The phyllodes tumor is a rare tumor of the breast, often appearing earlier than breast cancer. It is most often benign, but aggressive malignant forms exist. The preferred treatment is surgery, with a generally favorable prognosis, even if local recurrences cannot be ruled out.

Definition

Phyllodes tumor is a rare tumor of the breast, which begins in connective tissue. It is a mixed tumor, called fibroepithelial, characterized by the proliferation of epithelial cells and connective tissue cells, while the majority of breast cancers affect glandular cells. 

Phyllodes tumors fall into three groups:

• the majority (between 50% and 75% according to the authors) are benign tumors (grade 1)
• 15-20% are borderline tumors, or borderline (grade 2)
• 10 to 30% are malignant tumors, that is to say cancerous (grade 3), sometimes called phyllodes sarcomas.

Grade 1 phyllodes tumors proliferate more slowly and are often small (of the order of a centimeter), rapidly growing and large phyllodes tumors (up to 15 cm) are more often malignant.

Only malignant phyllodes tumors are likely to cause metastases.

Causes

The causes of the formation of these tumors remain poorly understood.

Diagnostic

The tumor, which forms a well-defined flexible mass, is often discovered during self-examination or clinical examination in a gynecological consultation.

The rapid growth of a known pre-existing mass may suggest the diagnosis, also guided by the age of the patient.

POSTERS

The preferred imaging exams are mammography and ultrasound, but MRI can provide information in specific cases. However, these examinations do not always make it possible to assess the grade of the phyllodes tumor, nor to distinguish it from fibradenoma, a fairly similar benign breast tumor.

biopsy

Percutaneous biopsy (taking tissue fragments using a needle inserted through the skin) is performed under ultrasound guidance. It allows histological verification: the tissues taken are analyzed under a microscope to determine the nature of the tumor.

The people concerned

Phyllodes tumors can occur at any age but mainly affect women between 35 and 55 years old, with a peak occurrence between 40 and 45 years old. They therefore appear later than fibradenoma, which affects young women more, but earlier than breast cancer.

They represent less than 0,5% of all breast tumors.

Risk factors

Researchers suspect the intervention of different genetic predisposing factors in the appearance and development of these tumors.

Most phyllodes tumors are painless and are not associated with axillary lymphadenopathy (no suspicious, hard or inflamed lymph nodes in the armpit).

On palpation the nodule is firm, mobile when it is small, adherent to the tissues when it grows.

Larger tumors can be accompanied by skin ulcers. Rarely, there is nipple discharge or nipple retraction.

surgery

Treatment is mainly based on surgical excision of non-metastatic tumors, whether benign or malignant, while maintaining a safety margin of 1 cm. Conservative surgery is increasingly preferred to mastectomy. This may however be necessary in the event of an aggressive recurrence.

Axillary lymph node dissection is rarely helpful.

Radiotherapy

Radiotherapy can constitute an adjuvant treatment of malignant phyllodes tumors, especially in the event of recurrence.

Chemotherapy

The usefulness of chemotherapy as an adjuvant treatment of malignant phyllodes tumors is discussed on a case-by-case basis. The protocols used are identical to those applied in the treatment of soft tissue sarcomas.

The prognosis for phyllodes tumors is generally good, with no recurrence at 10 years in 8 out of 10 women, regardless of the grade of the tumor. 

Local recurrences, however, remain relatively frequent. They mostly occur within two years of surgery, but can appear much later, which requires regular monitoring. Malignant tumors tend to recur earlier.

A phyllodes tumor that recurs may be more aggressive in nature than the original tumor. More rarely, on the contrary, it will have a more benign character. Certain benign tumors can therefore recur in the form of cancerous tumors, or even of metastatic evolution. The risk of metastasizing is higher when the primary phyllodes tumor was malignant.

In the event of local recurrence, the so-called “catch-up” mastectomy offers a high cure rate but remains a mutilating gesture, often badly experienced by women who are still young. The benefit of radiotherapy and / or chemotherapy is discussed on a case-by-case basis by the healthcare team.

The prognosis remains poor when an aggressive recurrence leads to the appearance of metastases. The response to chemotherapy is seldom durable, with death occurring within 4 to 6 months. Monitoring therefore has an essential role to play.