Phylloides tumours are very rare, accounting for less than 1% of all cases of breast cancer. They start in the connective (stromal) and glandular (duct and lobule) tissues of the breast. These tumours are often benign or low grade and are rarely malignant or high grade. They are also called cystosarcoma phylloides (or spelled phyllodes).
Phylloides tumours are classified based on the appearance of the cells under the microscope. They may be:
- benign – The majority of phylloides tumours are non-cancerous.
- malignant – Less than 5% of phylloides tumours are cancerous.
- uncertain malignant potential – It is not known if the phylloides tumour will become cancerous.
Occasionally, phylloides tumours spread (metastasize) to other organs, such as the lung, bones, heart or liver. Both benign and malignant phylloides tumours tend to come back (recur).
There are no known risk factors for phylloides tumours.
Signs and symptoms
Phylloides tumours look very similar to a benign lump called a fibroadenoma, although phylloides tumours tend to be larger when diagnosed and can grow very quickly.
The signs and symptoms of phylloides tumours may include:
- a lump that is firm, round, moveable and painless
- pain (if the tumour grows quickly and puts pressure on the skin and nerves of the breast)
If the signs and symptoms of a phylloides tumour are present, or if the doctor suspects a phylloides tumour, tests will be done to make a diagnosis. Tests may include:
- clinical breast exam (CBE)
Diagnostic tests may not be able to confirm that the lump is a phylloides tumour or a fibroadenoma.
Treatment for benign phylloides tumours is surgery. Because these tumours may recur if not all the tumour is removed, a wide area of normal breast tissue around the tumour (surgical margin) is removed along with the tumour during a lumpectomy. A mastectomy may be done for larger malignant phylloides tumours or recurrent phylloides tumours.
For large, high-grade malignant phylloides tumours, external beam radiation therapy to the breast or chest wall may be given after surgery. Phylloides tumours often do not respond well to radiation therapy.
Additional treatment with chemotherapy is not recommended. Phylloides tumours often do not respond well to chemotherapy.
I’m extremely grateful to the Canadian Cancer Society for funding my research with an Innovation Grant.
How can you stop cancer before it starts?
Discover how your lifestyle choices can affect cancer risk and how you can take action with our interactive tool – It’s My Life!