Excellent local control with stereotactic radiotherapy boost after external beam radiotherapy in patients with nasopharyngeal carcinoma

The Evolving Role of Stereotactic Body Radiation Therapy for Head and Neck Cancer: Where Do We Stand?

Stereotactic body radiation therapy (SBRT) is a precise and conformal radiation therapy (RT) that aims to deliver a high dose of radiation to the tumor whilst sparing surrounding normal tissue, making it an attractive option for head and neck cancer (HNC) patients who are not suitable for the traditional long course of RT with comprehensive RT target volume. Definitive SBRT for HNC has been investigated in different settings, including early stage glottis cancer, and as an alternative to brachytherapy boost after external beam RT. It is also used as a primary treatment option for elderly or medically unfit patients. More recently, an SBRT combination with immunotherapy in the neoadjuvant setting for HNC showed promising results. Salvage or adjuvant SBRT for HNC can be used in appropriately selected cases. Future studies are warranted to determine the optimum dose and fractionation schedules in any of these indications.

Radiation-Induced Retinopathy and Optic Neuropathy after Radiation Therapy for Brain, Head, and Neck Tumors: A Systematic Review

Background: Patients with brain, head, and neck tumors experience a decline in their quality of life due to radiation retinopathy and optic neuropathy. Little is known about the dose–response relationship and patient characteristics. We aimed to systematically review the prevalence of radiation retinopathy and optic neuropathy. Method: The primary outcome was the pooled prevalence of radiation retinopathy and optic neuropathy. The secondary outcome included the effect of the total radiation dose prescribed for the tumor according to the patient’s characteristics. Furthermore, we aimed to evaluate the radiation dose parameters for organs at risk of radiation retinopathy and optic neuropathy. Results: The pooled prevalence was 3.8%. No retinopathy was reported for the tumor’s prescribed dose of <50 Gy. Optic neuropathy was more prevalent for a prescribed dose of >50 Gy than <50 Gy. We observed a higher prevalence rate for retinopathy (6.0%) than optic neuropathy (2.0%). Insufficient data on the dose for organs at risk were reported. Conclusion: The prevalence of radiation retinopathy was higher compared to optic neuropathy. This review emphasizes the need for future studies considering retinopathy and optic neuropathy as primary objective parameters.

Escalating a Biological Dose of Radiation in the Target Volume Applying Stereotactic Radiosurgery in Patients with Head and Neck Region Tumours

Background: The treatment of head and neck tumours is a complicated process usually involving surgery, radiation therapy, and systemic treatment. Despite the multidisciplinary approach, treatment outcomes are still unsatisfactory, especially considering malignant tumours such as squamous cell carcinoma or sarcoma, where the frequency of recurrence has reached 50% of cases. The implementation of modern and precise methods of radiotherapy, such as a radiosurgery boost, may allow for the escalation of the biologically effective dose in the gross tumour volume and improve the results of treatment. Methods: The administration of a stereotactic radiotherapy boost can be done in two ways: an upfront boost followed by conventional radio(chemo)therapy or a direct boost after conventional radio(chemo)therapy. The boost dose depends on the primary or nodal tumour volume and localization regarding the organs at risk. It falls within the range of 10–18 Gy. Discussion: The collection of detailed data on the response of the disease to the radiosurgery boost combined with conventional radiotherapy as well as an assessment of early and late toxicities will contribute crucial information to the prospective modification of fractionated radiotherapy. In the case of beneficial findings, the stereotactic radiosurgery boost in the course of radio(chemo)therapy in patients with head and neck tumours will be able to replace traditional techniques of radiation, and radical schemes of treatment will be possible for future development.

Stereotactic radiotherapy as planned boost after definitive radiotherapy for head and neck cancers: Systematic review

Management of locoregionally advanced head and neck cancers (HNCs) remains a challenge. Some groups have attempted to use stereotactic radiotherapy (SBRT) to deliver "boost" treatment following conventional radiotherapy to improve local control (LC) and overall survival (OS), while aiming for acceptable toxicities. Medline, EMBASE, and Cochrane Library databases were queried for SBRT as curative-intent planned boost in HNC after conventional radiotherapy. Individual studies were reviewed from inception until January 2021, extracting patient, treatment, and outcome data. Nine studies met inclusion criteria, representing 454 unique patients treated with curative intent across multiple head and neck sites with conventional radiotherapy. At 3 years, median LC was 92% (90%-98%), and median OS was 80% (75%-91%). Seven treatment-related grade 5 toxicities (1.5%) were reported. Despite acceptable LC and OS rates, there were severe treatment-related late toxicities. As such, SBRT boost should only be used in investigational settings until more data is available.

Long-term survival outcomes and adverse effects of nasopharyngeal carcinoma patients treated with IMRT in a non-endemic region: a population-based retrospective study

OBJECTIVES

To evaluate the long-term survival outcomes and adverse effects of intensity-modulated radiotherapy (IMRT) for nasopharyngeal carcinoma (NPC) and to summarise the experiences of IMRT in NPC in the past few decades in non-endemic northwest China.

DESIGN

A population-based retrospective study.

SETTING

An experience of using IMRT in non-endemic region of China.

PARTICIPANTS

The study included 792 newly diagnosed and non-metastatic NPC patients who received IMRT from January 2006 to September 2018 in Xijing Hospital.

OUTCOME MEASURES

The survival outcomes, adverse effects and failure patterns were evaluated by univariate, multivariate and subgroup analyses.

RESULTS

With a median follow-up time of 46.2 months, the 5-year local recurrence-free survival, regional recurrence-free survival, distant metastasis-free survival, disease-free survival (DFS) and overall survival (OS) rates were 90.8%, 97.0%, 82.8%, 69.6% and 78.0%, respectively. Multivariate analysis showed that age, N stage, clinical stage, pathological type and primary tumour volume of more than 23 cm³ were the independent prognosis factors for DFS (all p<0.05); age, N stage, pathological type, cervical lymph node necrosis, and anaemia were significantly associated with OS (all p<0.05). The most common acute toxicities of IMRT were dermatitis, mucositis and dysphagia. Xerostomia and hearing impairment were the top two late toxicities. The main failure patterns were distant metastasis and local and/or regional relapses.

CONCLUSIONS

Similar survival, toxicities and failure patterns have been observed in patients treated with IMRT in a non-endemic area of China when compared with that in endemic areas. Induction chemotherapy combined with concurrent chemoradiotherapy may benefit locally advanced NPC in non-endemic areas of China.

Stereotactic body radiotherapy (SBRT) for primary non-metastatic head and neck cancer: When less is enough

The advantage of highly conformal dose distribution and steep dose gradient has resulted in rapidly increasing use of stereotactic body radiotherapy (SBRT) in multiple cancer sites. Also there has been a surge in the use of SBRT in head neck cancer over the last decade. It is predominantly exploited in retreatment setting for recurrent and second primary head neck cancer as well as in metastatic setting. The literature on SBRT in primary non-metastatic head neck cancer is sparse and evolving. In the current review, available literature was critically analyzed focusing on the potential applications of SBRT in primary untreated non-metastatic head neck cancer. SBRT boost following external beam radiotherapy is temping as a method of dose escalation. Special attention was paid to the application of SBRT as a sole modality of treatment. The shorter treatment schedule makes it an attractive option for treatment in primary head neck cancer especially in elderly, co-morbid and medically unfits patients. Future investigation is needed to establish SBRT as an additional armamentarium in the radiotherapeutic management of head and neck cancers.

Long-term outcomes following stereotactic body radiotherapy boost for oropharyngeal squamous cell carcinoma

Background/purpose: To determine the efficacy and toxicity profile of a stereotactic body radiotherapy (SBRT) boost as a first line treatment in patients with oropharyngeal squamous cell carcinoma (OPSCC). Materials and methods: We performed a retrospective cohort study in 195 consecutive OPSCC patients with T1-small T3 disease, treated at Erasmus MC between 2009 and 2016 with a SBRT (3 × 5.5 Gy) boost after 46 Gy IMRT. Primary endpoints were disease-specific survival (DSS) and Grade ≥3 toxicity (Common Terminology Criteria). The Kaplan-Meier method and Cox regression model were applied to determine rates and risk factors. Results: The median follow-up was 4.3 years. Treatment compliance was high (100%). Rates of 5-year DSS and late grade ≥3 toxicity were 85% and 28%, respectively. Five-year overall survival was 67%. The most frequently observed toxicities were mucosal ulceration or soft tissue necrosis (n = 30, 5 year 18%), dysphagia or weight loss (n = 18, 5 year 12%) and osteoradionecrosis (n = 11, 5 year 9%). Current smoker status (hazard ratio [HR] = 2.9, p = .001) and Charlson Comorbidity Index ≥2 (HR = 1.9, p = .03) were was associated with increased toxicity risk. Tooth extraction prior to RT was associated with increased osteoradionecrosis risk (HR = 6.4, p = .006). Conclusion: We reported on outcomes in the largest patient series to date treated with a hypofractionated boost for OPSCC. Efficacy was good with survival rates comparable to conventionally fractionated (chemo)radiotherapy. Grade ≥3 toxicity profiles showed high rates of soft tissue necrosis and osteoradionecrosis. Strategies to mitigate severe toxicity risks are under investigation to improve the tolerability of the SBRT boost.

Prognostic value of gross tumor regression and plasma Epstein Barr Virus DNA levels at the end of intensity-modulated radiation therapy in patients with nasopharyngeal carcinoma

PURPOSE

To assess gross tumor regression and plasma Epstein-Barr virus (EBV)-DNA levels at the end of intensity-modulated radiation therapy (IMRT) and its prognostic impact on patients with nasopharyngeal carcinoma (NPC).

PARTICIPANTS AND METHODS

In total, 397 patients with non-metastatic, histologically confirmed NPC were retrospectively examined. All patients underwent magnetic resonance imaging of the nasopharynx and neck, and plasma EBV DNA assays before treatment and at the end of IMRT.

RESULTS

The estimated 5-year loco-regional, local and regional relapse-free survival rates for patients with complete response (CR) and non-CR of the total tumor, primary tumor and metastatic lymph nodes at the end of IMRT were 94.9% vs. 85.8%, 96.6% vs. 87.3%, and 98.7% vs. 89.8%, respectively (P < 0.05). The estimated 5-year loco-regional relapse-free survival (LRRFS) rates for patients with persistent tumor with and without boost irradiation were 95.3% vs. 83%, respectively (P = 0.034). The estimated 5-year overall survival (OS), failure-free survival (FFS) and distant metastasis-free survival (DMFS) rates for patients with negative and positive plasma EBV DNA at the end of IMRT were 83.1% vs. 50.3%, 81.5% vs. 49.3%, and 87.6% vs. 61.5%, respectively (P < 0.001). Multivariate analyses indicated that regression of the total tumor and boost irradiation was an independent predictor of LRRFS, and plasma EBV DNA levels were independent predictors of OS, FFS and DMFS.

CONCLUSIONS

Gross tumor regression and plasma EBV DNA levels at the end of IMRT served as predictors of poor prognosis for patients with NPC. The patients with persistent tumor and/or positive plasma EBV DNA might require timely strengthening treatment.

Effect of intensity-modulated radiotherapy versus two-dimensional conventional radiotherapy alone in nasopharyngeal carcinoma

Background

Albeit intensity-modulated radiotherapy (IMRT) is currently the recommended radiation technique in treating nasopharyngeal carcinoma, the effect of IMRT versus two-dimensional conventional radiotherapy (2DCRT) alone is still contradictory.

Results

In the original unmatched cohort of 1198 patients, IMRT obtained comparable 5-year overall survival (OS) (91.3% vs 87.1%, P = 0.120), locoregional relapse-free survival (LRFS) (92.3% vs 90.4%, P = 0.221) and distant metastasis-free survival (DMFS) (92.9% vs 92.1%, P = 0.901) to 2DCRT. In the propensity-matched cohort of 604 patients, no significant survival differences were observed between the two arms (5-year OS 90.9% vs 90.5%, P = 0.655; LRFS 92.5% vs 92.4%, P = 0.866; DMFS 92.5% vs 92.9%, P = 0.384). In multivariate analysis, IMRT did not significantly lower the risk of death, locoregional relapse or distant metastasis, irrespective of tumor stage.

Methods

Overall, 1198 patients who underwent IMRT (316 patients) or 2DCRT (882 patients) without any chemotherapy was retrospectively analyzed. Patients in both arms were matched at equal ratio using propensity-score matching method. OS, LRFS and DMFS were assessed with Kaplan-Meier method, log-rank test and Cox regression.

Conclusions

In this propensity-matched study, IMRT showed no survival advantage over 2DCRT alone in nasopharyngeal carcinoma.

Clinically relevant radioresistant cell line: a simple model to understand cancer radioresistance

Radiotherapy (RT) is one of the major modalities for the treatment of human cancers and has been established as an excellent local treatment for malignant tumors. Conventional fractionated RT consists of 2-Gy X-rays, fractionated once a day, 5 days a week for 5-7 weeks in total 60 Gy. The efficacy of RT depends on the existence of radioresistant cells, which remains one of the most critical obstacles in RT and radio-chemotherapy. To improve the efficacy of RT, understanding the characteristics of radioresistant cells is one of the important subjects in radiation biology. Several studies have been reported to find out molecules implicated in radioresistance. However, it is noteworthy that cellular radioresistance has been mainly studied among cells with different genetic backgrounds and different origins. Therefore, making a system to compare between radioresistant and sensitive cells with the isogenic background is required. In this review, some aspects of cellular radioresistance mainly focusing on clinically relevant radioresistant (CRR) cell lines that can continue to proliferate even under exposure to 2-Gy X-rays, once a day, for more than 30 days, which is consistent with the conventional fractionated RT are discussed.

American Brachytherapy Society Task Group Report: Combined external beam irradiation and interstitial brachytherapy for base of tongue tumors and other head and neck sites in the era of new technologies

Irradiation plays an important role in the treatment of cancers of the head and neck providing a high locoregional tumor control and preservation of organ functions. External beam irradiation (EBI) results in unnecessary radiation exposure of the surrounding normal tissues increasing the incidence of side effects (xerostomy, osteoradionecrosis, and so forth). Brachytherapy (BT) seems to be the best choice for dose escalation over a short treatment period and for minimizing radiation-related normal tissue damage due to the rapid dose falloff around the source. Low-dose-rate BT is being increasingly replaced by pulsed-dose-rate and high-dose-rate BT because the stepping source technology offers the advantage of optimizing dose distribution by varying dwell times. Pulsed-dose and high-dose rates appear to yield local control and complication rates equivalent to those of low-dose rate. BT may be applied alone; but in case of high risk of nodal metastases, it is used together with EBI. This review presents the results and the indications of combined BT and EBI in carcinoma of the base of tongue and other sites of the head and neck region, as well as the role BT plays among other-normal tissue protecting-modern radiotherapy modalities (intensity-modulated radiotherapy, stereotactic radiotherapy) applied in these localizations.

Advanced-Stage Nasopharyngeal Carcinoma: Restaging System after Neoadjuvant Chemotherapy on the Basis of MR Imaging Determines Survival

Purpose To evaluate the prognostic value of the restaging system after neoadjuvant chemotherapy (NACT) in patients with advanced-stage nasopharyngeal carcinoma (NPC). Materials and Methods This study was approved by the clinical research committee and a written informed consent was required before enrolling in the study. Prospectively enrolled were 412 consecutive patients with stage III-IVb NPC treated with NACT followed by concurrent chemotherapy and radiation therapy. Patients were staged before NACT and restaged after NACT. The progression-free survival (PFS) and distant metastasis-free survival (DMFS) were calculated with the Kaplan-Meier method, and differences were compared by using the log-rank test. Results Post-NACT T classification (PFS, P = .001) and N classification (PFS, P < .001; DMFS, P = .001) resulted in better survival curve separations than pre-NACT T classification and N classification. Patients downstaged from N2-N3 to N0-N1 disease had a better prognosis than did patients who continued to have N2-N3 diseases (3-year PFS, 83.8% vs 66.6%, P = .001; 3-year DMFS, 88.0% vs 78.4%, P = .026). Multivariate analysis revealed that post-NACT T classification (hazard ratio [HR] = 1.67; 95% confidence interval [CI]: 1.18, 2.36; P = .003) and post-NACT N classification (HR = 1.54; 95% CI: 1.17, 2.03; P = .002) were independent prognostic factors for PFS; also, post-NACT N classification (HR = 1.48; 95% CI: 1.05, 2.07; P = .025) was an independent prognostic factor for DMFS. Multivariate analysis in patients with N2-N3 disease demonstrated that the N downstaging effects of NACT was the only independent prognostic factor for PFS (HR = 0.48; 95% CI: 0.29, 0.81; P = .006) and DMFS (HR = 0.52; 95% CI: 0.28, 0.97; P = .039). Conclusion The post-NACT stage is more representative of prognosis than the pre-NACT stage in advanced-stage NPC patients, which suggests that major clinical decisions should be based on the post-NACT stage. ^© RSNA, 2016 Online supplemental material is available for this article.

Image guided volumetric response during chemoradiotherapy for head and neck squamous cell carcinoma as a predictor of disease outcomes

PURPOSE

The goal of this study was to correlate volumetric image guided disease response to clinical outcomes in patients receiving chemoradiation therapy (CRT) for locally advanced head and neck squamous cell carcinoma (HNSCC).

MATERIALS AND METHODS

Thirty four patients completing definitive CRT for locally advanced HNSCC with megavoltage computed tomography (MVCT) guided tomotherapy IMRT were retrospectively reviewed for volumetric response. Grossly identifiable primary tumor (PT) and nodal disease (ND) response was evaluated by weekly MVCT regression. Percent end-of-treatment (EOT) residual volumes and regression rates were correlated with risk of local failure (LF), progression free survival (PFS), and overall survival (OS).

RESULTS

A total of 7 LFs were identified in 6 patients at a median follow-up of 8months. The mean percent EOT residual volumes for PT and ND in patients with and without LF were 20% vs. 5% (p=0.005) and 47% vs. 6% (p=0.0001), respectively. The PT and ND volume regression rates for patients with and without LF were 12.7% per week vs. 15.9% per week (p=0.04) and 3.4% per week vs. 10.5% per week (p<0.001), respectively. Utilizing an EOT cut-off value of 25% residual volume, the relative risks of LF for PT and ND were 14.7 (p=0.03) and 25 (p=0.001), respectively. Patients found with PT and/or ND residual volumes <25% at EOT had longer 2year OS of 100% vs. 67% (p=0.0023) and PFS of 87% vs. 17% (p<0.001) compared with patients with residual volumes >/= 25% at EOT.

CONCLUSION

Patients with locally advanced HNSCC who have significant MVCT volume reduction over the course of definitive CRT tend to have favorable clinical outcomes.

Stereotactic body radiotherapy for head and neck cancer: an addition to the armamentarium against head and neck cancer

In the recent years, stereotactic body radiation therapy (SBRT) has emerged as a potential therapy for head and neck malignancies. Although early results appear to be promising, serious acute and late effects have been observed, mainly in patients who have had prior external beam radiotherapy. This review will discuss the radiobiology of SBRT, clinical rationale and outcomes for SBRT in head and neck cancers and focus on the benefits and potential limitations in both de novo and re-irradiation settings.

Evidence on effectiveness of intensity-modulated radiotherapy versus 2-dimensional radiotherapy in the treatment of nasopharyngeal carcinoma: Meta-analysis and a systematic review of the literature

BACKGROUND

Current management of nasopharyngeal carcinoma (NPC) uses radiotherapy (RT) as the curative treatment modality. Radiation delivery techniques for NPC can be achieved using 2D conventional RT or intensity-modulated radiotherapy (IMRT).

METHODS

A systematic review and meta-analysis of the literature was undertaken to assess the effectiveness of IMRT versus 2D conventional RT in primary treatment of NPC.

RESULTS

IMRT showed better results than 2D conventional RT in terms of local control, regional control, and overall survival, but when stratified, only in T4, N2, and stage III were the differences that were seen. Objective saliva measurements and physician-graded xerostomia were better in IMRT. However, patient-reported xerostomia showed minimal improvement only in IMRT. The evidence of superiority of IMRT over 2D conventional RT is not clear.

CONCLUSION

In the absence of more clinical data demonstrating the superiority of IMRT in the treatment of nasopharyngeal carcinoma, 2D conventional RT seems to be a reasonable treatment option, especially in limited resource settings. © 2015 Wiley Periodicals, Inc. Head Neck 38: E2130-E2142, 2016.

A Randomized Pilot Trial Comparing Position Emission Tomography (PET)-Guided Dose Escalation Radiotherapy to Conventional Radiotherapy in Chemoradiotherapy Treatment of Locally Advanced Nasopharyngeal Carcinoma

Background

This pilot trial is designed to determine whether PET/CT-guided radiotherapy dose escalation can improve local control while minimizing toxicity for the treatment of locally advanced nasopharyngeal carcinoma.

Methods

67 patients were randomized into the three treatment arms: conventional chemoradiotherapy (group A), CT-guided dose escalation chemoradiotherapy (group B) and PET/CT-guided dose escalation chemoradiotherapy (group C). Radiotherapy was delivered using the simultaneous modulated accelerated radiation therapy (SMART) technique in the dose-escalation treatment arms. Patients received concurrent and adjuvant chemotherapy.

Results

The use of PET/CT significantly changed the treatment volume delineation of the gross tumor volume. 3-year local progression-free (LPF) survival rates of three groups were 83.3%, 90.9% and 100%, respectively. The 3-year regional progression-free survival (RPFS) rates were 95.8%, 95.5% and 100%, respectively. The 3-year disease free survival (DFS) rates were 79.2%, 86.4% and 95.2%, respectively. The 3-year overall survival (OS) rates were 83.3%, 90.9% and 95.2%, respectively. The 3-year disease-free survival (DFS) rates were 79.2%, 86.4% and 95.2%, respectively. No patient had grade 4 late toxicity.

Conclusions

PET/CT-guided dose escalation radiotherapy is well-tolerated and appears to be superior to conventional chemoradiotherapy for locally advanced NPC.

Trial Registration

ClinicalTrials.gov NCT02089204

Emerging applications of stereotactic body radiotherapy

Stereotactic body radiotherapy (SBRT) has been used extensively in patients with lung, liver and spinal tumors, and the treatment outcomes are very favorable. For certain conditions such as medically inoperable stage I non-small-cell lung cancer, liver and lung oligometastases, primary liver cancer and spinal metastases, SBRT is regarded as one of the standard therapies. In the recent years, the use of SBRT has been extended to other disease conditions and sites such as recurrent head and neck cancer, renal cell carcinoma, prostate cancer, adrenal metastasis, pancreatic cancer, gynecological malignancies, spinal cord compression, breast cancer, and stage II-III non-small-cell lung cancer. Preliminary data in the literature show promising results but the follow-up intervals are short for most studies. This paper will provide an overview of these emerging applications.

Analysis of simultaneous modulated accelerated radiotherapy (SMART) for nasopharyngeal carcinomas

The purpose of this study was to analyze the clinical outcomes of simultaneous modulated accelerated radiotherapy (SMART) in patients with nasopharyngeal carcinoma (NPC). A total of 97 patients who underwent SMART for NPC between August 2005 and November 2011 were evaluated. The prescribed dose was 69.9 Gy/30 fractions at 2.33 Gy/fraction to the primary gross tumor volume (PGTV) including the nasopharynx gross target volume and the positive neck lymph nodes, and 60 Gy/30 fraction at 2.0 Gy/fraction to the PCTV1; 54 Gy/30 fractions at 1.8 Gy/fraction was given to the PCTV2. Among 59 patients with local advanced disease, 31 patients received concurrent chemoradiotherapy (chemo-RT) with a regimen consisting of 135 mg/m(2) paclitaxel on Day 1 and 25 mg/m(2) cisplatin on Days 1-3. The median follow-up period was 42 months. The local control rate (LCR), distant metastases-free survival (DMFS) and overall survival (OS) rates were 93.3%, 90.3% and 91.6% at 3 years, and 87.6%, 87.9% and 85.7% at 5 years, respectively. There was no significant difference in outcome with respect to these three indicators for Stage III and IV disease treated with/without concurrent chemoradiotherapy (P > 0.05). Acute toxicities included Grade 3 mucositis, skin desquamation, and leucopenia, which occurred in 78 (80.4%), 8 (8.2%), and 45 (46.4%) patients, respectively. No patient had a Grade 3-4 late toxicity. SMART was associated with a favorable outcome for NPC with acceptable toxicity. The local-regional control was excellent but distant metastasis remains the main risk. The combination of SMART and chemotherapy needs to be optimized through further studies to enhance outcomes for locally advanced diseases.

Primary tumor regression speed after radiotherapy and its prognostic significance in nasopharyngeal carcinoma: a retrospective study

BACKGROUND

To observe the primary tumor (PT) regression speed after radiotherapy (RT) in nasopharyngeal carcinoma (NPC) and evaluate its prognostic significance.

METHODS

One hundred and eighty-eight consecutive newly diagnosed NPC patients were reviewed retrospectively. All patients underwent magnetic resonance imaging and fiberscope examination of the nasopharynx before RT, during RT when the accumulated dose was 46-50 Gy, at the end of RT, and 3-4 months after RT.

RESULTS

Of 188 patients, 40.4% had complete response of PT (CRPT), 44.7% had partial response of PT (PRPT), and 14.9% had stable disease of PT (SDPT) at the end of RT. The 5-year overall survival (OS) rates for patients with CRPT, PRPT, and SDPT at the end of RT were 84.0%, 70.7%, and 44.3%, respectively (P < 0.001, hazard ratio [HR] = 2.177, 95% confidence interval [CI] = 1.480-3.202). The 5-year failure-free survival (FFS) and distant metastasis-free survival (DMFS) rates also differed significantly (87.8% vs. 74.3% vs. 52.7%, P = 0.001, HR = 2.148, 95% CI, 1.384-3.333; 91.7% vs. 84.7% vs. 66.1%, P = 0.004, HR = 2.252, 95% CI = 1.296-3.912). The 5-year local relapse-free survival (LRFS) rates were not significantly different (95.8% vs. 86.0% vs. 81.8%, P = 0.137, HR = 1.975, 95% CI, 0.976-3.995). By multivariate analyses, the PT regression speed at the end of RT was the only independent prognostic factor of OS, FFS, and DMFS (P < 0.001, P = 0.001, and P = 0.004, respectively). The 5-year FFS rates for patients with CRPT during RT and CRPT only at the end of RT were 80.2% and 97.1%, respectively (P = 0.033). For patients with persistent PT at the end of RT, the 5-year LRFS rates of patients without and with boost irradiation were 87.1% and 84.6%, respectively (P = 0.812).

CONCLUSIONS

PT regression speed at the end of RT was an independent prognostic factor of OS, FFS, and DMFS in NPC patients. Immediate strengthening treatment may be provided to patients with poor tumor regression at the end of RT.

Preliminary results of a phase I/II study of simultaneous boost irradiation radiotherapy for locally advanced nasopharyngeal carcinoma

BACKGROUND

The purpose of this article is to present preliminary results of simultaneous boost irradiation radiotherapy for locally advanced nasopharyngeal carcinoma (NPC).

METHODS

Fifty-eight patients who underwent simultaneous boost irradiation radiotherapy for NPC in Cancer Center of Sun Yat-sen University between September 2004 and December 2009 were eligible. Acute and late toxicities were scored weekly according to the Radiation Therapy Oncology Group (RTOG) acute and late radiation morbidity scoring schemes. An especial focus was on evidence of post-radiation brain injury. Also quality of life was analysed according to the EORTC (European Organisation for Research and Treatment of Cancer) recommendations. Discrete variables were compared by ?2 test. The Kaplan-Meier method was used to calculate the survival rates and generate survival curves.

RESULTS

A total of 58 patients with a mean follow-up time of 36 months completed clinical trials.Fifty- seven patients (98.3) achieved complete remission in the primary sites and cervical lymph nodes, with only one patient (1.7%) showing partial remission.The most frequently observed acute toxicities during the concurrent chemoradiotherapy were mucositis and leucopenia. Four patients (6.9%) had RTOG grade 3 mucositis, whereas four patients (6.9%) had grade 3 leucopenia. No patient had grade 4 acute toxicity. Three (5.17%) of the patients exhibited injury to the brain on routine MRI examination, with a median observation of 32 months (range, 25-42months). All of them were RTOG grade 0. The 3-year overall, regional-free and distant metastasis-free survival rates were 85%, 94% and 91%, respectively.

CONCLUSION

Simultaneous boost irradiation radiotherapy is feasible in patients with locally advanced nasopharyngeal carcinoma. The results showed excellent local control and overall survival, with no significant increase the incidence of radiation brain injury or the extent of damage. A larger population of patients and a longer follow-up period are needed to evaluate ultimate tumor control and late toxicity.

Comparing treatment outcomes of different chemotherapy sequences during intensity modulated radiotherapy for advanced N-stage nasopharyngeal carcinoma patients

Background

N-stage is related to distant metastasis of nasopharyngeal carcinoma (NPC) patients. We performed this study to compare the efficacy of different chemotherapy sequences in advanced N-stage (N2 and N3) NPC patients treated with intensity modulated radiotherapy (IMRT).

Methods

From 2001 to 2008, 198 advanced N-stage NPC patients were retrospectively analyzed. Thirty-three patients received IMRT alone. Concurrent chemoradiotherapy (CCRT) was delivered to 72 patients, neoadjuvant chemotherapy (NACT) + CCRT to 82 patients and CCRT + adjuvant chemotherapy (AC) to 11 patients.

Results

The 5-year overall survival rate, recurrence-free survival rate, distant metastasis-free survival rate and progress-free survival rate were 47.7% and 73.1%(p<0.001), 74.5% and 91.3% (p = 0.004), 49.2% and 68.5% (p = 0.018), 37.5% and 63.8% (p<0.001) in IMRT alone and chemoradiotherapy group. Subgroup analyses indicated that there were no significant differences among the survival curves of CCRT, NACT + CCRT and CCRT + AC groups. The survival benefit mainly came from CCRT. However, there was only an improvement attendency in distant metastasis-free survival rate of CCRT group (p = 0.107) when compared with RT alone group, and NACT + CCRT could significantly improve distant metastasis-free survival (p = 0.017).

Conclusions

For advanced N-stage NPC patients, NACT + CCRT might be a reasonable treatment strategy.

Intensity-modulated radiation therapy for T4 nasopharyngeal carcinoma. Treatment results and locoregional recurrence

PURPOSE

The purpose of this work was to examine outcomes in patients with T4 nasopharyngeal carcinoma (NPC) treated with intensity-modulated radiation therapy (IMRT).

METHODS AND MATERIALS

Between 2007 and 2010, 154 patients with nonmetastatic T4 NPC were treated with IMRT to a total dose of 70 Gy in 33-35 fractions. In addition, 97% of patients received concurrent platinum-based chemotherapy. The median follow-up time was 52.8 months.

RESULTS

The rates of 5-year actuarial locoregional control, distant metastasis-free survival, progression free-survival, and overall survival (OS) were 81.2, 72.2, 61.9, and 78.1%, respectively. A total of 27 patients had locoregional recurrence: 85.2% in-field failures, 11.1% marginal failures, and 3.7% out-of-field failures. Fourteen patients with locoregional recurrence received aggressive treatments, including nasopharyngectomy, neck dissection, or re-irradiation, and the 5-year OS rate tended to be better (61.9%) compared to those receiving conservative treatment (32.0%, p=0.051). In patients treated with 1 course of radiotherapy, grade ≥3 toxicities of ototoxicity, neck fibrosis, xerostomia, epistaxis, and radiographic temporal lobe necrosis occurred in 18.2, 9.8, 6.3, 2.1, and 5.6% of patients, respectively. Increased ototoxicity, osteonecrosis, severe nasal bleeding, and temporal necrosis were observed in patients treated by re-irradiation.

CONCLUSION

IMRT offers good locoregional control in patients with T4 NPC. For patients with locoregional recurrence after definitive radiotherapy, aggressive local treatment may be considered for a better outcome.

Current controversies in radiotherapy for nasopharyngeal carcinoma (NPC)

Radiotherapy has a good track record in the treatment of NPC, yet the late toxicity profile and local failure rate for locally advanced disease remain a concern. Modern RT techniques incorporating IMRT and IGRT have widened our potential in treating NPC more effectively, and shall be regarded as the standard of care. Out of the various dose fractionation regimens in IMRT, 70 Gy in 35 fractions or the mini-SIB proves to be safe in combination with chemotherapy, but any further attempt of dose escalation must be tried out with extreme caution to avoid severe toxicities. CT-MRI image fusion improves the accuracy of GTV delineation, whereas the role of PET-CT has yet to be verified. RTOG definition of the CTV provides a reasonable template for the inclusion of sites at risk of microscopic involvement, and fine tuning has to be made in the future based on careful analysis of the pattern of local failure with long term follow-up. Toxicity reduction via radiation volume or dose reduction is tempting, but once again it has to be tested under scrutiny. Retrospective data have emerged that suggest a benefit of using adaptive IMRT replanning in NPC, however the optimal timing or frequency of replanning is still unclear. Future prospective studies are thus required to evaluate the cost-effectiveness of adaptive RT and streamline the workflow logistics before it can be widely accepted in routine practice.

A comparative study of locoregionally advanced nasopharyngeal carcinoma treated with intensity modulated irradiation and platinum-based chemotherapy

PURPOSE

To investigate the prognosis of three subgroups of locoregionally advanced nasopharyngeal carcinoma treated with intensity-modulated radiotherapy and platinum-based chemotherapy.

PATIENTS AND METHODS

Hundred and eighty-one consecutive patients with locoregionally advanced untreated nasopharyngeal carcinoma were retrospectively divided into three subgroups: locally advanced group (T3-4N0-1M0), regionally advanced group (T1-2N2-3M0) and the mixed group (T3-4N2-3M0). They were all treated with definitive intensity-modulated radiotherapy and platinum-based chemotherapy. Their prognosis were investigated and compared. Multivariate analysis was applied to identify the independent risk factors of study endpoints.

RESULTS

The 3-year locoregional control rates for locally advanced group, regionally advanced group, and the mixed group were 91.5%, 90.6% and 84.3% respectively, no significant difference was observed (P=0.656, P=0.429). The 3-year distant metastasis-free survival rates were 89.6%, 75.7% and 76.3%, respectively. The distant metastasis-free survival rate of the locally advanced group was significantly higher than the other two subgroups (P=0.028, P=0.028). The 3-year progression-free survival rates were 85.5%, 67.9% and 67.1% respectively with significance also favoring the locally advanced group (P=0.043, P=0.023). Nodal stage and the performance status were the independent risk factors of distant metastasis in the observed period.

CONCLUSIONS

In the context of intensity-modulated radiotherapy and platinum-based chemotherapy, the locally advanced group had a better prognosis compared with the regionally advanced group and the mixed group. Treatment stratification may be based on nodal stage.

Fractionated stereotactic radiotherapy for 136 patients with locally residual nasopharyngeal carcinoma

Background

To evaluate the efficacy and toxicity of fractionated stereotactic radiotherapy (FSRT) in patients with residual nasopharyngeal carcinoma (NPC).

Methods

From January 2000 to December 2009, 136 NPC patients with residual lesions after primary radiotherapy (RT) were treated by FSRT. The total dose of primary RT was 68.0-78.0 Gy (median, 70.0 Gy). The median time from the primary RT to FSRT was 24.5 days. Tumor volumes for FSRT ranged from 0.60 to 77.13 cm3 (median, 13.45 cm3). The total FSRT doses were 8.0-32.0Gy (median, 19.5 Gy) with 2.0-10.0 Gy per fraction.

Results

Five-year local failure-free survival (LFFS), freedom from distant metastasis (FFDM), overall survival (OS), and disease free survival (DFS) rates for all patients were 92.5%, 77.0%, 76.2%, and 73.6%, respectively. No statistical significant differences were found in LFFS, DFS and OS in patients with stage I/II versus stage III/ IV diseases. Nineteen patients exhibited late toxicity. T stage at diagnosis was a significant prognostic factor for OS and DFS. Age was a prognostic factor for OS.

Conclusion

FSRT after external beam radiotherapy provides excellent local control for patients with residual NPC. The incidence of severe late toxicity is low and acceptable. Further investigation of optimal fractionation regimens will facilitate reduction of long-term complications.

Concurrent chemoradiotherapy versus radiotherapy alone for locoregionally advanced nasopharyngeal carcinoma

OBJECTIVE

To compare the clinical effects of concurrent radiochemotherapy with those of radiotherapy in treating locally advanced nasopharyngeal carcinoma (Stage III~IVa).

METHODS

A total of 95 patients suffering from nasopharyngeal carcinoma (Stage III~IVa) were divided into two groups: concurrent radiochemotherapy (Group CCRT, n=49) and radiotherapy (Group RT, n=46). The two groups were both delivered conventional fractionated radiotherapy, while Group CCRT also received three cycles of PF (DDP+5-Fu) or PLF (DDP+5- Fu+CF) chemotherapy.

RESULTS

The complete remission rate and total remission rate of Group CCRT were higher than those of Group RT (X2=4.72~7.19, P<0.05). The one-year overall survival (OS) rate calculated by the life table method, was also higher than that of Group RT (X2=4.24, P<0.05) as well as the 3-year OS rate, nasopharyngeal control rate and cervical lymph nodes' control rate (X2=4.28~4.40, P<0.05). In addition, the 5-year OS and metastasis-free rates of Group CCRT were higher than those of Group RT and the differences were of statistical importance (X2=3.96~8.26, P<0.05). However, acute toxicity was also obviously higher, the difference in gastrointestinal reactions being statistically significant (X2=11.70, P<0.05).

CONCLUSION

This study demonstrated that concurrent radiochemotherapy could improve the remission rate, overall survival rate and locally control rate. The toxicity of concurrent radiochemotherapy could be tolerated by the patients.

Addition of intracavitary brachytherapy to external beam radiation therapy for T1-T2 nasopharyngeal carcinoma

PURPOSE

We compared efficacy and toxicity outcomes of patients with T1-T2 nasopharyngeal carcinoma (NPC) treated with external beam radiation therapy (EBRT) in combination with intracavitary brachytherapy (BT) vs. a historical cohort treated with EBRT alone.

METHODS AND MATERIALS

Of the 348 NPC patients diagnosed with T1-2N0-3M0 disease, 175 received EBRT + BT and 173 received EBRT alone. For the EBRT + BT group, median dose of EBRT was 58 Gy and median dose of BT was 20 Gy; for the EBRT group, median dose was 72 Gy (range, 60-82.4 Gy). Measured outcomes included 5- and 10-year local control (LC), regional failure-free survival, distant metastasis-free survival, disease-free survival, overall survival (OS), and late toxicity.

RESULTS

Median followup duration was 120 months (range, 5-190). Ten-year OS and LC rates for the EBRT + BT and EBRT-alone groups were 71.7% vs. 49.9% and 94.0% vs. 85.2%, respectively (χ(2) = 21.273, p = 0.000 for OS and χ(2) = 4.684, p = 0.030 for LC). Late complication rates for EBRT + BT were generally lower compared with the EBRT-alone group except for nasopharyngeal ulceration or necrosis, where the rate was higher but not statistically significant. Both stage of disease at diagnosis and treatment techniques (i.e., the use of BT) were significant predictive factors for OS and LC.

CONCLUSION

Intracavitary BT in combination with EBRT may improve the therapeutic ratio for T1-T2 NPC.

Early detection of nasopharyngeal carcinoma by plasma Epstein-Barr virus DNA analysis in a surveillance program

BACKGROUND

Nasopharyngeal carcinoma (NPC) is prevalent in Southeast Asia. Over the last decade, plasma Epstein-Barr virus (EBV) DNA has been developed as a tumor marker for NPC. In this study, the authors investigated whether plasma EBV DNA analysis is useful for NPC surveillance.

METHODS

In total, 1318 volunteers ages 40 to 60 years were prospectively recruited. Plasma EBV DNA and serology for viral capsid antigen immunoglobulin A (IgA) were measured. Participants who had detectable plasma EBV DNA or positive IgA serology underwent nasal endoscopic examination and a follow-up plasma EBV DNA analysis in approximately 2 weeks. All participants were followed for 2 years to record the development of NPC.

RESULTS

Three individuals with NPC were identified at enrolment. All of them were positive for EBV DNA and remained positive in follow-up analysis. Only 1 of those patients was positive for EBV serology. In 1 patient who had NPC with a small tumor confined to the mucosa, the tumor was not detectable on endoscopic examination. Because of a 2-fold increase in plasma EBV DNA on the follow-up analysis, that patient underwent magnetic resonance imaging, which revealed the tumor. Among the participants who did not have NPC but had initially positive plasma EBV DNA results, approximately 66% had negative EBV DNA results after a median of 2 weeks.

CONCLUSIONS

Plasma EBV DNA analysis proved useful for detecting early NPC in individuals without a clinical suspicion of NPC. Repeating the test in those who had initially positive results differentiated those with NPC from those who had false-positive results. Cancer 2013. © 2013 American Cancer Society.

Current management of nasopharyngeal cancer

Management of nasopharyngeal carcinoma is one of the greatest clinical challenges. Appropriate detection is not easy because of its anatomical location; sensitive biomarkers in addition to endoscopic and radiological examinations would be valuable. One useful biomarker (particularly for nonkeratinizing carcinoma) is the plasma level of Epstein-Barr viral deoxyribonucleic acid, and its role as a tool for prognostication and monitoring disease progress is presented. Radiotherapy is the primary treatment modality, and using radiation therapy in combination with chemotherapy is recommended for the treatment of locoregionally advanced tumors. Intensity-modulated radiotherapy techniques with image guidance to ensure setup precision are recommended if resources allow; adaptive replanning should be considered if major deviations from the intended dose distribution occur during the treatment course. Most contemporary series have reported encouraging results, with locoregional control exceeding 90%; the key problem is distant failure. The therapeutic margin is extremely narrow. Although significant reduction of some toxicities (eg, xerostomia) and better quality of life is now achievable especially for early stages, the risk of major late toxicities remains substantial. This review will focus on the primary treatment: the current consensus and controversies in the treatment strategy for different stages, the choice of chemotherapy regimen, and the key factors for improving the therapeutic ratio of radiotherapy will be discussed. Summary of the current achievement and direction for future improvement will be presented.

Long-term outcome and toxicity of hypofractionated stereotactic body radiotherapy as a boost treatment for head and neck cancer: the importance of boost volume assessment

Background

The aim of this study was to report the long-term clinical outcomes of patients who received stereotactic body radiotherapy (SBRT) as a boost treatment for head and neck cancer.

Materials and methods

Between March 2004 and July 2007, 26 patients with locally advanced, medically inoperable head and neck cancer or gross residual tumors in close proximity to critical structures following head and neck surgery were treated with SBRT as a boost treatment. All patients were initially treated with standard external beam radiotherapy (EBRT). SBRT boost was prescribed to the median 80% isodose line with a median dose of 21 (range 10–25) Gy in 2–5 (median, 5) fractions.

Results

The median follow-up after SBRT was 56 (range 27.6 − 80.2) months. The distribution of treatment sites in 26 patients was as follows: the nasopharynx, including the base of the skull in 10 (38.5%); nasal cavity or paranasal sinus in 8 (30.8%); periorbit in 4 (15.4%); tongue in 3 (11.5%); and oropharyngeal wall in 1 (3.8%). The median EBRT dose before SBRT was 50.4 Gy (range 39.6 − 70.2). The major response rate was 100% with 21 (80.8%) complete responses (CR). Severe (grade ≥ 3) late toxicities developed in 9 (34.6%) patients, and SBRT boost volume was a significant parameter predicting severe late complication.

Conclusions

The present study demonstrates that a modern SBRT boost is a highly efficient tool for local tumor control. However, we observed a high frequency of serious late complications. More optimized dose fractionation schedule and patient selection are required to achieve excellent local control without significant late morbidities in head and neck boost treatment.

Outcomes following treatment for patients with cranial nerve involvement from nasopharyngeal cancer

INTRODUCTION

Patients with locally advanced nasopharyngeal carcinoma (NPC) commonly present with cranial nerve (CN) involvement, which can cause significant morbidity. We aimed to characterise the pattern of involvement and outcomes of these patients, as well as determine if these differed according to the mode of diagnosis.

METHODS

Patients were included if they had non-distant metastatic NPC, presented with CN involvement and completed radiotherapy treatment between 2002 and 2008. The clinical response was categorised as complete response, partial response, stable or progressive disease. The radiological response was assessed using the Response Evaluation Criteria in Solid Tumors criteria. The loco-regional control and disease-free survival rates were estimated with the Kaplan-Meier method.

RESULTS

Forty-seven patients fulfilled the inclusion criteria. CN lesions were diagnosed on clinical examination in 15% of patients, radiologically in 40% and both clinically and radiologically in 45% of patients. A complete or partial response of the CN lesions was seen clinically in 82% and radiologically in 95% of patients. The 3-year local relapse free survival was 64.3%, distant metastasis-free survival was 46.1% and overall survival was 82.8%. There were no differences in outcomes between patients with clinically versus radiologically detected CN lesions.

CONCLUSION

Most of these patients are likely to undergo clinical and/or radiological resolution of the nerve lesions following chemoradiotherapy, but the outcome was not determined by the mode of diagnosis (radiological or clinical).

Nasopharyngeal carcinoma in Slovenia, 1990-2003 (results of treatment with conventional two-dimensional radiotherapy)

AIM

To review the treatment results and identify prognostic factors for disease control and survival in a cohort of nasopharyngeal carcinoma (NPC) patients from a non-endemic population in Slovenia, diagnosed between 1990 and 2003.

BACKGROUND

In Caucasians, nasopharyngeal carcinoma is a rare malignant tumor. Its diagnosis and treatment are complex and have been dramatically impacted by recent technological advances.

MATERIALS AND METHODS

In the Cancer Registry of Slovenia database, a total of 126 patients with NPC were identified, 93 of whom were available for analysis. All patients were treated with conventional two-dimensional radiotherapy (RT) and 29.3% underwent chemotherapy (ChT).

RESULTS

The median follow-up time for those alive at the last follow-up examination was 74.5 months. Disease recurred locally in 17 patients, regionally in 4 patients and at distant sites in 18 patients, resulting in 5-year locoregional control (LRC), distant failure-free survival (DFFS) and disease-free survival (DFS) of 73.7%, 78.6% and 59.3%, respectively. Disease-specific survival at 5 years was 59% and overall survival (OS) was 49.7%. In a multivariate analysis, LRC was favorably affected (P < 0.05) by an undifferentiated histology (hazard ratio [HR] = 2.86), DFFS through the absence of neck metastases (HR = 0.28), DFS by younger age (HR = 0.46), and more intensive RT (expressed as the isoeffective dose, EQD2,T ; HR = 2.08). The independent prognosticator for OS was age (≤55 years vs. >55 years, HR = 0.39); in the ≤55 years subgroup, an improved OS was connected to a more intensive RT regimen of EQD2,T  ≥ 66 Gy (HR = 4.17).

CONCLUSIONS

Our results confirm an independent and favorable effect from an undifferentiated histology, the absence of neck metastases, a younger patient age at diagnosis, and more intensive RT regimens for disease control and survival.

Short-term outcomes of CyberKnife therapy for advanced high-risk tumors: A report of 160 cases

The objective of the present study was to evaluate short-term outcomes of CyberKnife therapy in patients with advanced high-risk tumors. A total of 201 target areas from 341 advanced high-risk tumor lesions in 160 patients were treated with CyberKnife. A prescribed dose of 18-60 Gy to the gross tumor volume was delivered in 1-6 fractions to complete the entire treatment in 1 week. Radiographic studies and clinical examinations were performed at 1- to 3-month follow-up intervals, and the results were compared to outcomes of 160 similar advanced high-risk tumor patients who were treated by conformal radiotherapy (CRT). After CyberKnife therapy, the short-term improvement in the quality of life was significant according to radiographic study, radioimmunoassay and ZPS scores of these patients. The total rates of objective efficacy and alleviation of ascities were as high as 66.88 and 67.90%. The short-term outcomes in our series of patients with advanced high-risk tumors treated with CyberKnife appeared to be better compared to conventional CRT. CyberKnife may be an option for patients with incurable advanced high-risk tumors, although further studies of the long-term outcomes are required to confirm the validity.

Radiation induced temporal lobe necrosis in patients with nasopharyngeal carcinoma: a review of new avenues in its management

Temporal lobe necrosis (TLN) is the most debilitating late-stage complication after radiation therapy in patients with nasopharyngeal cancer (NPC). The bilateral temporal lobes are inevitably encompassed in the radiation field and are thus prone to radiation induced necrosis. The wide use of 3D conformal and intensity-modulated radiation therapy (IMRT) in the treatment of NPC has led to a dwindling incidence of TLN. Yet, it still holds great significance due to its incapacitating feature and the difficulties faced clinically and radiologically in distinguishing it from a malignancy. In this review, we highlight the evolution of different imaging modalities and therapeutic options. FDG PET, SPECT and Magnetic Spectroscopy are among the latest imaging tools that have been considered. In terms of treatment, Bevacizumab remains the latest promising breakthrough due to its ability to reverse the pathogenesis unlike conventional treatment options including large doses of steroids, anticoagulants, vitamins, hyperbaric oxygen and surgery.

Clinical application of CyberKnife for high-risk central nervous system tumors: A clinical trial report of 60 cases

The objective of the present study was to evaluate the application potential of CyberKnife for high-risk tumors of the central nervous system and to analyze the effectiveness of CyberKnife in relation to dose recovery and gain division (times). A total of Eighty-one targeted areas from 139 central nervous tumor lesions in 60 patients were treated with I-VI ranged CyberKnife for 1 week. Following CyberKnife treatment, imaging tests revealed a decrease in tumor volume, reduction of central nervous system symptoms and an increase in the life quality of patients. The advantages of CyberKnife include non-invasiveness, individualized treatment, flexibility, high accuracy and rapid treatment. CyberKnife produces slight damage and a favorable therapeutic effect and expands our concepts concerning precise radiotherapy for tumors. It is an indispensable method for personalized tumor treatment.

The accuracy of dose calculations by anisotropic analytical algorithms for stereotactic radiotherapy in nasopharyngeal carcinoma

Nasopharyngeal tumors are commonly treated with intensity-modulated radiotherapy techniques. For photon dose calculations, problems related to loss of lateral electronic equilibrium exist when small fields are used. The anisotropic analytical algorithm (AAA) implemented in Varian Eclipse was developed to replace the pencil beam convolution (PBC) algorithm for more accurate dose prediction in an inhomogeneous medium. The purpose of this study was to investigate the accuracy of the AAA for predicting interface doses for intensity-modulated stereotactic radiotherapy boost of nasopharyngeal tumors. The central axis depth dose data and dose profiles of phantoms with rectangular air cavities for small fields were measured using a 6 MV beam. In addition, the air-tissue interface doses from six different intensity-modulated stereotactic radiotherapy plans were measured in an anthropomorphic phantom. The nasopharyngeal region of the phantom was especially modified to simulate the air cavities of a typical patient. The measured data were compared to the data calculated by both the AAA and the PBC algorithm. When using single small fields in rectangular air cavity phantoms, both AAA and PBC overestimated the central axis dose at and beyond the first few millimeters of the air-water interface. Although the AAA performs better than the PBC algorithm, its calculated interface dose could still be more than three times that of the measured dose when a 2 × 2 cm(2) field was used. Testing of the algorithms using the anthropomorphic phantom showed that the maximum overestimation by the PBC algorithm was 20.7%, while that by the AAA was 8.3%. When multiple fields were used in a patient geometry, the dose prediction errors of the AAA would be substantially reduced compared with those from a single field. However, overestimation of more than 3% could still be found at some points at the air-tissue interface.