Phyllodes tumors of the breast are rare. They can be malignant or benign. Cancerous phyllodes tumors are different from the more common types of breast cancer because they occur in your connective tissue. They are less likely to spread, but when they do, they are more difficult to treat.
A phyllodes tumor is a rare type of tumor that develops in the connective tissue of your breast. When you think of your breast tissue, you probably think more of the fatty tissue that makes up the volume of your breast, or the glandular tissue that produces milk. The connective tissue is the fibrous, supportive tissue that holds these other tissues in place.
Phyllodes tumors are made of this stuff. They are tough and fibrous, like scar tissue. Under a microscope, they exhibit a leaf-like pattern, which gives them their name (“phyllon” is Greek for “leaf”). They have also been called, “cystosarcoma phyllodes”. They are usually benign (non-cancerous), but sometimes they can be malignant (cancerous).
Most are not, but 25% of phyllodes tumors are cancerous. Cancerous phyllodes tumors account for .05% of all breast malignancies. They are a type of sarcoma, a cancer of the connective tissue. Sarcoma is different from the more common types of breast cancer, which usually affect your glandular tissues (your milk ducts and lobules).
Phyllodes tumors don’t typically infiltrate your lymphatic system, which means they don't spread as easily. They can metastasize through your blood to other parts of your body, but this is uncommon. They are usually treated locally, often with a simple lumpectomy. They don’t respond to systemic treatments like chemotherapy the way other breast cancers do.
Phyllodes tumors make up less than 1% of all breast tumors. They almost always occur in the breasts of people assigned female at birth (AFAB), though rare cases have been reported in people assigned male at birth (AMAB). They can occur at any age, but are most commonly seen in middle age. They are also more common in people with Li-Fraumeni syndrome, a hereditary disorder associated with cancer risk.
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You may notice a hard, smooth, well-defined lump in your breast. A phyllodes tumor is usually bigger than 3 cm and may be much bigger. It can grow quickly in a matter of weeks. If it stretches your skin, the skin over it might appear shiny or translucent or might be sore. For some reason, phyllodes tumors more often appear in the left breast than the right.
Malignant phyllodes tumors can be accompanied by symptoms such as:
This might indicate the cancer has spread to your bones or lungs.
Your healthcare provider may begin with imaging tests to rule out other types of breast lumps. But it usually takes a biopsy to distinguish a phyllodes tumor from a fibroadenoma. That means your healthcare provider will need to take a tissue sample to send to the lab. Most of the time, they can do this with an ultrasound-guided hollow needle.
If the diagnosis is still in doubt, your healthcare provider will suggest an excision biopsy — cutting the whole tumor out. This would be their recommended treatment for a phyllodes tumor anyway. The biopsy will tell them the type of tumor it is and whether it is malignant or suspicious. If it is, they will look to make sure it hasn’t spread anywhere else in your body.
Fibroadenomas are the most common type of benign breast lumps. They also appear in breast connective tissue. They can be hard to tell apart from phyllodes tumors, even on medical imaging. Fibroadenomas are harmless, but they can occasionally change into another kind of tumor. Some believe that fibroadenomas may change into phyllodes tumors.
It’s important for your healthcare provider to determine whether your tumor is a fibroadenoma or a phyllodes tumor. Because the two types behave differently, providers treat them differently. While fibroadenomas tend to stay the same or shrink, phyllodes tumors can grow quickly and become painful, even when they are benign. They are often removed preventatively.
Healthcare providers recommend it, even if they are benign. Removing a benign phyllodes tumor prevents it from growing, becoming painful, or transforming and becoming malignant in the future. Since it can grow and change quickly, it also saves you and your healthcare provider from needing to keep watch over it with frequent biopsy exams.
Both benign and malignant phyllodes tumors are treated with lumpectomy, surgical removal of the tumor with a margin of healthy tissue around it. The margin helps prevent them from recurring, which can happen with both types. If your tumor is malignant, your healthcare provider may suggest following the surgery with radiation therapy to the breast.
Yes. If all of the cancer is removed, surgery can cure it. This is easier when it hasn’t spread beyond the original tumor. When cancer becomes metastatic, it’s much harder to locate and remove every stray cancer cell. Some metastatic cancers can be treated with chemotherapy to your whole body, but this doesn’t work well for phyllodes tumors.
Even when the cancer appears to be gone, it can come back. Both benign and malignant phyllodes tumors can recur even years after being removed. When this happens, removing the new tumor with a wider margin around it often cures it. However, up to 30% of people with cancerous phyllodes tumors of the breast may die of the disease.
Phyllodes tumors of the breast are rare, and cancerous ones are rarer. If you do find a tumor, chances are removing it will be the end of it. Your healthcare provider will continue to check you regularly for any signs of recurrence. You can do your part by performing your own regular breast self-exams. Catching tumors earlier than later leads to better outcomes.
Last reviewed by a Cleveland Clinic medical professional on 09/23/2022.
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