Prognostic significance of semi-quantitative FDG-PET parameters in stage I non-small cell lung cancer treated with carbon-ion radiotherapy.

PURPOSE: Prognostic significance of volumetric 18F-fluorodeoxyglucose (FDG) positron emission tomography/computer tomography (PET/CT) parameters in carbon-ion radiotherapy (C-ion RT) treated stage I non-small cell lung cancer, and need of histology-wise separate cut-off values for risk stratification were assessed. METHODS: Thirty-nine patients (29 men and 10 women, 71.9 ± 8.3 years) who underwent FDG PET/CT examinations before C-ion RT were retrospectively evaluated. FDG-PET parameters: standardized uptake values (SUVmax, SUVpeak, and SUVmean), metabolic tumor volume (MTV), and total lesion glycolysis (TLG), and clinicopathological variables were assessed for prognosis using Cox proportional hazards regression analysis. Mann-Whitney test compared medians of significant parameters between adenocarcinoma (AC) and squamous cell carcinoma (SCC), and Kaplan-Meier curves were plotted for median-based low- and high-risk groups. RESULTS: Median follow-up period was 44.8 months. 1/2/3-year overall survival (OS), progression-free survival (PFS) and local control (LC) rates were 94.9/84.3/70.8, 82.1/69.2/58.4 and 97.3/85.7/82.3%. Multivariate analysis revealed age (hazard ratio, HR: 1.09; 95% confidence interval, CI: 1.0-1.19, p < 0.05) and MTV (HR 4.83, 95% CI 1.21-19.27, p < 0.03) predicted OS, and only MTV predicted PFS (HR 5.3, CI 1.32-21.35, p < 0.02) independently. Compared with AC, SCC had higher MTV (median, 6.625cm3 vs 0.2 cm3, p < 0.01). Single MTV cut-off based on overall cohort was insignificant in SCC for PFS (p > 0.02); separate cut-offs of MTV, 0.2 cm3 for AC (p < 0.03) and 6.625 cm3 for SCC (p < 0.05) were relevant. CONCLUSION: Among all FDG PET/CT parameters, only MTV beared prognostic ability for stage I NSCLC treated with C-ion RT, and its histological variation may need consideration for risk-adapted therapeutic management.

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.

A retrospective multicenter study of carbon-ion radiotherapy for major salivary gland carcinomas: Subanalysis of J-CROS 1402 HN.

A retrospective multicenter study was carried out to assess the clinical outcomes of carbon-ion radiotherapy for head and neck malignancies (Japan Carbon-Ion Radiation Oncology Study Group [J-CROS] study: 1402 HN). We evaluated the safety and efficacy of carbon-ion radiotherapy in patients with major salivary gland carcinoma. Sixty-nine patients treated with carbon-ion radiotherapy at four Japanese institutions were analyzed. Thirty-three patients (48%) had adenoid cystic carcinomas, 10 (14%) had mucoepidermoid carcinomas, and 26 (38%) had other disease types. Three patients (4%) had T1 disease, 8 (12%) had T2, 25 (36%) had T3, and 33 (48%) had T4. The median radiation dose was 64 Gy (relative biological effectiveness) in 16 fractions. The median gross tumor volume was 27 mL. The median follow-up period was 32.7 months. The 3-year local control rate and overall survival rate were 81% and 94%, respectively. Regarding acute toxicities, seven patients had grade 3 mucositis and seven had grade 3 dermatitis. Regarding late toxicities, one patient had grade 3 dysphagia and one had a grade 3 brain abscess. No grade 4 or worse late reactions were observed. In conclusion, definitive carbon-ion radiotherapy was effective with acceptable toxicity for major salivary gland carcinomas.

Multi-institutional retrospective study of mucoepidermoid carcinoma treated with carbon-ion radiotherapy.

This study aimed to evaluate the clinical outcomes of patients with mucoepidermoid carcinomas in the head and neck treated with carbon-ion radiotherapy. Data from 26 patients who underwent carbon-ion radiotherapy in four facilities were analyzed in this multi-institutional retrospective study: the Japan Carbon-ion Radiation Oncology Study Group. The median follow-up time was 34 months. One patient experienced local recurrence, and the 3-year local control rate was 95%. One patient developed lymph node recurrence and five developed distant metastases. The 3-year progression-free survival rate was 73%. Five patients died, two of mucoepidermoid carcinoma and three of intercurrent disease. The 3-year overall survival rate was 89%. Acute mucositis and dermatitis of grade 3 or higher were experienced by 19% and 8% of patients, respectively; these improved with conservative therapy. Late mucositis and osteonecrosis of jaw were observed in 12% and 23% of patients, respectively. The 3-year cumulative rate of any late adverse event of grade 3 or higher was 14%. None of the patients died of the acute or late adverse events. Carbon-ion radiotherapy was efficacious and safe for treating mucoepidermoid carcinoma in this multi-institutional retrospective study (registration no. UMIN000024473). We are currently undertaking a prospective multicenter study.

Prospective observational study of carbon-ion radiotherapy for non-squamous cell carcinoma of the head and neck.

To evaluate the efficacy and safety of carbon-ion radiotherapy for non-squamous cell carcinoma of the head and neck, 35 patients were enrolled in this prospective study. The primary end-point was the 3-year local control rate, and the secondary end-points included the 3-year overall survival rate and adverse events. Acute and late adverse events were evaluated according to the Common Terminology Criteria for Adverse Events, version 4.0. The median follow-up time for all patients was 39 months. Thirty-two and three patients received 64.0 Gy (relative biological effectiveness) and 57.6 Gy (relative biological effectiveness) in 16 fractions, respectively. Adenoid cystic carcinoma was dominant (60%). Four patients had local recurrence and five patients died. The 3-year local control and overall survival rates were 93% and 88%, respectively. Acute grade 2-3 radiation mucositis (65%) and dermatitis (31%) was common, which improved immediately with conservative therapy. Late mucositis of grade 2, grade 3, and grade 4 were observed in 11, one, and no patients, respectively. There were no adverse events of grade 5. Carbon-ion radiotherapy achieved excellent local control and overall survival rates for non-squamous cell carcinoma. However, the late mucosal adverse events were not rare, and meticulous treatment planning is required. Trial registration no. UMIN000007886.

Incidence, risk factors, and dose-volume relationship of radiation-induced rib fracture after carbon ion radiotherapy for lung cancer.

BACKGROUND: The purpose of this study was to assess the incidence, risk factors, and dose-volume relationship of radiation-induced rib fracture (RIRF) after carbon ion radiotherapy for lung cancer. MATERIAL AND METHODS: Fifty-seven ribs of 18 patients with peripheral stage I non-small cell lung cancer treated with carbon ion radiotherapy were analyzed on rib fracture. The patients were treated at a total dose of 52.8 Gy [relative biologic effectiveness (RBE)] or 60.0 Gy (RBE) in 4 fractions and were followed at least six months. Patient characteristics and dosimetric parameters were analyzed for associations with RIRF. RESULTS: Eighteen patients and 57 ribs were included in this study. The median length of follow-up was 36.5 months. RIRF was observed in seven (39%) of the 18 patients, and in 11 (19%) of 57 ribs. Only one patient developed symptomatic fracture. The distance from the ribs to the tumor site was significantly shorter in fractured ribs than in non-fractured ribs (1.4 ± 0.3 cm vs. 2.5 ± 0.3 cm). Receiver operating characteristic curve analysis showed that [Formula: see text] as a cut-off value for discriminating RIRF had the largest area under the curve (AUC =0.78). Comparison of the two-year cumulative incidence of RIRF among two groups as determined by cut-off values, yielded the following result: 53% vs. 4% [[Formula: see text], ≥ 38.2 Gy (RBE) or less]. Results from the two groups were significantly different (p < 0.05). CONCLUSION: The crude incidence of RIRF after carbon ion radiotherapy was 39% but incidence of symptomatic fracture was low. The [Formula: see text] as cut-off values may be helpful for discriminating the risk of RIRF.

[Particle beam radiotherapy].

Recently, particle beam radiotherapy with protons or carbon ions has been used in cancer treatment. Energy deposition with particle beams increases as depth increases. Furthermore, carbon ion beams have stronger biological effects than X-rays or proton beams, because carbon beams generate denser ionization along the pathway of the particles. In Japan, clinical study with carbon ions for cancer therapy was initiated in 1994 at the National Institute of Radiological Science(NIRS). Four treatment facilities are now in operation, including Gunma University Heavy Ion Medical Center. The experience with carbon ion radiotherapy at NIRS has demonstrated advantages for the following types of cancer. In terms of histological type, adenocarcinomas, sarcomas, and melanomas that are relatively radioresistant to conventional X-ray radiotherapy may be sensitive to carbon ion radiotherapy. Primary sites that may be sensitive include the head and neck region, lung, liver, prostate, bone and soft tissue, and pelvis(for recurrence of rectal cancer). Combined with surgery, cytotoxic drugs, molecular targeted drugs, and immunotherapy, carbon ion radiotherapy promises to be an important modality in the future.

Remission With Radiation Therapy in Primary Tongue Mucosa-Associated Lymphoid Tissue Lymphoma: A Case Report.

Mucosa-associated lymphoid tissue (MALT) lymphoma arising from the tongue is a rare pathologic condition for which a standard treatment mode has not been established. This disease represents a low-grade lymphoma frequently found in the stomach but rarely in the lymphoid tissue of the tongue. Only six cases that have been reported could be retrieved. We present the case of a 79-year-old woman who manifested with a mass on her tongue. A biopsy of the mass confirmed a diagnosis of MALT lymphoma. Radiation therapy of 30.6 Gy in 17 fractions was performed, and a complete metabolic response was achieved.

Accelerated Fractionated Radiation Therapy for Localized Glottic Carcinoma.

BACKGROUND: The aim of this study is to examine the outcomes of an accelerated fractionated irradiation for N0 glottic carcinoma. METHODS: In this retrospective analysis, 29 patients with N0 glottic carcinoma treated by radiation therapy were enrolled. Thirteen patients had T1a disease, six had T1b disease, and ten had T2 disease. A fractional dose of 2.1 Gy was administered to seven patients. The total doses were 65.1 and 67.2 Gy in four and three patients, respectively. A fractional dose of 2.25 Gy was administered to 22 patients. The total doses were 63 and 67.5 Gy in 21 patients and 1 patient with T2 disease, respectively. Additionally, 13 patients underwent the use of TS-1 (80-100 mg per day). RESULTS: The median follow-up period was 33 months, and the 3-year local control rate was 95.6%. No patient had a lymph node or distant recurrence. As acute adverse events, grades 2 and 3 dermatitis were observed in 18 patients and 1 patient, and grades 2 and 3 mucositis were observed in 15 patients and 1 patient. As a late adverse event, one patient required tracheotomy because of laryngeal edema occurring. CONCLUSIONS: Accelerated fractionated irradiation may be an option in the radiation therapy of N0 glottic carcinoma because of its ability to shorten the treatment time.

Isofraxidin enhances hyperthermia­induced apoptosis via redox modification in acute monocytic leukemia U937 cells.

The cell­killing potential of most chemotherapeutic agents is enhanced by a temperature elevation. Isofraxidin (IF) is a coumarin compound widely found in plants, such as the Umbelliferae or Chloranthaceae families. IF induces anticancer effects in lung and colorectal cancer. To the best of our knowledge, the combined effects of hyperthermia (HT) and IF on heat­induced apoptosis have not been reported. Acute monocytic leukemia U937 cells were exposed to HT with or without IF pre­treatment. Apoptosis was measured by Annexin V­FITC/PI double staining assay using flow cytometry and cell viability was observed by cell counting kit assay, DNA fragmentation. The mechanism involved in the combination was explored by measuring changes in the mitochondrial membrane potential, (MMP), intracellular ROS generation, expression of apoptosis related protein, and intracellular calcium ion level. It was demonstrated that IF enhanced HT­induced apoptosis in U937 cells. The results demonstrated that combined treatment enhanced mitochondrial membrane potential loss and transient superoxide generation increased protein expression levels of caspase­3, caspase­8 and phosphorylated­JNK and intracellular calcium levels. Moreover, the role of caspases and JNK was confirmed using a pan caspase inhibitor (zVAD­FMK) and JNK inhibitor (SP600125) in U937 cells. Collectively, the data demonstrated that IF enhanced HT­induced apoptosis via a reactive oxygen species mediated mitochondria/caspase­dependent pathway in U937 cells.

Carbon-ion radiotherapy for inoperable upper tract ureteral cancer.

AIM: This study aimed to report initial results of hypofractionated carbon-ion radiotherapy (C-ion RT) for inoperable upper tract ureteral cancer. METHODS: Retrospective chart review was performed for five consecutive patients with medically inoperable ureter cancer that was treated with radical C-ion RT between December 2013 and December 2014. The median age of the patients was 80 years (range, 68-84 years). The reasons for inoperability were advanced age, post-contralateral nephrectomy, alcoholic cirrhosis, both advanced age and contralateral renal function degeneracy, and pneumonia. The median size of tumor was 2.8 cm (range, 2.2-4.0 cm). Diagnostic imaging did not identify lymph node metastases or distant metastases in any case. All patients underwent C-ion RT (52.8 Gy relative biological effectiveness; 12 fractions in 3 weeks). The clinical target volume encompassed the growth tumor volume with a 5-mm margin bilaterally; there was a 40-mm margin craniocaudally but the clinical target volume did not encompass the whole ureter. RESULTS: Within a median follow-up time of 32.9 months (range, 24-36 months), two patients died and three remained alive. Neither local recurrence nor regional lymph node metastases were observed. Secondary bladder tumor was observed in four patients, and one patient had a liver metastasis. Grade 1 hematuria was observed in two patients, and Grade 3 pyelonephritis was observed in one patient as acute toxicity. Ureteral obstruction was observed in two patients. CONCLUSION: C-ion RT might be a useful treatment option for inoperable ureter cancer.

Efficacy of immune checkpoint inhibitor treatment for head and neck mucosal melanoma recurrence in patients treated with carbon-ion radiotherapy.

BACKGROUND: Carbon-ion radiotherapy (C-ion RT) is effective for head and neck mucosal melanoma (HN-MM), including radioresistant mucosal melanoma. Melanoma also responds effectively to immune checkpoint inhibitors (ICIs). Data on the efficacy and safety of ICIs for HN-MM are insufficient. AIMS: To analyze the efficacy and safety of ICI salvage therapy in patients with HN-MM recurrence after C-ion RT. METHODS AND RESULTS: This retrospective study analyzed the medical records of 52 patients with HN-MM treated with C-ion RT between 2012 and 2020. A dose of 57.6 or 64.0 Gy (relative biological effectiveness) was provided in 16 fractions. The primary endpoint was 3-year overall survival (OS) rate. The median follow-up time was 26.8 months for all patients. A total of 29 patients had local recurrence or distant metastasis, and 16 patients who received ICI therapy. The 3-year OS rate in the ICI group (n = 16) and best supportive care group (n = 13) were 53.8% and 0.0%, respectively (p = 0.837); the difference was not statistically significant. There were no deaths after 1 year among patients who underwent ICI therapy. No adverse events associated with C-ion RT were related to or exacerbated by ICI. CONCLUSION: ICI salvage therapy is effective and safe for patients with HN-MM recurrence after C-ion RT.

Carbon-ion Radiotherapy for Inoperable Head and Neck Bone and Soft-tissue Sarcoma: Prospective Observational Study.

BACKGROUND/AIM: Bone and soft-tissue sarcomas of the head and neck have very poor prognoses. This prospective study aimed to investigate the efficacy and safety of carbon-ion radiotherapy (C-ion RT) for bone and soft-tissue sarcoma of the head and neck. PATIENTS AND METHODS: The present study was a prospective clinical study that included 10 consecutive patients diagnosed with bone and soft-tissue sarcoma of the head and neck who were treated with C-ion RT between 2012 and 2018 at our institution. C-Ion RT consisted of 70.4 Gy (relative biological effectiveness) in 16 fractions. RESULTS: The 3-year local control, overall survival, and progression-free survival rates for patients overall were 72.9%, 77.8%, and 36%, respectively. CONCLUSION: The present study demonstrated the efficacy of C-ion RT for bone and soft-tissue sarcoma of the head and neck; adverse events were within the expected range.

Stereotactic body radiotherapy for adenoid cystic carcinoma metastatic to the lung: a case report.

BACKGROUND: Adenoid cystic carcinoma (ACC) is a rare malignant tumor involving mostly the head and neck region, and frequently the salivary glands. The development of lung metastasis after treatment of the primary tumor is a common occurrence in ACC. Although lung metastases show a slow rate of growth, approximately 10% of patients die from distant metastases. The radioresistance of ACC limits the efficacy of conventional radiotherapy for lung metastases, and the optimal dose remains to be determined. Stereotactic body radiotherapy (SBRT) using CyberKnife can deliver a high dose to the lung tumor, while sparing the surrounding normal lung tissues, leading to favorable local control in non-squamous cell lung cancer and metastatic lung tumors. We report a case of lung metastases from ACC treated successfully with SBRT using CyberKnife. CASE PRESENTATION: A 76-year-old Japanese man with ACC who was treated with carbon ion radiotherapy for a primary oropharynx tumor presented with three metastatic lesions in the lung. The tumor masses were located in the right upper, right lower, and left lower lobes of the lungs. Surgical resection was not indicated because of the presence of multiple tumors. The patient underwent SBRT at 60 Gy in 10 sequential fractions for each tumor. The biologically effective dose based on an alpha/beta ratio of 2 Gy was 240 Gy per tumor. The percentage of the total lung volume irradiated with >20 Gy was 4.9%, 3.2%, and 2.6% for each tumor. The patient developed acute radiation pneumonitis during the initial therapy, which resolved at 6 months after the CyberKnife treatment. At 21 months after the first CyberKnife treatment, three tumors showed no signs of recurrence. No late toxicity was observed. CONCLUSIONS: SBRT using CyberKnife is an effective and feasible approach to the management of multiple lung metastases of ACC.

Clinical features and dosimetric evaluation of carbon ion radiation-induced osteoradionecrosis of mandible in head and neck tumors.

BACKGROUND AND PURPOSE: Osteoradionecrosis (ORN) affects the patient's quality of life by making eating and maintaining oral hygiene painful. This study aimed to analyze carbon ion radiotherapy (C-ion RT)-induced ORN of the mandible. MATERIALS AND METHODS: A retrospective study of 199 patients with head and neck tumors treated with C-ion RT was performed from 2010 to 2019. Only 11 patients with tumors located in the oropharynx and floor of the mouth were analyzed. C-ion RT consisted of 57.6 Gy or 64.0 Gy (relative biological effectiveness) in 16 fractions. The mandible was analyzed for magnetic resonance imaging (MRI) changes and bone exposure. The relationship between the radiation dose and ORN of the mandible was analyzed. RESULTS: Five patients (45.5%) had ORN of the mandible. The median follow-up time was 68 months. The median onset times based on MRI changes and bone exposure were 9 and 15 months, respectively. Doses of 30 Gy (relative biological effectiveness) to the mandible and teeth showed the most significant effect, causing ORN at 29.5 ± 6.7 cc and 3.9 ± 1.8 cc, respectively, with cut-off values at 16.5 cc (p = 0.002) and 1.8 cc (p = 0.0059), respectively. CONCLUSION: This is the first study reporting the incidence, onset time, and risk-predictive dosimetry parameters of C-ion RT-induced ORN of the mandible. Our study will be useful for establishing clinical strategies for C-ion RT to the head and neck near the mandible.

Efficacy and Safety of Carbon-Ion Radiotherapy for Stage I Non-Small Cell Lung Cancer with Coexisting Interstitial Lung Disease.

Interstitial lung disease (ILD) is a risk factor both for the development and treatment failure of lung cancer. In this retrospective study, we analyzed the outcome of carbon-ion radiotherapy (CIRT) in 124 patients with clinical stage I non-small cell lung cancer (NSCLC), of whom 26 (21%) had radiological signs of pre-existing ILD. ILD was diagnosed retrospectively by a pulmonologist based on critical review of CT-scans. Ninety-eight patients were assigned to the non-ILD group and 26 patients (21.0%) to the ILD group. There were significant differences in pre-treatment KL-6 values between the two groups. The three year overall survival and cause-specific survival rates were 83.2% and 90.7%, respectively, in the non-ILD group, and 59.7% and 59.7%, respectively, in the ILD group (between-group differences, p = 0.002 and p < 0.001). Radiation pneumonitis worse than Grade 2 was observed in three patients (3.0%) in the non-ILD group and two patients (7.6%) in the ILD group (p = 0.29). There were no cases of acute exacerbation in the ILD group. CIRT for stage I NSCLC was as safe in the ILD group as in the non-ILD group. Coexisting ILD was a poor prognostic factor in CIRT for clinical stage I lung cancer.

Multicenter Study of Carbon-ion Radiotherapy for Oropharyngeal Non-squamous Cell Carcinoma.

BACKGROUND/AIM: To evaluate treatment outcomes of carbon-ion radiotherapy for oropharyngeal non-squamous cell carcinoma at four carbon-ion facilities in Japan. PATIENTS AND METHODS: We retrospectively analyzed the cases of 33 patients with oropharyngeal non-squamous cell carcinoma who were treated with carbon-ion radiotherapy between November 2003 and December 2014. RESULTS: The histology included adenoid cystic carcinoma (n=25) and mucosal malignant melanoma (n=4). No patients had T1 tumors; 23 had T4 tumors. The most-commonly prescribed dose was 57.6 Gy (RBE) in 16 fractions. The median follow-up period was 34.8 months (range=4.2-122.8 months). The 3-year local control and overall survival rates were 94.7% and 90.7%, respectively. There were no grade ≥4 acute adverse events. Only one patient experienced a grade ≥4 late adverse event. No patients experienced late adverse events related to swallowing or salivary function. CONCLUSION: Carbon-ion radiotherapy appears to be a promising treatment option for oropharyngeal non-squamous cell carcinoma.

Comparison of Oncologic Outcomes between Carbon Ion Radiotherapy and Stereotactic Body Radiotherapy for Early-Stage Non-Small Cell Lung Cancer.

Lung cancer is a leading cause of cancer-related deaths worldwide. Radiotherapy is an essential treatment modality for inoperable non-small cell lung cancer (NSCLC). Stereotactic body radiotherapy (SBRT) is the standard treatment for early-stage NSCLC because of its favorable local control (LC) compared to conventional radiotherapy. Carbon ion radiotherapy (CIRT) is a kind of external beam radiotherapy characterized by a steeper dose distribution and higher biological effectiveness. Several prospective studies have shown favorable outcomes. However, there is no direct comparison study between CIRT and SBRT to determine their benefits in the management of early-stage NSCLC. Thus, we conducted a retrospective, single-institutional, and contemporaneous comparison study, including propensity score-adjusted analyses, to clarify the differences in oncologic outcomes. The 3-year overall survival (OS) was 80.1% in CIRT and 71.6% in SBRT (p = 0.0077). The 3-year LC was 87.7% in the CIRT group and 79.1% in the SBRT group (p = 0.037). Multivariable analyses showed favorable OS and LC in the CIRT group (hazard risk [HR] = 0.41, p = 0.047; HR = 0.30, p = 0.040, respectively). Log-rank tests after propensity score matching and Cox regression analyses using propensity score confirmed these results. These data provided a positive efficacy profile of CIRT for early-stage NSCLC.

Therapeutic effect of linac-based stereotactic radiotherapy with a micro-multileaf collimator for the treatment of patients with brain metastases from lung cancer.

OBJECTIVE: To assess the efficacy of hypofractionated linac-based stereotactic radiotherapy with a micro-multileaf collimator (mMLC) in lung cancer patients with brain metastases. METHODS: Seventy-eight lesions of brain metastases in 49 lung cancer patients treated by stereotactic radiotherapy between September 2003 and December 2006 were analyzed. In the treatment planning, the planning target volume (PTV) was defined as an enhanced lesion plus 3 mm margin. A total dose of 39-42 Gy in three fractions was delivered to the isocenters of the PTV. RESULTS: The median survival time after stereotactic radiotherapy was 17.4 months. The 1- and 2-year survival rates were 61% and 32%, respectively. The presence of extracranial tumors, the pre-treatment performance status, and the Radiation Therapy Oncology Group recursive partitioning analysis class were significant prognostic factors. The 1- and 2-year local recurrence rates were 14% and 17%, respectively, with no serious acute toxic effect. Injuries involving brain necrosis were observed in six patients. New brain metastases or meningeal carcinomatosis was seen in more than half of the patients following treatment with stereotactic radiotherapy. CONCLUSIONS: Hypofactionated stereotactic radiotherapy with mMLC is considered to be an effective and safe modality for the treatment of brain metastases in lung cancer patients.

Skin Dose Reduction by Layer-Stacking Irradiation in Carbon Ion Radiotherapy for Parotid Tumors.

Background: Layer-stacking irradiation (LSI) results in the accumulation of multiple small spread-out Bragg peaks along the beam direction. Although the superiority of LSI to conventional passive irradiation (CPI) regarding normal tissue sparing is theoretically evident, the clinical benefit of LSI has not been demonstrated. Here, we compared LSI with CPI using the same treatment planning-computed tomography images used for carbon ion radiotherapy (CIRT). Methods: Twenty-one parotid tumors were analyzed. The clinical target volume (CTV) 1 and CTV2 encompassed the parotid grand and the tumor, respectively. CTV1 and CTV2 received 36 Gy (RBE: relative biological effectiveness) in nine fractions and 64 Gy (RBE) in 16 fractions, respectively, using either LSI or CPI. CTV coverage was assessed by DX%, which is the dose covering at least X% of the target volume. Skin dose was assessed by SX, which is the skin surface area receiving at least X Gy (RBE). Results: For CTV1 and CTV2, there were no significant differences in D2% between LSI and CPI. D50% and D98% were slightly higher for CPI; however, the absolute difference between the two methods was <3%. S10-S60 (in increments of 10) were significantly lower for LSI than for CPI (P < 0.001 for all parameters). LSI was associated with a significant trend toward dose reduction at the skin area irradiated with a higher dose by CPI (P < 0.001). Conclusions: LSI achieved better skin sparing than CPI without sacrificing target volume coverage in parotid tumor patients.