Page 75 - SDIR5 Abstract book 21 12 2021.

POSTER PRESENTATIONS

P35

Organ preservation approach for distant located rectal cancer

1
1,2
3
3
Mladen Marinković , Suzana Stojanović-Rundić ,Aleksandra Stefanović , Radmila Janković , Milena
3
Čavić
1 Clinic for Radiation Oncology and Diagnostics, Department of Radiation Oncology, Institute for Oncology and
Radiology of Serbia, Belgrade, Serbia
2 Faculty of Medicine, University of Belgrade, Belgrade, Serbia
3 Department of Experimental Oncology, Institute for Oncology and Radiology of Serbia

Background: Standard treatment for locally advanced rectal carcinoma (LARC) is neoadjuvant
chemoradiotherapy (CRT) followed by surgery. Complete clinical (cCR) or pathologic response is registered
in up to 30% of patients, using standard fractionation and total dose (TD) of 45-50.4 Gy. The aim of this
study was to evaluate the optimal time for assessment of response in order to identify candidates for watch
and wait approach (WW). Patients and Methods: Patients with LARC were treated with long-course CRT.
Radiotherapy was delivered using new approach, volumetric modulated arc therapy-simultaneous
integrated boost with TD of 54 Gy. Concomitant chemotherapy (5FU, Leucovorine) was given during first
and fifth week of RT. Tumor response was assessed in eighth week after CRT with MRI scan and
proctoscopy. Patients with cCR (mrTRG1)/near cCR (mrTRG2) and distant located tumor were suggested
no immediate radical surgery, and were enrolled in WW with the aim of sphincter preservation. Results:
Between June 2020 and January 2021 thirty patients were included. cCR/near cCR according to
MRI was detected in 37% of patients. Four patients were enrolled in WW. In three of them, control
MRI was categorized as near cCR in combination with negative proctoscopy examination. In these
patients we postponed surgery longer and did one more MRI 4 weeks after, which was categorized
as mrTRG1. Conclusion: For patients with distant located tumors with cCR after CRT, where
sphincter preservation isn’t optional, WW would be beneficial. Further studies with identification
of prognostic biomarkers could be crucial to identify the best candidates for WW.
Keywords: chemoradiotherapy, complete clinical response, rectal carcinoma.
Acknowledgements: This study is supported by the Ministry of Education and Science of the Republic of
Serbia (Agreement No. 451-03-9/2021-14/200043). This article is based upon work from COST Action
CA17118, supported by COST (European Cooperation in Science and Technology); www.cost.eu. MC is
supported by the Science Fund of the Republic of Serbia (PROMIS TRACEPIGEN project No. 6060876).

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