Atsushi Musha

Prediction of Acute Radiation Mucositis using an Oral Mucosal Dose Surface Model in Carbon Ion Radiotherapy for Head and Neck Tumors.

Purpose To evaluate the dose-response relationship for development of acute radiation mucositis (ARM) using an oral mucosal dose surface model (OMDS-model) in carbon ion radiotherapy (C-ion RT) for head and neck tumors. Methods Thirty-nine patients receiving C-ion RT for head and neck cancer were evaluated for ARM (once per week for 6 weeks) according to the Common Terminology Criteria for Adverse Events (CTCAE), version 4.0, and the Radiation Therapy Oncology Group (RTOG) scoring systems. The irradiation schedule typically used was 64 Gy [relative biological effectiveness (RBE)] in 16 fractions for 4 weeks. Maximum point doses in the palate and tongue were compared with ARM in each patient. Results The location of the ARM coincided with the high-dose area in the OMDS-model. There was a clear dose-response relationship between maximum point dose and ARM grade assessed using the RTOG criteria but not the CTCAE. The threshold doses for grade 2–3 ARM in the palate and tongue were 43.0 Gy(RBE) and 54.3 Gy(RBE), respectively. Conclusions The OMDS-model was useful for predicting the location and severity of ARM. Maximum point doses in the model correlated well with grade 2–3 ARM.

Long-term pathological and immunohistochemical features in the liver after intraoperative whole-liver irradiation in rats

Radiation therapy (RT) has become particularly important recently for treatment of liver tumors, but there are few experimental investigations pertaining to radiation-induced liver injuries over long-term follow-up periods. Thus, the present study examined pathological liver features over a 10-month period using an intraoperative whole-liver irradiation model. Liver function tests were performed in blood samples, whereas cell death, cell proliferation, and fibrotic changes were evaluated pathologically in liver tissues, which were collected from irradiated rats 24 h, 1, 2, 4 and 40 weeks following administration of single irradiation doses of 0 (control), 15 or 30 Gy. The impaired liver function, increased hepatocyte number, and decreased apoptotic cell proportion observed in the 15 Gy group, but not the 30 Gy group, returned to control group levels after 40 weeks; however, the Ki-67 indexes in the 15 Gy group were still higher than those in the control group after 40 weeks. Azan staining showed a fibrotic pattern in the irradiated liver in the 30 Gy group only, but the expression levels of alpha smooth muscle actin (α-SMA) and transforming growth factor-beta 1 (TGF-β1) in both the 15 and 30 Gy groups were significantly higher than those in the control group (P < 0.05). There were differences in the pathological features of the irradiated livers between the 15 Gy and 30 Gy groups, but TGF-β1 and α-SMA expression patterns supported the gradual progression of radiation-induced liver fibrosis in both groups. These findings will be useful in the future development of protective drugs for radiation-induced liver injury.

Synergistic effect of heat shock protein 90 inhibitor, 17-allylamino-17- demethoxygeldanamycin and X-rays, but not carbon-ion beams, on lethality in human oral squamous cell carcinoma cells

The purpose of this study is to clarify the effect of a heat shock protein 90 inhibitor, 17-allylamino-17-demethoxygeldanamycin (17-AAG), in combination with X-rays or carbon-ion beams on cell killing in human oral squamous cell carcinoma LMF4 cells. Cell survival was measured by colony formation assay. Cell-cycle distribution was analyzed by flow cytometry. Expression of DNA repair-related proteins was investigated by western blotting. The results showed 17-AAG to have synergistic effects on cell lethality with X-rays, but not with carbon-ion beams. The 17-AAG decreased G2/M arrest induced by X-rays, but not by carbon-ion beams. Both X-ray and carbon-ion irradiation up-regulated expression of non-homologous end-joining-associated proteins, Ku70 and Ku80, but 17-AAG inhibited only X-ray-induced up-regulation of these proteins. These results show that 17-AAG with X-rays releases G2/M phase arrest; cells carrying misrepaired DNA damage then move on to the G1 phase. We demonstrate, for the first time, that the radiosensitization effect of 17-AAG is not seen with carbon-ion beams because 17-AAG does not affect these changes.

Radiosensitizing effect of carboplatin and paclitaxel to carbon-ion beam irradiation in the non-small-cell lung cancer cell line H460

Abstract The present study investigated the ability of carboplatin and paclitaxel to sensitize human non-small-cell lung cancer (NSCLC) cells to carbon-ion beam irradiation. NSCLC H460 cells treated with carboplatin or paclitaxel were irradiated with X-rays or carbon-ion beams, and radiosensitivity was evaluated by clonogenic survival assay. Cell proliferation was determined by counting the number of viable cells using Trypan blue. Apoptosis and senescence were evaluated by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining and senescence-associated β-galactosidase (SA-β-gal) staining, respectively. The expression of cleaved caspase-3, Bax, p53 and p21 was analyzed by western blotting. Clonogenic survival assays demonstrated a synergistic radiosensitizing effect of carboplatin and paclitaxel with carbon-ion beams; the sensitizer enhancement ratios (SERs) at the dose giving a 10% survival fraction (D10) were 1.21 and 1.22, respectively. Similarly, carboplatin and paclitaxel showed a radiosensitizing effect with X-rays; the SERs were 1.41 and 1.29, respectively. Cell proliferation assays validated the radiosensitizing effect of carboplatin and paclitaxel with both carbon-ion beam and X-ray irradiation. Carboplatin and paclitaxel treatment combined with carbon-ion beams increased TUNEL-positive cells and the expression of cleaved caspase-3 and Bax, indicating the enhancement of apoptosis. The combined treatment also increased SA-β-gal-positive cells and the expression of p53 and p21, indicating the enhancement of senescence. In summary, carboplatin and paclitaxel radiosensitized H460 cells to carbon-ion beam irradiation by enhancing irradiation-induced apoptosis and senescence.

Evaluation of therapeutic gain for fractionated carbon-ion radiotherapy using the tumor growth delay and crypt survival assays

BACKGROUND AND PURPOSE The aim of the study was to evaluate the therapeutic gain of carbon ion (C-ion) radiotherapy using a mouse model. MATERIALS AND METHODS Transplanted fibrosarcoma (NFSa) growing in C3H/He mice and murine small intestine were irradiated with 290 MeV/nucleon C-ion beams (C-ions) in 1-12 fractions separated by 4h. The cell killing efficiencies of C-ions were measured using jejunum crypt survival and tumor growth delay (TGD) assays. RESULTS The equieffect dose for crypt survival and TGD increased with increasing number of fractions after X-rays and 20 keV/μm C-ions, whereas TGD after 77 keV/μm C-ions rather decreased. Crypts showed stronger LET-dependent increase in α terms than the tumor while β terms less depended on LET irrespective of tissues. Therapeutic gain factor, i.e., a ratio of tumor RBE over crypt RBE, of 77 keV/μm C-ions was more than unity at any doses while that of 20 keV/μm C-ions increased with an increase in dose per fraction. CONCLUSIONS These specific data imply that use of large dose per fraction would be suitable for C-ion radiotherapy irrespective of LET from the point of view of therapeutic gain, though small dose per fraction by high-LET radiation decreases total dose for tumor.

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.

Clinicopathological investigation of odontogenic fibroma in tuberous sclerosis complex

Tuberous sclerosis complex (TSC) is an autosomal dominant inherited disease characterized by systemic hamartoma and diverse systemic features. TSC1 and TSC2 are the causative genes, and mental retardation, epileptic seizures, and facial angiofibroma develop in many patients with the disease. The case of a patient with TSC who developed a central odontogenic fibroma of the mandible is reported here. The patient was a 21-year-old woman who was referred with a swelling of the labial gingiva in the region of the right lower lateral incisor and canine. Dental radiography revealed a multilocular radiolucent region with a clear boundary. The right lower lateral incisor and canine were continuous with the lesion and thus were excised en bloc. The lesion was encapsulated and easily dissected. The diagnosis on immunohistological staining was odontogenic fibroma without an epithelial component. TSC1/2 gene mutation causes abnormal activation of mammalian target of rapamycin (mTOR) downstream of the PI3K-AKT pathway. The odontogenic fibroma in this patient was positive for mTOR, suggesting that the development of the odontogenic fibroma was the result of abnormal activation of mTOR, as in angiofibroma. The clinical course of this patient is presented and the developmental mechanism of central odontogenic fibroma is discussed.

Granular cell tumors of the tongue: fibroma or schwannoma

BackgroundGranular cell tumors are benign lesions that typically occur in the oral cavity, but can also be found in other sites. However, the characteristics of these tumors are unclear. Thus, the present study aimed to investigate the immunohistological characteristics of these tumors of the tongue.MethodsSeven patients were treated for granular cell tumors of the tongue at our institution during 2003–2017. Paraffin-embedded specimens were available for all cases; thus, retrospective immunohistochemical analyses were performed.ResultsAll cases exhibited cytoplasmic acidophilic granules in the muscle layer of the tumor. Both the normal nerve cells and tumor cells also stained positive for PGP9.5, NSE, calretinin, and GFAP. A nucleus of tumor cells was typically present in the margin. The PAS-positive granules were also positive for CD68 (a lysozyme glycoprotein marker). Various sizes of nerve fibers were observed in each tumor, and granular cells were observed in the nerve fibers of a representative case.ConclusionsBased on our immunohistological findings, granular cell tumors may be derived from Schwann cells, and the presence of CD68 indicates that Wallerian degeneration after nerve injury may be a contributor to tumor formation. Thus, a safe surgical margin is needed to detect the infiltrative growth of granular cell tumors.

Dose–volume histogram analysis of brainstem necrosis in head and neck tumors treated using carbon-ion radiotherapy

BACKGROUND AND PURPOSE We aimed to evaluate the relationship between brainstem necrosis and dose-volume histograms in patients with head and neck tumors after carbon-ion radiotherapy. MATERIAL AND METHODS We evaluated 85 patients with head and neck tumors who underwent carbon-ion radiotherapy and were followed-up for ≥12months. Brainstem necrosis was evaluated using the Common Terminology Criteria for Adverse Events (version 4.0). RESULTS The median follow-up was 24months, and four patients developed grade 1 brainstem necrosis, with 2-year and 3-year cumulative rates of 2.8% and 6.5%, respectively. Receiver operating characteristic curve analysis revealed the following significant cut-off values: a maximum brainstem dose of 48Gy (relative biological effectiveness [RBE]), D1cm3 of 27Gy (RBE), V40Gy (RBE) of 0.1cm3, V30Gy (RBE) of 0.7cm3, and V20Gy (RBE) of 1.4cm3. Multivariate analysis revealed that V30Gy (RBE) was most significantly associated with brainstem necrosis. The 2-year cumulative rates were 33% and 0% for V30Gy (RBE) of ≥0.7cm3 and <0.7cm3, respectively (p<0.001). CONCLUSIONS The present study indicated that the dose constraints might help minimize brainstem necrosis after carbon-ion radiotherapy.

Oral mucosal melanoma treated with carbon ion radiotherapy: a case report

BackgroundOral mucosal melanoma is a rare disease with a relatively poor prognosis. Carbon ion radiotherapy has been shown to be effective against radiotherapy-resistant tumors owing to its excellent dose concentration and high biological effect. Case presentationOur patient was a 66-year-old Japanese man with oral mucosal melanoma of his right maxillary gingiva (T4aN0M0). He received carbon ion radiotherapy at 57.6 Gy (relative biological effectiveness) in 16 fractions for 4 weeks. Concomitant chemotherapy (dacarbazine + nimustine + vincristine) was administered at the same time as carbon ion radiotherapy initiation. Two courses of adjuvant chemotherapy were given after carbon ion radiotherapy. Although he experienced grade 2 acute oral mucositis, his symptoms improved within a few weeks of undergoing carbon ion radiotherapy. He was alive at the time of reporting, 35 months after treatment, without any recurrence. Late toxicity has not been observed.ConclusionsCarbon ion radiotherapy for oral mucosal melanoma resulted in a good local effect.