Intensity-modulated radiotherapy for nasopharyngeal carcinoma: improvement of the therapeutic ratio with helical tomotherapy vs segmental multileaf collimator-based techniques

Is a total dose of 54 Gy with radiochemotherapy sufficient for treatment of intermediate-risk volumes in nasopharyngeal cancer?

BACKGROUND

The mainstay treatment of nasopharyngeal cancer (NPC) is radiation therapy (RT). The doses and volumes may differ from center to center. Most studies and guidelines recommend a total dose of 60 Gy for elective nodal and peritumoral volume treatment. This retrospective analysis aimed to analyze whether a dose reduction to 54 Gy to this volume would be associated with a higher risk of recurrence.

METHODS

A total of 111 patients treated by intensity-modulated radiotherapy (IMRT) and concurrent chemotherapy were retrospectively analyzed. The recurrent tumor volume was classified as "in field" if 95% of the recurrent volume was inside the 95% isodose, as "marginal" if 20-95% of the recurrence was inside the 95% isodose, or as "outside" if less than 20% of the recurrence was inside the 95% isodose.

RESULTS

Median follow-up was 67 months (range 6-142). The 2‑ and 5‑year overall survival (OS) rates were 88.6% and 70%, respectively. The 2‑year locoregional control (LRC), disease-free survival (DFS), and distant metastasis-free survival (DMFS) were 93.3%, 89.3%, and 87.4%, and the 5‑year LRC, DFS, and DMFS were 86.8%, 74%, and 81.1%, respectively. Ten patients (9%) had a local and or regional recurrence. Half of the patients with locoregional failure had in-field recurrences. For primary tumor, there was no recurrence in the volume of 54 Gy. For regional lymph node volume, recurrence was detected in two (1.8%) patients in the volume of 54 Gy.

CONCLUSION

These retrospective data suggest that a dose reduction may be possible for intermediate-risk volumes, especially for the primary site.

Nasopharyngeal carcinoma: A new synthesis of literature data (Review)

Nasopharyngeal carcinoma (NPC) is an epithelial tumor, which develops most frequently from the lateral pharyngeal recess and holds some complex epidemiological characteristics. Its unusual race and geographic distribution suggests that not only the environmental factors are a contributing factor to the development of this rare cancer type, but also the genetic traits play an important role, along with nitrosamine-containing food consumption and Epstein-Barr virus infection. The signs and symptoms which a patient can present and suffer from are various and include nasal, otic, neurological as well as general ones; the way this tumor manifests being dependent on the stage of the tumor. The therapeutic management applicable in NPC needs to be established according to the case of the patient and include radiotherapy, chemotherapy, surgery, immune therapy, targeted therapy or combined treatment. The main objective of the treatment is local and regional tumor control; relapse is an important factor for future development of distant metastases. New therapeutic concepts are always sought of, current research focusing on precision medicine, meaning systemic treatment with a personalized radiotherapy approach according to the characteristics of the tumor.

Nutritional status in patients of mandibular osteoradionecrosis: A single-institution experience

BACKGROUND

Mandibular osteoradionecrosis (ORN) is a devastating complication secondary to the radiotherapy of head and neck cancer. The nutritional status of ORN patients is compromised, but remains rarely studied. We aimed to evaluate the overall nutritional status of patients with ORN and explore the risk factors behind poor nutrition.

METHODS

This is a single-institution cross-sectional study. Patients diagnosed with ORN were consecutively recruited in a tertiary teaching hospital from July 2017 to August 2019. Multiple laboratory markers and physical indicators were examined to profile their nutritional status. The potential risk factors of poor nutrition were explored by logistic regression.

RESULTS

A total of 107 patients with ORN were recruited. Among them, almost all patients (95.3%) had at least one laboratory marker lower than the normal physiological range. A total of 40 (37.5%) patients were categorized as undernutrition, who had lower serum albumin (mean difference: 1.8 ± 0.8 g/L; p = .02), prealbumin (mean difference: 26.8 ± 10.8 mg/L; p = .02), and BMI (3.8 ± 0.4 kg/m² ; p < .0001) compared to patients of normal nutrition. Notably, the multivariate logistic regression indicated that patients with semi-liquid diet had 14.41 (95% CI: 3.03-68.54, p = .001) times; patients with liquid diet had 5.70 (95% CI: 1.55-20.98, p = .009) times more likely to be in undernutrition, as compared to patients with regular diets.

CONCLUSIONS

This is the first study characterizing the poor nutritional status in ORN patients. Patients having semi-liquid or liquid diets tended to have poorer nutritional status. The nutritional status of ORN patients should be underlined for professional nutritional supports so as to enhance their quality of life. More studies are warranted.

A longitudinal study on parotid and submandibular gland changes assessed by magnetic resonance imaging and ultrasonography in post-radiotherapy nasopharyngeal cancer patients

Objectives

With regard to the intensity modulated radiotherapy (IMRT) of nasopharyngeal carcinoma (NPC) patients, this longitudinal study evaluated the radiation-induced changes in the parotid and submandibular glands in terms of gland size, echogenicity and haemodynamic parameters.

Methods

21 NPC patients treated by IMRT underwent MRI and ultrasound scans before radiotherapy, and at 6, 12, 18 and 24 months after treatment. Parotid and submandibular gland volumes were measured from the MRI images, whereas the parotid echogenicity and haemodynamic parameters including the resistive index, pulsatility index, peak systolic velocity and end diastolic velocity were evaluated by ultrasonography. Trend lines were plotted to show the pattern of changes. The correlations of gland doses and the post-RT changes were also studied.

Results

The volume of the parotid and submandibular glands demonstrated a significant drop from pre-RT to 6 months post-RT. The parotid gland changed from hyperechoic before RT to either isoechoic or hypoechoic after treatment. The resistive index and pulsatility index decreased from pre-RT to 6 month post-RT, then started to increase at 12 month time interval. Both peak systolic velocity and end diastolic velocity increased after 6 months post-RT then followed a decreasing trend up to 24 months post-RT. There was mild correlation between post-RT gland dose and gland volume, but not with haemodynamic changes.

Conclusions

Radiation from IMRT caused shrinkage of parotid and submandibular glands in NPC patients. It also changed the echogenicity and vascular condition of the parotid gland. The most significant changes were observed at 6 months after radiotherapy.

Advances in knowledge

It is the first paper that reports on the longitudinal changes of salivary gland volume, echogenicity and haemodynamic parameters altogether in NPC patients after radiotherapy. The results are useful for the prediction of glandular changes that is associated with xerostomia, which help to provide timely management of the complication when the patients attend follow-up visits.

Quality of life and survival outcome for patients with nasopharyngeal carcinoma treated by volumetric-modulated arc therapy versus intensity-modulated radiotherapy

BACKGROUND

To evaluate the longitudinal changes of quality of life (QoL) and survival in patients with nasopharyngeal carcinoma (NPC) treated by volumetric-modulated arc therapy (VMAT) versus intensity-modulated radiotherapy (IMRT).

METHODS

One hundred and forty non-distant metastatic NPC patients treated by VMAT (n = 66) or IMRT (n = 74) with simultaneously integrated boost between March 2013 and December 2015 at a single institute were analyzed. QoL was prospectively assessed by the EORTC QLQ-C30 and HN35 questionnaires at the four time points: before RT, RT 42.4 Gy (20 fractions), and 3, 12 months after RT.

RESULTS

The 3-year locoregional relapse-free survival, distant metastasis-free survival, failure-free survival, and overall survival rates were 96.6, 89.4, 86.1%, and 87.4 for the VMAT group, respectively, compared with 91.4, 90.0, 79.8, and 91.3% for the IMRT group (p value > 0.05). The pattern of QoL changes was similar between the VMAT and IMRT group. No statistically or clinically significant difference in all the QoL scales was observed between VMAT and IMRT group at each time point. Compared to before RT, we observed statistically (p<0.05) and clinically (difference of mean scores≧10) better outcome in global QoL and social functioning, but worse head and neck symptomatic outcome in swallowing, taste/smell, opening mouth, dry mouth, and sticky saliva at the time point of 1 year after RT for both groups.

CONCLUSION

The study provides the evidence that the tumor control, survival and changes of QoL is compatible for NPC patients treated by VMAT versus IMRT.

Helical tomotherapy: Comparison of Hi-ART and Radixact clinical patient treatments at the Technical University of Munich

The helical tomotherapy (HT) Hi-ART system was installed at our department in April 2007. In July 2018 the first Radixact system in Germany has been launched for clinical use. We present differences, advantages and disadvantages and show future perspectives in patient treatment using two HT devices. We investigate patient characteristics, image quality, radiotherapy treatment specifications and analyze the time effort for treatments with the Hi-ART system from April 2010 until May 2017 and compare it to the data acquired in the first nine months of usage of the Radixact system. Comparing the Hi-ART and Radixact system, the unique option of integrated MVCT image acquisition has experienced distinct improvement in image quality. Time effort for irradiation treatment could be improved resulting in a mean beam on time for craniospinal axis treatment of 636.2 s for the Radixact system compared to 915.9 s for the Hi-ART system. The beneficial use of tomotherapy for complex target volumes is demonstrated by a head and neck tumor case and craniospinal axis treatment. With the Radixact system MVCT image quality has been improved allowing for fast and precise interfraction dose adaptation. The improved time effort for patient treatment could increase the accessibility for clinical usage.

Fighter Pilots With Nasopharyngeal Carcinoma Successfully Returning to Flight After Radiotherapy: A Case Series

For nasopharyngeal carcinoma (NPC), radiotherapy is the primary treatment. However, complications occur after radiation to the nasopharynx, which could potentially affect the flying safety. Four fighter pilots with NPC were reported. With early to locally advanced NPC, they received radiotherapy with or without concurrent chemotherapy. The prescribed radiation dose was 70 Gy to the primary tumor over the nasopharynx. Before treatment, all patients presented with various degrees of hearing loss on pure tone audiometry (main frequencies of 20-45 dB at 3-4.5 kHz for affected ears). After the full course of radiotherapy, tumor regression was noticed during months to years of follow-ups. The follow-up audiometry evaluation showed gradually recovered hearing function (average improvement of 5 dB at pretreatment frequencies) in all pilots. They then returned back to the flight line on annual waiver points. Here, we conclude that fighter pilots with NPC could successfully return to the flight line after radiotherapy. However, detailed physical examinations and confirmation of adaptation to flying condition are warranted.

Dosimetric Comparisons of Volumetric Modulated Arc Therapy and Tomotherapy for Early T-Stage Nasopharyngeal Carcinoma

Purpose

To compare the dosimetric differences between volumetric modulated arc therapy (VMAT) and helical tomotherapy (HT) in treating early T-stage nasopharyngeal carcinoma (NPC).

Method

Ten patients with early T-stage NPC who received tomotherapy using simultaneously integrated boost (SIB) strategies were replanned with VMAT (RapidArc of Varian, dual-arc). Dosimetric comparisons between the RapidArc plan and the HT plan included the following: (1) D98, homogeneity, and conformity of PTVs; (2) sparing of organs at risk (OARs); (3) delivery time and monitor units (MUs).

Results

(1) Compared with RapidArc, HT achieved better dose conformity (CI of PGTVnx + nd: 0.861 versus 0.818, P = 0.004). (2) In terms of OAR protection, RapidArc exhibited significant superiority in sparing ipsilateral optic nerve (Dmax: 27.5Gy versus 49.1Gy, P < 0.001; D2: 23.5Gy versus 48.2Gy, P < 0.001), contralateral optic nerve (Dmax: 30.4Gy versus 49.2Gy, P < 0.001; D2: 26.2Gy versus 48.1Gy, P < 0.001), and optic chiasm (Dmax: 32.8Gy versus 48.3Gy, P < 0.001; D2: 30Gy versus 47.6Gy, P < 0.001). HT demonstrated a superior ability to protect the brain stem (D1cc: 43.0Gy versus 45.2Gy, P = 0.012), ipsilateral temporal lobe (Dmax 64.5Gy versus 66.4 Gy, P = 0.015), contralateral temporal lobe (Dmax: 62.8Gy versus 65.1Gy, P = 0.001), ipsilateral lens (Dmax: 4.27Gy versus 5.24Gy, P = 0.009; D2: 4.00Gy versus 5.05Gy, P = 0.002; Dmean: 2.99Gy versus 4.31Gy, P < 0.001), contralateral lens (Dmax: 4.25Gy versus 5.09Gy, P = 0.047; D2: 3.91Gy versus 4.92Gy, P = 0.005; Dmean: 2.91Gy versus 4.18Gy, P < 0.001), ipsilateral parotid (Dmean: 36.4Gy versus 41.1Gy, P = 0.002; V30Gy: 54.8% versus 70.4%, P = 0.009), and contralateral parotid (Dmean: 33.4Gy versus 39.1Gy, P < 0.001; V30Gy: 48.2% versus 67.3%, P = 0.005). There were no statistically significant differences in spinal cord or pituitary protection between the RapidArc plan and the HT plan. (3) RapidArc achieved a much shorter delivery time (3.8 min versus 7.5 min, P < 0.001) and a lower MU (618MUs versus 5646MUs, P < 0.001).

Conclusion

Our results show that RapidArc and HT are comparable in D98, dose homogeneity, and protection of the spinal cord and pituitary gland. RapidArc performs better in shortening delivery time, lowering MUs, and sparing the optic nerve and optic chiasm. HT is superior in dose conformity and protection of the brain stem, temporal lobe, lens, and parotid.

Effectiveness of tomotherapy vs linear accelerator image-guided intensity-modulated radiotherapy for localized pharyngeal cancer treated with definitive concurrent chemoradiotherapy: a Taiwanese population-based propensity score-matched analysis

OBJECTIVE

This study used a population-based propensity score (PS)-matched analysis to compare the effectiveness of tomotherapy-based image-guided intensity-modulated radiotherapy (referred to as T-IMRT) with that of linear accelerator based (referred to as L-IMRT) for clinically localized pharyngeal cancer (LPC, divided into nasopharyngeal cancer and non-nasopharyngeal cancer) with definitive concurrent chemoradiotherapy (CCRT).

METHODS

Eligible LPC patients diagnosed between 2007 and 2014 were identified among all citizens in Taiwan from the Health and Welfare Data Science Center database. A PS-matched sample based on the PS estimated from the covariables of interest was constructed to compare the effectiveness of T-IMRT with L-IMRT. In the primary analysis, overall survival (OS) was compared for assessment of effectiveness. We also evaluated freedom from local regional recurrence and pharyngeal cancer-specific survival and performed supplementary analyses.

RESULTS

The study population included 960 patients equally divided into two groups. OS did not differ significantly between the T-IMRT and L-IMRT groups (hazard ratio for death: 0.82, p = 0.15, 5-year OS rate: 79 and 74% for T-IMRT and L-IMRT, respectively), and there were no significant differences in the other endpoints or supplementary analyses.

CONCLUSION

For LPC patients treated with definitive CCRT, we found no significant difference in disease control or survival between the T-IMRT and L-IMRT groups. However, further studies, especially randomized trials or studies focusing on other dimensions, such as quality of life, are needed. Advances in knowledge: We provide the first population-based study, as well as the largest study, on the clinical effectiveness of T-IMRT compared with L-IMRT in conjunction with CCRT in LPC patients.

TRIM24 siRNA induced cell apoptosis and reduced cell viability in human nasopharyngeal carcinoma cells

Nasopharyngeal carcinoma (NPC) is a common cancer occurring primarily in East Asia and Africa. The high rate of recurrence and metastasis of NPC continuously endangers the health of patients. The present study aimed to identify the underlying mechanisms involved in the progression of NPC and provide experimental basis to develop a novel and efficient agent against NPC. The present study measured the expression level of tripartite motif containing 24 (TRIM24) in tumor tissues from NPC patients using reverse transcription quantitative polymerase chain reaction. Subsequently, Cell Counting kit‑8 and flow cytometry were used to detect the cell proliferation and apoptosis of NPC cell lines HONE1 and CNE1 cells where the TRIM24 gene was knocked‑down with small interfering RNA (siRNA). Further, caspase kits and western blot analysis were used to detect the expression of apoptosis and angiogenesis‑associated proteins. The present study detected a higher expression level of TRIM24 in tumor tissues and NPC cell lines and lower cell viability and higher apoptotic rate were observed when TRIM24 was silenced. Meanwhile, upregulated caspase‑3 and caspase‑9 indicated induced cell apoptosis in HONE1 and CNE1 cells following the treatment with TRIM24 siRNA. Additionally, the downregulated expression level of vascular endothelial growth factor (VEGF) and VEGF receptor 2 suggested inhibited angiogenesis of NPC cells. Additionally, the reduced levels of janus kinase 2 (JAK2) and signal transducer and activator of transcription 3 (STAT3) indicated a blocked JAK2/STAT3 signaling pathway. However, there was no direct evidence that inactivation of the JAK2/STAT3 signaling pathway was involved in regulation of siTRIM24, these results suggested that TRIM24 has an important role in the growth of NPC. Additionally, silenced TRIM24 may lead to inhibited cell proliferation and induced cell apoptosis in NPC cells. The limitation of this study was that HONE1, CNE1 and CNE2 cells may have been contaminated with other cells. Further experiments with validated NPC cells may be needed.

Polymer gel dosimeters for pretreatment radiotherapy verification using the three-dimensional gamma evaluation and pass rate maps

Polymer gel dosimeters (PGDs) have been widely studied for use in the pretreatment verification of clinical radiation therapy. However, the readability of PGDs in three-dimensional (3D) dosimetry remain unclear. In this study, the pretreatment verifications of clinical radiation therapy were performed using an N-isopropyl-acrylamide (NIPAM) PGD, and the results were used to evaluate the performance of the NIPAM PGD on 3D dose measurement. A gel phantom was used to measure the dose distribution of a clinical case of intensity-modulated radiation therapy. Magnetic resonance imaging scans were performed for dose readouts. The measured dose volumes were compared with the planned dose volume. The relative volume histograms showed that relative volumes with a negative percent dose difference decreased as time elapsed. Furthermore, the histograms revealed few changes after 24h postirradiation. For the 3%/3mm and 2%/2mm criteria, the pass rates of the 12- and 24-h dose volumes were higher than 95%, respectively. This study thus concludes that the pass rate map can be used to evaluate the dose-temporal readability of PGDs and that the NIPAM PGD can be used for clinical pretreatment verifications.

A Phase II Clinical Trial of Concurrent Helical Tomotherapy plus Cetuximab Followed by Adjuvant Chemotherapy with Cisplatin and Docetaxel for Locally Advanced Nasopharyngeal Carcinoma

PURPOSE

The present clinical trial was designed to evaluate the efficacy and safety of concurrent helical tomotherapy (HT) with cetuximab followed by adjuvant chemotherapy with docetaxel and cisplatin (TP) in the treatment of patients with locoregionally advanced nasopharyngeal carcinoma.

MATERIALS AND METHODS

This phase II clinical trial included 43 patients with Stage III/IV LANC (33 Stage III and 10 Stage IV). The treatment consisted of concurrent HT with cetuximab (400 mg/m(2) loading dose and weekly 250mg/m(2)), followed by four cycles of chemotherapy [docetaxel (70 mg/m(2) on Day 1) and cisplatin (40 mg/m(2) on Days 1 and 2 every 3 weeks). Side effects were evaluated with CTCAE criteria (Common Terminology Criteria for Adverse Events 3.0).

RESULTS

The median follow-up duration was 48.0 months [95% confidence interval (CI) 41.7-58.0 months], the 2-year locoregional failure-free rate (LFFR), progression-free survival (PFS), distant failure-free rate (DFFR) and overall survival (OS) were 95.2%, 79.1%, 88.1% and 93.0% respectively; the 3-year LFFR, DFFR, PFS and OS were 92.7%, 85.6%, 72.0% and 85.7% respectively. The most common grade 3 toxicities were oropharyngeal mucositis (81.4%) and RT-related dermatitis (7.0%). No patients had more than grade 3 radiation related toxicities and no patients required nasogastric feeding. One patient experienced grade 3 osteonecrosis at 18 months after treatment.

CONCLUSIONS

Concurrent HT with cetuximab followed by adjuvant chemotherapy with TP is an effective strategy for the treatment of LANC with encouraging survival rates and minimal side effects.

Advances and challenges in intensity-modulated radiotherapy for nasopharyngeal carcinoma

Nasopharyngeal carcinoma is an endemic disease within specific regions in the world. Radiotherapy is the main treatment. In recent decades, intensity-modulated radiation therapy has undergone a rapid evolution. Compared with two-dimensional radiotherapy and/or three-dimensional conformal radiotherapy, evidence has shown it may improve quality of life and prognosis for patients with nasopharyngeal carcinoma. In addition, helical tomotherapy is an emerging technology of intensity-modulated radiation therapy. Its superiority in dosimetric and clinical outcomes has been demonstrated when compared to traditional intensity-modulated radiation therapy. However, many challenges need to be overcome for intensity-modulated radiation therapy of nasopharyngeal carcinoma in the future. Issues such as the status of concurrent chemotherapy, updating of target delineation, the role of replanning during IMRT, the causes of the main local failure pattern require settlement. The present study reviews traditional intensity-modulated radiation therapy, helical tomotherapy, and new challenges in the management of nasopharyngeal carcinoma.

Improving target dose coverage and organ-at-risk sparing in intensity-modulated radiotherapy of advanced laryngeal cancer by a simple optimization technique

OBJECTIVE

To evaluate a simple optimization technique intended to improve planning target volume (PTV) dose coverage and organ-at-risk (OAR) sparing in intensity-modulated radiotherapy (IMRT) of advanced laryngeal cancer.

METHODS

Generally acceptable initial IMRT plans were generated for 12 patients and were improved individually by the following two techniques: (1) base dose function-based (BDF) technique, in which the treatment plans were reoptimized based on the initial IMRT plans; (2) dose-controlling structure-based (DCS) technique, in which the initial IMRT plans were reoptimized by adding constraints for hot and cold spots. The initial, BDF and DCS IMRT plans and additionally generated volumetric modulated arc therapy (VMAT) plans were compared concerning homogeneity index (HI) and conformity index (CI) of PTVs prescribed at 70 Gy/60 Gy (PTV70/PTV60), OAR sparing, monitor units (MUs) per fraction and total planning time.

RESULTS

Compared with the initial IMRT and DCS IMRT plans, the BDF technique provided superior HI/CI, by approximately 19-37%/4-11%, and lower doses to most OARs, by approximately 1-7%, except for the comparable HI of PTV60 to DCS IMRT plans. Compared with VMAT plans, the BDF technique provided comparable HI, CI and most-OAR sparing, except for the superior HI of PTV70, by approximately 13%. The BDF technique produced more MUs and reduced the planning time.

CONCLUSION

The BDF optimization technique for IMRT of advanced laryngeal cancer can improve target dose homogeneity and conformity, spare most OARs and is efficient.

ADVANCES IN KNOWLEDGE

A novel optimization technique for improving IMRT was assessed and found to be effective and efficient.

Dosimetric Evaluation of a Simple Planning Technique for Improving Intensity-Modulated Radiotherapy for Nasopharyngeal Cancer

PURPOSE

To evaluate the dosimetric outcomes of a simple planning technique for improving intensity-modulated radiotherapy (IMRT) for nasopharyngeal cancer (NPC).

METHODS

For 39 NPC cases, generally acceptable original plans were generated and were improved by the two planning techniques, respectively: (1) a basal-dose-compensation (BDC) technique, in which the treatment plans were re-optimized based on the original plans; (2) a local-dose-control (LDC) technique, in which the original plans were re-optimized with constraints for hot and cold spots. The BDC, original, and LDC plans were then compared regarding homogeneity index (HI) and conformity index (CI) of planning target volumes (PTVs), organ-at-risk (OAR) sparing and monitor units (MUs) per fraction. The whole planning times were also compared between the BDC and LDC plans.

RESULTS

The BDC plans had superior HIs / CIs, by 13-24% / 3-243%, respectively, over the original plans. Compared to the LDC plans, the BDC plans provided better HIs only for PTVnx (the PTV of nasopharyngeal primary tumor) by 11% and better CIs for all PTVs by 2-134%. The BDC technique spared most OARs, by 1-9%. The average MUs of the BDC, original, and LDC plans were 2149, 2068 and 2179, respectively. The average whole planning times were 48 and 69 minutes for the BDC and LDC plans, respectively.

CONCLUSIONS

For the IMRT of nasopharyngeal cancer, the BDC planning technique can improve target dose homogeneity, conformity and OAR sparing, with better planning efficiency.

Helical tomotherapy for cancer treatment: a rapid health technology assessment

OBJECTIVES

Helical tomotherapy (HT) can be applied to treat complex malignant cancer with high-precise radiotherapy, and it can reduce the damage to normal tissues and improve treatment effects. But the procurement of HT must be approved by relevant departments of administration affairs. This study, appointed by the National Health and Family Planning Commission of China and undertook by the National Health Development Research Center and the Chinese Evidence-Based Medicine Centre, was aimed to rapidly assess the effectiveness, safety, costs, and applicability of HT, so as to provide currently available best evidence for decision-makers of health policies.

METHODS

We electronically searched databases including PubMed, EMbase, The Cochrane Library, CNKI, WanFang Data, VIP, CBM, and other professional websites. Two reviewer independently screened literature according to the inclusion and exclusion criteria, extracted data, assessed quality, and then performed descriptive analysis.

RESULTS

(i) We finally included 150 studies, encompassing 5 HTAs, 18 CCTs, and 127 observational studies. (ii) The included HTAs were published during 2006-2009, providing fairly less evidence of low quality and the results of 145 primary studies showed that: HT had been used mainly in the treatments of 14 kinds of cancer, with low total toxicity and high survival rates. Although the quality of the included studies was poor, there was much evidence about prostate cancer, head and neck cancer, nasopharynx cancer, cervical cancer, lung cancer and liver cancer, with enough sample and fairly reliable results in HT efficacy and safety. And (iii) a total of 56 clinical trials were registered in Clinicaltrials.gov, most of which were registered by the occident. Among them, 9 were completed but the results had not been published yet.

CONCLUSIONS

The evidence of this study showed that, HT is safe and effective in clinic. But the abovementioned conclusion needs to be verified by conducting more high-quality studies with long-term follow-up. The costs of HT in procurement, maintenance, and application are high; and the skills, training, and qualification of operators are required. We suggest that the procurement of HT should be reduced; it should be allocated rationally and effectively used after comprehensive assessment in China's cancer epidemiology characteristics, health resource allocation, disease burden, medical service level, etc.; and also high-quality studies with long-term follow-up should be financially supported on the basis of establishing projects, so as to provide local evidence and consistently guide and improve scientific decision-making.

Current status of IMRT in head and neck cancer

BACKGROUND

IMRT provides highly conformal dose distributions creating non uniform spatial intensity using different segments in the beam.

MATERIAL & METHODS AND RESULTS

Different retrospective studies have shown a high capability of IMRT to treat tumours close to the base of skull. Prospective studies have shown a decrease in xerostomia compared with conventional 3D conformal treatment (3DCRT). Modulation of intensity is performed by the movement of the multileaf collimator (MLC) that can deliver the radiation in different ways, such as static field segments, dynamic field segments and rotational delivery (arc therapy and tomotherapy). There are slight differences among the different techniques in terms of homogeneity, dose conformity and treatment delivery time.

CONCLUSIONS

The best method to deliver IMRT will depend on multiple factors such as deliverability, practicality, user training and plan quality.

Treatment of nasopharyngeal carcinoma by tomotherapy: five-year experience

Purpose

To analyze of survival curve and toxicity outcomes for patients treated for nasopharyngeal carcinoma (NPC) by intensity-modulated radiotherapy (IMRT) delivered by helical TomoTherapy (HT).

Materials and methods

Since May 2006, 72 patients with primary NPC were treated. In 67 cases PET-CT was used to help delineate the gross tumor volume (GTV); in 4 of these cases distant metastases in bone, mediastinal lymph nodes and unexpected small neck nodes were detected by high SUV uptake. 3, 22, 19, and 27 patients, respectively, had AJCC stage I to IV disease. Patients received a median total dose of 72 Gy to the GTV, 64.8 Gy to the elective PTV, and 54 Gy to the clinically negative neck region.

Results

At a median follow-up of 41 months (range 0.2 to 67 months), no patient has recurred locally. Two patients with stage IIb disease, both of whom received chemotherapy, recurred regionally. Ten patients developed distant metastases. One died from progressive disease with initial proved bony metastasis. Two patients with stage IIb disease, both of whom received chemotherapy, experienced neck node recurrence. 5-year locoregional control rate was 97%; freedom from distant metastases was 84.6% at 5 years. No evidence of disease was detected in 13 early stage (I/IIa/IIb) patients who did not receive chemotherapy. Acute grade 3 toxicity occurred in four patients and grade 4 in two patients. Late toxicities were low, with no grade 3+ xerostomia, grade 2 xerostomia in two patients (3%), and grade 3 hearing loss in two patients (3%).

Conclusions

HT resulted in excellent long-term disease control and survival in heterogeneous NPC patients. Generally mild acute and late toxicity, with low rates of xerostomia, were obtained. Image-guided HT offers the ability to deliver conformal, OAR-sparing dose distributions to a wide variety of NPC patients with good long-term clinical outcomes.

Critical structure sparing in stereotactic ablative radiotherapy for central lung lesions: helical tomotherapy vs. volumetric modulated arc therapy

Background

Helical tomotherapy (HT) and volumetric modulated arc therapy (VMAT) are both advanced techniques of delivering intensity-modulated radiotherapy (IMRT). Here, we conduct a study to compare HT and partial-arc VMAT in their ability to spare organs at risk (OARs) when stereotactic ablative radiotherapy (SABR) is delivered to treat centrally located early stage non-small-cell lung cancer or lung metastases.

Methods

12 patients with centrally located lung lesions were randomly chosen. HT, 2 & 8 arc (Smart Arc, Pinnacle v9.0) plans were generated to deliver 70 Gy in 10 fractions to the planning target volume (PTV). Target and OAR dose parameters were compared. Each technique’s ability to meet dose constraints was further investigated.

Results

HT and VMAT plans generated essentially equivalent PTV coverage and dose conformality indices, while a trend for improved dose homogeneity by increasing from 2 to 8 arcs was observed with VMAT. Increasing the number of arcs with VMAT also led to some improvement in OAR sparing. After normalizing to OAR dose constraints, HT was found to be superior to 2 or 8-arc VMAT for optimal OAR sparing (meeting all the dose constraints) (p = 0.0004). All dose constraints were met in HT plans. Increasing from 2 to 8 arcs could not help achieve optimal OAR sparing for 4 patients. 2/4 of them had 3 immediately adjacent structures.

Conclusion

HT appears to be superior to VMAT in OAR sparing mainly in cases which require conformal dose avoidance of multiple immediately adjacent OARs. For such cases, increasing the number of arcs in VMAT cannot significantly improve OAR sparing.