- 學位論文
以回溯性研究方式評估使用合併性低次分放射治療在貓注射部位肉瘤之效果
Evaluation of Adjuvant Hypofractionated Radiation Therapy in Feline Injection-site Sarcomas: A Retrospective Study
摘要
貓注射部位肉瘤(Feline injection-site sarcomas, FISS)，又稱為貓疫苗相關肉瘤(feline vaccine-associated sarcomas, VAS)，是貓最常見的皮下腫瘤，約佔所有貓皮膚腫瘤的40%。FISS是一個局部侵犯性高，生長快速，但遠端移轉率低，且有時有較長的潛伏期。由於其局部復發機率非常高，因此合併使用多種治療方法是目前建議的治療方式，其中包括手術切除、放射治療和化學治療。手術前或手術後加上輔助性放射治療(Adjuvant radiation therapy)仍然是達到腫瘤長時期控制最理想的治療方式。低分次放射治療(Hypofractionated radiation therapy)是將照射劑量由傳統單次200 cGy左右的劑量調高，總次數減少的方式給予，此方式不僅可以減少動物接受麻醉的次數，更能創造更高的生物效應。然而，在FISS使用低分次放射治療的治療效果仍不明確。因此，本篇研究回溯性討論在FISS使用手術切除合併輔助性低分次放射治療的臨床經驗。結果顯示單接受手術治療組的局部腫瘤復發率為57% (12/21)，而接受手術切除合併輔助性低分次放射治療組的局部腫瘤復發率為21% (3/14) (P=0.039)。單接受手術治療組的中位數無病時間為338天，而接受手術切除合併輔助性低分次放射治療組的中位數無病時間為609天(P=0.104)。貓接受保守切除的中位數無病時間為192天，而接受大範圍切除或徹底切除的中位數無病時間為844天(P=0.001)。比較原始腫塊大小≤3公分和>3公分的中位數無病時間有顯著差異，其中位數無病時間分別為1053天和337天(P=0.04)。此外，原始腫塊大小>3公分的局部腫塊復發率為原始腫塊大小≤3公分的6倍，因此原始腫塊大小或許能作為預後因子之一。術前或術後接受輔助性低分次放射治療的中位數無病時間，並無顯著差異(P=0.479)。由此我們推論以大範圍或徹底的手術方式切除是治療FISS的主要方式之一，但單獨的手術治療仍有較高的局部腫塊復發率，因此手術切除合併輔助性低分次放射治療有助達到長時間的腫瘤控制，且治療效果和使用傳統的輔助性放射治療相似。
並列摘要
Feline injection-site sarcomas (FISS) also known as vaccine-associated sarcomas (VAS) is the most common subcutaneous tumor in feline and accounts for about 40% of all feline skin tumors. FISS is highly local invasive in spite of a low metastatic rate with often rapidly growing and occasionally long latency period. A multimodal treatment protocol is recommended due to the high local recurrence rate. Pre- or post-surgery combined with adjuvant radiation therapy (RT) remains the ideal approach for those animals in which long-term control may be achieved. Hypofractionated RT is a treatment, in which larger single fraction dose (beyond conventional 200 cGy/fraction) was used with less fraction numbers that can decrease the frequency of anesthesia as well as increase the biological effect in less total dose. However, the clinical reports of adjuvant hypofractionated RT in FISS were limited. Therefore, we retrospectively review our experiences on hypofractionated RT combined with surgery in FISS. Result showed that local tumor recurrences were reported in 12 of 21 (57%) for surgery alone group and 3 of 14 (21%) cats for adjuvant hypofractionated RT group (P=0.039). The median disease free intervals (DFI) for surgery alone group and adjuvant hypofractionated RT group were 338 days (range, 7 to 364 days) and 609* days (range, 37 to 337 days), respectively (P = 0.104). Median DFI in cats receiving conservative surgery was 192 days compared to cats receiving wide margin or radical surgery where median DFI was 844* days (P=0.001). Median DFI in cats with primary tumor size ≤3 cm in diameter at greatest dimension was 1053* days compared to cats with primary tumor size >3 cm where median DFI was 337 days (P=0.04). We also found that primary tumor size >3 cm was 6 times in local tumor recurrence when compared with primary tumor size ≤3 cm; therefore tumor size might be one of the prognostic factors. There is no significant difference when compared DFI for cats receiving pre- or post-surgery adjuvant hypofractionated RT (P=0.479). We concluded that wide margin or radical surgery was mandatory for FISS; furthermore, surgery excision combined with adjuvant hypofractionated RT can achieve a similar long-term control rate when compared with conventional adjuvant RT in treating FISS.