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Proton Therapy Delivery and Its Clinical Application in Select Solid Tumor Malignancies
Published on: February 6, 2019
Postoperative radiation therapy for extramammary Paget's disease
1Department of Radiology, Yokohama City University Graduate School of Medicine, 3-9 Fukuura, Kanazawa-ku, 236-0004, Yokohama, Kanagawa, Japan.
Background:
Extramammary Paget's disease (EMPD) is a rare cutaneous malignancy that is usually treated with surgery. Patients with positive surgical margins require adjuvant therapy, but there have been few reports on the use of radiation therapy.
Objectives:
To investigate the effectiveness of postoperative radiation therapy in EMPD.
Materials And Methods:
Twenty-one patients with EMPD involving the genitalia underwent radiation therapy as adjuvant therapy after surgery. Ten patients had inguinal lymph node involvement before radiation therapy, but none had distant metastases. A median total dose of 59·4 Gy (range, 45-64·8 Gy) was delivered to the tumour bed in 30 fractions (range, 23-36 fractions).
Results:
At a median follow-up period of 38 months, all patients had local control. However, six patients had developed distant metastases 6-43 months after radiation therapy. The distant metastasis-free rates were 66% at 3 years and 55% at 5 years. Inguinal lymph node involvement was a significant risk factor for distant metastases. Four patients died 33-58 months after irradiation; the causes of death were tumour progression in three patients and infectious pneumonia in one. The overall and cause-specific survival rates were both 92% at 3 years, and 62% and 71% at 5 years, respectively. No therapy-related toxicities of grade ≥ 3 were observed.
Conclusions:
Postoperative radiation therapy is safe and effective in maintaining local control in patients with EMPD.
