Breast cancer occurs when breast cells develop abnormally and grow out of control forming a malignant (cancerous) tumor. It is possible for cancer cells to spread (metastasise) from the breast to other parts of the body via the lymphatic system and by direct entry into the blood vessels. Once there, they can form “secondary” cancers. Prior to menopause the majority of new breast lumps found are benign (non-cancerous). However after menopause one in two new breast lumps found will be malignant. Approximately 75% of all breast cancers will occur in women over the age of 50 years. Internationally, breast cancer rates have increased in most developed countries over the last 40 years. Breast cancer can recur. Once a woman has had breast cancer her chances of developing it again are increased fivefold.
Causes of Breast Cancer
The causes of breast cancer are not known. However, it is known which women are more at risk of developing the condition. The main risk factors for developing breast cancer are:
• Being a woman over the age of 40 years.
• Having a family history of breast cancer – the younger the family member was when they developed breast cancer, the greater the risk.
• Having had breast cancer previously.
• Having had a biopsy showing an “at risk” breast lump or thickening.
• Having a breast cancer gene (BRCA-1 or BRCA-2). Women with a breast cancer gene have a 50% chance of developing breast cancer before the age of 70.
Other risk factors include
• Having had an early onset of periods or the late onset of menopause.
• Having had a first child after the age of 30 years or not having had children at all.
• A diet high in fat, excessive alcohol and a reduced intake of fiber, fruits and vegetables.
• Being on HRT medication for longer than 5-7 years.
• Taking the oral contraceptive pill may slightly increase the risk of developing breast cancer, but this has not been conclusively proven.
• Having dense breasts – dense breasts do not increase the risk of developing breast cancer, but they may make lumps difficult to feel and see.
• Being in a high socio-economic group or having Jewish ancestry may also be risk factors for developing breast cancer.
Types of Breast Cancer
There are several different types of breast cancer. The two most common types are ductal breast cancer (to do with the milk ducts) and lobular breast cancer (to do with the milk lobules). Each of these breast cancers can be either “in situ” or “invasive”.
In Situ Carcinoma
These are pre cancers and are the earliest stage of breast cancer; they can either develop into invasive breast cancer or raise the risk of developing invasive cancer. Caught and treated early, they are often completely curable.
Ductal Carcinoma in situ (DCIS)
This is where the breast cancer cells are completely contained within the milk ducts and have not spread into the surrounding breast tissue. DCIS is usually treated with surgery (mastectomy) or combined surgery (partial mastectomy) and radiotherapy.
Lobular Carcinoma in Situ (LCIS)
This is where the breast cancer cells are completely contained within the milk lobules and have not spread into the surrounding breast tissue. Often LCIS does not need treatment. Instead, regular breast exams and mammograms may be used to monitor for the early changes of developing breast cancer.
This is where the ductal or lobular cancer spreads into the surrounding tissues. Approximately 90% of invasive breast cancers are ductal cancers. Other less common breast cancers include inflammatory breast cancer and medullary breast cancer.
Signs and Symptoms
Most commonly, the first sign of breast cancer is a new lump in the breast. The lump is usually painless.
Other signs of breast cancer include
• A new area of thickened tissue in the breast.
• Nipple discharge or a change in the nipple.
• Dimpling or puckering of the skin of the breast.
• A change in breast size or shape.
While these symptoms may not be related to breast cancer, it is important to see a doctor promptly for assessment and accurate diagnosis if any of these symptoms are present. Early detection is vital in the successful treatment of breast cancer.
If an abnormal lump is found, or other symptoms are present, a referral to a breast specialist for assessment and diagnosis will probably be recommended. In order for an accurate diagnosis to be made the three step approach of clinical examination, imaging (mammography and ultrasound scanning), and biopsy will be required.
The doctor will begin by examining both breasts. They will then check the abnormal lump’s size, location and other characteristics such as whether it is mobile, hard or soft, regular or irregular. The doctor will ask about the history of the lump such as how long it had been there, has it grown, is it painful. Risk factors such as family history or previous breast lumps will be asked about.
Imaging (Mammograms and / or Ultrasound Scanning)
A mammogram (specialized breast x-ray) shows the soft tissue of the breast and can indicate any suspicious areas. Ultrasound scanning uses sound waves to form an image of the breast tissue. Pictures of any suspicious areas can be taken. Ultrasound scanning is particularly useful for assessing whether a lump is fluid filled or solid.
There are different types of biopsies used to take cells or tissue samples from a suspicious lump so they can be sent to a laboratory for analysis under a microscope.
Fine Needle Aspiration
This is usually the first type of biopsy used. It is performed using a local anaesthetic and involves inserting a fine needle into the lump and removing a small sample of cells and/or fluid. At the laboratory the sample is spread onto a glass slide and analyzed. The insertion of the needle may be guided by ultrasound.
This uses a larger needle to remove a sample of tissue from the lump. A local anaesthetic is used and a very small incision (1-2mm) is made in the skin over the lump. The needle is usually guided into the lump by ultrasound. At the laboratory the tissue sample is sliced very finely and placed on a glass slide for analysis.
Stereotactic Core Biopsy
This is a core biopsy performed on a special x-ray table allowing three dimensional computerized images of the lump to be taken and used to guide the biopsy needle into the lump. This is useful for testing lumps seen on a mammogram that cannot be felt or visualized using an ultrasound scanner.
This is a minor surgical procedure where part or all of the abnormal area is removed. It can be performed using a local or general anaesthetic. If the lump is unable to be precisely located using mammogram or ultrasound scanning, it may need to be marked by a thin wire called a “hook wire”. This is inserted under x-ray guidance using a local anaesthetic just prior to the surgery. If a diagnosis of breast cancer is made, blood tests, x-rays and scans of the bones and liver may be performed to assess whether the cancer has spread to other organs.
Stages of Breast Cancer
After diagnosis, breast cancers are given a “stage”. The stage indicates the tumor’s size and how far it has spread within the breast, surrounding tissues or to other organs in the body. Stages range from 0 to IV – a higher stage indicates more severe cancer.
The cancer has not spread beyond the ducts of the breast (ie ductal carcinoma in situ or DCIS).
These tumors measure less than two centimeters. The axillary lymph nodes are not affected and there are no signs that the cancer has spread elsewhere in the body.
These tumors measure between two and five centimeters, or the axillary lymph nodes are affected, or both. There are no signs that the cancer has spread elsewhere in the body.
These tumors are larger than five centimeters, the axillary lymph nodes are usually affected, but there are no signs that there has been any further spread.
These tumors are of any size, but the axillary lymph nodes are usually affected and the cancer has spread to other parts of the body.
Treatment of breast cancer depends on the type of breast cancer, its size and position, whether it has spread, the woman’s age and general health, and the woman’s preference. In general, some type of surgery is recommended followed by additional treatments (adjuvant therapies). Surgery and radiotherapy are classed as local treatments (as they affect a localized, specific area) while chemotherapy and hormone therapy are classed as systemic treatments (as they have the potential to affect the whole body).
In most cases, the breast cancer tumor can be removed without having to remove the entire breast (referred to as breast conserving surgery). The area of the cancer is removed along with a ”margin” of healthy surrounding tissue (usually about 1cm), to ensure that all of the breast cancer is removed.
This operation involves removing the entire breast and all of the breast tissue from just below the collarbone to the upper abdomen. A “simple mastectomy” is when just breast tissue is removed. A “modified radical mastectomy” is when the lymph glands under the arm are also removed. Mastectomy may be recommended if the tumor is large, there is more than one area of breast cancer in the breast, or for cases of recurrent breast cancer. A hospital stay of 2-5 days and a recovery period of 3-6 weeks can be expected after a mastectomy.
Surgical treatment may also involve
Axillary Node Dissection
It is usual practice during breast cancer surgery to remove up to half of the axillary lymph nodes for testing. Testing of the lymph nodes can indicate whether the cancer has spread into the lymphatic system, thus increasing the risk of the cancer spreading to the rest of the body.
Sentinel Node Biopsy
This type of lymph node biopsy is used in some cases to minimize problems associated with axillary node dissection. During a sentinel node biopsy two special dyes are injected around the breast cancer tumor. One is visible to the naked eye during the biopsy surgery and the other is a weak radioactive substance detectable by either a Gamma camera or a hand-held device like a Geiger counter. The dyes drain through the lymph vessels and into the first node to be involved – the sentinel node. This node is then removed for analysis. If the sentinel node is clear of cancer cells, then it can safely be presumed that the cancer has not spread to the rest of the axillary nodes. If however the sentinel node is positive for cancer cells, a subsequent procedure to remove the remaining lymph nodes would be needed.
After mastectomy, some women may choose to have the breast reconstructed. This can be done at the time of the mastectomy or at a later date. The surgery is usually performed by a plastic surgeon. The aim of breast reconstruction is to recreate a breast that feels and looks as natural as possible.
Additional treatments are commonly given after surgical removal of a breast cancer. One or a combination of these treatments may be recommended. An oncologist (cancer specialist) will be involved in deciding which treatments will be given
This uses radiation to destroy any cancer cells that may be left in the breast. It is most commonly used after lumpectomy/partial mastectomy. However, it may be used after mastectomy if there was more than one tumor, the tumor was large, or the tumor was growing close to the chest wall. A course of radiotherapy is usually given over 4-6 weeks, consisting of daily treatments from Monday to Friday. Side effects of the treatment include severe tiredness and burns similar to bad sunburn on the treated area.
This may be given if spread of the cancer is suspected or confirmed and is usually given soon after surgery. Chemotherapy medications can be given by tablet or as injections into the blood stream. Usually it is a combination of both. The medications aim to kill off any cancer cells that may be circulating in the body. There are different strengths and combinations of chemotherapy medications, which are given in cycles. Side effects of chemotherapy treatment may include nausea, hair loss, sores in the mouth and diarrhoea.
For cases where the breast cancer is hormone receptor positive, hormone therapy may be prescribed to help prevent recurrence of the breast cancer. These medications work by blocking the hormone receptors on the breast cancer cells, preventing hormones binding to them and stimulating growth. One common example of this type of medication is tamoxifen. This is commonly given for up to five years after diagnosis of breast cancer. Other types of hormone treatments include anastrozole (Arimidex) or letrozole (Letara).
This type of treatment includes a class of anticancer medications called “monoclonal antibodies”. These medications are formulated to target cancer cells, rather than normal healthy cells. A monoclonal antibody medication used in New Zealand is Herceptin (trastuzumab). This is used to treat women with HER-2 positive breast cancer. Herceptin works by binding to the HER-2 proteins, preventing them from stimulating the cancer cells to grow. It also acts to “flag” the cancer cells to the body, which then stimulates the immune system to destroy the abnormal cells. In New Zealand, Herceptin is funded and approved for up to 12 months use in the treatment of women with HER-2 positive breast cancer.
After the diagnosis and treatment of breast cancer, regular follow up visits with the healthcare specialists involved in the treatment will be scheduled. This will include seeing the oncologist and surgeon. Initially this may be as frequently as every three months, but will eventually be less often. During these visits monitoring procedures such as imaging (mammograms/ultrasound scans), blood tests and clinical examinations will be conducted. Other healthcare professionals who may be involved in the ongoing care and monitoring include the patient’s GP, a breast physician, breast care nurse and physiotherapist. Some women may find it beneficial to see a counselor to help them deal with the emotional and psychological impact of the breast cancer diagnosis and the implications of treatment.