The Role of External Beam Radiation Therapy in the Adjuvant Treatment of Pigmented Villonodular Synovitis

Aim: Pigmented villonodular synovitis (PVNS) is a rare proliferative disorder arising from synovial cells of the tendon sheets and joint capsules. The potential value of external beam radiation therapy in the interdisciplinary management of PVNS is demonstrated by a comprehensive literature review on the clinical use of radiotherapy and the results of national patterns of care study (PCS) which was conducted by the German Cooperative Group on Radiotherapy in Benign Diseases (GCG-BD) in 2008-2009. Material and Method: A structured questionnaire was mailed to all 227 RT institutions in Germany to assess all previous treatments, the RT indication and techniques, the rate of local control, the functional outcome and the possible adverse effects related to the use of external beam radiation therapy (RT). For comparison of the clinical outcome data, a systematic literature research in several international electronic databases and a conventional library search were performed to identify publications addressing the use of RT for PVNS. Results: Based on an overall response rate of 83.2%, the PCS was nationally representative. Ten percent of institutions presented clinical experience with the use of RT for PVNS; from this database a total of 41 treated sites from 14 institutions were evaluable for long-term analysis. The primary therapeutic approach was cytoreductive surgery in all cases. In cases of residual tissue or complete resection of extensive local recurrences, RT was applied in 39 cases (95.1%). An excellent or good functional outcome was noted in 34 cases (82.9%). The use of RT was not associated with early or late toxicity larger than RTOG grade II. The literature review identified 19 published studies (1940-2009) which represented a total of 140 cases or patients, respectively. After follow-up periods ranging from 1-250 months and administration of total doses in the range of 16-50 Gy the overall rate of local control was 84.5%. Conclusion: Both the results of the national PCS and the literature review demonstrate that RT is a very safe and effective treatment option for the prevention of disease progression or recurrence in PVNS after primary surgical interventions. The planned treatment volume should include the whole synovial space and eventually all invasive components of the disease. Currently, total doses in the range of 30-36 Gy are recommended.