Reduced toxicity in the treatment of locally advanced rectal cancer: a comparison of volumetric modulated arc therapy and 3D conformal radiotherapy.
BACKGROUND
Excellent dosimetric characteristics were demonstrated for volumetric modulated arc therapy (VMAT) in preoperative chemoradiotherapy (CRT) for locally advanced rectal cancer (LARC). In a single-center retrospective analysis, we tested whether these advantages may translate into significant clinical benefits. We compared VMAT to conventional 3D conformal radiotherapy (3DCRT) in patients, homogeneously treated according to the control arm of the CAO/ARO/AIO-04 trial.


METHODS
CRT consisted of pelvic irradiation with 50.4/1.8Gy by VMAT (n = 81) or 3DCRT (n = 107) and two cycles of 5-fluorouracil. Standardized total mesorectal excision surgery was performed within 4-6 weeks. The tumor regression grading (TRG) was assessed by the Dworak score. Acute and late toxicity were evaluated via the Common Terminology Criteria for Adverse Events and the Late effects of normal tissues scale, respectively. Side effects greater than or equal to grade 3 were considered high-grade.


RESULTS
Median follow-up was 18.3 months in the VMAT group and 61.5 months in the 3DCRT group with no differences in TRG between them (p = 0.1727). VMAT treatment substantially reduced high-grade acute and late toxicity, with 5 % versus 20 % (p = 0.0081) and 6 % vs. 22 % (p = 0.0039), respectively. With regard to specific organs, differences were found in skin reaction (p = 0.019) and proctitis (p = 0.0153).


CONCLUSIONS
VMAT treatment in preoperative CRT for LARC showed the potential to substantially reduce high-grade acute and late toxicity. Importantly, we could demonstrate that VMAT irradiation did not impair short-term oncological results. We conclude, that the reduced toxicity after VMAT irradiation may pave the way for more efficient systemic therapies, and hopefully improved patient survival in the multimodal treatment of LARC.
Department of Radiotherapy and Radiation Oncology, University Medical Center Göttingen, Robert-Koch-Straße 40, 37075, Göttingen, Germany. hendrik.droege@med.uni-goettingen.de.
Leif Hendrik
LH
Dröge
Department of Radiotherapy and Radiation Oncology, University Medical Center Göttingen, Robert-Koch-Straße 40, 37075, Göttingen, Germany. hanne.weber@med.uni-goettingen.de.
Hanne Elisabeth
HE
Weber
Department of Radiotherapy and Radiation Oncology, University Medical Center Göttingen, Robert-Koch-Straße 40, 37075, Göttingen, Germany. manuel.guhlich@med.uni-goettingen.de.
Manuel
M
Guhlich
Department of Radiotherapy and Radiation Oncology, University Medical Center Göttingen, Robert-Koch-Straße 40, 37075, Göttingen, Germany. martin.leu@med.uni-goettingen.de.
Martin
M
Leu
Department of General, Visceral and Pediatric Surgery, University Medical Center Göttingen, Göttingen, Germany. lena.conradi@med.uni-goettingen.de.
Lena-Christin
LC
Conradi
Department of General, Visceral and Pediatric Surgery, University Medical Center Göttingen, Göttingen, Germany. jochen.gaedcke@med.uni-goettingen.de.
Jochen
J
Gaedcke
Department of Radiotherapy and Radiation Oncology, University Medical Center Göttingen, Robert-Koch-Straße 40, 37075, Göttingen, Germany. steffen.hennies@med.uni-goettingen.de.|Present address: Radiologie München, Burgstrasse 7, 80331, München, Germany. steffen.hennies@med.uni-goettingen.de.
Steffen
S
Hennies
Department of Radiotherapy and Radiation Oncology, University Medical Center Göttingen, Robert-Koch-Straße 40, 37075, Göttingen, Germany. markusherrmann@gmx.net.|MVZ Klinik Dr. Hancken, Strahlentherapie und Radioonkologie, Stade, Germany. markusherrmann@gmx.net.
Markus Karl
MK
Herrmann
Department of Radiotherapy and Radiation Oncology, University Medical Center Göttingen, Robert-Koch-Straße 40, 37075, Göttingen, Germany. mfraenk@med.uni-goettingen.de.
Margret
M
Rave-Fränk
Department of Radiotherapy and Radiation Oncology, University Medical Center Göttingen, Robert-Koch-Straße 40, 37075, Göttingen, Germany. drhawolff@googlemail.com.|Present address: Radiologie München, Burgstrasse 7, 80331, München, Germany. drhawolff@googlemail.com.
Hendrik Andreas
HA
Wolff
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003131:Combined Modality Therapy; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011300:Preoperative Care; D020266:Radiotherapy, Conformal / Q000009:adverse effects / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects / Q000379:methods; D012004:Rectal Neoplasms / Q000401:mortality / Q000473:pathology* / Q000532:radiotherapy* / Q000601:surgery; D012189:Retrospective Studies; D016896:Treatment Outcome