Radiation-Induced Temporal Lobe Injury for Nasopharyngeal Carcinoma: A Comparison of Intensity-Modulated Radiotherapy and Conventional Two-Dimensional Radiotherapy

Abstract

BackgroundTo compare the radiation-induced temporal lobe injury (TLI) in patients with nasopharyngeal carcinoma (NPC) treated with intensity-modulated radiotherapy (IMRT) or two-dimensional conventional radiotherapy (2D-CRT).Patients and Methods1276 cases of NPC treated with IMRT or 2D-CRT were retrospectively reviewed. A diagnosis of TLI was made on follow-up magnetic resonance imaging (MRI).ResultsThe crude incidence of TLI was 7.5% and 10.8% (P = 0.048), and the actuarial 5-year incidence was 16% and 34.9% (P<0.001) for the IMRT and 2D-CRT groups, respectively. Multivariate analysis revealed both T stage (P<0.001) and radiation technique (P<0.001) as independent predictors. Patients with T1, T2 and T3 disease had a significantly higher risk when treated with 2D-CRT (P = 0.005, 0.016, <0.001, respectively). This trend was not evident for T4 patients (P = 0.680). The 2D-CRT group had a longer latency for the development of TLI (P<0.001). Those with T4 disease had a shorter median time to TLI (P = 0.006, 0.042, <0.001 when compared with T1, T2 and T3, respectively).ConclusionsIMRT is superior to 2DRT for the management of T1-T3 NPC in terms of sparing the temporal lobe. The high incidence of TLI in T4 disease needs to be addressed.

Intensity-modulated radiation therapy versus 2D-RT or 3D-CRT for the treatment of nasopharyngeal carcinoma: A systematic review and meta-analysis

“…Of the 79 full articles retrieved, 38 were further excluded for no matched comparison, 19 for reviews, 12 for insufficient data, and 2 for repeated patients. Finally, 8 articles [6,[12][13][14][26][27][28][29] met the inclusion criteria and the flowchart of the retrieved studies are presented in Fig. 1.…”

“…Many clinical studies have shown that IMRT was significantly better than conventional RT in terms of parotid sparing and improved QoL for NPC [11,12]. It is also reported increasingly that IMRT is able to reduce the rates of TLN compared with 2D-RT [13,14]. Despite the potential advantages of IMRT for NPC, it is still not clear if IMRT might be better than 2D-RT or 3D-CRT for patients with NPC.…”

Temporal Cerebral Microbleeds Are Associated With Radiation Necrosis and Cognitive Dysfunction in Patients Treated for Nasopharyngeal Carcinoma

“…This explanation is further endorsed by previous report of the association between the T stage of NPC and temporal lobe injury in IMRT patients, where a larger tumor extension indicated a compromise in planning dose for the temporal lobe. The reported incidence rate is between 4.8% to 16%, and may gradually increase over time after IMRT (4,26,27).…”

Radiation associated brain image changes after proton therapy for skull base head and neck cancers

“…Analysis of dosimetric correlations with RAIC suggest that risk can be kept below 5% when doses of 63 Gy is delivered to small volumes of the brain (≤ 2cc), but increases towards 50% with doses of 70 Gy to 80 Gy (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12).…”