Comparative Analysis of Efficacy, Toxicity, and Patient-Reported Outcomes in Rectal Cancer Patients Undergoing Preoperative 3D Conformal Radiotherapy or VMAT

Abstract

BackgroundLocally advanced rectal cancer (LARC) patients are usually treated within a multimodal therapy regime, in which the tumor resection plays the major role. This treatment ideally includes 5-fluorouracile (5FU)-based chemoradiation (CRT) leading to significantly improved local control rates. Local therapy as radiotherapy (RT) is required to be adapted referring to side effects and efficacy. Purpose of this study is the comparison of dosimetric parameters, acute and late toxicity, and quality of life in terms of patient-reported outcome (PRO) in patients treated with VMAT or 3D conformal radiotherapy (3DCRT) for LARC.MethodsPelvic RT for LARC was performed with a prescription dose of 45 Gy in 1.8 Gy per fraction, 50.4 Gy in 1.8 Gy per fraction, or 50 Gy in 2 Gy per fraction. Chemotherapy included 5FU or 5FU/Oxaliplatin or Capecitabine-based RT. Acute and late toxicity were evaluated via National Institute Common Terminology Criteria for Adverse Events version (CTCAE) v4.03 and the Scoring System Late effects of Normal Tissue. Quality of life was established via EORTC QLQCR29.ResultsAfter a median follow-up of 38 months (VMAT) and 78 months (3DCRT) there was no significant difference in progression-free survival (p = 0,85) but a significant difference in overall survival (p = 0.032). Regarding dose–volume parameters, patients treated with VMAT plans had a lower V20 of the bladder than 3DCRT-treated patients (p = 0.004). VMAT plans can also reduce Dmean of the right (p = 0.002) and left (p < 0.001) femoral head. Acute side effects between the VMAT and 3DCRT patients showed no significant difference. But concerning long-term effects, VMAT-treated patients had a significant lower appearance of high grade anal incontinence (p = 0.032). Quality of life (PRO) showed no significant different between the patients except of hair loss and worrying about weight.ConclusionVMAT treatment of LARC in preoperative CRT revealed a reduction of dose to organs at risk (OARs) as bladder and femoral heads. However, no changes in acute and long-term toxicity profiles were detectable. For late toxicity and quality of life data longer follow-up times are required.

Long-Term Outcome in a Phase II Study of Regional Hyperthermia Added to Preoperative Radiochemotherapy in Locally Advanced and Recurrent Rectal Adenocarcinomas

“…In the present study, there was no unexpected long-term toxicity associated with addition of hyperthermia and the overall acute and long-term toxicity seems to be in line with current use of preoperative radiochemotherapy for rectal cancer [1,77,78]. No negative effects on quality of life with addition of hyperthermia to neoadjuvant radiochemotherapy was reported in this setting [79].…”

Radiation Therapy for Rectal Cancer: Executive Summary of an ASTRO Clinical Practice Guideline

“…83 However, additional studies and a meta-analysis report that IMRT and VMAT result in reduced toxicity versus 3-D conformal radiation therapy. [72][73][74][75][76][77] Modern planning techniques like 3-D conformal radiation therapy and IMRT/VMAT produce plans that are more conformal but less robust to daily variations in setup. This is particularly true of IMRT/VMAT because of the creation of concave dose distributions designed precisely to follow the contour of the target and spare critical structures.…”

Intra-abdominal Surgery and Intestinal Syndromes After Pelvic Radiation Therapy

“…Comparative studies have investigated the occurrence of radiation-induced bowel symptoms among patients treated with 3D-CRT and IMRT, and while it appears that the modern radiation techniques result in less bowel toxicity both early and late after radiation therapy, 20 , 21 some studies reported inconclusive findings or suggested that the advantages concerning bowel health might diminish over time. 22 , 23 With modern radiation therapy techniques, the distal part of the colorectum still receives very high radiation doses when treating patients with gynecologic cancer. The radiation oncologist may also take advantage of the high-precision radiation therapy by increasing the dose to the tumor to increase local control and the chances of curing the patient.…”