Which radiotherapy technique is better for neoadjuvant treatment of rectal cancer: A dosimetric comparison

Abstract

Objective: Our aim was to compare helical tomotherapy (HT) and volumetric modulated arc therapy (VMAT) plans with 3-dimensional conformal radiotherapy (3D-CRT) considering the planning target volume (PTV) and organs at risk (OARs) in rectal cancer patients treated with neoadjuvant radiotherapy.

Patients and Methods: Thirty patients, previously treated with intensity modulated radiotherapy (IMRT) or 3D-CRT from January 2014 to February 2020 were selected and 3 plans were generated for each patient using VMAT, HT and 3D-CRT. Dosimetric comparisons were made for each plan regarding PTV and OARs. Integral dose (ID) was calculated and beam on times were analyzed.

Results: The homogeneity index (HI) was significantly better in HT plans compared with VMAT and 3D-CRT plans (p<0.001), conformity index (CI) was better in VMAT plans. For small bowel, high doses were higher in 3D-CRT plans (p <0.001). HT produced lower doses for the bladder as compared to VMAT and 3D-CRT (p<0.005). The mean and maximum doses of bilateral femoral heads were higher in 3D-CRT plans. Beam on times were longer and IDs were higher in HT plans (p<0.001).

Conclusion: Both VMAT and HT improved target homogeneity and conformity and decreased OAR doses compared to 3D-CRT. Although, VMAT was the best method to decrease ID, HT produced better bladder sparing.

Keywords

• Rectum cancer
• Volumetric modulated arc therapy
• Helical tomotherapy
• 3-dimensional conformal radiotherapy
• Plan comparison

References

1. [1] Sung H, Ferlay J, Siegel RL, Laversanne M, et al. Global Cancer Statistics 2020: GLOBOCAN Estimates of Incidence and Mortality Worldwide for 36 Cancers in 185 Countries. CA Cancer J Clin 2021;71:209-49. doi: 10.3322/caac.21660.
2. [2] Sauer R, Sauer R, Liersch T, et al. Preoperative versus postoperative chemoradiotherapy for rectal cancer. N Engl J Med 2004. 351: 1731-40. doi: 10.1056/NEJMoa040694.
3. [3] Bosset JF, Collette L, Calais G, et al. Chemotherapy with preoperative radiotherapy in rectal cancer. N Engl J Med 2006; 355:1114-23. doi: 10.1056/NEJMoa060829.
4. [4] Zorcolo L, Rosman AS, Restivo A, et al. Complete pathologic response after combined modality treatment for rectal cancer and long-term survival: a meta-analysis. Ann Surg Oncol 2012. 19:2822-32. doi: 10.1245/s10434.011.2209-y.
5. [5] Clifford R, Govindarajah N, Parsons JL, Gollins S, West NP, Vimalachandran D. Systematic review of treatment intensification using novel agents for chemoradiotherapy in rectal cancer. Br J Surg 2018 ;105:1553-72. doi: 10.1002/ bjs.10993.
6. [6] Burbach JP, den Harder AM, Intven M, van Vulpen M, Verkooijen HM, Reerink O. Impact of radiotherapy boost on pathological complete response in patients with locally advanced rectal cancer: a systematic review and metaanalysis. Radiother Oncol 2014; 113:1-9. doi: 10.1016/j.radonc.2014.08.035.
7. [7] Valentini V, Gambacorta MA, Cellini F, et al. The INTERACT Trial: Long-term results of a randomised trial on preoperative capecitabine-based radiochemotherapy intensified by concomitant boost or oxaliplatin, for cT2 (distal)-cT3 rectal cancer. Radiother Oncol 2019 ;134:110-8. doi: 10.1016/j. radonc.2018.11.023.
8. [8] Baglan KL, Frazier RC, Yan D, Huang RR, Martinez AA, Robertson JM. The dose-volume relationship of acute small bowel toxicity from concurrent 5-FU-based chemotherapy and radiation therapy for rectal cancer. Int J Radiat Oncol Biol Phys 2002;52:176-83. doi: 10.1016/s0360-3016(01)01820-x.

9. [9] International Commission on Radiation Units and Measurements. ICRU Report 62. Prescribing, recording, and reporting photon beam therapy (Supplement to ICRU Report 50). Bethesda, MD: ICRU, 1999:1-20.
10. [10] Theodore S Hong, Jennifer Moughan, Michael C Garofalo, et al. NRG Oncology Radiation Therapy Oncology Group 0822: A Phase 2 Study of Preoperative Chemoradiation Therapy Using Intensity Modulated Radiation Therapy in Combination With Capecitabine and Oxaliplatin for Patients With Locally Advanced Rectal Cancer. Int J Radiat Oncol Biol Phys 2015 ;93:29-36. doi: 10.1016/j.ijrobp.2015.05.005.
11. [11] Aoyama H, Westerly DC, Mackie TR, et al. Integral radiation dose to normal structures with conformal external beam radiation. Int J Radiat Oncol Biol Phys 2006;64:962-7. doi: 10.1016/j.ijrobp.2005.11.005.
12. [12] Marco D’Arienzo, Stefano G Masciullo, Vitaliana de Sanctis, et al. Integral dose and radiation-induced secondary malignancies: comparison between stereotactic body radiation therapy and three-dimensional conformal radiotherapy Int J Environ Res Public Health 2012; 9:4223-40. doi:10.3390/ ijerph9114223.
13. [13] Onay Ö, Ünal Karabey A, Morgül Y, Karabey MS. A comparative planning study of step – and – shoot IMRT versus helical tomotherapy IMRT in the treatment of craniospinal tumor. Turkish J Oncol 2014;29:46-52. doi: 10.5505/tjoncol.2014.1059
14. [14] Arbea L, Ramos LI, Martínez-Monge R, Moreno M, Aristu J: Intensity modulated radiation therapy (IMRT) vs. 3D conformal radiotherapy (3DCRT) in locally advanced rectal cancer (LARC): dosimetric comparison and clinical implications. Radiat Oncol 2010;5:17. doi: 10.1186/1748- 717X-5-17.
15. [15] Yu M, Jang HS, Jeon DM, et al. Dosimetric evaluation of tomotherapy and four-box field conformal radiotherapy in locally advanced rectal cancer. Radiat Oncol J 2013;31: 252-9. doi: 10.3857/roj.2013.31.4.252.
16. [16] Lin JC, Tsai JT, Chen LJ, Li MH, Liu WH. Compared planning dosimetry of TOMO, VMAT and IMRT in rectal cancer with different simulated positions. Oncotarget 2017;8: 42020-29. doi: 10.18632/oncotarget.14923.
17. [17] Wen G, Zhang J, Chi F, et al. Dosimetric comparison of volumetric modulated arc therapy (VMAT), 5F intensity modulated radiotherapy (IMRT) and 3D conformal radiotherapy (3DCRT) in rectal carcinoma receiving neoadjuvant chemoradiotherapy. Int J Med Phys Clin Eng and Radiol Oncol 2015;4:54-63.doi: 10.4236/ijmpcero.2015.41008.
18. [18] Simson DK, Mitra S, Ahlawat P, Sharma MK, Yadav G, Mishra MB. Dosimetric comparison between intensity modulated radiotherapy and 3 dimensional conformal radiotherapy in the treatment of rectal cancer. Asian Pac J Cancer Prev 2016 ;17:4935-7. doi: 10.22034/APJCP.2016.17.11.4935.
19. [19] Bakkal BH, Elmas O. Dosimetric comparison of organs at risk in 5 different radiotherapy plans in patients with preoperatively irradiated rectal cancer. Medicine (Baltimore) 2021;100(1):e24266. doi: 10.1097/MD.000.000.0000024266.
20. [20] Braendengen M, Tveit KM, Berglund A, et al. Randomized phase III study comparing preoperative radiotherapy with chemoradiotherapy in nonresectable rectal cancer. J Clin Oncol 2008 ;26:3687-94. doi: 10.1200/JCO.2007.15.3858.
21. [21] Tho LM, Glegg M, Paterson J, et al. Acute small bowel toxicity and preoperative chemoradiotherapy for rectal cancer: investigating dose-volume relationships and role for inverse planning. Int J Radiat Oncol Biol Phys 2006;66:505-13. doi: 10.1016/j.ijrobp.2006.05.005.
22. [22] Robertson JM, Lockman D, Yan D, Wallace M. The dosevolume relationship of small bowel irradiation and acute grade 3 diarrhea during chemoradiotherapy for rectal cancer. Int J Radiat Oncol Biol Phys 2008;70:413-8. doi: 10.1016/j. ijrobp.2007.06.066.
23. [23] Holyoake DLP, Partridge M, Hawkins MA. Systematic review and meta-analysis of small bowel dose-volume and acute toxicity in conventionally-fractionated rectal cancer radiotherapy. Radiother Oncol 2019;138:38-44. doi: 10.1016/j. radonc.2019.05.001.
24. [24] Temelli O, Demirtas M, Ugurlu BT, Bag HG. Integral dose and dosimetric comparison of neoadjuvant simultaneous integrated boost (SIB) radiotherapy technique for rectal cancer using intensity-modulated radiotherapy (IMRT), volumetric modulated arc therapy (VMAT), and helical tomotherapy (HT). Int J Hematol Oncol 2019; 29: 147-56. doi: 10.4999/ uhod.193839.
25. [25] Grigsby PW, Roberts HL, Perez CA. Femoral neck fracture following groin irradiation. Int J Radiat Oncol Biol Phys 1995 ;32::63-7. doi: 10.1016/0360-3016(95)00546-B.
26. [26] Rasmusson E, Nilsson P, Kjellén E, Gunnlaugsson A. Longterm risk of hip complications after radiation therapy for prostate cancer: A dose-response study. Adv Radiat Oncol 2020;;6:100571. doi: 10.1016/j.adro.2020.09.011.