Breast cancer is the most common type of cancer among women in Singapore today. 1 out of every 13 women in Singapore is likely to be afflicted by breast cancer, with more than new cases diagnosed every year.
Normal cells divide and reproduce in an orderly manner. Your body relies on this orderly activity to repair injuries and replace wornout tissue. Sometimes this orderly process is disrupted. Cells grow and divide out of control, producing extra tissue to form a mass or lump called a tumour. A tumour can be benign or malignant.
Benign tumours are not cancers. They may grow slowly but do not spread to other parts of the body.
Malignant tumours are cancerous growths and have the potential to spread to other parts of the body.
Breast cancer is a malignant tumour which occurs when breast cells become abnormal and divide without control or order.
The majority of breast cancers start in the milk ducts. A small number start in the milk sacs or lobules. Within these two groups, some grow very slowly while others develop more rapidly.
Breast cancer can spread to the lymph nodes and to other parts of the body such as the bones, liver, lung and sometimes to the brain.
Ductal carcinoma in situ (DCIS) generally does not cause symptoms, and is most commonly discovered in screening mammograms. Occasionally, women with Ductal carcinoma in situ (DCIS) may present with a breast lump or bloody nipple discharge.
Breast cancer is otherwise usually painless and there may be no symptoms in the early phase when breast cancer first develops.
When the cancer grows, signs and symptoms may develop and they can include:
The causes of breast cancer are not exactly known but there are risk factors that increase the chance of developing breast cancer. Having risk factors do not mean a woman will definitely develop breast cancer, as many women who have had breast cancer did not have any apparent risk factors.
Some risk factors such as gender and age, or those related to our environment cannot be changed (non-modifiable), while others are modifiable as they are related to our lifestyle choices.
Being a woman is a risk factor for developing breast cancer. Women have a much higher chance of developing breast cancer than men due to the female hormones oestrogen and progesterone.
This risk is increased with longer hormonal exposure in women with early menarche (onset of menstruation) before the age of 12 and late menopause (after the age of 55).
Other hormonal-related factors include never having children, late childbearing (after the age of 30), and obesity, especially excessive weight gain in post-menopausal women. This risk also increases with age.
Genetic factors and family history of breast cancer, especially in a first-degree relative (mother, sister or daughter), or two or more close relatives such as cousins and the presence of genetic alterations in certain genes such as BRCA1 and BRCA2 which are associated with significant lifetime risks of breast cancer.
A past history of breast cancer, radiation exposure for medical reasons and certain benign conditions such as atypical ductal hyperplasia, atypical lobular hyperplasia or lobular carcinoma in-situ diagnosed on breast biopsy also increase the risk.
However, most women who have breast cancer have none of the above risk factors. Likewise, not possessing any of these risk factors does not mean that one will not get breast cancer. There is ongoing research to learn more about these factors, as well as ways to prevent breast cancer.
There is no sure way to prevent breast cancer, but the risks can be lowered. These include
modifying the risk factors which we have control over such as:
In high-risk women, such as those with a very strong family history or have genetic mutations such as the BRCA, risk-reducing options include taking drugs or having surgery that can reduce their risk. Risk-reducing surgeries include removal of the breast (mastectomy) and removal of the ovaries.
An alternative management strategy to risk-reduction methods is close surveillance. While this does not reduce the risk of cancer development, it does improve outcome by discovering the cancers in earlier stages, allowing earlier treatment and hence better outcomes.
About 5 to 10 percent of breast cancers can be attributed to hereditary breast and ovarian cancer (HBOC) syndrome. Genetic change (mutation) in the BRCA1 or BRCA2 gene is the most common cause of Hereditary Breast and Ovarian Cancer (HBOC).
BRCA2 mutation tend to develop cancer at an earlier age than the general population and have higher risk for bilateral breast cancer, a second primary tumour in a different tissue, and cancer recurrence.
Mutations in other less common genes have also been found to increase the risk of developing breast and other cancers.
Hereditary Breast and Ovarian Cancer (HBOC) is an adult-onset, cancer predisposition syndrome which can be passed down through generations.
The history of cancer in your close relatives is a clue about the chance of HBOC syndrome in your family. It is more likely if one or more of the following features can be confirmed in your family:
Genetic testing for Hereditary Breast and Ovarian Cancer (HBOC) syndrome is a blood test that is available at the Cancer Genetics Service at NCCS when specific criteria are met. Genetic testing is complex, thus it does not take place without genetic counselling and the process of informed consent.
Cancer genetic counselling is a process to assess a person's risk of having an inherited susceptibility to cancer. It is usually provided by a genetic counsellor and/or cancer geneticist to help people understand and adapt to the medical, psychological and familial implications of genetic contributions to cancer.
Genetic counselling can help you better understand the outcomes and impacts of genetic testing and the possible implications when finding a genetic mutation of Hereditary Breast and Ovarian Cancer (HBOC) syndrome.
Increased surveillance (clinical breast exam, mammogram and MRI) and consideration of risk-reducing interventions (such as chemoprevention and preventive mastectomy or oophorectomy) are recommended.
If your family history of cancer suggests Hereditary Breast and Ovarian Cancer (HBOC) syndrome, please talk to your doctor regarding your concerns and they will make the necessary arrangements if a genetic risk assessment is needed.
Finding a genetic mutation of Hereditary Breast and Ovarian Cancer (HBOC) syndrome may help to:
Breast cancer can be classified by the stage of cancer at diagnosis and their biological characteristics. These will determine treatment recommendations as it has prognostic (most likely outcome of the disease) implications and treatment implications.
Understanding the stage of the cancer is important to understand the prognosis and the treatment recommendation.
Cancers treated in earlier stages have better outcomes, more advanced cancers will need more aggressive treatment.
Cancer stage is based on:
The TNM staging system is based on:
T: Size of the tumourN: Lymph node involvementM: Metastasis when cancer has spread to other organs like the lung, liver and bones.Different T, N and M in combination will determine the stage of the cancer.
Stage 0 or Ductal Carcinoma in Situ (DCIS) is a common non-invasive breast cancer, where cancer cells are still within the ducts and have not grown out to breach the duct linings into the surrounding normal breast tissue.
DCIS, also known as Stage 0 breast cancer, unlike invasive breast cancer, is not life-threatening, but it can increase the risk of developing an invasive breast cancer.
lnvasive breast cancer occurs when cancer cells spread beyond the ducts or lobules resulting in invasive ductal and invasive lobular breast cancer, the two most common subtypes of breast cancer.
Metastatic breast cancer refers to the stage when the cancer has spread beyond the breast to distant organs such as the lungs, liver or bones.
Breast cancers are also differentiated by the presence of special receptors on the surface of the cancer cells, such as the:
This is associated with the aggressiveness of the cancer and affects the prognosis of the patient.
More importantly, there are drugs to target these changes, and hence directed treatment for them will improve the outcome.
The histopathological (microscopic appearance) subtype of the cancer also helps to determine the prognosis, and nature of breast cancer overall.
The grade (assessment of how abnormal the cancer cells look) also determines the aggressiveness and hence, treatment recommendations.
The most common subtype is the invasive carcinoma of no special type (NST). Specific subtypes include invasive lobular, tubular, cribriform, metaplastic, apocrine, mucinous, papillary and micropapillary carcinoma, as well as carcinoma with medullary and neuroendocrine (WHO classification 2012).
If there is an unusual lump or changes in the breasts, seek medical attention. Try to pinpoint the area accurately as this will assist the doctor with the examination. Tests will be recommended to obtain a definite diagnosis.
Tests to diagnose Breast Cancer include:
Mammography is a low-powered X-ray technique that gives a picture of the internal structure of the breast. Usual screening mammograms involve taking X-ray images of the breast compressed between two plates with two views taken — cranial caudal or horizontal and mediolateral oblique or diagonal.
Additional angles and magnified views may be taken if there are areas of concern. It can detect the presence and position of the abnormalities and help in the diagnosis of breast problems, including cancer.
Any previous mammograms (and reports if available) should be brought along when seeing a doctor.
Sometimes a lump that can be felt is not seen on a mammogram. Other tests may be necessary to determine if the lump is cancerous.
What to expect when you go for a mammogram.
Breast ultrasound is the use of high-frequency sound waves to produce an image of breast tissue.
The sound waves are transmitted from the probe through the gel into the body. The transducer collects the sounds that bounce back and a computer then uses those sound waves to create an image.
This uses a combination of magnetism and radio waves to build up a picture consisting of detailed cross-sections of pictures of the breasts.
The test involves lying on the stomach on a padded platform, with cushioned openings for the breasts, that passes through a tunnel-like structure (which forms a very large magnet). It may take up to one hour to complete, but is completely painless.
Magnetic Resonance lmaging (MRI) is useful when mammograms are not suitable, e.g. in young women with dense breast tissue or when findings on mammograms and ultrasound are not conclusive to achieve a diagnosis.
It is used as a screening tool for young women with high-risk factors like
BRCA gene carriers or those with a very strong family history of breast cancer.
This involves taking multiple X-rays of each breast from many angles. The breast is positioned the same way as in a conventional mammogram, but only a little pressure is applied, just enough to keep the breast in a stable position during the procedure.
An X-ray tube moves in an arc around the breast while images are taken. Information is sent to a computer, where it is assembled to produce clear, highly-focussed 3-dimensional images throughout the breast.
A syringe with a very fine needle is used to withdraw fluid or cells from a breast lump. This is a simple procedure and can be uncomfortable but is usually tolerable enough for it to be done in the clinic.
If the lump is just a cyst, withdrawing fluid in this manner will usually make the cyst disappear.
However, if the lump is solid, your doctor may use this procedure to withdraw some cells from it. The cells will then be sent to a laboratory for examination.
This is a minimally invasive method that obtains a few tiny strips of tissue from an area of abnormality with a wide bore needle. Local anaesthetic is injected to numb the breast area, followed by a small incision in the skin to allow easy insertion of the needle.
If the abnormality is non-palpable (not detectable by clinical examination) and visible on the ultrasound, ultrasound guidance is used to obtain the tissue. Usually 2 to 6 cores of tissue will be obtained for examination.
A nurse will apply compression to the breast to stop any bleeding. The wound is closed by a steristrip and the dressing applied. Strenuous activity is to be avoided for 2 days after the biopsy.
Vacuum-assisted biopsy (VAB) devices use a larger bore needle with a vacuum component to obtain tissue samples from non-palpable lesions.
Like the usual core biopsy, this minimally invasive procedure is also performed under local anaesthesia, which is injected to numb the breast area, followed by a small incision in the skin to allow easy insertion of the needle. It is used for lesions seen by mammography (stereotactic-guided biopsy), ultrasound or MRI.
The surgeon or radiologist places the probe into the suspicious area of the breast accurately. A vacuum then draws the tissue into the probe, a cutting device removes the tissue sample and then carries it through the probe into a collection area.
More tissue is usually obtained using the Vacuum-assisted biopsy (VAB) than the usual core needle biopsy and the number of strips removed is dependent on the area that needs to be examined.
A small titanium clip (microclip) may be placed at the biopsy site as a location marker for future treatment. This clip is very small (2 mm), is harmless, and will not cause any problems when left inside the breast. An X-ray is taken post-biopsy to ensure proper clip placement. New biodegradable markers are also available now.
A nurse will apply compression to the breast to stop any bleeding, the wound is closed by a steristrip and the dressing applied. Strenuous activity is to be avoided for 2 days after the biopsy.
This procedure is minimally invasive as compared to an open surgical biopsy. It is performed as a day surgery procedure. lt has the ability to sample tiny abnormalities called microcalcifications, making early diagnosis of breast cancer possible.
Under local anaesthesia, it takes about 30 to 45 minutes to complete. The procedure is usually not painful but you may experience some discomfort.
An excision biopsy is the removal of a lump or sample of suspicious tissue by surgery for examination under a microscope to give a definite diagnosis.
For lesions that are small or not palpable, accurate marking of the area for surgery is necessary. These include using ultrasound during surgery, or with procedures done just before surgery to mark the area to be operated.
Ultrasound, mammogram or MRI can be used to insert a small thin wire to the abnormal spot in the breast.
This wire is used to guide the surgeon to remove the area accurately. This technique is known as
Hook Wire Localisation (HWL) Biopsy.
An alternative method known as
Radioisotope Occult Lesion Localisation (ROLL) uses a small amount of radioactive substance injected into the lesion. This area is detected with a radioactive sensor used during surgery that allows the lesion to be accurately removed.
This technique does not have the discomfort of the hookwire and the need to perform mammograms after the wire placement to check their positions.
Excision biopsies are often performed under general anaesthesia, depending on the size and position of the lump, but local anaesthesia may be used for small lesions close to the skin.
As a minor day surgery procedure, patients can return home after surgery. Strenuous activity is to be avoided for the first few days; immediate ability for usual light activities of daily living is expected.
Post-operative advice may differ between individuals depending on their needs and circumstances. In general, most will be able to return to work in a week.
Treatment of breast cancer often involves more than one therapy, and may be a combination of therapies.
Treatment recommendations depend on factors such as the cancer type, stage of the cancer, size of the tumour in relation to the breast size, whether breast preservation is desired and the patient’s general health.
Personal preferences de-termine certain choices, if the option is available, such as the options for the type of surgery. Being diagnosed with breast cancer and having to decide on the treatment options may be difficult. The support of friends and family during the consult and discussion on the results of tests and treatment is recommended.
In early breast cancer, surgery is the first treatment of choice. Chemotherapy, targeted and hormonal therapy may be used before surgery (neoadjuvant therapy), or after surgery (adjuvant therapy). Radiotherapy is usually given after surgery.
In stage IV cancer, the goal is to stabilise the disease with systemic therapy. However, local treatment of tumours with radiation therapy or surgery may be recommended when symptoms need to be alleviated.
Surgery for breast cancer is considered in two parts:
axillary lymph nodes.
The two broad options are
breast-conserving surgery (BCS) or
Image-Guided Localisation for Surgery
For non-palpable tumours that need to be removed with surgery, localisation with a hookwire or a localising substance under image guidance done prior to the surgery is needed.
This procedure is performed under local anaesthesia, prior to surgery. Mammogram, ultrasound or MRI guidance is used to accurately locate the site for surgery.
A fine wire (hookwire) is inserted or a radioactive substance is injected into the breast, within or in close proximity to the lesion of interest, which will be removed during the surgery.
Mastectomy is the removal of the whole breast (incorporating the breast tumour). In general, there are two types of mastectomy:
Skin, fat and sometimes muscle (a flap) from another part of your body may be used to make into a breast shape. This operation takes about 6 to 8 hours and requires a hospital stay of between 1 to 2 weeks. Several drains are used and removed after 1 to 2 weeks. Flaps may be from the following areas:
Additional procedures to improve the look of the breast after the initial surgery may include adding a nipple, surgery to the opposite breast to create a good match, or refining the shape of the recreated breast.
Silicone implants may be used to create a new breast and the operation takes about 4 to 5 hours. There are usually 2 to 3 drains inserted and the hospital stay is 2 to 5 days.
1-stage procedure is when the permanent implant is inserted at the time of mastectomy. A
2-stage procedure is when a temporary expander is placed at the time of mastectomy and gradually expanded to stretch the skin. The expander will be exchanged for a permanent implant at a later surgery.
Sentinel Lymph Node Biopsy (SLNB) is recommended for early-stage breast cancer when the lymph nodes in the armpit do not appear to have cancer.
Sentinel lymph nodes (SLN) are the first few lymph nodes in the armpit where the lymphatic vessels from the breast drain to. These will be removed during surgery and examined under the microscope (frozen section) to determine if cancer has spread to the SLN.
This is done under general anaesthesia (GA). A blue dye or a radioactive substance is injected around the cancer site or at the nipple prior to surgery to locate the SLN. The radioactive substance will be injected before the operation. The blue dye will be injected during the operation.
If cancer is detected in the SLN, lymph nodes in the axilla will be removed. If no cancer is detected in the SLN, no further surgery is needed.
The final histology (microscopic assessment) will be reviewed about 1 week after surgery. In up to 5 percent of cases, the final assessment of the SLN may be different from the initial frozen section result and a second operation may be recommended.
If the dye or radioactive substance is not able to identify the SLN, removal of all the lymph nodes (axillary clearance) will be done.
Axillary Clearance is the removal of all lymph nodes from the underarm when the lymph nodes are found to have cancer cells. Side effects of axillary clearance include shoulder stiffness and numbness of the inner part of your upper arm. Lymphoedema (swelling of the arm) may occur in 10 to 15 percent of women. This is because lymph nodes drain fluid from the arm and their removal may cause fluid to accumulate in the arm on the operated side.
A separate axillary incision is often needed for patients undergoing breast conserving surgery.
As with all surgical procedures, complications can occur. Risks of general anaesthesia include allergy to anaesthetic agents, heart attack, stroke and deep vein thrombosis, especially for longer surgeries.
Our anaesthetists will assess all patients before surgery to ensure they are optimised and prepared for surgery to minimise these risks.
Surgical complications include:
After surgery is planned, referral to the Breast Care Nurse (BCN) Service is necessary. Our Breast Specialist Nurse will explain and explore concerns and issues pertaining to breast cancer and the treatment options, and plan pre-operative, operative and post-operative management to ensure successful treatment and recovery.
Consult time for individual patients vary from 30 to 75 minutes. A personal contact number will be provided for convenience and the BCN will be a resource person for patients and their families in the coordination of the various appointments before and after surgery in the treatment journey.
Post-operative services include wound and drain care, rehabilitation, education programmes and prosthesis-fitting.
Radiotherapy is a form of cancer treatment where cancer cells are damaged and killed with high energy radiation. Together with surgery and other treatments, radiotherapy reduce the amount of cancer in your body and increases the chance of you staying cancer free.
Radiotherapy is almost always recommended after breast-conserving surgery and often in patients with high risks disease after mastectomy. This include patients with large tumours and those where the cancer has spread to involve multiple lymph nodes. Almost always, radiotherapy is performed after surgery and chemotherapy, when needed.
Radiotherapy is performed over a period of about 3 weeks. The actual treatment duration may be adjusted further based on an assessment of your needs.
Following a consultation with your specialist, an appointment will be made for scans to be performed of the part of the body to be irradiated. This process is called Simulation.
Your doctor and team of specialists will then perform a personalized planning for radiotherapy according to your needs.
Radiotherapy is delivered every day, 5 days a week for the duration of the treatment. Daily treatment lasts for under an hour and is performed on an outpatient basis. Treatment is entirely painless and without any perceptible sensation.
During the weeks of radiotherapy, you would notice redness of the skin on the irradiated breast. This may be accompanied by dryness, itch and occasionally, pigmentation and mild discomfort from temporary swelling. These effects are short-term and would resolve rapidly in the weeks to months following the completion of radiotherapy.
In the longer term over months and years, a small proportion of patients may experience progressive hardening of the breast and the overlying skin which may lead to a shrinking or distortion of the breast or chest wall. Other late complications to the heart and lungs are much rarer and your doctor will advise you further as the risks vary between patients.
Intraoperative Radiotherapy (IORT) is a specialized form of radiotherapy used in the treatment of breast cancer. Like all radiotherapy, high energy radiation is used to damage and kill cancer cells, so as to reduce the amount of cancer in your body and increases the chance of you staying cancer free.
IORT is performed only in patients undergoing breast-conserving surgery. Additionally, IORT is suitable only for patients with early stage cancers and meet conditions that your radiation oncologists will advise you on.
In suitable patients, IORT is performed during the cancer surgery immediately upon removal of the tumour. A specialized applicator will be placed into the excision cavity to irradiate the immediate breast tissue from inside out hence limiting the dose to the rest of the involved breast and normal organs. As patients will remain under anesthesia, IORT is completely painless.
For most patients, this single fraction IORT will be the only radiotherapy they require, hence the treatment burden in well selected patients can be reduced. Occasionally, the surgery and subsequent examination of the cancer may reveal additional information about the cancer which may lead to your doctor recommending for the use of additional external beam RT after IORT.
Patients will experience the usual symptoms relating to breast cancer surgery. In addition, some patients may experience a slower resolution of the seroma associated with the surgical cavity. A smaller group of patients may find localized hardening of the breast tissue and skin in the region of the operation. Rarely, this may lead to a distortion of the breast in the long term.
This treatment uses anti-cancer drugs to prevent cancer cells from growing and reproducing themselves. These drugs are usually given by injection through veins into the blood stream to all parts of the body.
It is usually given over 3 to 6 months and may be used alone, before surgery (neoadjuvant) or after surgery (adjuvant) therapy, or together with targeted therapy to increase the effectiveness of the treatment, depending on the type and stage of cancer.
Chemotherapy is given in cycles. Each cycle consists of a treatment period followed by a resting (recovery) period. As cancer drugs also affect normal cells, the resting period is to allow the body to recover before the next treatment cycle starts.
Breast cancers are also tested for special receptors. One such receptor is the Human Epidermal Growth Factor 2 (HER2) receptor. This receptor is over-expressed in about 25 percent of all breast cancers; the presence needs to be confirmed by laboratory tests performed on the biopsy specimen before the treatment is given.
The aim of the treatment is to reduce and hopefully eliminate existing cancer cells in the human body while minimising side effects on normal cells.
Trastuzumab, also known as Herceptin®, targets the HER2 (Human Epidermal Growth Factor 2) receptors on cancer cells to prevent cell growth and division.
Herceptin® has been shown to prolong survival in breast cancer patients with early and advanced disease (Stage IV) when used in combination with chemotherapy.
An increasing number of targeted drugs are becoming available for the treatment of breast cancer, including Lapatinib (which targets HER2 and EGFR) and Bevacizumab (which targets a factor associated with new blood vessel formation in tumours.
Breast cancers are tested for oestrogen receptors (ER) and progesterone receptors (PR) on their surfaces as such cancers can be stimulated by oestrogen or progesterone to grow.
Hormonal therapy is aimed at blocking this effect. The drug recommended is dependent on the menopausal status of the women.
Hormonal therapy can cause some side effects, and they are dependent on the type of drug taken and can vary from one patient to another.
Regular follow up by the doctor after treatment is recommended due to the risk of developing breast cancer again.
This will include physical examination of the chest, underarms, neck, and the other breast with periodic mammograms.
Changes to look out for include:
Wounds are often closed with absorbable stitches, hence stitch removal is not needed.
Wound care is simple and patients will be taught and given specific instructions in the management of various types of wound coverage.
Patients are recommended to shower 2 days after most surgeries such as breast-conserving surgery and simple mastectomies.
Soft flexible tube drains are placed under the skin at the time of surgery. These help to remove blood and other fluids that accumulate at the site of surgery. Patients without breast reconstruction surgery are usually discharged from the hospital with the tube drain on the day after surgery.
The nurse in the ward will teach the drain care and provide a chart to keep a record of the drainage, to be reported to the Breast Care Nurse (BCN) daily. The drain will be removed in the clinic when the drainage is minimal and this usually takes 1 to 2 weeks.
Patients are recommended to see a doctor if there is:
Routine medications prescribed by doctors are usually resumed immediately after surgery and there are diet restrictions unless otherwise advised by the doctor.
Patients are encouraged to resume normal mobility and function as soon as it is suitable after surgery.
Most patients with breast-conserving surgery (BCS) and simple mastectomies will be able to resume usual daily activities immediately after surgery, with special precautions for those with breast reconstruction surgery, where management will differ according to their surgeries.
Our Arm Exercise Programme conducted by our Occupational Therapists or Physiotherapists on the day after surgery aims to prevent shoulder and arm stiffness. This will enable you to use the arm as you had before surgery in activities at home, work and in recreation.
The exercises also promote circulation of the lymphatic system, thus preventing swelling of the affected arm. Over-strenuous activities are to be avoided in the first few weeks after discharge.
These exercises are to be done once daily, and each set of exercises is to be repeated 5 times. Instructions from the Occupational Therapist or Breast Care Nurse on the limitations will be advised as needed.
Following axillary surgery, lymphoedema and increased risk of infection of the arm may occur as lymph nodes also contain cells which fight infection.
Therefore, extra care to protect the hand and arm on the operated side from injury is recommended.
Patients will be referred to a physiotherapist or occupational therapist specially-trained in treating lymphoedema. They will recommend programmes which include skin care, exercise, manual lymphatic drainage (a special massage technique), and compression garments to help reduce the swelling.
Preventive measures include:You will be referred to an occupational or physio therapist for rehabilitation advice and arm exercise. Exercises may begin as early as the first post-operative day. The following basic steps can greatly reduce the risk of arm swelling:
With a mastectomy, physical appearance can be maintained by wearing a prosthesis (called a breast form), or by undergoing breast reconstruction.
There are women who choose not to have breast reconstruction after mastectomy. Some make this decision because they want to avoid extra surgery. For others, it is because they are comfortable with their appearance and body image.
Breast forms or prostheses are used to maintain appearance and a sense of balance, as well as to relieve the strain on posture that may occur after a mastectomy. They are available in a variety of sizes, shapes and colours. Some are designed to fit into a special bra. Others can be attached securely to your chest using a special adhesive.