Neoadjuvant volumetric modulated arc therapy in rectal cancer and the correlation of pathological response with diffusion-weighted MRI and apoptotic markers



In this prospective observational study, we aimed to report the applicability and tolerability of neoadjuvant volumetric modulated arc therapy with simultaneous integrated boost (SIB-VMAT) and concurrent chemotherapy in patients with locally advanced rectal cancer (LARC), and to evaluate the correlation of pathological response with apparent diffusion coefficient (ADC) measurements on diffusion-weighted magnetic resonance imaging (DW-MRI) and apoptotic markers.


The study enrolled 30 patients with T3 to T4 and/or N+ rectal cancer who preoperatively received SIB-VMAT and concurrent chemotherapy. Before and after the neoadjuvant treatment, apoptotic markers including the nucleosomes and cell-free DNA fragments in the serum samples were examined; DNA integrity was assessed by amplifying the ACTB gene; and the ADC measurements on the DW-MRI were analyzed.


No patients had acute or chronic grade III-IV toxicity. Pathologic complete response (pCR) was achieved in 8 patients (27%), while in 10 patients (33%) near-complete pathological response was obtained. Posttreatment ADC was significantly higher in patients with pCR compared with the others (1.28 vs. 1.10, p = 0.017). ROC curve analysis showed that posttreatment ADC values had a sensitivity of 75% and a specificity of 77.3% for distinguishing the patients with pCR from other responders. On the other hand, posttreatment DNA integrity values were revealed lower than the pretreatment values (p = 0.36). Also, the results revealed an insignificant increase in the posttreatment serum level of nucleosomes (p = 0.72).


Neoadjuvant SIB-VMAT with concurrent chemotherapy was proved to be a feasible treatment regimen in LARC with tolerable side effects, and improved local control rate and pCR rate.

Post author correction




Necla Gurdal, Merdan Fayda, Nijat Alishev, Baris Bakir, Didem Tastekin, Faruk Aykan, Ugur Gezer, Emre Balik, Esra Kaytan Saglam, Ethem Nezih Oral, Mine Gulluoglu, Ahmet Kizir

Article History


Financial support: No grants or funding have been received for this study.
Conflict of interest: None of the authors has financial interest related to this study to disclose.
Meeting presentation: A part of this study was selected for presentation in the Poster Viewing Session at the ASTRO’s 57th Annual Meeting. October 2015, San Antonio, TX, USA.

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  • 1 Department of Radiation Oncology, Institute of Oncology, Istanbul University, Istanbul - Turkey
  • 2 Department of Radiation Oncology, Istinye University, Faculty of Medicine, Istanbul - Turkey
  • 3 Department of Radiology, Istanbul University, Istanbul Faculty of Medicine, Istanbul - Turkey
  • 4 Department of Medical Oncology, Institute of Oncology, Istanbul University, Istanbul - Turkey
  • 5 Department of Basic Oncology, Institute of Oncology, Istanbul University, Istanbul - Turkey
  • 6 Department of General Surgery, Istanbul University, Istanbul Faculty of Medicine, Istanbul - Turkey
  • 7 Deparment of Pathology, Istanbul University, Istanbul Faculty of Medicine, Istanbul - Turkey

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