Comparison of Radiation-Induced Secondary Malignancy Risk Between Sequential and Simultaneous Integrated Boost for the Treatment of Nasopharyngeal Carcinoma: Intensity-Modulated Radiotherapy versus Volumetric-Modulated Arc Therapy

CANCER MANAGEMENT AND RESEARCH, vol.12, pp.2513-2521, 2020 (SCI-Expanded)

Publication Type: Article / Article
Volume: 12
Publication Date: 2020
Doi Number: 10.2147/cmar.s244901
Journal Name: CANCER MANAGEMENT AND RESEARCH
Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, EMBASE, Directory of Open Access Journals
Page Numbers: pp.2513-2521
Karadeniz Technical University Affiliated: Yes

Purpose: This study aimed to compare the secondary cancer risk (SCR) between the

sequential boost (SEQ) technique and simultaneous integrated boost (SIB) technique in

intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT)

in patients with nasopharyngeal carcinoma (NPC) using the concepts of organ equivalent

dose (OED) and excess absolute risk (EAR).

Patients and Methods: IMRT-SEQ, VMAT-SEQ, IMRT-SIB, and VMAT-SIB plans were

created with identical objective functions for five patients with early-stage NPC. Three

different planning tumor volumes (PTVs; PTV1, PTV2, and PTV3) were delineated for

each patient, and the prescribed doses were 50 Gy, 60 Gy, and 70 Gy (2 Gy/fraction),

respectively, for the SEQ technique and 52.8 Gy, 59.4 Gy, and 69.3 Gy (33 fractions),

respectively, for the SIB technique.

Results: All plans were clinically acceptable. There was no difference in most OED-based

SCRs between IMRT and VMAT when the same fractionation scheme was used. Compared

with the SEQ technique, the SIB technique in IMRT and VMAT was associated with the

lowest OEDs for the oral cavity, pharynx, parotids, and submandibular glands, resulting in

SCR reduction. SCR for the parotids was much lower than that for the other assessed organs

when the SIB technique was used.

Conclusion: Our findings suggest that OED-based SCRs are lower with the SIB technique

than with the SEQ technique in IMRT and VMAT in most organs for which SCR was

calculated; furthermore, SCR for the parotids is much lower than that for other organs when

the SIB technique is used in patients with NPC.

Keywords: excess absolute risk, intensity-modulated radiotherapy, organ equivalent dose,

secondary cancer risk, volumetric-modulated arc therapy