[show abstract][hide abstract] ABSTRACT: BACKGROUND: The radiation tolerance dose-volume in brain remains unclear for nasopharyngeal carcinoma (NPC) patients treated with intensity modulated radiotherapy (IMRT). We performed this study to investigate dosimetric factors associated with temporal lobe necrosis (TLN) in NPC patients treated with IMRT. METHODS: From 2001 to 2008, 870 NPC patients were treated with IMRT. For the whole group, 40 patients have developed MRI-diagnosed TLN, and 219 patients were followed-up more than 60 months. Predictive dosimetric factors for TLN were identified by using univariate and multivariate analysis in these 259 patients. RESULTS: By univariate analyses, rVX ( percent of temporal lobes receiving >= X Gy) and aVX ( absolute volumes of temporal lobes receiving >= X Gy, values of X considered were 10, 20, 30, 40, 50, 60, 66 and 70) were all significantly associated with TLN. Multivariate analysis by logistic regression showed that rV40 and aV40 were significant factors for TLN. All dosimetric factors in current serials were highly correlated one another (p < 0.001). The 5-year incidence of TLN for rV40 <10% or aV40 <5 cc is less than 5%. The incidence for rV40 >= 15% or aV40c >= 10c is increased significantly and more than 20%. CONCLUSIONS: In this study, all dosimetric factors were highly correlated, rV40 and aV40 were independent predictive factors for TLN, IMRT with rV40 <10% or aV40 <5 cc in temporal lobe is relatively safe.
[show abstract][hide abstract] ABSTRACT: To evaluate the temporal lobe injury (TLI) in nasopharyngeal carcinoma (NPC) patients who had received intensity modulated radiotherapy (IMRT) and to assess the dosimetric parameters associated with TLI.
Forty of 870 patients were diagnosed with TLI after IMRT, the clinical and dosimetric characteristics of these TLI were analyzed.
A total of 4.6% (40/870) patients have developed TLI. However, TLI is not observed in T1-2 patients, the incidences are 3.1% and 13.4% in T3 and T4 patients respectively. The Dmax (maximum point dose, Gy) and D1cc (the dose delivered to the 1 cubic centimeter volume, Gy) in injured temporal lobes (TLs) are greater than that in normal TLs (P<0.01). TLI is not observed in TLs with Dmax<64Gy or D1cc<52Gy, and the 5-year incidence of TLI in patients with Dmax 64-68Gy or D1cc 52-58Gy is <5.0%. A linear regression demonstrates a 2.6% augment of TLI per Gy of Dmax exceeding 64Gy and a 2.5% augment of TLI per Gy of D1cc exceeding 52Gy; TLI is correlated with Dmax (r=0.89, P<0.01) and D1cc (r=0.87, P<0.01) respectively.
The incidence of TLI is relatively high, especially for patients with advanced T-stage NPC, and correlated with Dmax and D1cc. IMRT with Dmax<68Gy or D1cc<58Gy in TLs is relatively safe.
Radiotherapy and Oncology 07/2012; 104(3):312-6. · 4.52 Impact Factor
[show abstract][hide abstract] ABSTRACT: Although many studies have investigated intensity-modulated radiation therapy (IMRT) for nasopharyngeal carcinoma (NPC), sample sizes in the reported studies are usually small and different in outcomes in different T and N subgroups are seldom analyzed. Herein, we evaluated the outcomes of NPC patients treated with IMRT and further explored treatment strategy to improve such outcome. We collected clinical data of 865 NPC patients treated with IMRT alone or in combination with chemotherapy, and classified all cases into the following prognostic categories according to different TNM stages: early stage group (T1-2N0-1M0), advanced local disease group (T3-4N0-1M0), advanced nodal disease group (T1-2N2-3M0), and advanced locoregional disease group (T3-4N2-3M0). The 5-year overall survival (OS), local relapse-free survival (LRFS), and distant metastases-free survival (DMFS) were 83.0%, 90.4%, and 84.0%, respectively. The early disease group had the lowest treatment failure rate, with a 5-year OS of 95.6%. The advanced local disease group and advanced nodal disease group had similar failure pattern and treatment outcomes as well as similar hazard ratios for death (4.230 and 4.625, respectively). The advanced locoregional disease group had the highest incidence of relapse and death, with a 5-year DMFS and OS of 62.3% and 62.2%, respectively, and a hazard ratio for death of 10.402. Comparing with IMRT alone, IMRT in combination with chemotherapy provided no significant benefit to locoregionally advanced NPC. Our results suggest that the decision of treatment strategy for NPC patients should consider combinations of T and N stages, and that IMRT alone for early stage NPC patients can produce satisfactory results. However, for advanced local, nodal, and locoregional disease groups, a combination of chemotherapy and radiotherapy is recommended.
[show abstract][hide abstract] ABSTRACT: At present, the clinical data about the effect of overall treatment time (OTT) on local control for nasopharyngeal carcinomas (NPC) patients mainly derived from conventional radiotherapy (CRT). The effect of OTT on local control for NPC patients treated with IMRT is still unclear. This study was to explore the effect of OTT on local control in IMRT for NPC patients.
Clinical data of 850 NPC (T1-4N0-3M0) patients that had undergone radical radiotherapy with IMRT from May 2001 to January 2008 in Sun Yat-sen University Cancer Center were analyzed retrospectively. All patients were divided into two groups, which were group with OTT ≤ 42 and group with OTT > 42 days respectively. Survival was calculated using the Kaplan-Meier method. The log-rank test was used to compare survival curves. The effect of clinical factors and treatment related factors on LCR were studied with univariate and multivariate analyses using logistic regression.
The 5-years local recurrence-free survival (LRFS) rate of group with OTT ≤ 42 were 90.7%, and 90.9% in group with OTT > 42, no significant differences were found between these two groups (χ² = 0.028, P = 0.866). Further stratified analysis found that the LRFS rate for early T-stage patients was no significant difference between group with OTT ≤ 42 and group with > 42 days, they were 97.2% and 97.9% (χ² = 0.672, P = 0.412). For advanced T-stage patients, the LRFS rate of OTT ≤ 42 and > 42 days were 86.5% and 87.2% respectively (χ² = 0.151, P = 0.698). The 5-year LRFS rate were 94.4% vs 93.0% (χ² = 0.090, P = 0.764) at OTT > 42 vs ≤ 42 days for patients treated with IMRT alone, and 89.7% vs 87.6% (χ² = 0.060, P = 0.807) for patients in combination chemotherapy with IMRT. We divided all patients into three groups: OTT ≤ 42 d, 43 - 49 d and ≥ 50 d, the 5-years LRFS rate of the three group was 90.7%, 91.7% and 88.4%, respectively, there was no significant difference of LRFS among those three groups (χ² = 0.136, P = 0.934). Univariate analysis showed that T-stage and GTV volume were correlation with local control. In multivariate analysis, GTV volume was confirmed as independent prognostic factors for local control.
Within the range of the OTT observed in our study, prolonged OTT did not have adverse effect on local control. GTV volume was independent prognostic factors in local control for NPC patients treated with IMRT.
[show abstract][hide abstract] ABSTRACT: Reports of intensity-modulated radiotherapy (IMRT) for early-stage nasopharyngeal carcinoma (NPC) have been limited. The present study evaluated the long-term survival outcomes and toxicity of early-stage NPC patients treated with IMRT alone.
Between February 2001 and January 2008, 198 early-stage (T1-T2bN0-N1M0) NPC patients had undergone IMRT alone. The data from these patients were retrospectively analyzed. The patients were treated to 68 Gy at 2.27 Gy/fraction prescribed to the planning target volume of the primary nasopharygeal gross tumor volume. The Radiation Therapy Oncology Group scoring system was used to assess the toxicity.
At a median follow-up of 50.9 months (range, 12-104), the 5-year estimated disease-specific survival, local recurrence-free survival, and distant metastasis-free survival rate was 97.3%, 97.7%, and 97.8%, respectively. The 5-year local recurrence-free survival rate was 100% for those with Stage T1 and T2a and 94.2% for those with Stage T2b lesions (p = 0.252). The 5-year distant metastasis-free survival rate for Stage T1N0, T2N0, T1N1, and T2N1 patients was 100%, 98.8%, 100%, and 93.8%, respectively (p = .073). All local recurrence occurred in patients with T2b lesions. Five patients developed distant metastasis. Of these 5 patients, 4 had had Stage T2bN1 disease and 1 had had Stage T2bN0 disease with retropharyngeal lymph node involvement. The most common acute toxicities were mainly Grade 1 or 2. At 24 months after IMRT, no Grade 3 or 4 xerostomia had developed, and 62 (96.9%) of 64 evaluated patients were free of trismus; only 2 patients (3.1%) had Grade 1 trismus. Radiation encephalopathy and cranial nerve injury were not observed.
IMRT alone for Stage T1N0, T2N0, T1N1, and T2N1 yielded satisfactory survival outcomes with acceptable toxicity, and no differences were found in survival outcomes among these four subgroups. Patients with Stage T2b lesions might have relatively greater risk of local recurrence and those with T2bN1 disease mighth have a greater risk of distant metastasis.
International journal of radiation oncology, biology, physics 10/2010; 82(1):327-33. · 4.59 Impact Factor