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. 2023 Jul 29;15(15):3869.
doi: 10.3390/cancers15153869.

Preoperative Radiotherapy with a Simultaneous Integrated Boost Compared to Chemoradiotherapy for cT3-4 Rectal Cancer: Long-Term Results of a Multicenter Randomized Study

Benedikt Engels  1 , Antonino De Paoli  2 , Elena Delmastro  3 , Fernando Munoz  4 , Stefano Vagge  5 , Darius Norkus  6 , Hendrik Everaert  7 , Gianna Tabaro  2 , Elisabetta Gariboldi  3 , Umberto Ricardi  4 , Eugenio Borsatti  2 , Pietro Gabriele  3 , Roberto Innocente  2 , Elisa Palazzari  2 , Emilie Dubaere  1 , Marc-André Mahé  8 , Sven Van Laere  1 , Thierry Gevaert  1 , Mark De Ridder  1
Affiliations

Preoperative Radiotherapy with a Simultaneous Integrated Boost Compared to Chemoradiotherapy for cT3-4 Rectal Cancer: Long-Term Results of a Multicenter Randomized Study

Benedikt Engels et al. Cancers (Basel). .

Abstract

Background: Preoperative chemoradiotherapy (CRT) is the standard treatment for T3-4 rectal cancer. Here, we compared image-guided and intensity-modulated RT (IG-IMRT) with a simultaneous integrated boost (SIB) (instead of concomitant chemotherapy) versus CRT in a multi-centric randomized trial.

Methods: cT3-4 rectal cancer patients were randomly assigned to receive preoperative IG-IMRT 46 Gy/23 fractions plus capecitabine 825 mg/m² twice daily (CRT arm) or IG-IMRT 46 Gy/23 fractions with an SIB to the rectal tumor up to a total dose of 55.2 Gy (RTSIB arm).

Results: A total of 174 patients were randomly assigned between April 2010 and May 2014. Grade 3 acute toxicities were 6% and 4% in the CRT and RTSIB arms, respectively. The mean fractional change in SUVmax at 5 weeks after completion of preoperative RT were -55.8% (±24.0%) and -52.9% (±21.6%) for patients in the CRT arm and RTSIB arm, respectively (p = 0.43). The pathologic complete response rate was 24% with CRT compared to 14% with RTSIB. There were no differences in 5-year overall survival (OS), progression-free survival (PFS) or local control (LC).

Conclusions: The preoperative RTSIB approach was not inferior to CRT in terms of metabolic response, toxicity, OS, PFS and LC, and could be considered an available option for patients unfit for fluorouracil-based CRT.

Keywords: chemoradiotherapy (CRT); image-guided and intensity-modulated RT (IG-IMRT); radiation therapy; randomized clinical trial; rectal cancer; simultaneous integrated boost (SIB).

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Consort diagram. Abbreviations: CRT arm, chemoradiotherapy 46 Gy in 23 fractions of 2 Gy by image-guided and intensity-modulated RT (IG-IMRT) with concurrent capecitabine 825 mg/m2 twice daily started on the first day of RT and given 5 days per week, excluding weekends. RTSIB arm, 46 Gy in 23 fractions of 2 Gy by IG-IMRT with a simultaneous integrated boost (SIB) of 0.4 Gy/day on the primary tumor up to a total dose of 55.2 Gy. PET, positron emission tomography. TME, total mesorectal excision.
Figure 2
Figure 2
Kaplan–Meier survival curves for local control, progression-free survival and overall survival in the intent-to-treat population by study group. Abbreviations: ChemoRT, chemoradiotherapy; RT-SIB, radiotherapy with a simultaneous integrated boost.
Figure 3
Figure 3
Forest plot analysis. Overall and progression-free survival of subgroups defined according to anticipated CRM, sex, T stage and tumor location. Unadjusted hazard ratios are indicated, and 95% CIs are indicated by the crossing horizontal lines. Abbreviations: CRT, chemoradiotherapy; RT-SIB, radiotherapy with a simultaneous integrated boost; CRM, circumferential resection margin.
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