Margin-negative surgical resection combined with adjuvant radiation therapy is effective for local control of borderline and malignant phyllodes tumors, a rare type of breast cancer, according to a new study.
The results of the first prospective study of outcomes of patients with phyllodes tumors were published in the August issue of Annals of Surgical Oncology (2009, Vol. 16:8, pp. 2288-2294).
Approximately 500 cases of phyllodes tumors are diagnosed each year in the U.S. They occur in young and middle-aged women, tend to be 4-5 cm in size, and metastasize in 10% to 30% of the patients. Local control is obtained in 90% of patients who have mastectomies; however, for women who elect to have breast conservation surgery instead, local recurrence is high, averaging 35% for patients with malignant tumors and 29% for patients with borderline malignancies.
Thirty cancer treatment centers located in 16 states participated in the prospective study to determine if adding adjuvant radiation after breast conservation surgery would decrease the rate of local recurrence. The study commenced in 1998, enrolling 46 patients over a seven-year time span.
The patients ranged in age from 18 to 76 years, with 65% diagnosed with malignant phyllodes tumors and 35% with borderline malignant ones. Tumor diameters ranged from 1 to 11 cm (mean, 3.7 cm), and 37% of the patients had tumors larger than 4 cm in diameter.
All patients received a total dose of 5,040 cGy of whole-breast radiation at 180 cGy per fraction, with 28 treatments performed within a six-week period within three months of surgery. Patients also received a 1,000 cGy boost to the tumor bed area, including the resection site and a 2-cm margin, in five fractions of 200 cGy each.
Two patients with malignant phyllodes tumors died from metastatic disease at nine and 14 months following diagnosis. During a median follow-up of 56 months (range, 12-129), none of the remaining cohort developed a local recurrence.
Principal investigator Dr. Richard Barth Jr., section chief of general surgery at Dartmouth-Hitchcock Medical Center in Lebanon, NH, reported that an analysis of peer-reviewed literature reported local recurrence rates of 21% after a margin-negative breast conservation resection of borderline or malignant phyllodes tumors.
Approximately half of women diagnosed with malignant phyllodes tumors have breast conservation surgery, but only 5% receive radiation therapy. The authors believe that adding radiation therapy will significantly reduce the risk of local recurrence for these patients.
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