Volumetric Arc Therapy Seems More Promising for Sparing Organs at Risk in Adjuvant Postoperative Radiotherapy for Pancreatic Adenocarcinoma than Step-and-Shoot Intensity-Modulated Radiotherapy

Yasemin Bölükbaşı
2017 Turkish Journal of Oncology  
OBJECTIVE The aim of the present study was to determine if volumetric modulated arc therapy (VMAT) provided superior dose distribution than intensity-modulated radiotherapy (step-and-shoot; ssIMRT) based on target volume coverage and organs at risk (OARs) doses in postoperative radiotherapy for pancreatic cancer patients. METHODS New 4-dimensional computed tomography plans for 10 pancreatic cancer patients were created. The ssIMRT plans had 6 coplanar fields (330-0-30-60-90°) and VMAT plans
more » ... and VMAT plans were generated with 2 268-92° arcs. RESULTS VMAT plans revealed better overall sparing of right kidney (volume receiving 15% of prescribed dose [V15]: 28.3% vs 46.9%, p=0.012; V20: 16.1% vs 27.6%, p=0.007; V25: 8.6% vs 15.2%, p=0.005; mean dose 1549 centigray [cGy] vs 1987 cGy, p=0.005). VMAT delivered similar isodose distribution (planning target volume [PTV] mean dose: 5164 vs 5183 cGy, PTV max: 5526 cGy vs 5505 cGy; p=0.541) with significantly fewer monitor units (MU) (MU: 468 vs 527; p=0.032) in comparison with ssIMRT. VMAT was also found to be superior for V30 intestinal dose, but mean dose was similar (1963 cGy vs 2032 cGy; p=0.05). CONCLUSION VMAT provided more effective protection for bilateral kidneys and small intestine with better OAR doses, as well as for liver, with reduced high-dose volumes in this cohort. This could be investigated as more tolerable concurrent radiochemotherapy treatment with better OAR preservation. Introduction Pancreas cancer is named as one of the most complex cancer to treat, and even if surgical resection is per-formed, the recurrence rate is high and the survival rate after surgery is poor. There are two different approaches in worldwide such as "chemoradiotherapy followed by chemotherapy" is considered the optimal
doi:10.5505/tjo.2017.1588 fatcat:2fm2ztswcvaffi6ku35i7udryy