Organ-specific radiation-induced cancer risk estimates due to radiotherapy for benign pigmented villonodular synovitis

Abstract

Pigmented villonodular synovitis (PVNS) is a benign disease affecting synovial membranes of young and middle-aged adults. The aggressive treatment of this disorder often involves external-beam irradiation. This study was motivated by the lack of data relating to the radiation exposure of healthy tissues and radiotherapy-induced cancer risk. Monte Carlo methodology was employed to simulate a patient's irradiation for PVNS in the knee and hip joints with a 6 MV photon beam. The average radiation dose received by twenty-two out-of-field critical organs of the human body was calculated. These calculations were combined with the appropriate organ-, age- and gender-specific risk coefficients of the BEIR-VII model to estimate the lifetime probability of cancer development. The risk for carcinogenesis to colon, which was partly included in the treatment fields used for hip irradiation, was determined with a non-linear mechanistic model and differential dose-volume histograms obtained by CT-based 3D radiotherapy planning. Risk assessments were compared with the nominal lifetime intrinsic risk (LIR) values. Knee irradiation to 36 Gy resulted in out-of-field organ doses of 0.2-24.6 mGy. The corresponding range from hip radiotherapy was 1.2-455.1 mGy whereas the organ equivalent dose for the colon was up to 654.9 mGy. The organ-specific cancer risks from knee irradiation for PVNS were found to be inconsequential since they were at least 161.5 times lower than the LIRs irrespective of the patient's age and gender. The bladder and colon cancer risk from radiotherapy in the hip joint was up to 3.2 and 6.6 times smaller than the LIR, respectively. These cancer risks may slightly elevate the nominal incidence rates and they should not be ignored during the patient's treatment planning and follow-up. The probabilities for developing any other solid tumor were more than 20 times lower than the LIRs and, therefore, they may be considered as small.

Pigmented Villonodular Synovitis of the Knee Joint in a 10-Year-Old Patient Treated With an All-Arthroscopic Synovectomy: A Case Report

“…However, radiation is not a complication-free therapy. Stiffness, skin necrosis and radiation-induced malignancies have been reported [19]. Recently, new targeted therapies have been developed for the treatment of PVNS.…”

Image-guided, intensity-modulated radiotherapy for the treatment of diffuse-type tenosynovial giant cell tumor of the knee

“…At present, most scholars believe that the total dose of 36Gy is lower than the long-term threshold of joint fibrosis, which is a safe and effective dose. [ 47 , 48 ]…”

Recurrence of pigmented villonodular synovitis of the knee

“…[36] Mazonakis et al found that knee irradiation may result in an inconsequential risk for carcinogenesis irrespective. [48] Another study also found that skin cancer is clearly a potential risk, thus caution is advised when considering radiotherapy for these conditions in children and young adults. [49] A report showed that external-beam irradiation for PVNS might have a role in the development of two aggressive neoplasms at the primary treatment site.…”