Date Published: October 17, 2018
Publisher: Public Library of Science
Author(s): Min Wook Joo, Yong Koo Kang, Koichi Ogura, Shintaro Iwata, June Hyuk Kim, Won Ju Jeong, Xiaohui Niu, Pramod S. Chinder, Han Soo Kim, Sung Wook Seo, Yang-Guk Chung, Hiroyuki Tsuchiya.
The oncologic risk of ionizing radiation is widely known. Sarcomas developing after radiotherapy have been reported, and they are a growing problem because rapid advancements in cancer management and screening have increased the number of long-term survivors. Although many patients have undergone radiation treatment in Asian countries, scarce reports on post-radiation sarcomas (PRSs) have been published. We investigated the feature and prognostic factors of PRSs in an Asian population. The Eastern Asian Musculoskeletal Oncology Group participated in this project. Cases obtained from 10 centers were retrospectively reviewed. Patients with genetic malignancy predisposition syndrome, or who had more than one type of malignancy before the development of secondary sarcoma were excluded. Forty-two high-grade sarcomas among a total of 43 PRSs were analyzed. There were 29 females and 13 males, with a median age of 58.5 years; 23 patients had bone tumors and 19 had soft tissue tumors. The most common primary lesion was breast cancer. The median latency period was 192 months. There were no differences in radiation dose, latency time, and survival rates between bone and soft tissue PRSs. The most common site and diagnosis were the pelvic area and osteosarcoma and malignant fibrous histiocytoma for bone and soft tissue PRSs. The median follow-up period was 25.5 months. Five-year metastasis-free and overall survival rates were 14.5% and 16.6%, and 39.1% and 49.6% for bone and soft tissue PRSs. Survival differences depending on initial metastasis and surgery were significant in soft tissue sarcomas. Although this study failed to find ethnic differences, it is the largest review on PRS in an Asian population. As early recognition through long-term surveillance is a key to optimal management, clinicians should take efforts to understand the real status of PRS.
The oncologic risk of ionizing radiation is widely known . In 1922, bone sarcomas developing after radiotherapy in patients with benign conditions were reported as one of the first solid malignant tumors related to radiotherapy, which implicate radiation treatment as one of the pathogeneses of sarcomas . In 1948, 11 cases of post-radiation osteosarcoma (PRS) were first reported in the English literature . A recent analysis of the Surveillance, Epidemiology, and End Results (SEER) registries demonstrated that the risk of second primary bone sarcoma in patients who had received radiotherapy was increased by 257% compared to that of primary bone sarcoma in the general population . PRSs are uncommon, and they account for 0.5–5% of all sarcomas [1, 5]. While the precise incidence is not known, one of the most comprehensive studies demonstrated that the cumulative incidence was estimated to be less than 1% at 15 years after the previous cancer diagnosis . However, PRSs are a growing problem and a critical clinical subgroup of sarcomas because rapid advancements in cancer management and screening have increased the number of long-term cancer survivors [1, 7].
Cases obtained from 10 tertiary musculoskeletal oncology centers in four nations were retrospectively reviewed. Based on the existing diagnostic criteria for PRS [3, 11, 12], we included the following subjects: (1) patients with histologically proven sarcoma which developed within the external beam radiotherapy field; (2) a latency period of more than three years between radiation therapy and appearance of sarcoma. Patients with genetic malignancy predisposition syndrome such as familial retinoblastoma, Li-Fraumeni syndrome, or Rothmund-Thomson syndrome, who had secondary sarcomas at sites distant to the radiation field, who received brachytherapy or total-body irradiation, or who had more than one type of malignancy before the development of secondary sarcoma were excluded from this study. This study was approved by the Institutional Review Board of Catholic Medical Center in Korea. Because we conducted a retrospective review and this was a minimal risk study, and we did not collect any personally identifiable information, any informed consents were not collected from participants.
We conducted this study to understand the current status of PRS in an Asian population and to explore the differences from the existing results of Western researches. Although recent rapid advances in tumor treatment and surveillance have improved the prognosis, comprehension of treatment-related risks seems to be too inadequate to reduce the therapy-related long-term complications, especially in Asia.
To the best of our knowledge, this study is the largest review on PRS in an Asian population although it failed to find ethnic differences. Radiotherapists should avoid unnecessary radiation exposure. Early recognition through long-term surveillance and a high degree of awareness regarding PRS are current unique keys to optimal and timely management by a multidisciplinary team. Clinicians should be concerned about this entity and they should make efforts to understand the real status of PRS.