Phyllodes Tumors of the Breast

Phyllodes tumors (FILL-odes or full-OH-deez) can also be spelled phylloides tumors (full-OY-deez). These are rare breast tumors that start in the connective (stromal) tissue of the breast.

Phyllodes tumors are most common in women in their 30s and 40s, but women of any age can have them. Women with Li-Fraumeni syndrome (a rare, inherited genetic condition) have an increased risk for phyllodes tumors.

Most phyllodes tumors are benign (not cancer), but about 1 out of 10 of these tumors are malignant (cancer).

Diagnosis

The tumors are usually felt as a painless lump, but some may hurt. They tend to grow quickly and stretch the skin. They’re often hard to tell from fibroadenomas on imaging tests (like an ultrasound or mammogram), or even with certain types of needle biopsies. In most cases, the entire tumor needs to be removed (during an excisional biopsy) to know for sure that it’s a phyllodes tumor that’s not cancer.

Treatment

Breast-conserving surgery is the main treatment. Phyllodes tumors can sometimes come back in the same place if they’re removed without taking enough of the normal tissue around them. For this reason, they’re treated by taking out the tumor and at least a 1 cm (a little less than ½ inch) margin of normal breast tissue around the tumor. Mastectomy may be needed if a cancer-free margin of normal breast tissue cannot be taken out with the tumor.

Phyllodes tumors that are cancer are treated by removing them along with a wider area of normal tissue, or by removing the entire breast (mastectomy). Malignant phyllodes tumors are different from the more common types of breast cancer. They don’t respond to hormone therapy and are less likely than most breast cancers to respond to radiation therapy or the chemotherapy drugs normally used for breast cancer. Phyllodes tumors that have spread to other parts of the body are often treated more like sarcomas (soft-tissue cancers) than breast cancers.

Because these tumors can come back, close follow-up with frequent breast exams and imaging tests are usually recommended after treatment.

How do phyllodes tumors affect your risk for breast cancer?

Having a phyllodes tumor that’s not cancer does not affect your breast cancer risk, but you may be watched more closely and get regular imaging tests, because these tumors can come back after surgery.1

The American Cancer Society medical and editorial content team
Our team is made up of doctors and master’s-prepared nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

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Last Medical Review: March 16, 2015 Last Revised: April 21, 2016

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