Affiliation:
1. National Hospital Organization Kyushu Cancer Center: Kokuritsu Byoin Kiko Kyushu Gan Center
2. National Kyushu Cancer Center: Kyushu Gan Center
3. Saga Heavy Ion Medical Accelerator in Tosu: Kyushu Kokusai Juryushisen Gan Chiryo Center
Abstract
Abstract
Background We explored the relative clinical efficacy of intensity-modulated radiation therapy (IMRT) in the treatment of patients with oropharyngeal cancer (OPC) compared with three-dimensional conformal radiation therapy (3D-CRT). Particular attention was paid to osteoradionecrosis (ORN).
Materials and methods Seventy-four OPC patients treated with definitive IMRT or 3D-CRT between May 2010 and December 2018 were analyzed. Of these, 42 patients were treated with IMRT and 32 with 3D-CRT. We compared clinical benefits. In particular, we focused on ORN, and evaluated the irradiated mandibular volumes.
Results Late Grade 2 xerostomia was detected in 6 (19.4%) and 15 patients (71.4%) in the IMRT and 3D-CRT groups, respectively (P = 0.003). Five patients had Grade 2–3 ORN in the 3D-CRT group. In contrast, no ORN was observed in the IMRT group. A comparison of the mandible volumes between the two groups showed that the IMRT group had lower mandibular volumes than the 3D-CRT group in the high-dose range of V40, V50, V60 and V70. In addition, a comparison of the mandibular volumes between ORN and non-ORN showed a significant difference in the V60 and V70. ORN incidence was higher in V60 ≥ 25% and V70 ≥ 15%.
Conclusion On comparing IMRT with 3D-CRT, the advantages of IMRT translated into a significant reduction of late xerostomia and ORN in patients with OPC. Reducing of the mandibular V60 and V70 values by IMRT seemed to reduce the risk of ORN.
Publisher
Research Square Platform LLC