Simultaneous Integrated Boost Volumetric Modulated Arc Therapy for Rectal Cancer: Long-Term Results after Protocol-Based Treatment

Dong Soo Lee; Seong-Taek Oh; Chang-Hyeok Ahn; Jaeim Lee; Kil-Yong Lee; Hiun Suk Chae; Sung Soo Kim; Sang Woo Kim; Kyung Jin Seo

doi:10.1155/2022/6986267

Simultaneous Integrated Boost Volumetric Modulated Arc Therapy for Rectal Cancer: Long-Term Results after Protocol-Based Treatment

J Oncol. 2022 Apr 7:2022:6986267. doi: 10.1155/2022/6986267. eCollection 2022.

Authors

Dong Soo Lee¹, Seong-Taek Oh², Chang-Hyeok Ahn², Jaeim Lee², Kil-Yong Lee², Hiun Suk Chae³, Sung Soo Kim³, Sang Woo Kim³, Kyung Jin Seo⁴

Affiliations

¹ Department of Radiation Oncology, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.
² Department of Surgery, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.
³ Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.
⁴ Department of Hospital Pathology, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.

Abstract

Background: Volumetric modulated arc therapy (VMAT) with simultaneous integrated boost (SIB) is an advanced form of radiotherapy (RT) technology. The purpose of this study was to report long-term treatment outcomes in patients with locally advanced rectal cancer undergoing VMAT-SIB based concurrent chemoradiotherapy (CRT).

Methods: Between January 2016 and January 2018, a total of 22 patients with operable stage II-III rectal adenocarcinoma were recruited for the pre-designed VMAT-SIB RT protocol. All patients underwent standard diagnostic and staging work-up. The RT target volumes included the following areas: PTV1 = mesorectum that contained gross tumors and enlarged lymph node regions and PTV2 = mesorectum and regional lymphatics from L4-5/S1 to 3-4 cm below the tumor or levator ani muscle, excluding PTV1. The VMAT-SIB dose prescription was as follows: PTV1 = 52.5 Gy/daily 2.1 Gy/25 fractions, PTV2 = 45 Gy/daily 1.8 Gy/25 fractions.

Results: The mean age of the study population was 64 (range, 18-84) years, and 15 (68.2%) patients were male. Radical operation (total mesorectal excision) was performed by either low anterior resection, ultralow anterior resection, or abdominal perineal resection. All five (22.7%) of the patients with confirmed increasing serum carcinoembryonic antigen (CEA) level at diagnosis showed normalization of serum CEA level after the planned treatment. Among 20 patients who underwent preoperative CRT and surgery, tumor down staging in T- and N-stages was achieved in 10 patients (50%) and 13 patients (65%), respectively, with 20% of ypT0/Tis. With a median follow-up of 54.2 (range, 22.6-61.1) months, the 5-year disease-free survival, overall survival, and local control rates were 64.6%, 81.8%, and 84.4%, respectively. Five patients developed distant metastasis and one developed local recurrence as a first event. Two cases with anastomosis site leakage, three with adhesive ileus, and two with abscess formation were observed during postoperative periods.

Conclusions: The current VMAT-SIB-based CRT protocol provided acceptable treatment and toxicity outcomes.