A malignant phyllodes tumor is an uncommon type of breast tumor that originates in the connective tissue, or stroma, of the breast. Unlike more common breast cancers that arise from ducts or lobules, phyllodes tumors have both stromal and epithelial components, with the stromal part exhibiting increased cellularity. These tumors are characterized by rapid growth and, while rare, understanding their specific treatment approaches is important for patients.
Surgical Treatment
Surgical removal is the primary treatment for malignant phyllodes tumors. The goal is to completely excise the tumor with a surrounding border of healthy tissue, known as “clear margins,” to reduce the risk of the tumor returning. The two main surgical options are wide local excision, also known as lumpectomy, and mastectomy.
Wide local excision involves removing the tumor along with a margin of normal breast tissue, typically aiming for at least a 1-centimeter margin for malignant tumors. If the tumor is large relative to the breast or if clear margins cannot be achieved with lumpectomy, a mastectomy, which is the removal of the entire breast, may be necessary.
Lymph node dissection, the removal of lymph nodes in the armpit, is generally not performed for malignant phyllodes tumors unless there is evidence of lymph node involvement. This is because these tumors rarely spread to the lymph nodes; instead, if they metastasize, they typically spread through the bloodstream to distant sites. Axillary lymph node dissection is usually reserved for cases where clinical suspicion of lymph node involvement persists after non-diagnostic needle biopsy results.
Adjuvant Therapies
Adjuvant therapies are treatments given after primary surgery to reduce the risk of recurrence or to manage advanced disease. For malignant phyllodes tumors, the role of these additional treatments, particularly radiation therapy and chemotherapy, is less defined compared to other breast cancers due to the tumor’s rarity. Decisions regarding adjuvant therapy are highly individualized and depend on specific tumor characteristics.
Radiation therapy may be considered following surgery, especially for large tumors, those with positive or very narrow margins, or in cases of local recurrence. Studies suggest that adjuvant radiation therapy can decrease the rate of local recurrence, particularly after breast-conserving surgery, though its impact on overall survival is not consistently shown.
Chemotherapy is generally not routinely used for localized malignant phyllodes tumors and its benefit is not well-established. It is primarily considered for metastatic disease, which is an infrequent occurrence. When chemotherapy is used for metastatic malignant phyllodes tumors, the regimens are often similar to those for soft tissue sarcomas, as these tumors share cellular characteristics with sarcomas.
Post-Treatment Surveillance
After the initial treatment for a malignant phyllodes tumor, ongoing monitoring, or surveillance, is important to detect any potential recurrence early. These tumors have a tendency for local recurrence. Regular follow-up helps in timely intervention if a recurrence occurs.
The typical surveillance schedule often involves regular clinical examinations of the breast and imaging studies. These imaging studies can include mammograms, ultrasound, and sometimes MRI, depending on individual patient factors and the treating physician’s assessment. The frequency of these follow-up appointments and imaging tests can vary, but commonly involves checks every 6 months for the first 2 years, followed by annual examinations for up to 5 years.
This close monitoring allows healthcare providers to assess for any new lumps or changes in the breast tissue. Early detection of a recurrence can lead to more effective management, as localized recurrences are often treatable with further surgery. The duration of follow-up is generally extended to account for the possibility of recurrence even years after the initial treatment.
Managing Recurrence
If a malignant phyllodes tumor does recur, the approach to management depends on whether the recurrence is local or if it has spread to distant sites. Local recurrence is the most common type of recurrence for phyllodes tumors.
Treatment for local recurrence often involves further surgery, such as re-excision with wider margins or, if necessary, a mastectomy. Radiation therapy may also be considered in conjunction with surgery, especially if the initial margins were close or positive, or if the recurrence is extensive.
Distant metastasis, where the tumor spreads to other parts of the body, is less common but can occur, most frequently to the lungs, followed by bone, heart, and liver. When distant metastasis occurs, treatment strategies are often guided by principles used for soft tissue sarcomas and may involve chemotherapy, radiation therapy, or surgical removal of the metastatic lesions, depending on their location and extent. Managing recurrent or metastatic malignant phyllodes tumors often requires a multidisciplinary team approach, involving surgical oncologists, radiation oncologists, and medical oncologists, to develop a comprehensive treatment plan.