MRT-boost as the last fraction may be the most efficient irradiation schedule for increased survival times in a rat glioma model.

Synchrotron microbeam radiation therapy (MRT) is based on the spatial fractionation of the incident synchrotron beam into arrays of parallel microbeams, typically a few tens of micrometres wide and depositing several hundred Gray. This high dose, high dose rate, spatially fractionated radiotherapy has a high therapeutic impact on tumors, especially in intracranial locations. MRT leads to better control of incurable high-grade glioma than from homogeneous radiotherapy. The schedule of MRT within a conventional irradiation protocol (three fractions of 11 Gy) of brain tumors was evaluated on the 9L glioma model in rats. MRT delivered as a first fraction increased the median survival time of the animals by four days compared with conventional radiotherapy, while the last MRT fraction improved the lifespan by 148% (+15.5 days compared with conventional radiotherapy, p < 0.0001). The most efficient radiation regimen was obtained when the MRT-boost was applied as the last fraction, following two conventional clinical exposures.

Impact of dose escalation on colostomy-free survival and treatment outcome in squamous cell anal carcinoma.

PURPOSE: Primary radiochemotherapy (RCT) constitutes the standard of care for early- and advanced-stage anal carcinoma. This retrospective study investigates the impact of dose escalation on colostomy-free survival (CFS), overall survival (OS), locoregional control (LRC), progression-free survival (PFS), and acute and late toxicities in patients with squamous cell anal cancer. METHODS: Considered were the outcomes of 87 patients with anal cancer treated with radiation/RCT between May 2004 and January 2020 at our institution. Toxicities were evaluated according to the Common Terminology Criteria for Adverse Events (CTCAE version 5.0). RESULTS: The 87 patients received treatment with a median boost of 63 Gy to the primary tumor. With a median follow-up of 32 months, the 3­year CFS, OS, LRC, and PFS were 79.5%, 71.4%, 83.9%, and 78.5%, respectively. Tumor relapse occurred in 13 patients (14.9%). Dose escalation to > 63 Gy (maximum 66.6 Gy) to the primary tumor in 38/87 patients revealed a nonsignificant trend for improved 3­year CFS (82.4% vs. 97%, P = 0.092), a significantly improved CFS for T2/T3 tumors (72.6% vs. 100%, P = 0.008), and a significantly improved 3­year PFS for T1/T2 tumors (76.7% vs. 100%, P = 0.035). While acute toxicities did not differ, dose escalation > 63 Gy led to a higher rate of chronic skin toxicities (43.8% vs. 69%, P = 0.042). Treatment with intensity-modulated radiotherapy (IMRT) showed a significant improvement in 3­year OS (75.4% vs. 53.8%, P = 0.048). In multivariate analysis, significant improvements for T1/T2 tumors (CFS, OS, LRC, PFS), G1/2 tumors (PFS), and IMRT (OS) were shown. The nonsignificant trend for CFS improvement with dose escalation > 63 Gy was also apparent in multivariate analysis (P = 0.067). CONCLUSION: Dose escalation > 63 Gy (maximum 66.6 Gy) may improve CFS and PFS for certain subgroups, with a concomitant increase in chronic skin toxicities. Modern IMRT seems to be associated with an improvement in OS.

Does external beam radiation boost to pelvic lymph nodes improve outcomes in patients with locally advanced cervical cancer?

BACKGROUND: Current recommendation for locally advanced cervical cancer includes pelvic external beam radiation therapy (EBRT) with concurrent chemotherapy followed by brachytherapy. Involvement of pelvic lymph nodes is an important prognostic factor in locally advanced cervical cancer and recurrence commonly occurs despite definitive treatment. To date, there is no standard guideline on whether an EBRT boost should be applied to involved pelvic lymph nodes. Our study aims to assess if pelvic EBRT boost would reduce recurrence, benefit survival, and affect associated toxicities. METHODS: We conducted a retrospective review of locally advanced cervical cancer cases treated with definitive treatment at our institution. Involvement of pelvic lymph nodes were assessed on CT, MRI (> 10 mm or suspicious features) or PET scan (SUVmax > 2.5). EBRT dose ranged from 45 to 50.4 Gy with nodal boost ranging from 3.6-19.8 Gy. RESULTS: Between 2008 to 2015, 139 patients with locally advanced cervical cancer underwent treatment. Sixty-seven patients had positive pelvic lymph nodes, of which 53.7% received a nodal boost. Five-year recurrence free survival was 48.6% with vs. 64.5% without nodal boost (P = 0.169) and 5-year overall survival in those with positive pelvic lymph nodes was 74.3% with vs. 80.6% without nodal boost (P = 0.143). There was no significant difference in toxicity with nodal boost. CONCLUSIONS: EBRT boost to pelvic lymph nodes does not reduce recurrence or improve survival in locally advanced cervical cancer with lymph node involvement at diagnosis.

Is a higher boost dose of radiation necessary after breast-conserving therapy for patients with breast cancer with final close or positive margins?

To determine rates of loco-regional recurrence (LRR), distant failure and overall survival for patients with breast cancer treated with breast-conserving therapy (BCT) with a close or positive surgical margin (C/PM) treated with standard dose boost radiation compared with a higher boost of radiation. We retrospectively studied 1476 patients with T1-T3 invasive breast cancer treated with BCT between 1992 and 2009. Median age was 57 years. Patients were divided into three groups: Group I included 1197 patients (81 %) with negative margins who received a standard boost (median 60 Gy) total dose to the lumpectomy cavity; Group II included 116 patients (8 %) with C/PM who received a standard boost (median 60 Gy); and Group III included 163 patients (11 %) with C/PM who received a higher boost (median 68 Gy). Biological subtypes (e.g., ER, PR, HER2/neu) were available for 858 patients (58 %) and were also assessed for any relationship to LRR rate. The Kaplan-Meier, Cox-regression, and log-rank tests were used to estimate rates of LRR and the significance of risk factors. Median follow-up was 8.6 years. The overall 5- and 10-year cumulative incidences of LRR were 2.1 % (95 % CI 0.8-2.1 %) and 4.5 % (95 % CI 3.4-6.0 %), respectively. The 5- and 10-year cumulative incidences of LRR for Group I (negative margins + standard boost) were 1.9 and 4.4 %; for Group II (C/PM + standard boost) were 3.9 and 7.0 %; and for Group III (C/PM + higher boost) were 2.9 and 3.8 %, respectively. No statistically significant differences in LRR rates were found among the three groups (p = 0.4). Similar results were obtained for distant failure (p = 0.3) and overall survival (p = 0.4). On multivariate analysis, tumor grade (p = 0.03), systemic-therapy (p = 0.005), node positivity (p = 0.05), young age (p = 0.001), and biological subtype (p = 0.04) were statistically significantly associated with higher LRR. Higher boost dose and margin positivity were not significant. Our data suggest that the 10-year risk of local recurrence for patients with close or positive margins receiving a standard boost was 7 % compared to 3.8 % for those receiving a higher boost; however, this difference was not significant. A higher boost dose did not significantly improve local control, nor did margins impact LRR risk in our cohort of patients.

Competing risk analysis of cardiovascular disease risk in breast cancer patients receiving a radiation boost.

BACKGROUND: Thoracic radiotherapy may damage the myocardium and arteries, increasing cardiovascular disease (CVD) risk. Women with a high local breast cancer (BC) recurrence risk may receive an additional radiation boost to the tumor bed. OBJECTIVE: We aimed to evaluate the CVD risk and specifically ischemic heart disease (IHD) in BC patients treated with a radiation boost, and investigated whether this was modified by age. METHODS: We identified 5260 BC patients receiving radiotherapy between 2005 and 2016 without a history of CVD. Boost data were derived from hospital records and the national cancer registry. Follow-up data on CVD events were obtained from Statistics Netherlands until December 31, 2018. The relation between CVD and boost was evaluated with competing risk survival analysis. RESULTS: 1917 (36.4%) received a boost. Mean follow-up was 80.3 months (SD37.1) and the mean age 57.8 years (SD10.7). Interaction between boost and age was observed for IHD: a boost was significantly associated with IHD incidence in patients younger than 40 years but not in patients over 40 years. The subdistribution hazard ratio (sHR) was calculated for ages from 25 to 75 years, showing a sHR range from 5.1 (95%CI 1.2-22.6) for 25-year old patients to sHR 0.5 (95%CI 0.2-1.02) for 75-year old patients. CONCLUSION: In patients younger than 40, a radiation boost is significantly associated with an increased risk of CVD. In absolute terms, the increased risk was low. In older patients, there was no association between boost and CVD risk, which is likely a reflection of appropriate patient selection.

Whole-breast Radiotherapy With Boost for Node-negative Breast Cancer: Conventional vs. Hypo-fractionation.

BACKGROUND/AIM: Many breast cancer patients receive adjuvant radiotherapy. Tumor bed boost may reduce risk of local failure in high risk patients. We compared hypofractionated whole-breast irradiation (WBI) plus boost (HF+boost) and conventionally fractionated WBI plus boost (CF+boost). PATIENTS AND METHODS: One-hundred-and-twenty-eight patients receiving HF-WBI (40 Gy in 15 fractions) plus boost (group A) were matched to 127 patients receiving CF-WBI (50.4 Gy in 28 fractions) plus boost (group B), utilizing 10 characteristics. RESULTS: Grade ≥2 dermatitis rates were 16.4% in group A vs. 44.1% in group B (p<0.0001), and grade ≥2 pneumonitis rates were 1.6% vs. 2.4% (p=0.68). Four-year rates of local control, metastases-free survival, and overall survival were 100% vs. 99% (p=0.81), 98% vs. 100% (p=0.29), and 98% vs. 100% (p=0.17), respectively. CONCLUSION: HF+boost was associated with significantly less grade ≥2 dermatitis with similar disease control and survival.

Hotspot on 18F-FET PET/CT to Predict Aggressive Tumor Areas for Radiotherapy Dose Escalation Guiding in High-Grade Glioma.

The standard therapy strategy for high-grade glioma (HGG) is based on the maximal surgery followed by radio-chemotherapy (RT-CT) with insufficient control of the disease. Recurrences are mainly localized in the radiation field, suggesting an interest in radiotherapy dose escalation to better control the disease locally. We aimed to identify a similarity between the areas of high uptake on O-(2-[18F]-fluoroethyl)-L-tyrosine (FET) positron emission tomography/computed tomography (PET) before RT-CT, the residual tumor on post-therapy NADIR magnetic resonance imaging (MRI) and the area of recurrence on MRI. This is an ancillary study from the IMAGG prospective trial assessing the interest of FET PET imaging in RT target volume definition of HGG. We included patients with diagnoses of HGG obtained by biopsy or tumor resection. These patients underwent FET PET and brain MRIs, both after diagnosis and before RT-CT. The follow-up consisted of sequential brain MRIs performed every 3 months until recurrence. Tumor delineation on the initial MRI 1 (GTV 1), post-RT-CT NADIR MRI 2 (GTV 2), and progression MRI 3 (GTV 3) were performed semi-automatically and manually adjusted by a neuroradiologist specialist in neuro-oncology. GTV 2 and GTV 3 were then co-registered on FET PET data. Tumor volumes on FET PET (MTV) were delineated using a tumor to background ratio (TBR) ≥ 1.6 and different % SUVmax PET thresholds. Spatial similarity between different volumes was performed using the dice (DICE), Jaccard (JSC), and overlap fraction (OV) indices and compared together in the biopsy or partial surgery group (G1) and the total or subtotal surgery group (G2). Another overlap index (OV') was calculated to determine the threshold with the highest probability of being included in the residual volume after RT-CT on MRI 2 and in MRI 3 (called "hotspot"). A total of 23 patients were included, of whom 22% (n = 5) did not have a NADIR MRI 2 due to a disease progression diagnosed on the first post-RT-CT MRI evaluation. Among the 18 patients who underwent a NADIR MRI 2, the average residual tumor was approximately 71.6% of the GTV 1. A total of 22% of patients (5/23) showed an increase in GTV 2 without diagnosis of true progression by the multidisciplinary team (MDT). Spatial similarity between MTV and GTV 2 and between MTV and GTV 3 were higher using a TBR ≥ 1.6 threshold. These indices were significantly better in the G1 group than the G2 group. In the FET hotspot analysis, the best similarity (good agreement) with GTV 2 was found in the G1 group using a 90% SUVmax delineation method and showed a trend of statistical difference with those (poor agreement) in the G2 group (OV' = 0.67 vs. 0.38, respectively, p = 0.068); whereas the best similarity (good agreement) with GTV 3 was found in the G1 group using a 80% SUVmax delineation method and was significantly higher than those (poor agreement) in the G2 group (OV'= 0.72 vs. 0.35, respectively, p = 0.014). These results showed modest spatial similarity indices between MTV, GTV 2, and GTV 3 of HGG. Nevertheless, the results were significantly improved in patients who underwent only biopsy or partial surgery. TBR ≥ 1.6 and 80-90% SUVmax FET delineation methods showing a good agreement in the hotspot concept for targeting standard dose and radiation boost. These findings need to be tested in a larger randomized prospective study.

Radiation boost for synchronous solitary inguinal lymph node metastasis during neoadjuvant chemoradiotherapy for locally advanced rectal cancer.

BACKGROUND: Some patients with locally advanced rectal cancer (LARC) present with inguinal lymph node metastases without evidence of other systemic disease, known as solitary inguinal lymph node metastasis (SILNM). These patients may represent a distinct subset who have a more favorable prognosis and should be treated with curative intent. The optimal treatment strategy for these patients has not been determined. METHODS: We retrospectively reviewed 16 consecutive LARC patients diagnosed between January 2017 and December 2019, who had SILNM, were treated with an inguinal lymph nodes (ILN) radiation boost with curative intent during neoadjuvant chemoradiotherapy (nCRT) and underwent total mesorectal excision (TME). We used Kaplan-Meier survival curves to calculate survival rates, and recorded radiation-related toxicity. RESULTS: None of these 16 patients developed pelvic or inguinal recurrences, and 3 of the patients developed distant metastases. The 3-year overall survival rate and locoregional relapse-free survival rate were both 100%. The 3-year disease-free rate and distant metastasis-free survival rate were both 81.3%. Of 5 patients who had ILN dissection for suspicious ILNs after neoadjuvant treatment, 2 had residual nodal tumor confirmed. Grade 3 toxicity was found in 5 patients, and no patients had lymphedema or other grade 4 or 5 toxicities. CONCLUSIONS: In LARC patients with synchronous SILNM, a radiation boost to the ILNs during nCRT achieved excellent local control with acceptable toxicity. Though the optimal treatment strategy remains unclear, nCRT with an ILN radiation boost prior to TME may be a reasonable therapeutic approach to consider for this subset of patients.

Post-lumpectomy radiation therapy boost in breast cancer patients: evidence revisited.

PURPOSE: Radiation therapy is an integral part in the management of breast cancer after breast conservative surgery. In selected patients at high risk for local recurrence (LR), a boost radiation dose is commonly applied to the tumour bed. METHODS: We performed a review of the English literature using PubMed, Medline and Google Scholar for published manuscripts addressing the effect of boost radiation in breast cancer patients, focusing mainly on LR and overall survival (OS). RESULTS: A total of seven studies were included in our review. Most studies (6/7, 85.7%) showed a significant improvement in local control independent of age (hazard ratios ranging between 0.34 and 0.73), with the largest absolute benefit in younger patients. None of the studies, however, was able to demonstrate an improvement in OS. CONCLUSIONS: With lack of sufficient studies addressing the role of boost radiation, individualised treatment decisions are recommended, taking into account the risk factors for LR, including tumour biology. Real-life data are sorely needed to better assess the role of tumour bed boost in the contemporary era.

Comparison of two radiation boost schedules in postlumpectomy patients with breast cancer.

BACKGROUND: We have been practicing hypofractionation, 40 Gy in 16 fractions over 3 weeks for whole breast irradiation (WBI) for the past five decades with or without boost at our center. In this study, we compared two boost schedules of 10 Gy/5#/1 week with 16 Gy/8#/1.5 weeks in postlumpectomy patients with breast cancer after WBI. MATERIALS AND METHODS: From June 2012 to June 2016, the study included 87 breast cancer patients postbreast conservation surgery. The institutional ethics committee approved the study, which was registered with ClinicalTrials.gov (ClinicalTrials.gov identifier no. CT02142907). All patients were treated with WBI of 40 Gy/16#/3 weeks. WBI was followed by tumor bed boost of 10 Gy/5#/1 week in 44 patients and 16 Gy/8#/1.5 weeks in 43 patients, either with electron beam therapy or 3D CRT with photons. The primary endpoint of the study was the comparison of local control between two schedules. Secondary endpoints were acute and late radiation toxicities, cosmetic score analysis, disease-free survival (DFS), and overall survival (OS). The assessment of acute and late skin toxicity was made as per RTOG scores and LENT-SOMA scale. The cosmetic assessment was made with Harvard/NSABP/RTOG Breast Cosmesis Grading Scale. RESULTS: Median follow-up was 55 months (range 18-78 months). Local recurrence was seen in 1 (2.3%) patient in the 16 Gy boost only. Acute Grade 2 skin toxicity was 33% in 16 Gy boost arm compared to 23% in 10 Gy boost arm. Late skin toxicities were also high in patients with 16 Gy boost. Grade ≥2 induration was seen in 4.5% and 14% of patients with 10 Gy and 16 Gy boost, respectively. None of the patients with 10 Gy boost had Grade 2 edema as compared to 5% with 16 Gy. Pigmentation was observed in 9% and 23% patients with 10 Gy and 16 Gy boost, respectively. Grade 1 fibrosis was 2% versus 12% in patients with 10 Gy and 16 Gy boost, respectively. The cosmetic score was good/excellent in 91% and 84% of patients with 10 Gy and 16 Gy boost, respectively. Distant metastasis occurred in 2 (4%) and 3 (7%) patients in 10 Gy and 16 Gy boost, respectively. DFS and OS at 5 years were comparable between the two boost schedules. CONCLUSION: Local control was comparable with 10 Gy and 16 Gy boost. Acute and late skin toxicities were higher with 16 Gy boost dose. The cosmetic score was better with 10 Gy boost. DFS and OS was comparable with the two boost schedules. Hence, a boost of 10 Gy/5# after WBI may be adequate in patients with breast cancer.

Whole brain radiation therapy plus focal boost may be a suitable strategy for brain metastases in SCLC patients: a multi-center study.

BACKGROUND: The treatment for brain metastases in small cell lung cancer (SCLC) is still controversial. The purpose of this study was to compare different brain radiotherapy treatments on SCLC patients with brain metastases. METHODS: In this multi-center retrospective study, SCLC patients who had undergone whole brain radiation therapy (WBRT) or stereotactic radiosurgery (SRS) for brain metastases from January 2012 to December 2018 were retrospectively screened. RESULTS: A total of 263 eligible SCLC patients were included in this study, among whom, 73 were women and 190 were men. According to accepted brain radiotherapy, the remaining patients were divided into WBRT plus focal radiation boost (WBRT+boost), WBRT, and SRS groups. In pairwise comparisons of the overall survival (OS), WBRT+boost group led to longer survival than did WBRT both in all patients (17.9 vs 8.7 months; P < 0.001) and 140 matched patients (17.9 vs 11.7 months; P = 0.045). There were no significant differences in OS between WBRT+boost and SRS groups in all patients (17.9 vs 14.5 months; P = 0.432). Among 74 matched patients between WBRT+boost and SRS groups, however, patients who received WBRT+boost led to a longer survival than did SRS alone (21.8 vs 12.9 months; P = 0.040). In pairwise comparison of the intracranial progression-free survival time (iPFS), WBRT+boost group also showed survival advantages over WBRT (10.8 vs 6.5 months; P = 0.005) and SRS groups (10.8 vs 7.5 months; P = 0.032). CONCLUSION: Due to the SCLC-derived multiple brain metastases and better survival time, focal radiation boost combined with adjuvant WBRT may be a preferred strategy for SCLC patients with brain metastases.

Elderly Patients With Single Brain Metastasis - Overall Survival After Surgery Plus Whole-Brain Irradiation and a Radiation Boost.

BACKGROUND/AIM: Elderly patients with a single brain metastasis likely benefit from personalized treatment protocols. To add to treatment personalization, a survival score was generated for these patients. PATIENTS AND METHODS: This retrospective study included 36 elderly patients, each with a single brain metastasis, who received surgery followed by whole-brain irradiation and a radiation boost. Six pre-treatment characteristics were evaluated regarding survival, namely age, gender, Karnofsky performance score (KPS), type of primary tumor, non-cerebral metastasis and interval from diagnosis of the neoplasm until surgery. RESULTS: When applying the Cox regression model, KPS (p=0.005) and tumor type (p=0.018) were significant and incorporated in the score. Based on 12-month survival probabilities, three groups of 6-9 (n=5), 10-11 (n=15) and 14-19 points (n=16) were formed, with 12-month survival rates of 0%, 33% and 100%, respectively (p<0.0001). CONCLUSION: A survival score was generated specifically for elderly patients with a single brain metastasis that can improve personalization of their treatment.

Stereotactic radiotherapy boost after definite chemoradiation for non-responding locally advanced NSCLC based on early response monitoring 18F-FDG-PET/CT.

BACKGROUND AND PURPOSE: Prognosis of locally advanced non-small cell lung cancer remains poor despite chemoradiation. This planning study evaluated a stereotactic boost after concurrent chemoradiotherapy (30 × 2 Gy) to improve local control. The maximum achievable boost directed to radioresistant primary tumor subvolumes based on pre-treatment fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) (pre-treatment-PET) and on early response monitoring 18F-FDG-PET/CT (ERM-PET) was compared. MATERIALS AND METHODS: For ten patients, a stereotactic boost (VMAT) was planned on ERM-PET (PTVboost;ERM) and on pre-treatment-PET (PTVboost;pre-treatment), using a 70% SUVmax threshold with 7 mm margin to segmentate radioresistant subvolumes. Dose was escalated till organ at risk (OAR) constraints were met, aiming to plan at least 18 Gy in 3 fractions (EQD2 84 Gy/BED 100.8 Gy). RESULTS: In five patients, PTVboost;ERM was 9-40% smaller relative to PTVboost;pre-treatment. Overlap of PTVboost;ERM with OARs decreased also compared to overlap of PTVboost;pre-treatment with OARs. However, any overlap with OAR remained in 4/5 patients resulting in minimal differences between planned dose before and during treatment. Median dose (EQD2) covering 99% and 95% of PTVboost;ERM were 15 Gy and 18 Gy respectively. Median boost volume receiving a physical dose of  ≥ 18 Gy (V18) was 88%. V18 was ≥ 80% for PTVboost in six patients. CONCLUSIONS: A significant stereotactic boost to volumes with high initial or persistent 18F-FDG-uptake could be planned above 60 Gy chemoradiation. Differences between planned dose before and during treatment were minimal. However, as an ERM-PET also monitors changes in tumor position, we recommend to plan the boost on the ERM-PET.

Comparison of composite prostate radiotherapy plan doses with dependent and independent boost phases.

Prostate cases commonly consist of dual phase planning with a primary plan followed by a boost. Traditionally, the boost phase is planned independently from the primary plan with the risk of generating hot or cold spots in the composite plan. Alternatively, boost phase can be planned taking into account the primary dose. The aim of this study was to compare the composite plans from independently and dependently planned boosts using dosimetric and radiobiological metrics. Ten consecutive prostate patients previously treated at our institution were used to conduct this study on the Raystation™ 4.0 treatment planning system. For each patient, two composite plans were developed: a primary plan with an independently planned boost and a primary plan with a dependently planned boost phase. The primary plan was prescribed to 54 Gy in 30 fractions to the primary planning target volume (PTV1) which includes prostate and seminal vesicles, while the boost phases were prescribed to 24 Gy in 12 fractions to the boost planning target volume (PTV2) that targets only the prostate. PTV coverage, max dose, median dose, target conformity, dose homogeneity, dose to OARs, and probabilities of benefit, injury, and complication-free tumor control (P+) were compared. Statistical significance was tested using either a 2-tailed Student's t-test or Wilcoxon signed-rank test. Dosimetrically, the composite plan with dependent boost phase exhibited smaller hotspots, lower maximum dose to the target without any significant change to normal tissue dose. Radiobiologically, for all but one patient, the percent difference in the P+ values between the two methods was not significant. A large percent difference in P+ value could be attributed to an inferior primary plan. The benefits of considering the dose in primary plan while planning the boost is not significant unless a poor primary plan was achieved.

Treatment outcomes and late toxicities of 869 patients with nasopharyngeal carcinoma treated with definitive intensity modulated radiation therapy: new insight into the value of total dose of cisplatin and radiation boost.

This study was to report the long-term outcomes and toxicities of nasopharyngeal carcinoma (NPC) treated with intensity-modulated radiation therapy (IMRT). From 2009 to 2010, 869 non-metastatic NPC patients treated with IMRT were retrospectively enrolled. With a median follow-up of 54.3 months, the 5-year estimated local recurrence-free survival (LRFS), regional recurrence-free survival (RRFS), distant metastasis-free survival (DMFS), disease-free survival (DFS) and overall survival (OS) were 89.7%, 94.5%, 85.6%, 76.3%, 84.0%, respectively. In locally advanced NPC, gender, T, N, total dose of cisplatin more than 300 mg/m(2) and radiation boost were independent prognostic factors for DMFS and DFS. Age, T, N and total dose of cisplatin were independent prognostic factors for OS. Radiation boost was an adverse factor for LRFS, RRFS, DMFS and DFS. Concurrent chemotherapy was not an independent prognostic factor for survival, despite marginally significant for DMFS in univariate analysis. Concurrent chemotherapy increased xerostomia and trismus, while higher total dose of cisplatin increased xerostomia and otologic toxicities. In conclusion, IMRT provided satisfactory long-term outcome for NPC, with acceptable late toxicities. Total dose of cisplatin was a prognostic factor for distant metastasis and overall survival. The role of concurrent chemotherapy and radiation boost in the setting of IMRT warrants further investigation.