Carbon-Ion Radiotherapy for Postoperative Locoregional Recurrence of Pancreatic Cancer

PURPOSE/OBJECTIVE(S)

To evaluate the efficacy and safety of carbon-ion radiotherapy (CIRT) for patients with locoregional recurrence after surgery for pancreatic cancer.

MATERIALS/METHODS

A total of 32 patients, who underwent CIRT for locoregional recurrence after surgery for pancreatic cancer between January 2015 and July 2022, were retrospectively analyzed. The total dose of CIRT was 55.2 Gy (RBE) in 12 fractions. Concurrent chemotherapy included gemcitabine for 17 patients and S-1 for 3 patients. The overall survival (OS), local control (LC), progression free survival (PFS), and toxicity were evaluated.

RESULTS

The median follow-up time from the initiation of CIRT was 21.4 months. The 1- and 2-year OS were 84.2 and 55.3%, respectively. The median survival were 24.2 months. The 1- and 2-year PFS were 40.7 and 14.8%, respectively, with a median PFS of 9.9 months. The 1- and 2-year LC were 100 and 50.2 %, respectively. 4 patients experienced grade 3 acute toxicities: hematologic toxicity in 2 patients, anorexia in 1 patient and gastric ulcer/bleeding in 1 patient. The patients with grade 3 gastric ulcer/bleeding underwent blood transfusion and recovered quickly. There was no grade 4 or 5 acute toxicity. In terms of late toxicity, no grade 3 or greater toxicity was observed.

CONCLUSION

CIRT for postoperative locoregional recurrence of pancreatic cancer resulted in relatively long survival with acceptable toxicity. CIRT may be one of the choices of treatment for patients with this disease.

Temperature dependent local inhomogeneity and magnetic moments of (Li1-xFex)OHFeSe superconductors

We have combined the extended X-ray absorption fine structure (EXAFS) and X-ray emission spectroscopy (XES) to investigate the local structure and the local iron magnetic moments of (Li_1-xFe_x)OHFeSe (x∼0.2) superconductors. The local structure, studied by Fe K-edge EXAFS measurements, is found to be inhomogeneous that is characterized by different Fe-Se bond lengths. The inhomogeneous phase exhibits a peculiar temperature dependence with lattice anomalies in the local structural parameters at the critical temperature T_c (36 K) and at the spin density wave (SDW) transition temperature T_N (130 K). Fe Kβ XES shows iron to be in a low spin state with the local Fe magnetic moment evolving anomalously as a function of temperature. Apart from a quantitative measurement of the local structure of (Li_1-xFe_x)OHFeSe, providing direct evidence of nanoscale inhomogeneity, the results provide further evidence of the vital role that the coupled electronic, lattice and magnetic degrees of freedom play in the iron-based superconductors.

The local structure of self-doped BiS2-based layered systems as a function of temperature

We have studied the local structure of layered Eu(La,Ce)FBiS2 compounds by Bi L3-edge extended X-ray absorption fine structure (EXAFS) measurements as a function of temperature. We find that the BiS2 sub-lattice is largely distorted in EuFBiS2, characterized by two different in-plane Bi-S1 distances. The distortion is marginally affected by partial substitutions of Ce (Eu0.5Ce0.5FBiS2) and La (Eu0.5La0.5FBiS2). The temperature dependence of the local structure distortion reveals an indication of possible charge density wave like instability in the pristine self-doped EuFBiS2 and Ce substituted Eu0.5Ce0.5FBiS2 while it is suppressed in La substituted Eu0.5La0.5FBiS2. In compounds with higher superconducting transition temperature, the axial Bi-S2 bond distance is elongated and the related bond stiffness decreased, suggesting some important role of this in the charge transfer mechanism for self-doping in the active BiS2-layer. In-plane Bi-S1 distances are generally softer than the axial Bi-S2 distance and they suffer further softening by the substitutions. The results are discussed in relation to an important role of the Bi defect chemistry driven asymmetric local environment in the physical properties of these materials.

Temperature dependent local atomic displacements in NaSn2As2 system

NaSn₂As₂ is mechanically exfoliable layered van der Waals (vdW) Zintl phase that is getting interesting due to its low thermal conductivity and recently observed superconductivity. Here, we have investigated the temperature dependent local structure of NaSn₂As₂ by a combined analysis of As K-edge and Sn K-edge extended x-ray absorption fine structure measurements. The system is intrinsically disordered with the interatomic distances largely consistent to those estimated by average structure measurements. The stretching force constants of different bond distances have been determined using temperature dependent mean square relative displacements. The Sn-As distance is the strongest bond in this system, having covalent nature, unlike the weaker interlayer distances which are characterized by vdW type bonding. Among them, As-Na distance is slightly weaker than Sn-Sn(i) below  ∼200 K and tends to get stronger above this temperature. The anomalous behavior of As-Na bond suggests that the mechanical exfoliation in this system is likely to be temperature dependent. The anomaly in the interlayer atomic correlations may be due to a charge density wave-like instability around this temperature, indicated by earlier experiments. The local structure and disorder are discussed in relation to the physical properties of NaSn₂As₂.

Asymmetric Phosphorus Incorporation in Homoepitaxial P-Doped (111) Diamond Revealed by Photoelectron Holography

Diamond has two crystallographically inequivalent sites in the unit cell. In doped diamond, dopant occupation in the two sites is expected to be equal. Nevertheless, preferential dopant occupation during growth under nonequilibrium conditions is of fundamental importance, for example, to enhance the properties of nitrogen-vacancy (N-V) centers; therefore, this is a promising candidate for a qubit. However, the lack of suitable experimental techniques has made it difficult to study the crystal- and chemical-site-resolved local structures of dopants. Here, we confirm the identity of two chemical sites with asymmetric dopant incorporation in the diamond structure, via the photoelectron holography (PEH) of heavily phosphorus (P)-doped diamond prepared by chemical vapor deposition. One is substitutionally incorporated P with preferential site occupations and the other can be attributed to a PV split vacancy complex with preferential orientation. The present study shows that PEH is a valuable technique to study the local structures around dopants with a resolution of crystallographically inequivalent but energetically equivalent sites/orientations. Such information provides strategies to improve the properties of dopant related-complexes in which alignment is crucial for sensing of magnetic field or quantum spin register using N-V centers in diamond.

Suppression of structural instability in LaOBiS2-x Se x by Se substitution

Isovalent substitution of S by Se in LaOBiS_2-x Se _x has a substantial effect on its electronic structure and thermoelectric properties. To investigate the possible role of BiS₂ structural instability, we have studied the local structure of LaOBiS_2-x Se _x ([Formula: see text]) using temperature dependent Bi L₃-edge extended x-ray absorption fine structure measurements. The results reveal that the local structure of the two compounds is significantly different. The BiS₂ sub-lattice is largely distorted in LaOBiS₂ (x  =  0.0), with two in-plane Bi-S1 distances separated by  ∼0.4 Å instead LaOBiSSe (x  =  1.0) showing much smaller local disorder with two in-plane Bi-Se distances in the plane being separated by  ∼0.2 Å. Temperature dependent study shows that the two Bi-S1 distances are characterized by different bond strength in LaOBiS₂ (x  =  0.0) while it is similar for the Bi-Se distances in LaOBiSSe (x  =  1.0). The out of plane Bi-S2 bond is harder in LaOBiSSe indicating that the structural instability of BiS₂ layer has large effect on the out-of-plane atomic correlations. The results suggest that the local structure of LaOBiS_2-x Se _x is an important factor to describe differing electronic and thermal transport of the two compounds.

A single institutional experience of combined carbon-ion radiotherapy and chemotherapy for unresectable locally advanced pancreatic cancer

PURPOSE

The aim of this study was to evaluate the efficacy and safety of carbon-ion radiotherapy (C-ion RT) for unresectable locally advanced pancreatic cancer (LAPC).

METHODS AND MATERIALS

Patients with LAPC treated with definitive C-ion RT between April 2014 and July 2017 were analyzed retrospectively. The prescribed dose was 55.2 Gy (relative biological effectiveness [RBE] weighted absorbed dose) in 12 fractions. Overall survival (OS), local control (LC), progression free survival (PFS), and toxicity were evaluated.

RESULTS

Sixty-four patients were enrolled. All patients completed planned course of C-ion RT. The median follow-up time for survivors from the initiation of C-ion RT was 24.4 months (range, 5.1-46.1 months). Median survival time was 25.1 months. Two-year OS, LC, and PFS were 53% (95% confidence interval [CI], 39%-66%), 82% (95% CI, 66%-91%), and 23% (95% CI, 14%-36%), respectively. Four patients experienced acute grade 3 toxicities including 3 gastrointestinal (GI) toxicities. There was no grade 3 or more late toxicity.

CONCLUSIONS

The clinical results of C-ion RT for LAPC at our institution were comparable to those of a recent multi-institutional analysis.

A case of the cirrhotic patient performed living donor liver transplantation after carbon-ion radiotherapy for hepatocellular carcinoma

The patient was a 50-year-old female with an initial diagnosis of a single hepatocellular carcinoma in liver cirrhosis. The tumor was located in the posterior liver segment (S7) and measured 5 cm with a rapid growth rate and portal invasion. The pre-treatment Child-Pugh (C-P) was grade A (six points). The total prescribed dose of carbon-ion radiotherapy (C-ion RT) was 60 Gy (relative biological effectiveness) given in 4 fractions. Thereafter, tumor shrinkage and rapid decrease of the serum alpha-fetoprotein level were observed. At 1-year follow-up a new lesion was diagnosed in the left lobe and the underlying liver failure had worsened to C-P grade B (eight points). Thus, she was recommended to undergo living-donor liver transplantation (LDLT). The postoperative course was uneventful. At pathological examination, no viable tumor cells in the region treated with C-ion RT were detected. At the time of the last follow-up, the patient was in overall good general condition with no signs of tumor recurrence.

Metallic phase in stoichiometric CeOBiS2 revealed by space-resolved ARPES

Recently CeOBiS₂ system without any fluorine doping is found to show superconductivity posing question on its origin. Using space resolved ARPES we have found a metallic phase embedded in the morphological defects and at the sample edges of stoichiometric CeOBiS₂. While bulk of the sample is semiconducting, the embedded metallic phase is characterized by the usual electron pocket at X point, similar to the Fermi surface of doped BiS₂-based superconductors. Typical size of the observed metallic domain is larger than the superconducting correlation length of the system suggesting that the observed superconductivity in undoped CeOBiS₂ might be due to this embedded metallic phase at the defects. The results also suggest a possible way to develop new systems by manipulation of the defects in these chalcogenides with structural instability.

Abstract 4411: Loss of fructose-1,6-bisphosphatase expression induces altering glucose metabolism and tumor progression in hepatocellular carcinoma

Background:

A recent study reported the loss of gluconeogenic capacity in hepatocellular carcinoma (HCC). Fructose-1,6-bisphosphatase (FBP1), the rate-limiting enzyme in gluconeogenesis, is reduced in expression in some cancers. However, the role of FBP1 in altered glucose metabolism in HCC was unclear. Therefore, the objective of this study was to examine the function and clinical significance of FBP1 expression in HCC.

Materials and Methods:

First, three independent cohorts totaling 594 cases of HCC (118 real-time RT-PCR data from our institution, 242 expression array data from GSE14520, and 234 RNA-sequencing data from The Cancer Genome Atlas (TCGA)) were analyzed to address clinical significance. Data from methylation arrays, SNP arrays, and whole-exome sequencing were also analyzed to investigate the regulation of FBP1 expression in the TCGA cohort.

Second, we analyzed mRNA expression, promoter methylation, and DNA copy number profiles of 967 human cancer cell lines, including 27 liver cancer, in the Cancer Cell Line Encyclopedia.

Third, we established HCC cell lines stably expressing FBP1 or empty vector control. We performed sphere formation assay and xenograft studies to evaluate the role of FBP1 on HCC progression. Furthermore, in order to assess the effect of FBP1 on altered glucose metabolism, isotopomer distribution analysis was performed using [U-13C] glucose.

Finally, to validate the effects of FBP1 expression on survival, risk of recurrence, and glucose metabolism, we performed gene set enrichment analysis (GSEA).

Results:

Lower FBP1 expression associated with advanced tumor stage, poor overall survival (OS), and poor recurrence-free survival (RFS) in three independent HCC cohorts. For either OS or RFS in each cohort, this prognostic impact persisted, even after adjusting for tumor stage. In HCC cell lines, where endogenous FBP1 expression is low, engineering its ectopic overexpression inhibited tumor growth and intracellular glucose uptake by reducing aerobic glycolysis. In patient specimens, promoter methylation and copy-number loss of FBP1 were independently associated with decreased FBP1 expression. Similarly, FBP1 downregulation in HCC cell lines was also associated with copy-number loss. HCC specimens exhibiting low expression of FBP1 had a highly malignant phenotype, including large tumor size, poor

differentiation, impaired gluconeogenesis, and enhanced aerobic glycolysis. The effects of FBP1 expression on prognosis and glucose metabolism were confirmed by GSEA.

Conclusion:

Our findings established that FBP1 downregulation in HCC contributed to tumor progression and poor prognosis by altering glucose metabolism, and they rationalize further study of FBP1 as a prognostic biomarker and therapeutic target in HCC patients.

Citation Format: Hiroaki Wakiyama, Hidenari Hirata, Keishi Sugimachi, Takaaki Masuda, Naoki Hayashi, Yohsuke Kuroda, Shuhei Ito, Hidetoshi Eguchi, Kotaro Terashima, Katsumi Sakamoto, Masakazu Hirakawa, Hiroshi Honda, Koshi Mimori. Loss of fructose-1,6-bisphosphatase expression induces altering glucose metabolism and tumor progression in hepatocellular carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4411. doi:10.1158/1538-7445.AM2017-4411

Carbon-Ion Radiation Therapy for Pelvic Recurrence of Rectal Cancer

PURPOSE

Investigation of the treatment potential of carbon-ion radiation therapy in pelvic recurrence of rectal cancer.

METHODS AND MATERIALS

A phase 1/2 dose escalation study was performed. One hundred eighty patients (186 lesions) with locally recurrent rectal cancer were treated with carbon-ion radiation therapy (CIRT) (phase 1/2: 37 and 143 patients, respectively). The relapse locations were 71 in the presacral region, 82 in the pelvic sidewalls, 28 in the perineum, and 5 near the colorectal anastomosis. A 16-fraction in 4 weeks dose regimen was used, with total dose ranging from 67.2 to 73.6 Gy(RBE); RBE-weighted absorbed dose: 4.2 to 4.6 Gy(RBE)/fraction.

RESULTS

During phase 1, the highest total dose, 73.6 Gy(RBE), resulted in no grade >3 acute reactions in the 13 patients treated at that dose. Dose escalation was halted at this level, and this dose was used for phase 2, with no other grade >3 acute reactions observed. At 5 years, the local control and survival rates at 73.6 Gy(RBE) were 88% (95% confidence interval [CI], 80%-93%) and 59% (95% CI, 50%-68%), respectively.

CONCLUSION

Carbon-ion radiation therapy may be a safe and effective treatment option for locally recurrent rectal cancer and may serve as an alternative to surgery.

Prognostic Significance of a Minute Amount of Ascites During Chemoradiotherapy for Locally Advanced Pancreatic Cancer

AIM

The aim of this study was to investigate the clinical factors for predicting overall survival (OS) and the significance of a minute amount of ascites on computed tomography (CT) in patients with locally advanced pancreatic cancer (LAPC) treated with chemoradiotherapy (CRT).

PATIENTS AND METHODS

Between 2003 and 2011, 48 consecutive patients with LAPC were treated with CRT. Various clinical factors, including ascites, were evaluated for correlation with OS. A subset analysis of 16 patients with a minute amount of ascites was also performed.

RESULTS

The median survival duration and the 1-year OS rates were 11.5 months and 50%, respectively. A minute amount of ascites on CT and elevated carbohydrate antigen 19-9 (CA19-9) level were significantly associated with poorer OS. In 16 patients with ascites, the amount of ascites increased in the course of the disease, and these were considered to be cancerous clinically, regardless of the amount.

CONCLUSION

A minute amount of ascites and CA19-9 were important prognostic factors in CRT. Any amount of ascites was considered an early indicator of peritoneal carcinomatosis in LAPC.

Treatment Outcome of Radiotherapy for Localized Primary Ocular Adnexal MALT Lymphoma--Prognostic Effect of the AJCC Tumor-Node-Metastasis Clinical Staging System

AIM

To analyze the treatment outcome of radiotherapy for localized primary ocular adnexal mucosa-associated lymphoid tissue lymphoma (POAML) and evaluate the prognostic effect of the American Joint Committee on Cancer (AJCC) tumor-node-metastasis (TNM) clinical staging system for POAML.

PATIENTS AND METHODS

Seventy-three patients with Ann Arbor stage IE POAML who were treated with radiotherapy alone were analyzed. T-Factor based on the AJCC staging system was T1 in 28, T2 in 33 and T3 in 12 patients.

RESULTS

Out of nine patients with relapse, six had distant and three had contralateral ocular adnexal relapse. One patient died of lymphoma progression. The 5-year local control and progression-free survival (PFS) rates were 100% and 81.5%, respectively. T-Factor was not significantly associated with PFS.

CONCLUSION

Radiotherapy achieved excellent local control and survival rates for stage IE POAML. The AJCC TNM clinical staging system was not significantly predictive for PFS of stage IE POAML.

Clinical characteristics and outcome of pneumothorax after stereotactic body radiotherapy for lung tumors

BACKGOUND

We retrospectively investigated the clinical characteristics and outcome of pneumothorax after stereotactic body radiotherapy (SBRT) for lung tumors.

METHODS

Between April 2003 and July 2012, 473 patients with lung tumors were treated with SBRT. We identified 12 patients (2.5 %) with pneumothorax caused by SBRT, and evaluated the clinical features of pneumothorax.

RESULTS

All of the tumors were primary lung cancers. The severity of radiation pneumonitis was grade 1 in 10 patients and grade 2 in two patients. Nine patients had emphysema. The planning target volume and pleura overlapped in 11 patients, and the tumors were attached to the pleura in 7 patients. Rib fractures were observed in three patients before or at the same time as the diagnosis of pneumothorax. The median time to onset of pneumothorax after SBRT was 18.5 months (4-84 months). The severity of pneumothorax was grade 1 in 11 patients and grade 3 in one patient.

CONCLUSION

Although pneumothorax was a relatively rare late adverse effect after SBRT, some patients demonstrated pneumothorax after SBRT for peripheral lung tumors. Although most pneumothorax was generally tolerable and self-limiting, careful follow-up is needed.

Definitive fractionated re-irradiation for local recurrence following stereotactic body radiotherapy for primary lung cancer

AIM

To retrospectively evaluate the efficacy and safety of definitive fractionated re-irradiation for local recurrence following stereotactic body radiotherapy (SBRT) for primary lung cancer.

PATIENTS AND METHODS

Between April 2003 and December 2011, 398 patients with primary lung tumor underwent SBRT at the Kyushu University Hospital, and 46 out of these developed local recurrence after SBRT. Definitive fractionated re-irradiation was performed for 17 out of the 46 patients. The median dose of re-irradiation was 60 Gy/ 30 fractions. Concurrent chemotherapy was given to four patients.

RESULTS

The median follow-up duration was 12.6 months. At one year post-re-irradiation, local progression-free survival was 33.8%; progression-free survival, 30.9%; cause-specific survival, 79.3%; and overall survival, 74.7%. No severe adverse events were observed during the follow-up.

CONCLUSION

Definitive fractionated re-irradiation is thought to be a safe alternative therapy for local recurrence following SBRT, although its efficacy may be not entirely satisfactory.

Radiotherapy for early-stage primary ocular adnexal mucosa-associated lymphoid tissue lymphoma

BACKGROUND

Primary ocular adnexal mucosa-associated lymphoid tissue lymphoma (POAML) is a rare disease. The purpose of this study was to evaluate the treatment outcome and patterns of failure of patients with early-stage POAML treated with radiotherapy.

PATIENTS AND METHODS

From 1995 to 2008, 53 patients with early-stage POAML were reviewed. Tumors were categorized as either superficial or mass-forming type. In principle, superficial lesions (n=11) were treated with 24 Gy, while the mass-forming lesions (n=42) were irradiated with 30 Gy. The median follow-up period was 3.9 years.

RESULTS

All four cases of relapse had mass-forming lesions. The 5-year overall and progression-free survival rates were 100% and 91.5%, respectively. Although 30 patients experienced grade 2 or 3 late adverse events, no patients had radiation-related retinopathy.

CONCLUSION

Early-stage POAML can be well-controlled with radiotherapy. However, the risk of distant relapse should be noted, in particular, for mass-forming tumors.

Particle therapy using carbon ions or protons as a definitive therapy for patients with primary sacral chordoma

OBJECTIVE

This study retrospectively evaluated the efficacy and toxicity of particle therapy using carbon ions or protons for primary sacral chordomas.

METHODS

We evaluated 23 patients with primary sacral chordoma treated with carbon ion therapy (CIT) or proton therapy (PT) between July 2005 and June 2011 at the Hyogo Ion Beam Medical Center, Hyogo, Japan. The median patient age was 72 years. 14 patients were treated with 70.4 Gy equivalents (GyE) in 16 fractions and 9 were treated with 70.4 GyE in 32 fractions. CIT was used for 16 patients, and PT was used for 7 patients.

RESULTS

The median follow-up period was 38 months. At 3 years, local control (LC), overall survival (OS) and progression-free survival (PFS) for all patients were 94%, 83% and 68%, respectively. The log-rank test revealed that male sex was significantly related to better PFS (p=0.029). No other factors, including dose fractionation and ion type, were significant for LC, OS or PFS. In nine patients, ≥ Grade 3 acute dermatitis was observed, and ≥ Grade 3 late toxicities were observed in nine patients. The 32-fraction protocol reduced severe toxicities in both the acute and late phases compared with the 16-fraction protocol.

CONCLUSION

Particle therapy for patients with sacral chordoma showed favourable LC and OS. Severe toxicities were successfully reduced by modifying the dose fractionation and treatment planning in the later treatment era. Thus, this therapeutic modality should be considered useful and safe.

ADVANCES IN KNOWLEDGE

This is the first study including both CIT and PT for sacral chordomas.

Can a Belly Board Reduce Respiratory-Induced Prostate Motion in the Prone Position? — Assessed by Cine-Magnetic Resonance Imaging

The purpose of this study is to evaluate the real-time respiratory motion of the prostate and surrounding tissues/organs in the supine and prone positions and to investigate, using cine-MRI, whether a belly board can reduce respiratory-induced motion in the prone position. Cine-MRI scans were made of 13 volunteers in the supine and prone positions on a flat board and in two different prone positions using a belly board. Images in cine mode were recorded for 20 seconds. For each session, the points of interest (POIs) were located at the apex, base, mid-anterior surface and mid-posterior surface of the prostate; the tip of the seminal vesicle; the pubic symphysis; and the sacrum. The maximum range and standard deviation (SD) of the displacement from the mean value were calculated. The SDs for each of the four different positions were compared using a paired t-test. Respiratory-induced prostate motion was significantly larger in the prone position than in the supine position. However, when a belly board was used in the prone position, motion in the prostate and surrounding tissues/organs was significantly reduced. There were no significant differences between the two different positions using a belly board in any of the POIs.

Stereotactic body radiation therapy for stage I non-small cell lung cancer patients with chronic respiratory insufficiency requiring domiciliary oxygen therapy

BACKGROUND

The efficacy of stereotactic body radiation therapy (SBRT) for patients treated with domiciliary oxygen therapy is not well-known.

PATIENTS AND METHODS

We collected the clinical records of 15 patients with chronic respiratory insufficiency requiring domiciliary oxygen therapy at 1-3 l/min who were treated with SBRT for stage I non-small cell lung cancer. All patients were fixed with a thermoplastic body cast system. SBRT was given in 7-8 fields with an isocenter dose of 40-60 Gy in 4-10 fractions (median, 48 Gy in 4 fractions).

RESULTS

The overall 2-year and 5-year survival rates for all patients were 67.4% and 34.7%, while the disease-specific 2-year and 5-year survival rates were 90.0% and 72.0%, respectively. Pulmonary adverse effects were mild in the majority of the patients, although two patients had grade 2 radiation pneumonitis. The oxygen flow required increased slightly at follow-up periods greater than one year, but was still at an acceptable level.

CONCLUSION

SBRT was feasible for patients requiring domiciliary oxygen therapy.

Radiation-induced rib fractures after hypofractionated stereotactic body radiation therapy: risk factors and dose-volume relationship

PURPOSE

The purpose of this study was to clarify the incidence, the clinical risk factors, and the dose-volume relationship of radiation-induced rib fracture (RIRF) after hypofractionated stereotactic body radiation therapy (SBRT).

METHODS AND MATERIALS

One hundred sixteen patients treated with SBRT for primary or metastatic lung cancer at our institution, with at least 6 months of follow-up and no previous overlapping radiation exposure, were included in this study. To determine the clinical risk factors associated with RIRF, correlations between the incidence of RIRF and the variables, including age, sex, diagnosis, gross tumor volume diameter, rib-tumor distance, and use of steroid administration, were analyzed. Dose-volume histogram analysis was also conducted. Regarding the maximum dose, V10, V20, V30, and V40 of the rib, and the incidences of RIRF were compared between the two groups divided by the cutoff value determined by the receiver operating characteristic curves.

RESULTS

One hundred sixteen patients and 374 ribs met the inclusion criteria. Among the 116 patients, 28 patients (46 ribs) experienced RIRF. The estimated incidence of rib fracture was 37.7% at 3 years. Limited distance from the rib to the tumor (<2.0 cm) was the only significant risk factor for RIRF (p = 0.0001). Among the dosimetric parameters used for receiver operating characteristic analysis, the maximum dose showed the highest area under the curve. The 3-year estimated risk of RIRF and the determined cutoff value were 45.8% vs. 1.4% (maximum dose, ≥42.4 Gy or less), 51.6% vs. 2.0% (V40, ≥0.29 cm(3) or less), 45.8% vs. 2.2% (V30, ≥1.35 cm(3) or less), 42.0% vs. 8.5% (V20, ≥3.62 cm(3) or less), or 25.9% vs. 10.5% (V10, ≥5.03 cm(3) or less).

CONCLUSIONS

The incidence of RIRF after hypofractionated SBRT is relatively high. The maximum dose and high-dose volume are strongly correlated with RIRF.

Successful hyperbaric oxygen therapy for laryngeal radionecrosis after chemoradiotherapy for mesopharyngeal cancer: case report and literature review

Laryngeal radionecrosis is one of the most troublesome late complications of radiotherapy, because it is frequently resistant to treatment and laryngectomy is required in the worst case. Here, we report a case of laryngeal radionecrosis, successfully treated by use of hyperbaric oxygen (HBO) therapy, in which laryngectomy was avoided. A 67-year-old male received radical chemoradiotherapy (CRT) for mesopharyngeal cancer, which included radiotherapy with a total dose of 71.4 Gy/38 Fr and chemotherapy with CDDP + S-1. He developed dyspnea and throat pain 9 months after completion of CRT. Laryngoscopy revealed vocal cord impairment because of severe laryngeal edema. He was diagnosed as having laryngeal radionecrosis and initially received conservative therapy combined with antibiotics, steroids, and prostaglandins. Because his dyspnea was persistent despite this treatment, HBO therapy was administered 20 times, and resulted in complete remission of the dyspnea. HBO therapy, therefore, is regarded as an effective conservative therapeutic option for laryngeal radionecrosis.

Esophageal stenosis associated with tumor regression in radiotherapy for esophageal cancer: frequency and prediction

PURPOSE

To determine clinical factors for predicting the frequency and severity of esophageal stenosis associated with tumor regression in radiotherapy for esophageal cancer.

METHODS AND MATERIALS

The study group consisted of 109 patients with esophageal cancer of T1-4 and Stage I-III who were treated with definitive radiotherapy and achieved a complete response of their primary lesion at Kyushu University Hospital between January 1998 and December 2007. Esophageal stenosis was evaluated using esophagographic images within 3 months after completion of radiotherapy. We investigated the correlation between esophageal stenosis after radiotherapy and each of the clinical factors with regard to tumors and therapy. For validation of the correlative factors for esophageal stenosis, an artificial neural network was used to predict the esophageal stenotic ratio.

RESULTS

Esophageal stenosis tended to be more severe and more frequent in T3-4 cases than in T1-2 cases. Esophageal stenosis in cases with full circumference involvement tended to be more severe and more frequent than that in cases without full circumference involvement. Increases in wall thickness tended to be associated with increases in esophageal stenosis severity and frequency. In the multivariate analysis, T stage, extent of involved circumference, and wall thickness of the tumor region were significantly correlated to esophageal stenosis (p = 0.031, p < 0.0001, and p = 0.0011, respectively). The esophageal stenotic ratio predicted by the artificial neural network, which learned these three factors, was significantly correlated to the actual observed stenotic ratio, with a correlation coefficient of 0.864 (p < 0.001).

CONCLUSION

Our study suggested that T stage, extent of involved circumference, and esophageal wall thickness of the tumor region were useful to predict the frequency and severity of esophageal stenosis associated with tumor regression in radiotherapy for esophageal cancer.