Metaplastic Breast Cancer: Comprehensive Cancer Information

Metaplastic Breast Cancer: A Comprehensive Guide

General Information

Metaplastic breast cancer (MBC) is a rare and aggressive form of breast cancer. It typically presents as a fast-growing lump or mass within the breast.

In imaging examinations, the tumour can resemble an invasive ductal carcinoma, which is a common breast cancer that begins in the milk ducts and spreads to surrounding tissue. However, metaplastic breast cancer tumours are often larger at the point of diagnosis.

Under microscopic analysis, MBC cells display a mix of different cancer cell types. While it was once thought to originate from two separate cancers merging, current evidence suggests that metaplastic breast cancer is a single cancer that may begin in very young cells with the potential to develop into various mature cell types.

Prognosis

Compared to other types of breast cancer, metaplastic breast cancer grows faster and is more likely to spread (metastasise) to other parts of the body. There is also a higher likelihood of the cancer recurring after initial successful treatment.

The five-year survival rate for patients with metaplastic breast cancer is approximately 55%. This figure does not account for recent advancements in treatment, meaning the current survival rate may be higher due to newer, more effective therapies.

Symptoms & Signs

Breast cancer symptoms can vary between individuals, and no two lumps or masses feel exactly alike. We recommend familiarising yourself with the normal look and feel of your breasts, and reporting any changes to your doctor. It is important to note that many breast cancers are detected through routine screening mammograms before any symptoms even appear.

Possible symptoms of breast cancer may include:

  • A lump or mass in the breast or armpit.
  • Changes to the breast skin, such as redness and thickening, which can result in an orange-peel texture.
  • Dimpling or puckering on the breast surface.
  • Discharge from the nipple.
  • Scaliness on the nipple, sometimes extending to the areola (the dark circle around the nipple).
  • Nipple changes, including the nipple turning inward, pulling to one side, or changing direction.
  • An ulcer on the breast or nipple, sometimes extending to the areola.
  • Swelling of the breast.

These symptoms do not automatically confirm a breast cancer diagnosis. However, it is essential to discuss any new or concerning symptoms with your doctor, as they may also indicate other underlying health problems. Genetic counselling may be appropriate for you and your family to understand inherited risks.

Diagnosis

If you notice changes in your breasts, experience symptoms, or receive an abnormal mammogram result, your doctor will need to perform further investigations to reach a definitive diagnosis.

Diagnosis often begins with a breast exam, where your doctor manually checks your breasts and armpit for any lumps or abnormalities. If breast cancer is suspected, further imaging tests may be ordered:

Imaging Tests

  • Mammogram: X-ray images of the breasts are taken from different angles to check for signs of cancer.
  • Ultrasound: A device uses high-energy sound waves to create an image, known as a sonogram, of the breast tissue.
  • In some cases, your doctor may use a Magnetic Resonance Imaging (MRI) scan or other specialised examinations.

Biopsy

If imaging tests show an unusual mass or suspicious skin thickening, a tissue sample is required for a definitive diagnosis. This process of removing and examining tissue under a microscope is called a biopsy.

For breast cancer, an image-guided core needle biopsy is typically performed. During this procedure, live imaging of the breast tissue helps the doctor accurately guide the needle to the suspected cancerous area. This is sometimes performed during the initial imaging appointment to expedite the diagnosis.

If the biopsy confirms cancerous tissue, additional imaging and biopsies may be needed to determine the exact scope of the disease, including whether the cancer has spread to nearby lymph nodes or other distant parts of the body.

Molecular Diagnosis

Following a breast cancer diagnosis, the cancer cells are analysed to identify their molecular receptor subtype. This crucial step informs the development of a comprehensive, personalised treatment plan.

Treatment

Breast cancer treatment is primarily centred on surgery, often combined with chemotherapy, radiation therapy, or both. Other treatment options may include targeted therapy and angiogenesis inhibitors. Treatment plans are always unique and tailored to the individual patient.

Triple-Negative Status

Most metaplastic breast cancers have a triple-negative receptor status. This means the cancer cells do not have high levels of the oestrogen receptor, progesterone receptor, or the HER2 gene/protein. As a result, drugs designed to target these specific features are not effective against triple-negative cancers, necessitating alternative treatment strategies.

Treatment for Localised Disease

If the cancer is diagnosed before it has spread beyond the breast and surrounding lymph nodes, treatment usually begins with chemotherapy, potentially combined with immunotherapy, to shrink the tumour. This initial therapy is then followed by surgery and, in some cases, radiation therapy.

Treatment for Metastatic Disease

If the cancer has spread beyond the breast and surrounding lymph nodes, it is generally treated with chemotherapy or other cancer drugs, either alone or in combination. Radiation therapy may also be used as a palliative measure to reduce pain caused by a tumour mass.

Surgery

Many patients undergo a form of surgery as part of their treatment. Chemotherapy or targeted therapy may be given before surgery to shrink the tumour, making the procedure and recovery easier. There are two main categories of surgery:

  • Lumpectomy: The tumour and a small margin of normal surrounding tissue are removed. This is often suitable for early-stage cases with small tumours and is usually followed by radiation therapy. Lumpectomies are generally outpatient procedures with shorter recovery times.
  • Mastectomy: The entire breast and the tumour are removed. There are several types, including procedures that preserve the breast's skin and nipple/areola complex. Mastectomy and breast reconstruction can often be performed during the same procedure. A double mastectomy (removal of both breasts) may be recommended for patients with a high risk of developing new breast cancer due to family history or a genetic profile, such as a BRCA mutation.

In both lumpectomy and mastectomy, surgeons may also remove nearby lymph nodes. These nodes are examined for cancer cells, which helps determine the risk of the disease spreading further and guides the need for additional chemotherapy and radiation therapy.

SSCHRC's breast cancer surgeons are among the most skilled and renowned in the world. They perform a large number of breast cancer surgeries each year, employing the least-invasive and most effective techniques.

Chemotherapy

Chemotherapy involves the use of powerful drugs to directly kill cancer cells, control their growth, or provide pain relief. It is frequently administered before surgery to shrink the tumour and simplify the procedure. Patients can receive chemotherapy either orally or intravenously.

Radiation Therapy

Radiation therapy uses carefully directed beams of energy designed to destroy breast cancer cells.

It can be used before surgery to reduce the size of large tumours, or after surgery to kill any remaining cancer cells that are undetectable to the naked eye. Following a lumpectomy, patients often receive three to four weeks of daily radiation therapy, or sometimes one to two weeks. When lymph nodes are involved or a mastectomy is performed, patients usually require about six weeks of daily radiation therapy.

For metastatic breast cancer, radiation can be used as palliative care to reduce symptoms caused by cancer spread and improve the patient's quality of life.

Radiation therapy treatments offered at SSCHRC include:

  • 3D Conformal Radiation Therapy: Uses radiation beams that are shaped to match the tumour's dimensions.
  • Intensity-Modulated Radiation Therapy (IMRT): Uses multiple beams of varying intensity to deliver a precise, high dose of radiation to the tumour.
  • Volumetric Arc Therapy (VMAT): A specialised type of IMRT where the machine rotates around the patient in an arc, allowing for more precise tumour targeting and shorter procedure times.
  • Accelerated Partial Breast Irradiation (APBI): A form of brachytherapy that uses radioactive pellets or seeds to kill cancer cells that may remain after a lumpectomy.
  • Stereotactic Body Radiation Therapy (SBRT): Delivers very high doses of radiation using several beams aimed at different angles to precisely target the tumour.
  • Stereotactic Radiosurgery (SRS): Most commonly used for breast cancer that has spread to the brain. It uses numerous tiny radiation beams to target tumours with a precise, high dose of radiation.

At SSCHRC's Breast Centre, our radiation oncologists are exclusively dedicated to breast cancer care, providing them with the deep experience needed to design highly effective treatment plans.

Targeted Therapy

Cancer cells rely on specific molecules (proteins) to survive, multiply, and spread. Targeted therapies work by interfering with, or 'targeting,' these molecules or the genes that produce them, thereby stopping or slowing cancer growth.

In recent years, targeted therapy has significantly improved the prognosis for breast cancer subtypes that were previously considered difficult to treat.

  • Endocrine (Hormone) Therapy: Given to patients with hormone receptor-positive breast cancer. It can be given before surgery to shrink the tumour and is used for five to ten years after surgery to prevent recurrence. Patients with metastatic disease also receive endocrine therapy to prevent disease progression.
  • Targeted Drugs for HER2-Positive Cancer: Patients with HER2-positive breast cancer receive a different set of targeted drugs both before and after surgery. Since about half of HER2-positive breast cancers are also hormone receptor-positive, these patients receive both HER2-targeted drugs and endocrine therapy.
  • Currently, there are no targeted therapies for triple-negative breast cancer, but research is ongoing to identify potential drug targets.

Angiogenesis Inhibitors

Angiogenesis is the process by which a tumour creates new blood vessels to increase its blood supply and grow rapidly. Vascular Endothelial Growth Factor (VEGF) is a key molecule controlling this process.

Researchers developed drugs called angiogenesis inhibitors, or anti-angiogenic therapy, to disrupt this growth. These drugs bind themselves to VEGF molecules or receptor proteins, thereby prohibiting them from activating new blood vessel formation.

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