reconstruction post-mastectomy.

“at the individual physician level, breast surgeons who were aware of the importance of breast reconstruction and had knowledge of the indications, patient eligibility criteria, and surgical techniques used by the plastic surgeons were identified as key enablers to advancing breast reconstruction. from an organizational perspective, having dedicated operating room resources for breast reconstruction enabled its implementation. from a system perspective, a collaborative network of plastic and breast cancer surgeons has been identified as a key enabler to support standard implementation,” the authors note.

sources:

canadian cancer society – surgery for breast cancer

current oncology, february 2021 – implementation of the canadian national standards

in breast cancer surgical care: gaps, barriers, enablers and opportunities

radiation therapy

radiation therapy uses high-energy rays to damage or destroy cancer cells. high doses of radiation induce apoptosis, a form of cell death that eliminates cells without releasing harmful substances into the surrounding area.

to limit possible damage to normal tissue, your breast is not usually given more than one series of radiation treatments, even if cancer comes back in the same breast. other parts of the body, including the other breast, may receive radiation if needed.

what’s known as adjuvant radiation therapy is given after breast cancer surgery has healed, usually in about three to four weeks with no complications. the aim is to kill any cancer cells remaining after your surgery and to help further reduce the risk of a recurrence. if chemotherapy is required after your surgery, radiation is given after the chemotherapy is completed. this is because the side effects of some chemotherapy drugs can be worse if you’re undergoing radiation at the same time. some treatments, like hormone therapy and targeted therapy, can be given along with radiation.

also, you may be given radiation therapy to shrink a tumour before surgery, called neoadjuvant therapy this is also used to relieve pain or prevent the symptoms of advanced breast cancer in palliative therapy.

during external radiation therapy, a machine directs radiation through your skin to the tumour and some of the surrounding tissue. radiation therapy is usually given five days a week for one to six weeks. after the radiation therapy to the breast is complete, you may get an extra dose of radiation to the area from where the cancer was removed.

you may get an extra dose if one of the following applies:

cancer cells are found in the tissue removed along with the tumour
your tumour is larger than 5 cm
your cancer is high grade
you are younger than 50

you may not need radiation therapy if all of the following apply to your situation:

you are 70 or older
tumour is 2 cm or smaller
cancer has not spread to lymph nodes
cancer cells are hormone-receptor positive and you are taking hormone therapy

there are a number of common side effects of radiation therapy for breast cancer, including:

fatigue
skin problems
changes to breast size and shape or feeling in your breast
breast pain
problems moving your shoulder
inflammation of the lung caused by radiation therapy to the chest

the other type of radiation therapy is internal radiation or brachytherapy. this advanced form of radiation uses a device that contains radioactive pellets that are placed internally into the breast where the cancer was originally growing and removed. brachytherapy is dependent on the size and location of the cancer and is recommended for people aged 45 years and older with early-stage invasive breast cancer who have had bcs surgery. this therapy can involve one treatment or more in an outpatient radiation clinic.

sources:

canadian breast cancer network – understanding my treatment options

bc cancer – internal radiation therapy – brachytherapy

canadian cancer society – surgery for breast cancer

chemotherapy

chemotherapy uses drugs to treat cancer. the drugs slow or even stop the growth of the cancer cells, so these cells don’t multiply and spread to other parts of your body. however, these drugs target rapidly dividing cells throughout your body, so while chemotherapy kills cancer cells, it can also damage healthy cells. chemotherapy can be offered for early-stage or locally advanced breast cancer before or after surgery.

in most types of chemotherapy, drugs travel through your blood to reach and destroy cancer cells all over the body, including cells that have broken away from the primary tumour. this is known as systemic therapy.

chemotherapy is often combined with other treatments for breast cancer, often before surgery to shrink a large tumour so it can be removed with bcs, and to see how well the cancer responds to certain drugs. it’s also used after surgery to reduce the risk of recurrence or to treat cancer that has come back. in advanced breast cancer, palliative chemotherapy helps to relieve pain or control the symptoms.

chemotherapy is usually given every three weeks. most chemotherapy drugs used for breast cancer are given through a needle in a vein, known as intravenous (iv) administration.

dose-dense chemotherapy is given every two weeks instead of three weeks to stop the rapid growth phase of tumour cells. it may be used for breast cancer that has a higher risk of coming back.

what’s termed neoadjuvant chemotherapy is started before surgery as soon as possible after diagnosis. adjuvant chemotherapy is started as soon as you have healed from surgery, no later than 12 weeks following the procedure.

there are different drugs and combinations of drugs for breast cancer, depending on:

breast cancer type and stage
risk of recurrence
your overall health, including any heart problems you have
any previous chemotherapy treatments you have had
lifestyle, preferences and future plans, like having children

chemotherapy is most effective in combination chemotherapy, where two or three drugs are used. most combinations used to treat breast cancer include both an anthracycline drug and a taxane drug, while other drugs may be added.

the drugs listed below may be combined for chemotherapy before or after surgery:

anthracycline drugs, like doxorubicin or epirubicin
taxane drugs, like paclitaxel or docetaxel
cyclophosphamide
fluorouracil, also called 5-fluorouracil or 5-fu
carboplatin

metastatic breast cancer, where cancer has spread to other parts of the body and is now stage 4, is usually treated with a single chemotherapy drug because of fewer side effects than a combination of drugs. but a drug combination can also be used from the following list:

anthracycline drugs – doxorubicin, pegylated liposomal doxorubicin and epirubicin
taxane drugs – paclitaxel, docetaxel and nab-paclitaxel
capecitabine
gemcitabine
vinorelbine
cyclophosphamide
carboplatin
cisplatin
epirubicin
eribulin

chemotherapy for recurrent breast cancer will depend on where the cancer has recurred. localized recurrence is when the cancer has recurred in the breast and lymph nodes around the breast. then metastatic recurrence is when the cancer has come back in other parts of your body, like the liver, bones or brain.

these drugs may be used for recurrent breast cancer:

anthracycline drugs – doxorubicin, pegylated liposomal doxorubicin and epirubicin
taxane drugs – paclitaxel, docetaxel and nab-paclitaxel
cyclophosphamide
fluorouracil (also known as 5-fluorouracil or 5-fu)
capecitabine
carboplatin

there can be side effects with these drugs, including:

nausea and vomiting
hair loss
sore throat and mouth
diarrhea
constipation
fatigue
fertility problems
infection
low blood cell counts
loss of appetite
treatment-induced menopause
heart problems
nervous system damage
cognitive changes

sources:

canadian cancer society – chemotherapy for breast cancer

public health agency of canada – breast cancer

hormone therapy

hormone therapy is only used for breast cancer that is hormone-receptor positive, which means that cancer cells have receptors for estrogen (estrogen-receptor positive, or er+) or progesterone (progesterone-receptor positive, or pr+) or both. what happens is when cancer cells have these receptors, the hormones can attach to the cells, helping them grow. essentially, hormone therapy stops the hormones from attaching to the cancer cells, so they starve and die. this reduces the risk that breast cancer will recur and improves chances of survival.

in fact, most people with breast cancer have hormone therapy because most breast cancers are hormone-receptor positive. the therapy can be used in conjunction with other cancer treatments, or it may be the only treatment you have.

it works to:

lower the risk of developing a second breast cancer
lower the risk of recurrence of ductal carcinoma in situ, or dcis, or an invasive breast cancer after bcs and radiation therapy
lower the risk of breast cancer body parts other than the breast and lymph nodes
shrink a large tumour so it can be removed more easily with bcs
treat locally advanced or recurrent breast cancer
shrink tumours and control the symptoms of advanced metastatic breast cancer in palliative therapy

hormone therapy is started after surgery if you are only having breast cancer surgery. if your specialist has introduced chemotherapy, your hormone begins after the chemotherapy is finished. you can have hormone therapy during radiation therapy, although certain health problems, like osteoporosis or high risk of blood clots, may rule out certain types of hormone therapy.

the most common of the hormone therapy drugs used to treat er+ breast cancer are tamoxifen and aromatase inhibitors, or ais.

tamoxifen is an estrogen receptor blocker. these drugs block estrogen in your body from attaching to er+ breast cancer cells. estrogen receptor blockers don’t stop estrogen from being made in your body. tamoxifen is taken in pill form for premenopausal and postmenopausal people. it is the most common hormone therapy drug taken for breast cancer. it can increase your risk for uterine cancer, blood clots and stroke.

fulvestrant is another type of anti-estrogen drug that attaches to the estrogen receptors in breast cancer cells and causes the receptors to shrink and break down. the drug is given to people with hormone receptor–positive metastatic breast cancer in cases where tamoxifen is no longer working. it can be used in premenopausal and postmenopausal people. with premenopausal people, a gonadotropin-releasing hormone, or gnrh agonist is used with fulvestrant. fulvestrant is injected into your buttocks once a month.

your ovaries no longer make estrogen after menopause, but your fat tissues, adrenal glands and other areas of the body continue to produce the hormone. your body uses the enzyme aromatase to make estrogen in these other areas. aromatase inhibitors halt the production of estrogen in these areas so that there are only very small amounts of estrogen for hormone receptor–positive breast cancer cells to use. these inhibitors are taken as pills, such as the following:

anastrozole (arimidex)
letrozole (femera)
exemestane (aromasin)

a cautionary note: hormone therapy with these aromatase inhibitors can lead to bone density loss, or osteoporosis, where your bones are fragile and can easily break or fracture. they have also been linked to sleep problems, high cholesterol and tendon inflammation.

gonadotropin-releasing hormone, or gnrh agonists are drugs that also influence hormones in breast cancer. your pituitary gland releases luteinizing hormone and follicle stimulating hormone, or fsh — hormones that signal the ovaries to produce estrogen or the testicles to produce hormones that can be turned into estrogen. gnrh agonists temporarily stop the pituitary gland from releasing these hormones, so you have less estrogen to help stop hormone receptor–positive breast cancer cells from growing.

gnrh agonists are given to premenopausal people who are taking an aromatase inhibitor. the most common ones for breast cancer treatment are:

leuprolide (lupron)- injected into your buttocks
goserelin (zoladex) – injected as a small pellet under your skin

another option is surgery to remove the ovaries or the testicles.

hormone therapy for breast cancer may have side effects, including:

hot flashes, sweating from treatment-induced menopause
sexual difficulties for people with female sex organs or male sex organs
weight gain
constipation
diarrhea
nausea
fatigue
thinning hair
fertility problems
abnormal vaginal discharge
increased bone or tumour pain
depression
headache
body aches and pain
loss of appetite
taste changes

sources:

national cancer institute – hormone therapy for breast cancer

canadian cancer society – hormone therapy for breast cancer

targeted therapy

targeted therapy, or molecular targeted therapy, uses drugs to target specific molecules that are on or inside cancer cells. these molecules are responsible for signaling the cancer cells to grow or divide. through targeting, drugs work to stop the cancer’s growth and spread, reducing harm to other normal cells.

targeted therapy can treat locally advanced breast cancer that has spread to lymph nodes before bcs or after surgery, breast cancer that has spread to other parts of the body, or breast cancer that is not responding to treatment or has come back.

there are designated targeted therapy drugs for her2-positive breast cancer where the her2 gene controls a growth protein on breast cells. each healthy cell contains two copies of the her2 gene, but in some cases your body produces too much of the her2 protein. her2 status testing is done when you’re diagnosed with breast cancer.

there are a number of targeted therapy drugs for her2-positive breast cancer.

trastuzumab (herceptin and biosimilars) is the most widely used drug, offered intravenously. it’s used in combination with taxane chemotherapy drugs before or after surgery in locally advanced breast cancer. usually it’s given by itself for a year after adjuvant chemotherapy for breast cancer has been completed. trastuzumab can cause temporary heart problems, so heart function tests are done before treatment and throughout to check for any heart-related issues.

pertuzumab (perjeta), given by iv, may be used with trastuzumab and chemotherapy before or after surgery for her2-positive breast cancer that has spread to your lymph nodes.

another option is phesgo, which is pertuzumab, trastuzumab and hyaluronidase combined into a single dose, administered by a needle under the skin. it’s prescribed for neoadjuvant therapy of her2-positive, locally advanced, inflammatory or early-stage (stage 1 or 2) breast cancer, or adjuvant therapy of early-stage her2-positive breast cancer that has spread to the lymph nodes or is hormone-receptor negative. it’s also provided in combination with the chemotherapy drug docetaxel for people who have metastatic her2-positive breast cancer that has not yet been treated with targeted therapy or has recurred since chemotherapy treatment.

trastuzumab emtansine (kadcyla or t-dm1) combines trastuzumab and the chemotherapy drug emtansine (dm1), given by iv. it’s used to treat her2-positive breast cancer when cancer is still in the breast or lymph nodes after treatment with chemotherapy and trastuzumab. usually, the drug is given to complete a year of anti-her2 therapy, or to treat metastatic breast cancer where the combination of trastuzumab and pertuzumab has stopped working.

trastuzumab deruxtecan (enhertu) is a combination of trastuzumab and the chemotherapy drug deruxtecan, given by iv. it can treat unresectable or metastatic her2-positive breast cancer that has already undergone treatment with trastuzumab and pertuzumab.

neratinib (nerlynx) is for early-stage her2-positive breast cancer after a year of treatment with trastuzumab. it can be combined with capecitabine for metastatic her2-positive breast cancer after two or more treatments have been used.

lapatinib (tykerb) is combined with capecitabine for metastatic her2-positive breast cancer when other types of chemotherapy or trastuzumab are no longer effective. lapatinib can also be combined with letrozole for hormone-receptor positive and her2 positive metastatic breast cancer.

tucatinib (tukysa) is combined with trastuzumab and capecitabine for locally advanced or metastatic breast cancer that is her2 positive and has been treated with at least three other targeted therapy drugs.

other targeted therapy drugs are designed for her2-negative breast cancer to target a protein called mammalian target of rapamycin (mtor) that controls cell growth and reproduction. in breast cancer, mtor causes cancer cells to keep growing and dividing. mtor inhibitors work to block the action of mtor. everolimus (afinitor) is the mtor inhibitor for locally advanced or metastatic hormone receptor–positive, her2-negative breast cancer that has recurred or has continued to progress despite treatment with letrozole or anastrozole (arimidex). everolimus is combined with the hormone therapy drug exemestane (aromasin).

also, cdk4/6 inhibitors slow or stop breast cancer cells from dividing and multiplying by targeting proteins called cyclin-dependent kinases 4 and 6 (cdk4/6). these drugs in pill format are combined with hormone therapy. cdk4/6 inhibitors can treat advanced or metastatic hormone receptor–positive, her2-negative breast cancer.

for example, palbociclib (ibrance) may be used in combination with an aromatase inhibitor as the first treatment or fulvestrant if breast cancer is progressing while you’re on hormone therapy. palbociclib is combined with a gnrh agonist if you are premenopausal or perimenopausal.\

ribociclib (kisqali) can be combined with an aromatase inhibitor as the first treatment given, or with fulvestrant as the first treatment given. it’s also used when your cancer has progressed during treatment with other hormone therapy drugs. ribociclib is combined with a gnrh agonist if you are premenopausal or perimenopausal.

abemaciclib (verzenio) may be used in combination with an aromatase inhibitor as the first hormone therapy treatment, or fulvestrant if the cancer has progressed during treatment with hormone therapy. it is also used with a gnrh agonist and fulvestrant if you are premenopausal or perimenopausal. on its own, abemaciclib treats metastatic breast cancer that has progressed after hormone therapy and has been treated with chemotherapy using at least one taxane drug. abemaciclib can treat early-stage breast cancer that is hormone-receptor positive and her2 negative that has spread to lymph nodes.

sacituzumab govitecan (trodelvy) is an antibody drug conjugate — a targeted therapy drug combined with a chemotherapy drug. it treats unresectable locally advanced or metastatic breast cancer that is hormone-receptor positive and her2 negative and has been treated with hormone therapy and at least two other chemotherapy drugs used for metastatic breast cancer. it can also treat unresectable triple-negative breast cancer (tnbc) that is locally advanced or metastatic and has been treated with two or more chemotherapy treatments, if one of them addresses metastatic cancer.

the pik3ca gene makes a protein that helps with cell growth, division and survival. pik3ca inhibitors stop the gene from making this protein to prevent cancer cells from growing or dividing. alpelisib (piqray) is a pik3ca inhibitor for locally advanced or metastatic breast cancer that is hormone-receptor positive and her2 negative and has mutations in the pik3ca gene. it is used for post-menopausal people and can be combined with fulvestrant if the cancer when hormone therapy is no longer working.

there is also targeted therapy for breast cancer with brca gene mutations.

poly (adp-ribose) polymerase (parp) is another enzyme for cell repair. parp inhibitors stop parp from repairing cancer cells leading to cell death. these are parp inhibitors, given as pills:

olaparib (lynparza) can treat people with metastatic her2-negative breast cancer who have already undergone chemotherapy. if the cancer is also hormone-receptor positive, olaparib may be used if the cancer stopped responding to hormone therapy or wasn’t suitable for hormone therapy. olaparib may also be used as an adjuvant therapy for people with the brca gene mutation who are at high risk of recurrence.

talazoparib (talzenna) is another drug for locally advanced or metastatic her2-negative breast cancer in people who have already had chemotherapy.

possible side effects of targeted therapy include the following:

flu-like symptoms
diarrhea
constipation
nausea and vomiting
skin problems
sleep problems
fatigue
hair loss
tingling in the hands and feet
low blood cell counts
loss of appetite
changes to taste
confusion
problems with major organs, including heart, lung, liver, bladder and kidney
pain in the muscles, joints and bones

sources:

canadian cancer society – targeted therapy for breast cancer

canadian cancer survivor network – breast cancer treatment

breast cancer now – targeted therapy

immunotherapy

while the traditional cancer therapies like chemotherapy and radiation have shown widespread success, they can damage healthy cells as well. this is where immunotherapy comes into play by strengthening or restoring your immune system’s ability to fight cancer. experts say that cancer immunotherapy represents one of the most significant advances in oncology in recent years. breakthroughs with immune checkpoint inhibitors (ici) in other cancers, along with increasing evidence of the influence of the immune system in cancer behaviour, have led to the development of effective immune therapies for breast cancer patients.

the immune system normally stops itself from attacking normal cells in your body by using proteins called checkpoints, which are made by some of your immune cells. pd-1 is an immune checkpoint protein that attaches to a protein on cells called pd-l1 to basically turn off your body’s immune response so it doesn’t destroy healthy cells. but it also means that your immune system doesn’t recognize cancer cells. checkpoint inhibitor drugs can target either pd-1 or pd-l1 proteins. they stop the proteins from attaching and allow your immune system to recognize and destroy cancer cells.

the pd-1 or pd-l1 checkpoint inhibitors used to treat triple-negative breast cancer (tnbc) are atezolizumab (tecentriq, tecentriq sq) and pembrolizumab (keytrudawhich).

atezolizumab can be combined with the chemotherapy drug nab-paclitaxel (abraxane) to treat advanced or metastatic tnbc, while pembrolizumab is used in combination with chemotherapy before surgery (called neoadjuvant therapy) for high-risk early-stage tnbc, or after surgery for tnbc by itself, and continued until the cancer stops responding. it can also be used in combination with chemotherapy for tnbc that is metastatic or can’t be removed with surgery and has not yet been treated.

the common side effects of immunotherapy for breast cancer, depending on the drug, dose and your overall health, include:

fatigue
nausea and vomiting
loss of appetite
constipation
diarrhea
infection
fever
skin problems
cough
low white blood cell count
low levels of thyroid hormone
breathing problems
muscle and joint pain
stomach pain

personalized cancer therapy is still in its infancy, but the field of oncology is moving toward a point where we will be able to fully understand the immune markers for every single patient. the oncology team will then design personalized therapeutic regimens based on that immune environment unique to your cancer.

most breast cancers, though, are well managed by current treatments outlined here where patients often endure aggressive treatments but go on to live full lives. breast cancer can be a manageable disease for patients and their families with growing options, access to care and support.

sources:
canadian cancer society – immunotherapy for breast cancer

canadian breast cancer network – immunotherapy and breast cancer explained

nature february 2023, immunotherapy in breast cancer – an overview of current strategies and perspectives

karen hawthorne

karen hawthorne worked for six years as a digital editor for the national post, contributing articles on health, business, culture and travel for affiliated newspapers across canada. she now writes from her home office in toronto as a freelancer, and takes breaks to bounce with her son on the backyard trampoline and walk bingo, her bull terrier.

health canada-approved treatments: breast cancer

this complete guide outlines all the treatments available for breast cancer in canada.

diagnosed with breast cancer: managing treatments, support and resources

what it feels like: ‘i will never be my normal’ after surviving multiple cancers

surgery

breast-conserving surgery (bcs)

mastectomy

breast reconstruction

radiation therapy

chemotherapy

hormone therapy

targeted therapy

immunotherapy

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health canada-approved treatments: breast cancer

this complete guide outlines all the treatments available for breast cancer in canada.

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targeted therapy

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