title: Temporal lobe injury after re-irradiation of locally recurrent nasopharyngeal carcinoma using intensity modulated radiotherapy: clinical characteristics and prognostic factors.
abstract: Temporal lobe injury (TLI) is a debilitating complication after radiotherapy for nasopharyngeal carcinoma (NPC), especially in patients who suffer treatment relapses and receive re-irradiation. We explored the clinical characteristics and prognostic factors of TLI in locally recurrent NPC (rNPC) patients after re-irradiation using intensity modulated radiotherapy (IMRT). A total of 454 temporal lobes (TLs) from 227 locally rNPC patients were reviewed. The clinical characteristics of TLI were analyzed. In the two radiotherapy courses, the equivalent dose in 2 Gy per fraction (EQD2) for the TLs was recalculated to facilitate comparison of the individual data. The median follow-up time was 31 (range, 3-127) months. After re-irradiation using IMRT, 31.3 % (71/227) of patients developed TLI. The median latency of TLI was 15 (range, 4-100) months. Univariate and multivariate analysis showed that the interval time (IT) between the two courses of radiotherapy and the summation of the maximum doses of the two radiotherapy courses (EQD2 - ∑max) were independent factors influencing TLI. The 5-year incidence of TLI for an IT ≤26 or >26 months was 35.9 and 53.7 % respectively (p = 0.024). The median maximum doses delivered to the injured TLs were significantly higher than was the case for the uninjured TLs after two courses of radiotherapy (135.3 and 129.8 Gy, respectively: p < 0.001). The incidence of TLI with an EQD2 - ∑max < 125 Gy was <5 %, and with an EQD2 - ∑max <145 Gy it was <50 %. A treatment mode limiting EQD2 - ∑max <125 Gy with a >2-year interval was found to be relatively safe.
authors.affiliation: Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, Guangdong, People's Republic of China.
authors.forename: Shuai
authors.initials: S
authors.lastname: Liu
authors.forename: Taixiang
authors.initials: T
authors.lastname: Lu
authors.forename: Chong
authors.initials: C
authors.lastname: Zhao
authors.forename: Jingxian
authors.initials: J
authors.lastname: Shen
authors.forename: Yunming
authors.initials: Y
authors.lastname: Tian
authors.forename: Ying
authors.initials: Y
authors.lastname: Guan
authors.forename: Lei
authors.initials: L
authors.lastname: Zeng
authors.forename: Weiwei
authors.initials: W
authors.lastname: Xiao
authors.forename: Shaomin
authors.initials: S
authors.lastname: Huang
authors.forename: Fei
authors.initials: F
authors.lastname: Han
mesh_terms: D000328:Adult; D000368:Aged; D002277:Carcinoma; D017024:Chemotherapy, Adjuvant; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000188:drug therapy / Q000532:radiotherapy*; D009364:Neoplasm Recurrence, Local / Q000188:drug therapy / Q000532:radiotherapy*; D011379:Prognosis; D011832:Radiation Injuries / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology / Q000503:physiopathology*; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects* / Q000379:methods; D013702:Temporal Lobe / Q000293:injuries* / Q000473:pathology / Q000528:radiation effects; D055815:Young Adult