First retrospective dosimetric comparison of three radiotherapy techniques for nasopharyngeal carcinoma in Mauritania: 3D-CRT, 3D-CRT+E, and VMAT

Abstract

Introduction: Radiotherapy remains the primary therapeutic option for nasopharyngeal carcinoma (NPC). The choice of technique, however, directly influences tumor control and the preservation of healthy tissues.

Objective: This study aims to evaluate the dosimetry outcomes of three approaches: three-dimensional conformal radiation therapy (3D-CRT), 3D-CRT with electron boost (3D-CRT+E), and volumetric-modulated arc therapy (VMAT), as implemented at the National Oncology Center in Nouakchott, Mauritania.

Methods: Sixty-seven patients with NPC were included. For each patient, three plans (3D-CRT, 3D-CRT+E, and VMAT) were available or retrospectively reconstructed from archived CT datasets, yielding 201 plans for paired dosimetric comparison. Treatment planning was performed using Eclipse 3.0, with delivery on the Clinac 2100 for 3D-CRT and 3D-CRT+E, and Halcyon 3.0 for VMAT. Dosimetric parameters, including dose coverage (D95%), conformity index, homogeneity index, and doses to organs at risk (OARs), were evaluated. Isodose volumes (ISO30, ISO20, ISO10) were also assessed. Statistical analyses were performed using the Wilcoxon test.

Results: VMAT exhibited significantly higher dose coverage (D95%, p = 0.01) and demonstrated optimal homogeneity and conformity (p < 0.001) compared to 3D-CRT and 3D-CRT+E. It also reduced radiation exposure to critical OARs ( p < 0.008) and lowered isodose volumes (ISO30, ISO20, ISO10, p = 0.0187), thereby enhancing healthy tissue sparing.

Conclusion: The findings confirm that VMAT offers clear dosimetric advantages over 3D-CRT and 3D-CRT+E, consistent with international evidence. The novelty of this study lies in its demonstration, for the first time in Mauritania, that VMAT can be successfully implemented in routine practice. By validating global standards in a local context, this study supports the integration of VMAT into national treatment protocols and highlights its potential to improve clinical outcomes for patients with NPC.

Keywords

Conformity index / Dose coverage / Homogeneity index / Nasopharyngeal cancer / Volumetric-modulated arc therapy

Acknowledgements

We would like to express our deepest gratitude to all the institutions and individuals who contributed to the initiation and successful completion of this work. The Technical Cooperation Department of the Tunisian Ministry of Higher Education and Research should be commended for its valuable support and coordination during the project. We are also profoundly grateful to the Higher Institute of Medical Technologies of Tunis for providing the academic foundation and necessary resources. We extend our gratitude to the Laboratory of Energy and Matter for their collaborative spirit and technical input, and to the National Center of Oncology for their significant contributions in providing clinical insights and support.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Conflict of interest

The authors declare they have no competing interests.

Author contributions

Conceptualization: Zeinebou Yacoub Cheikh Sidiya, Leila Ounalli

Formal analysis: Zeinebou Yacoub Cheikh Sidiya

Investigation: Zeinebou Yacoub Cheikh Sidiya, Ahmedou Seyed, Ahmedou Tolba, Cheibetta Moussa, Leila Ounalli

Methodology: Zeinebou Yacoub Cheikh Sidiya, Leila Ounalli

Writing–original draft: Zeinebou Yacoub Cheikh Sidiya

Writing–review & editing: Leila Ounalli

Ethics approval and consent to participate

In accordance with the regulations of our oncology center (CNO) and national guidelines, the use of anonymized retrospective data does not require Ethics Committee/Institutional Review Board approval. The authors confirm that all procedures were performed in line with the ethical standards of the Declaration of Helsinki.

Consent for publication

In accordance with the regulations of our oncology center (CNO) and national guidelines, the use of anonymized retrospective data does not require individual consent for publication

Availability of data

No datasets were generated or analyzed during the current study.

References

[1] Madhan K, Aruna JS, Shyamaladevi B. PD-L1 mediated immune escape in nasopharyngeal carcinoma: Impact of LMP1 and IFN-γ on immune surveillance. Oral Oncol Rep. 2024; 12: 100688. doi: 10.1016/j.oor.2024.100688

[2] Qing D, Lu Z, Lu H. Long-term immune checkpoint inhibitor therapy in a patient with metastatic nasopharyngeal carcinoma: a case report. Front Immunol. 2025; 16: 1585844. doi: 10.3389/fimmu.2025.1585844

[3] Chang ET, Ye W, Ernberg I, Zeng YX, Adami HO. A novel causal model for nasopharyngeal carcinoma. Cancer Causes Control. 2022; 33(7): 1013-1018. doi: 10.1007/s10552-022-01582-x

[4] Astari AA, Azam M, Ariyanto F, Firdausi KS. Comparative Analysis of OAR and PTV Radiation Dose Achievements for Planning 3D-CRT and IMRT Radiotherapy Techniques for Nasopharyngeal Cancer. Int J Res Rev. 2024; 11(12): 528-537. doi: 10.52403/ijrr.20241258

[5] Van Khac P, Doanh VT, Thao MT, et al. Optimizing intensity-modulated radiation therapy for stage II nasopharyngeal cancer: A comparative study of 7-field and 9-field treatment plans. Radiat Phys Chem. 2025; 236: 112700. doi: 10.1016/j.radphyschem.2025.112700

[6] Xu S, Frakulli R, Lin Y. Comparison of the Effectiveness of Radiotherapy with 3D-CRT, IMRT, VMAT and PT for Newly Diagnosed Glioblastoma: A Bayesian Network Meta-Analysis. Cancers. 2023; 15(23): 5698. doi: 10.3390/cancers15235698

[7] You R, Liu YP, Xie YL, et al. Hyperfractionation compared with standard fractionation in intensity-modulated radiotherapy for patients with locally advanced recurrent nasopharyngeal carcinoma: a multicentre, randomised, open-label, phase 3 trial. Lancet. 2023; 401(10380): 917-927. doi: 10.1016/S0140-6736(22)02145-7

[8] Ng WT, Chow JCH, Beitler JJ, et al. Current Radiotherapy Considerations for Nasopharyngeal Carcinoma. Cancers. 2022; 14(23): 5773. doi: 10.3390/cancers14235773

[9] Yeh SA, Hwang TZ, Wang CC, et al. Outcomes of patients with nasopharyngeal carcinoma treated with intensity-modulated radiotherapy. J Radiat Res. 2021; 62(3): 438-447. doi: 10.1093/jrr/rrab008

[10] Liu Y, Du Z, Song S, Yi J. Progress in the comprehensive treatment of nasopharyngeal carcinoma: a review for risk-stratified management strategies. Holist Integr Oncol. 2023; 2(1): 19. doi: 10.1007/s44178-023-00046-9

[11] Kwong DLW. Locoregionally advanced nasopharyngeal carcinoma: integrating immunotherapy into definitive treatment. Lancet Oncol. 2024; 25(12): 1511-1513. doi: 10.1016/S1470-2045(24)00570-9

[12] Huang SH, Ng WT, Bakst RL, et al. Precision in Practice: A Critical Overview of Recent Advances in Nasopharyngeal Cancer Management. Int J Radiat Oncol Biol Phys. 2025:S0360-3016(25)06581-2. doi: 10.1016/j.ijrobp.2025.11.064

[13] Xiang L, Rong JF, Xin-Chen J, et al. Reducing Target Volumes of Intensity Modulated Radiation Therapy After Induction Chemotherapy in Locoregionally Advanced Nasopharyngeal Carcinoma: Long-Term Results of a Prospective, Multicenter, Randomized Trial. Int J Radiat Oncol Biol Phys. 2023; 117(4): 914-924. doi: 10.1016/j.ijrobp.2023.06.001

[14] Jiarpinitnun C, Prayongrat A, Jeerapradit K, et al. A Multicenter Study Comparing Survival Outcomes of IMRT and Non-IMRT Techniques in Non-Metastatic Nasopharyngeal Cancer Using Propensity Score Matching. Int J Radiat Oncol Biol Phys. 2025; 123(1): e348. doi: 10.1016/j.ijrobp.2025.06.2294

[15] Jain S, Kumar P, Kumar P, Nigam J, Silambarasan NS, Sachan R. Intensity-modulated Radiotherapy Versus Volumetric Modulated Arc Therapy in Head and Neck Cancers: A Comparative Analysis of Compliance, Toxicities and Dosimetric Parameters. Cureus. 2025; 17(6): e86143. doi: 10.7759/cureus.86143

[16] Sundaram V, Khanna D, Palanisamy M, et al. A study on clinical evaluation of generalized equivalent uniform dose (gEUD) photon optimizer based VMAT planning on the halcyon platform for head and neck cancer. Med Dosim. 2025. doi: 10.1016/j.meddos.2025.10.004

[17] Farooq MU, Kakakhel MB, Razzaq A, Amjad N, Afridi TA. A Dosimetric Comparison of VMAT and IMRT for Head & Neck and Pelvis Cancers. Malays J Sci Health Technol. 2023; 9(1): 18-24. doi: 10.33102/mjosht.v9i1.311

[18] Kaur H, Thakur N, Sharma R, et al. Dosimetric comparison between carotid-sparing IMRT and 3DCRT in early glottic cancer patients treated with definitive radiation therapy. J Cancer Res Ther. 2024; 20(1): 327-332. doi: 10.4103/jcrt.jcrt_1912_22

[19] ICRU. ICRU Report 62: Prescribing, Recording and Reporting Photon Beam Therapy (Supplement to ICRU Report 50).ICRU; 1999. Available from: https://www.xatrivietnam.vn/wp-content/uploads/2015/10/ICRU-62-Prescribing-Recording-and-Reporting-Photon-Beam-Therapy-Supp-to-ICRU-50.pdf [Last accessed on July 29, 2024].

[20] Tiwari A, Lee SL, MacCabe T, et al. Intraoperative electron radiotherapy (IOERT) in colorectal cancer: Updated systematic review of techniques, oncological outcomes and complications. Eur J Surg Oncol. 2025; 51(5): 109724. doi: 10.1016/j.ejso.2025.109724

[21] Nanda S, Parida S, Ahirwar MK. A Dosimetric Comparison of Volumetric-modulated Arc Therapy and IMRT for Cochlea-sparing Radiation Therapy in Locally Advanced Nasopharyngeal Cancer. J Med Phys. 2023; 48(3): 248-251. doi: 10.4103/jmp.jmp_21_23

[22] Jurado-Bruggeman D, Angerud A, Fredriksson A, Muñoz-Montplet C. On the PTV homogeneity objective in the era of photon advanced dose calculation algorithms: Bridging robust and PTV-based planning. Radiother Oncol. 2025; 207: 110878. doi: 10.1016/j.radonc.2025.110878

[23] Huang X, Guo C, Liu S, Men K, Wang H. Dosimetric analysis of orthogonal collimator configuration in volumetric modulated arc therapy planning: a comparative study. Front Oncol. 2025; 15: 1612643. doi: 10.3389/fonc.2025.1612643

[24] Dolezel M, Slavik M, Cermakova ZZ, et al. Hypoxia Region Dose Escalation in Head and Neck Cancer: Dosimetric Analysis and Acute Toxicity. Int J Radiat Oncol Biol Phys. 2025; 123(1): e331-e332. doi: 10.1016/j.ijrobp.2025.06.2259

[25] Bai R, Sun J, Xu Y, Sun Z, Zhao X. Incidence and mortality trends of nasopharynx cancer from 1990 to 2019 in China: an age-period-cohort analysis. BMC Public Health. 2022; 22(1): 1351. doi: 10.1186/s12889-022-13688-7

[26] Abdul Hamid G. Epidemiology and Outcomes of Nasopharyngeal Carcinoma. In: Pharynx - Diagnosis and Treatment. IntechOpen; 2021. doi: 10.5772/intechopen.96802

[27] Di Gravio EJ, Lang P, Kim HAJ, et al. Modern treatment outcomes for early T-stage oropharyngeal cancer treated with intensity-modulated radiation therapy at a tertiary care institution. Radiat Oncol. 2020; 15(1): 261. doi: 10.1186/s13014-020-01705-1

[28] Su X, Schroder A, Tse L, Yu I, Xie SH. Hormonal and reproductive factors and risk of nasopharyngeal carcinoma in Chinese women: a case-control study. BMC Res Notes. 2025; 18(1): 483. doi: 10.1186/s13104-025-07471-1

[29] Mishra V, Yadav R, Chaudhary S, Pandey L, Pandey A. Retrospective Analysis of Dosimetric Comparison Between Intensity-Modulated Radiation Therapy and Volumetric-Modulated Arc Therapy in Patients With Esophageal Cancer. Cureus. 2025; 17(1): e76981. doi: 10.7759/cureus.76981

[30] Chen D, Cai S, Soon YY, et al. Dosimetric comparison between Intensity Modulated Radiation Therapy (IMRT) vs dual arc Volumetric Arc Therapy (VMAT) for nasopharyngeal cancer (NPC): Systematic review and meta-analysis. J Med Imaging Radiat Sci. 2023; 54(1): 167-177. doi: 10.1016/j.jmir.2022.10.195

[31] Hu B, Meng Q, Peng X, et al. A Unified Planning Platform Comparison of VMAT, Helical Tomotherapy, and IMRT in Nasopharyngeal Carcinoma: Dosimetric Superiority and Organ Sparing Analysis. Technol Cancer Res Treat. 2026; 25: 15330338251413154. doi: 10.1177/15330338251413154

[32] Morgan HE, Sher DJ. Adaptive radiotherapy for head and neck cancer. Head Neck. 2020; 5(1). doi: 10.1186/s41199-019-0046-z

[33] Liu R, Chen P, Zhao K, Wang H, Zhao P, Su Y. Assessment of optic disc parameter changes in head and neck cancer patients undergoing radiotherapy based on OCT. Front Oncol. 2026; 15: 1674684. doi: 10.3389/fonc.2025.1674684

[34] Shaaban SG, LeCompte C, Kleinberg LR, Redmond KJ, Page BR. Recognition and Management of the Long-term Effects of Cranial Radiation. Curr Treat Options Oncol. 2023; 24(7): 880-891. doi: 10.1007/s11864-023-01078-z

[35] Zahu R, Farcasanu A, Eva A, et al. Anatomy-based definition of posterior neck in head and neck VMAT plan optimization as potential new organ at risk. Med Dosim. 2026:S0958-3947(26)00006-3. doi: 10.1016/j.meddos.2026.01.003