The Clinical Application Of Precision Radiotherapy In Advanced Malignant Tumors Of The Biliary Tract

Purpose:High dose hypofractionated radiotherapy or stereotactic body radiation therapy(SBRT)has been proved effective on both local control and survival improvement for locally unresectable biliary tract cancer(BTC).It was still challenging to deliver high doses to large biliary tumor volumes due to increased toxicity.Our study aimed to evaluate the role of hypofractionated helical tomotherapy in the treatment of large size(radiation field range over 10cm)unresectable or recurrent biliary tract cancer.Methods:23 locally advanced unresectable BTC patients were treated with definitive helical tomotherapy from Feb' 2015 to Oct'2017,with intrahepatic cholangiocarcinoma(n ?11),gallbladder cancer(n = 6),distal cholangiocarcinoma(n = 2)and hilar cholangiocarcinoma(n = 1).The age of the patients ranged from 40 to85years(median:58 years).Of these thirteen were female.Twelve patients(52.2%)received systemic chemotherapy before radiotherapy(RT).The most commonly recurrent sites were retroperitoneal lymph nodes(9 patients).The median RT field size was 13.0cm(range 10.5 to 18 cm).RT was delivered in 8 to 28 fractions and doses were 28 to 72 Gy(median,54Gy),with a median biologic equivalent dose(BED)of 74.4 Gy(range 37.8 to 115.2 Gy).Results:Median overall survival time before RT was 11.3 months.The local control(LC)rate was 65.2%and 1-year survival rate was 56.5%.Significant correlation was found between doses and the median overall survival time,for patients receiving BED greater than 70Gy was 16.8 months versus 5.05 months for those receiving lower BED(P=0.0085).The most common toxicities observed after RT were grade 1 to 2 nausea and meteorism.Bile stricture was seen in one patient 8 months after RT with BED of 115.2 Gy.No bowel bleeding was found.Conclusion:The initial clinical practice of hypofractionated helical tomotherapy for large size advanced biliary tract cancers proved effective and tolerable.A greater than 70 Gy BED seemed correlated with better survival improvement.Multi-disciplinary team approach(MDT)contributed to the recommendation and implementation of radiation therapy for patients with biliary tract cancers.Further study is needed in developing ideal fractionated doses and new combination therapies.