Treatment intensity and control rates in combining external-beam radiotherapy and radioactive iodine therapy for metastatic or recurrent differentiated thyroid cancer

• Published in: International journal of clinical oncology 2020-04, Vol.25 (4), p.691-697
• Main Authors: Makita, Kenji, Hamamoto, Yasushi, Tsuruoka, Shintaro, Takata, Noriko, Urashima, Yusuke, Miyagawa, Masao, Mochizuki, Teruhito
• Format: Article
• Language: English
• Subjects: Cancer Research; Iodine; Lesions; Medicine; Medicine & Public Health; Metastases; Metastasis; Multivariate analysis; Oncology; Original Article; Radiation therapy; Statistical analysis; Surgical Oncology; Thyroid cancer
• ISSN: 1341-9625; 1437-7772
• DOI: 10.1007/s10147-019-01591-y

Background To evaluate the treatment outcomes of external-beam radiotherapy (EBRT) with or without radioactive iodine therapy (RAIT) for metastatic or recurrent lesions of differentiated thyroid cancer (DTC). Methods Between August 1997 and March 2018, 73 lesions (distant metastases, 50; regional lymph-node metastases, 17; postoperative tumor-bed recurrences, 6) in 36 patients that had received EBRT with or without RAIT were reviewed. Doses of EBRT were 8–70 Gy (median 40 Gy). Seventeen patients received RAIT after EBRT. Results Median follow-up time of imaging studies was 14 months (range 1–110 months). Two-year overall survival rates and control rates of EBRT sites were 71% and 62%, respectively. Two-year control rates for EBRT of  50 Gy ( n  = 8) were 0%, 56%, 53%, 79%, and 100%, respectively. There were statistically significant differences in control rates between  50 Gy ( p  = 0.037). Control rates of > 50 Gy were significantly better compared to ≤ 50 Gy ( p  = 0.021). Two-year control rates with ( n  = 28) and without ( n  = 45) post-EBRT RAIT were 89% and 45%, respectively ( p  = 0.009). In multivariate analysis, EBRT of > 50 Gy and post-EBRT RAIT were significant independent factors for favorable control of EBRT sites (hazard ratio [HR], 5.72; 95% confidence interval [CI], 1.21–27.1; p  = 0.028 and HR, 2.98; 95% CI, 1.28–6.98; p  = 0.012, respectively). Conclusion EBRT of > 50 Gy and post-EBRT RAIT appeared to be useful for long-term control of EBRT sites for metastatic or recurrent lesions of DTC.