Adjuvant radiotherapy combined with margin-negative resection is an effective therapy for controlling malignant phyllodes tumors of the breast, according to a study published in the August issue of the Annals of Surgical Oncology.
According to Richard Barth, MD, department of surgery, section of general surgery at Dartmouth-Hitchcock Medical Center in Lebanon, N.H., and colleagues, malignant phyllodes tumors of the breast occur relatively infrequently—approximately 500 cases are reported in the United States annually.
Malignant phyllodes tumors tend to be large in size, the authors say, and metastasize in 10 to 30 percent of patients. Although mastectomy is commonly performed—and sometimes required—many women choose to have breast-conserving surgery. The problem, according to the authors, is that recurrence rates after margin-negative breast-conserving resections are “unacceptably high”--24 percent for borderline malignant phyllodes tumors and 20 percent for malignant tumors.
High recurrence rates have several adverse consequences, the authors said, pointing to several studies showing that local recurrence is a strong predictor of metastatic spread.
“In this study,” the authors wrote, “it was determined that for every four local recurrences that were avoided, one breast cancer death was prevented.”
In the study, 46 women were treated at 30 different institutions. Adjuvant radiotherapy was started within 12 weeks of breast surgery. After completion of radiotherapy, patients received follow-up exams at six-month intervals and then underwent mammography six and 12 months after resection, and annually after that.
Barth and colleagues found that two of the 30 patients with malignant phyllodes tumors died of metastatic phyllodes tumor, nine and 14 months after diagnosis. None of the 16 patients with borderline malignant tumors has died. None of the 46 patients developed a local recurrence.
A comparable group of patients with borderline and malignant phyllodes tumors in the literature (who underwent margin-negative resections without adjuvant radiotherapy) had a recurrence rate of 21 percent, the authors said.
The researchers concluded that "adjuvant radiotherapy after breast-conserving resections of borderline malignant and malignant phyllodes tumors decreases the rate of local recurrence.”