Cone-beam computed tomography-guided online adaptive radiotherapy for pharyngeal cancer with whole neck irradiation: dose-volume histogram analysis between adapted and scheduled plans

The present study aimed to evaluate whether an adapted plan with Ethos™ could be used for pharyngeal cancer. Ten patients with pharyngeal cancer who underwent chemoradiotherapy with available daily cone-beam computed tomography (CBCT) data were included. Simulated treatments were generated on the Ethos™ treatment emulator using CBCTs every four to five fractions for two plans: adapted and scheduled. The simulated treatments were divided into three groups: early (first-second week), middle (third-fourth week), and late (fifth-seventh week) periods. Dose-volume histogram parameters were compared for each period between the adapted and scheduled plans in terms of the planning target volume (PTV) (D98%, D95%, D50% and D2%), spinal cord (Dmax and D1cc), brainstem (Dmax) and ipsilateral and contralateral parotid glands (Dmedian and Dmean). The PTV D98%, D95% and D2% of the adapted plan were significantly higher than those of the scheduled plans in all periods, except for D98% in the late period. The adapted plan significantly reduced the spinal cord Dmax and D1cc compared with the scheduled plan in all periods. Ipsilateral and contralateral parotid glands Dmean of the adapted plan were lower than those of scheduled plan in the late period. In conclusion, the present study revealed that the adapted plans could maintain PTV coverage while reducing the doses to organs at risk in each period compared with scheduled plans.

The effects of mega-voltage CT scan parameters on offline adaptive radiation therapy

TomoTherapy involves image-guided radiation therapy (IGRT) using Mega-voltage CT (MVCT) for each treatment session. The acquired MVCT images can be utilized for the retrospective assessment of dose distribution. The TomoTherapy provides 18 distinct imaging conditions that can be selected based on a combination of algorithms, acquisition pitch, and slice interval. We investigated the accuracy of dose calculation and deformable image registration (DIR) depending on MVCT scan parameters and their effects on adaptive radiation therapy (ART). We acquired image values for density calibration tables (IVDTs) under 18 different MVCT conditions and compared them. The planning CT (pCT) was performed using a thoracic phantom, and an esophageal intensity-modulated radiation therapy (IMRT) plan was created. MVCT images of the thoracic phantom were acquired under each of the 18 conditions, and dose recalculation was performed. DIR was performed on the MVCT images acquired under each condition. The accuracy of DIR, depending on the MVCT scan parameters, was compared using the mean distance to agreement (MDA) and Dice similarity coefficient (DSC). The dose distribution calculated on the MVCT images was deformed using deformed vector fields (DVF). No significant differences were observed in the results of the 18 IVDTs. The esophageal IMRT plan also showed a small dose difference. Regarding verifying the DIR accuracy, the MDA increased, and the DSC decreased as the acquisition pitch and slice interval increased. The difference between the dose distributions after dose mapping was comparable to that before DIR. The MVCT scan parameters had little effect on ART.

Clinical course of longer than five years after definitive radiotherapy for nasopharyngeal carcinoma

BACKGROUND

This study aimed to reveal the long-term outcomes and late toxicities (> 5 years) after definitive intensity-modulated radiation therapy (IMRT) in patients with nasopharyngeal carcinoma (NPC).

METHODS

Data from 43 patients (median age, 55 years; range, 17-72 years) with NPC who underwent definitive IMRT between 2001 and 2018 were analyzed. All patients were alive and disease-free 5 years after IMRT. A total dose of 70 (range, 66-70) Gy was delivered in 35 (33-35) fractions with concurrent cisplatin chemotherapy.

RESULTS

The median follow-up duration was 119 (range, 61.5-242.1) months. Three patients developed locoregional failure at 79, 92, and 149 months after IMRT, respectively. Of these, 2 patients died of disease progression at 136 and 153 months after IMRT. One patient died of aspiration pneumonia 141 months after IMRT, despite salvage of the recurrent tumor by re-irradiation. In addition, one patient died of aspiration pneumonia 62 months after the IMRT. Thus, the 10-year overall survival, progression-free survival, and locoregional control rates were 98%, 92%, and 94%, respectively. Grade ≥ 2 and ≥ 3 late toxicities were observed in 28 (65%) and 9 (21%) patients, respectively. Nine second primary cancers, including five tongue cancers and two external auditory canal carcinomas, were observed in seven (16%) patients.

CONCLUSION

Late recurrences, severe late toxicities, and second primary cancers were observed > 5 years after IMRT. A long-term follow-up of > 5 years is needed in patients with NPC.

Potential benefits of adaptive intensity-modulated proton therapy in nasopharyngeal carcinomas

Purpose

To investigate potential advantages of adaptive intensity‐modulated proton beam therapy (A‐IMPT) by comparing it to adaptive intensity‐modulated X‐ray therapy (A‐IMXT) for nasopharyngeal carcinomas (NPC).

Methods

Ten patients with NPC treated with A‐IMXT (step and shoot approach) and concomitant chemotherapy between 2014 and 2016 were selected. In the actual treatment, 46 Gy in 23 fractions (46Gy/23Fx.) was prescribed using the initial plan and 24Gy/12Fx was prescribed using an adapted plan thereafter. New treatment planning of A‐IMPT was made for the same patients using equivalent dose fractionation schedule and dose constraints. The dose volume statistics based on deformable images and dose accumulation was used in the comparison of A‐IMXT with A‐IMPT.

Results

The means of the D_mean of the right parotid gland (P < 0.001), right TM joint (P < 0.001), left TM joint (P < 0.001), oral cavity (P < 0.001), supraglottic larynx (P = 0.001), glottic larynx (P < 0.001), , middle PCM (P = 0.0371), interior PCM (P < 0.001), cricopharyngeal muscle (P = 0.03643), and thyroid gland (P = 0.00216), in A‐IMPT are lower than those of A‐IMXT, with statistical significance. The means of, D_0.03cc, and D_mean of each sub portion of auditory apparatus and D_30% for Eustachian tube and D_0.5cc for mastoid volume in A‐IMPT are significantly lower than those of A‐IMXT. The mean doses to the oral cavity, supraglottic larynx, and glottic larynx were all reduced by more than 20 Gy (RBE = 1.1).

Conclusions

An adaptive approach is suggested to enhance the potential benefit of IMPT compared to IMXT to reduce adverse effects for patients with NPC.

Clinical and dosimetric impact of adaptive intensity-modulated radiotherapy in locally advanced head-and-neck cancer

Background

Radiotherapy in head-and-neck cancer (HNC) is a challenging task, and the anatomical alterations occurring during the course of intensity-modulated radiotherapy (IMRT) can be compensated by adaptive radiotherapy (ART) which utilizes repeat computed tomography (CT) scans during the treatment course for replanning. In this study, the clinical and dosimetric benefits of ART were compared with the conventional IMRT.

Materials and Methods

Sixty patients with locally advanced HNC were randomized into two arms to receive IMRT up to a curative dose of 70 Gy with concurrent weekly chemotherapy and were prospectively analyzed between March 2018 and March 2019. Repeat CT scan was acquired after the 3^rd week of radiation. Patients in the study arm underwent replanning, whereas those in the control arm continued with the first IMRT plan. Assessment was done weekly till the end of treatment and at 1, 3, and 6 months post IMRT for disease response and toxicities. Tumor volume reduction rate (TVRR) and dose reduction to organs at risk were also recorded.

Results

Complete response was observed in 90% and 96.7% patients in the control and study arms, respectively, at the end of 6 months. Insignificant differences were found between the two arms in terms of toxicities. Xerostomia was statistically significantly higher in the control arm at 6 months (P = 0.01). TVRR was found to be 31.85%. Dose to spinal cord, ipsilateral, and contralateral parotid reduced by 4.3%, 6%, and 2.2%, respectively, with ART.

Conclusion

Mid-treatment adaptive replanning can help in better target coverage and minimize toxicities in HNC patients.

Dose-volume histogram analysis and clinical evaluation of knowledge-based plans with manual objective constraints for pharyngeal cancer

The present study aimed to evaluate whether knowledge-based plans (KBP) from a single optimization could be used clinically, and to compare dose-volume histogram (DVH) parameters and plan quality between KBP with (KBPCONST) and without (KBPORIG) manual objective constraints and clinical manual optimized (CMO) plans for pharyngeal cancer. KBPs were produced from a system trained on clinical plans from 55 patients with pharyngeal cancer who had undergone intensity-modulated radiation therapy or volumetric-modulated arc therapy (VMAT). For another 15 patients, DVH parameters of KBPCONST and KBPORIG from a single optimization were compared with CMO plans with respect to the planning target volume (D98%, D50%, D2%), brainstem maximum dose (Dmax), spinal cord Dmax, parotid gland median and mean dose (Dmed and Dmean), monitor units and modulation complexity score for VMAT. The Dmax of spinal cord and brainstem and the Dmed and Dmean of ipsilateral parotid glands were unacceptably high for KBPORIG, although the KBPCONST DVH parameters met our goal for most patients. KBPCONST and CMO plans produced comparable DVH parameters. The monitor units of KBPCONST were significantly lower than those of the CMO plans (P < 0.001). Dose distribution of the KBPCONST was better than or comparable to that of the CMO plans for 13 (87%) of the 15 patients. In conclusion, KBPORIG was found to be clinically unacceptable, while KBPCONST from a single optimization was comparable or superior to CMO plans for most patients with head and neck cancer.

A phase II study of adaptive two-step intensity-modulated radiation therapy (IMRT) with chemotherapy for loco-regionally advanced nasopharyngeal cancer (JCOG1015)

BACKGROUND

A phase II study of adaptive two-step intensity-modulated radiotherapy (IMRT) with chemotherapy for nasopharyngeal cancer (NPC) (JCOG1015) was conducted to evaluate the efficacy and safety.

METHODS

Patients aged 20-75 years with stages II-IVB NPC were enrolled. As adaptive two-step IMRT, computed tomography planning was performed twice before IMRT for the initial plan of 46 Gy/23 fractions and during treatment for the boost plan of 24 Gy/12 fractions with a total dose of 70 Gy. Chemotherapy (cisplatin 80 mg/m²/3-weeks × 3 courses) was administered concurrently with IMRT, followed by adjuvant chemotherapy (cisplatin at 70 mg/m² with 5-FU 700 at mg/m² for 5 days/4 weeks × 3 courses).

RESULTS

Between 2011 and 2014, 75 patients were enrolled from 12 institutions. The 3-year overall survival (OS) for the 75 patients was 88%, and the upper and lower limits of the 95% CI of 78%-94% were higher than the expected 3-year OS of 75% for the target population adjusted by the actual proportion of stage II:III:IV = 21%:44%:35%. The 3-year progression-free survival (PFS) and loco-regional PFS were 71% [59-80%] and 77% [66-85%], respectively. Although no grade 4-5 late toxicities were observed, 15 patients (20%) developed grade 3 late toxicities. Grade 2 xerostomia was noted in 26%, 12%, and 9% at 1, 2, and 3 years after starting IMRT, respectively.

CONCLUSIONS

Adaptive two-step IMRT for NPC demonstrated an excellent 3-year OS with acceptable toxicities. This method may be one treatment option for locally advanced NPC.

Dosimetric factors associated with long-term patient-reported outcomes after definitive radiotherapy of patients with head and neck cancer

Background

The aim of this study was to explore the relationships between dosimetric parameters of organs at risk and patient-reported outcomes (PRO) after radiotherapy of patients with head and neck cancer.

Methods

PRO data of 53 patients with head and neck cancer treated with radiotherapy were prospectively collected. These data concerned health-related quality of life (HRQOL) and were collected using the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (QLQ-C30) and head and neck cancer module (QLQ-H&N35). Patients were divided into “severe-deterioration” and “mild-deterioration” groups on the basis of degree of deterioration HRQOL > 6 months after completing treatment. The relationships between HRQOL deteriorations and patient-related or dosimetry-related factors were evaluated. P < 0.0013 according to Bonferroni correction was considered to denote statistical significance.

Results

Regarding “trouble with social eating (HNSO)” and “coughing (HNCO),” there were significant differences between the severe-deterioration and mild-deterioration groups in mean dosages to the superior pharyngeal constrictor muscle (SPC) (HNSO: 62.5 Gy vs 54.2 Gy; p = 0.00029, and HNCO: 61.5 Gy vs 54.1 Gy; p = 0.0012) and parotid gland (HNSO: 24.1 Gy vs 20.5 Gy; p = 0.000056, and HNCO: 24.2 Gy vs 20.3 Gy; p = 0.00043). Regarding “nausea and vomiting,” there was a significant difference between the two groups in the mean dosage to the middle pharyngeal constrictor muscle (MPC: 61.9 Gy vs. 58.4Gy; P = 0.00059).

Conclusions

We found that dosages to the SPC and parotid gland were associated with severe deterioration in HRQOL attributable to difficulty in HNSO and HNCO, whereas dosage to the MPC was associated with severe deterioration attributable to nausea and vomiting.

A scoring system predicting acute radiation dermatitis in patients with head and neck cancer treated with intensity-modulated radiotherapy

Background and purpose

We created a scoring system incorporating dosimetric and clinical factors to assess the risk of severe, acute skin reactions in patients undergoing intensity-modulated radiation therapy (IMRT) to treat head and neck cancer (HNC).

Materials and methods

A total of 101 consecutive patients who received definitive IMRT or volumetric modulated arc therapy (VMAT) with a prescription dose of 70 Gy to treat HNC between 2013 and 2017 in our hospital were enrolled. Skin V_5Gy, V_10Gy, V_20Gy, V_30Gy, V_40Gy, V_50Gy, and V_60Gy values delivered 5 mm within the body contour were compared between patients with Grades 1–2 and Grade 3 dermatitis. A scoring system was created based on logistic regression analysis (LRA) that identified the most significant dosimetric and clinical factors.

Results

The V_60Gy was significantly associated with radiation dermatitis grade in both LRA and recursive partitioning analysis (RPA). A scoring system incorporating the V_60Gy, concurrent chemotherapy status, age, and body mass index was used to divide all patients into three subgroups (0–1, 2–3, and 4–6 points) in the RPA. The incidence of Grade 3 dermatitis significantly differed among the subgroups (0, 20.5, and 58.6%, respectively, P < 0.01).

Conclusions

A risk analysis model incorporating dose-volume parameters successfully predicted acute skin reactions and will aid in the appropriate management of radiation dermatitis.

Radiotherapy alone and with concurrent chemotherapy for nasopharyngeal carcinoma: A retrospective study

We sought to evaluate clinical outcomes and toxicities of radiation therapy (RT) alone compared to RT with concurrent chemotherapy (CCT) for nasopharyngeal carcinoma (NPC) treatment.We conducted a retrospective review of consecutive patients with biopsy-proven nonmetastatic NPC who underwent RT at our institution. From May 2001 to April 2015; 62 newly diagnosed NPC patients were treated with three-dimensional conformal radiotherapy (3D-CRT) or intensity-modulated radiotherapy (IMRT) with or without CCT. The patients were classified as follows: 8% stage I, 15% stage II, 32% stage III, and 45% stage IVA/IVB. A total of 76% of tumors were World Health Organization types II or III. Acute and late toxicities were graded according to the Common Terminology Criteria for Adverse Events version 3.0. Overall survival (OS), progression-free survival (PFS), locoregional progression-free survival (LRPFS), and distant metastasis-free survival (DMFS) were analyzed.The median follow-up period for living patients was 53 months. The median actual delivered dose was 70 Gy with a range of 28 to 70 Gy in fraction sizes of 2 Gy. The estimated 5-year OS, PFS, LRPFS, and DMFS rates were 72.7%, 59.8%, 77.9%, and 84.2%, respectively. The use of CCT was a predictive factor of significantly better OS and PFS, whereas stage IV was a significant predictor of poor OS and PFS. The most severe acute toxicities included Grade 3 mucositis in 56% and Grade 3 dermatitis in 8%. Subset analysis revealed that Grade 2 xerostomia was significantly lower in the IMRT (23%) group than in the 3D-CRT (52%) group (P = .02).RT yielded favorable outcomes. CCT was associated with longer PFS and OS than RT alone.

Clinical outcomes of concurrent chemoradiotherapy with volumetric modulated arc therapy in patients with locally advanced nasopharyngeal carcinoma

PURPOSE

The purpose of this study was to analyze the clinical results of concurrent chemoradiotherapy (CCRT) with volumetric modulated arc therapy (VMAT) for nasopharyngeal carcinoma (NPC) patients.

MATERIALS AND METHODS

Patients with stage II-IVB NPC who received CCRT with VMAT between 2010 and 2014 were included in this study. The planned dose was 70 Gy in 35 fractions.

RESULTS

Twenty patients aged between 28 and 85 years (median 60 years) were assessed. With a median follow-up time of 47 months, the 3-year overall survival and progression-free survival rates were 85 and 65%, respectively. The 3-year local, regional and distant control rates were 78, 88 and 79%, respectively. At 0, 3, 6 and 12 months from CCRT, 19, 6, 3, and 1 patients had grade 2 dry mouth, respectively. No cases of grade 3 or worse dry mouth were observed. The severity of dry mouth was downgraded from grade 2 to grade 0 or 1 significantly earlier in younger patients (<70 years, p = 0.02) or patients in whom the mean dose to one parotid gland was lower (<26 Gy, p = 0.04).

CONCLUSIONS

Our clinical results regarding CCRT with VMAT for NPC patients showed favorable survival rates while maintaining organ function.

Radiation therapy for nasopharyngeal carcinoma: the predictive value of interim survival assessment

Pretreatment characteristics are suggested as predictive and/or prognostic factors for nasopharyngeal carcinoma (NPC); however, individual tumor radiosensitivities have previously not been considered. As boost planning is recommended for NPC, we performed interim assessments of magnetic resonance (MR) images for boost planning and retrospectively evaluated their predictive value for the survival of NPC patients. Radiation therapy via elective nodal irradiation (median dose: 39.6 Gy) with/without chemotherapy was used to treat 63 NPC patients. Boost irradiation (median total dose: 70 Gy) was performed based on the interim assessment. The largest lymph node (LN) was measured on MR images acquired at the time of interim assessment. The site of first failure was local in 8 (12.7%), regional in 7 (11.1%), and distant in 12 patients (19.0%). All 7 patients with regional failure harbored LNs ≥15 mm at interim assessment. We divided the 63 patients into two groups based on LN size [large (≥15 mm), n = 10 and small (<15 mm), n = 53]. Univariate analysis showed that 5-year overall survival (OS) and cause-specific survival (CSS) rates for large LNs were significantly lower than for small LNs (OS: 12.5% vs 70.5%, P < 0.001 and CSS: 25.0% vs 80.0%, P < 0.001). Multivariate analysis showed that large LNs were a significantly unfavorable factor for both OS (hazard ratio = 4.543, P = 0.002) and CSS (hazard ratio = 6.020, P = 0.001). The results suggest that LN size at interim assessment could predict survival in NPC patients.

A prospective picture collection study for a grading atlas of radiation dermatitis for clinical trials in head-and-neck cancer patients

Radiation dermatitis is one of the most common acute toxicities of both radiotherapy and chemoradiotherapy. Many clinical trials have evaluated the level of toxicity using the Common Terminology Criteria for Adverse Events ver. 4.03. This criterion accounts for severity in a single sentence only, and no visual classification guide has been available. Thus, there is a risk of subjective interpretation by the individual investigator. This contrasts with the situation with hematologic toxicities, which can be interpreted objectively. The aim of this prospective picture collection study was to develop a grading tool for use in establishing the severity of radiation dermatitis in clinical trials. A total of 118 patients who were scheduled to receive definitive or postoperative radiotherapy or chemoradiotherapy were enrolled from the four participating cancer centers. All researchers in our group used the same model of camera under the same shooting conditions to maintain consistent photographic quality. In all, 1600 photographs were collected. Of these, 100 photographs qualified for the first round of selection and were then graded by six experts, basically in accordance with the CTCAE ver. 4.03 (JCOG ver. in Japanese). After further study, 38 photographs were selected as representing typical models for Grade 1-4 radiation dermatitis; the radiation dermatitis grading atlas was produced from these photographs. The atlas will play a major role in ensuring that the dermatitis rating system is consistent between the institutions participating in trials. We hope that this will contribute to improving the quality of clinical trials, and also to improving the level of routine clinical practice.

A randomized phase II/III study of adverse events between sequential (SEQ) versus simultaneous integrated boost (SIB) intensity modulated radiation therapy (IMRT) in nasopharyngeal carcinoma; preliminary result on acute adverse events

BACKGROUND

To investigate acute and late toxicities comparing sequential (SEQ-IMRT) versus simultaneous integrated boost intensity modulated radiotherapy (SIB-IMRT) in nasopharyngeal carcinoma (NPC) patients.

METHODS

Newly diagnosed stage I-IVB NPC patients were randomized to receive SEQ-IMRT or SIB-IMRT, with or without chemotherapy. SEQ-IMRT consisted of two sequential radiation treatment plans: 2 Gy x 25 fractions to low-risk planning target volume (PTV-LR) followed by 2 Gy x 10 fractions to high-risk planning target volume (PTV-HR). In contrast, SIB-IMRT consisted of only one treatment plan: 2.12 Gy and 1.7 Gy x 33 fractions to PTV-HR and PTV-LR, respectively. Toxicities were evaluated according to CTCAE version 4.0.

RESULTS

Between October 2010 and November 2013, 122 eligible patients were randomized between SEQ-IMRT (54 patients) and SIB-IMRT (68 patients). With median follow-up time of 16.8 months, there was no significant difference in toxicities between the two IMRT techniques. During chemoradiation, the most common grade 3-5 acute toxicities were mucositis (15.4% vs 13.6%, SEQ vs SIB, p = 0.788) followed by dysphagia (9.6% vs 9.1%, p = 1.000) and xerostomia (9.6% vs 7.6%, p = 0.748). During the adjuvant chemotherapy period, 25.6% and 32.7% experienced grade 3 weight loss in SEQ-IMRT and SIB-IMRT (p = 0.459). One-year overall survival (OS) and progression-free survival (PFS) were 95.8% and 95.5% in SEQ-IMRT and 98% and 90.2% in SIB-IMRT, respectively (p = 0.472 for OS and 0.069 for PFS).

CONCLUSION

This randomized, phase II/III trial comparing SIB-IMRT versus SEQ-IMRT in NPC showed no statistically significant difference between both IMRT techniques in terms of acute adverse events. Short-term tumor control and survival outcome were promising.

Impact of repeat computerized tomography replans in the radiation therapy of head and neck cancers

Anatomical changes can occur during course of head-and-neck (H and N) radiotherapy like tumor shrinkage, decreased edema and/or weight loss. This can lead to discrepancies in planned and delivered dose increasing the dose to organs at risk. A study was conducted to determine the volumetric and dosimetric changes with the help of repeat computed tomography (CT) and replanning for selected H and N cancer patients treated with IMRT plans to see for these effects. In 15 patients with primary H and N cancer, a repeat CT scan after 3^rd week of radiotherapy was done when it was clinically indicated and then two plans were generated on repeat CT scan, actual plan (AP) planned on repeat CT scan, and hybrid plan (HP), which was generated by applying the first intensity-modulated radiation therapy (IMRT) plan (including monitoring units) to the images of second CT scan. Both plans (AP and HP) on repeat CT scan were compared for volumetric and dosimetric parameter. The mean variation in volumes between CT and repeat CT were 44.32 cc, 82.2 cc, and 149.83 cc for gross tumor volume (GTV), clinical target volumes (CTV), and planning target volume (PTV), respectively. Mean conformity index and homogeneity index was 0.68 and 1.07, respectively for AP and 0.5 and 1.16, respectively for HP. Mean D₉₅ and D₉₉ of PTV was 97.92% (standard deviation, SD 2.32) and 93.4% (SD 3.75), respectively for AP and 92.8% (SD 3.83) and 82.8% (SD 8.0), respectively for HP. Increase in mean doses to right parotid, left parotid, spine, and brainstem were 5.56 Gy (D_mean), 3.28 Gy (D_mean), 1.25 Gy (D_max), and 3.88 Gy (D_max), respectively in HP compared to AP. Repeat CT and replanning reduces the chance of discrepancies in delivered dose due to volume changes and also improves coverage to target volume and further reduces dose to organ at risk.

JCOG Radiation Therapy Study Group: history and achievements

The Radiation Therapy Study Group (RTSG) of the Japan Clinical Oncology Group (JCOG) was established in 2003. The missions of this group are to develop new standards of care with innovative, advanced technology radiation therapy, both for single- and multi-modality cancer treatment, and to improve radiation therapy quality and outcomes of JCOG trials conducted by other organ-oriented groups. In 2004, the first RTSG trial, a Phase II study of stereotactic body radiation therapy for Stage IA non-small cell lung cancer (JCOG 0403), was initiated. Four other trials are currently open for accrual. JCOG 0702 is a Phase I study of stereotactic body radiation therapy in patients with T2N0M0 non-small cell lung cancer. JCOG 0701 is a Phase III study comparing accelerated fractionation with conventional fractionation radiation therapy for T1-2N0M0 glottic cancer. JCOG 0906 is a multicenter safety trial of hypofractionated radiation therapy after breast-conserving surgery in patients with margin-negative invasive breast cancer. JCOG 1015 is a Phase II study of intensity-modulated radiation therapy with chemotherapy for loco-regionally advanced nasopharyngeal cancer. Other RTSG activities include a medical physics working group responsible for dosimetry audits; a genetic analysis working group involved in accompanying research to analyze single-nucleotide polymorphisms to identify predictors of radiation toxicities; a working group that has developed atlases of clinical target volumes for uterine cervical cancer; and participation in the Harmonisation Group to promote global harmonization of radiotherapy and radiotherapy quality assurance among trial groups. Further efforts to improve radiation therapy quality and outcomes of cancer treatment are necessary.