Patterns of Intraosseous Recurrence following Stereotactic Body Radiotherapy for Coxal Bone Metastasis

Publication date: Available online 5 September 2017
Source:International Journal of Radiation Oncology*Biology*Physics
Author(s): Kei Ito, Takuya Shimizuguchi, Keiji Nihei, Tomohisa Furuya, Hiroaki Ogawa, Hiroshi Tanaka, Keisuke Sasai, Katsuyuki Karasawa
PurposeThis study aimed to analyze the detailed pattern of intraosseous failure after stereotactic body radiotherapy (SBRT) for coxal bone metastasis.MethodsPatients treated with SBRT to coxal bone metastasis were identified by retrospective chart review. SBRT doses were 30 Gy or 35 Gy in 5 fractions. A margin of 5-10 mm was added to the gross tumor volume to create the clinical target volume. We evaluated the presence or absence of intraosseous recurrence using magnetic resonance imaging. Intraosseous recurrences were assessed as "in-field" or "marginal/out-of-field". In addition, we measured the distance between the center of the recurrent tumor and the nearest edge of the initial bone metastasis in cases of marginal/out-of-field recurrence.ResultsSeventeen patients treated for 17 coxal bone metastases were included. Median age was 64 years (range, 48-79 years). Coxal lesions involved the ilium in 14 cases, pubis in 3 and ischium in 4 (3 lesions crossed over multiple regions). Patients most commonly had renal cell carcinoma (29.4%), followed by lung, hepatic cell and colorectal cancers (23.5%, 11.8% and 11.8%, respectively). Median follow-up after SBRT was 13 months (range, 2-44 months). Among all 17 cases, 7 cases developed 8 intraosseous recurrences, including in-field recurrence in 1 case and marginal/out-of-field recurrences in 7 cases. Median time to intraosseous recurrence was 10 months (range, 2-35 months). Among 7 cases with marginal/out-of-field recurrence, mean distance to the center of the recurrent tumor from the nearest edge of the initial bone metastasis was 34 mm (range, 15-55 mm).ConclusionsMost recurrences were observed out-of-field in the same coxal bone. These results suggest that defining the optimal clinical target volume in SBRT for coxal bone metastasis to obtain sufficient local tumor control is difficult.

Teaser

Patterns of intraosseous failure in 17 patients treated with stereotactic body radiation therapy (SBRT) for coxal bone metastases were analyzed retrospectively. Although SBRT achieved good local control at the target, marginal/out-of-field recurrences in the coxal bone were observed in 7 cases. Tumor recurrence occurred at an average distance of more than 30 mm from the initial metastasis.


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