A comparison of chromosome repair kinetics in G(0) and G(1) reveals that enhanced repair fidelity under noncycling conditions accounts for increased potentially lethal damage repair

Potentially lethal damage (PLD) and its repair were studied in confluent human fibroblasts by analyzing the kinetics of chromosome break rejoining and misrejoining in irradiated cells that were either held in noncycling G(0) phase or allowed to enter G(1) phase of the cell cycle immediately after 6 Gy irradiation. Virally mediated premature chromosome condensation (PCC) methods were combined with fluorescence in situ hybridization (FISH) to study chromosomal aberrations in interphase. Flow cytometry revealed that the vast majority of cells had not yet entered S phase 15 h after release from G(0). By this time some 95% of initially produced prematurely condensed chromosome breaks had rejoined, indicating that most repair processes occurred during G(1). The rejoining kinetics of prematurely condensed chromosome breaks was similar for each culture condition. However, under noncycling conditions misrepair peaked at 0.55 exchanges per cell, while under cycling conditions (G(1)) it peaked at 1.1 exchanges per cell. At 12 h postirradiation, complex-type exchanges were sevenfold more abundant for cycling cells (G(1)) than for noncycling cells (G(0)). Since most repair in G(0)/G(1) occurs via the non-homologous end-joining (NHEJ) process, increased PLD repair may result from improved cell cycle-specific rejoining fidelity of the NHEJ pathway.

Evaluation of the dosimetric parameters for 125I brachytherapy determined in prostate medium using CT images

In the present study, the prostate medium determined from the CT images of 149 patients was developed. The dosimetric parameters such as Λ, g(L)(r) and F(r, θ) used in TG-43U1-based calculation for an iodine-125 ((125)I) brachytherapy-source were examined using Monte Carlo code Geant4. Clinical dosimetry parameters such as the D(90) were evaluated among a subgroup of 50 randomly selected patients who had been treated with permanent brachytherapy between January 2008 and December 2008 at the Tokyo Medical Center. The results show a slight difference in the dose rate constant Λ (within 1.0%). The radial dose function g(L)(r) exhibits a prominent difference in the region over 3 cm, and this difference is maintained within 2.9% in the region close to the source. The calculated values of F(r, θ) for the prostate medium were similar to values for water (within 1%), except in the longitudinal axis. A comparison of D(90) values shows a systematic dose overestimation of 2.8 ± 0.7 Gy in water, where the distribution of the differences can be seen with a spread of 1.8 ± 0.3% compared to that in prostate medium. It was concluded that the introduction of any kind of tissue correction for the TG-43U1-based calculation was not necessary to allow for the differences in elemental compositions and densities between water and prostate medium. PACS number: 87.00.00; 87.55.dk; 87.55.K-; 87.56.B-.

Dose distribution analysis in stereotactic body radiotherapy using dynamic conformal multiple arc therapy

PURPOSE

We have used dynamic conformal multiple arc therapy (DCMAT) for stereotactic body radiotherapy (SBRT) since 2001. We investigated the consistency of DCMAT for SBRT using dose-volume histogram analysis.

METHODS AND MATERIALS

A total of 50 patients with peripheral lung tumors underwent SBRT. The median tumor diameter was 2.4 cm (range, 0.9-5.9). Treatment planning was performed using a superposition algorithm. The prescribed 50 Gy dose was divided into five fractions. The prescribed dose was defined as 80% of the maximal dose in the planning target volume (PTV), and the leaf margins were modified to ensure the PTV was included in the 80% isodose surface. The dose-volume histogram analysis was used to assess the PTV and normal lung volume.

RESULTS

The median dose covering 95% of the PTV was 50.27 Gy (range, 46.14-52.67), essentially consistent with the prescribed dose. The median homogeneity and conformity index was 1.41 (range, 1.31-1.53) and 1.73 (range, 1.41-2.21), respectively. The median volume of lung receiving > or =20 Gy (V(20)) was 4.2% (range, 1.4-10.2%). A linear correlation was found between the tumor diameter and V(20), and an even stronger correlation was found between the PTV/(normal lung volume) and V(20). The estimated V(20) was 7.1% (range, 3.9-10.4%) for a 5-cm-diameter tumor, assumed to be the maximal size limitation for SBRT.

CONCLUSION

SBRT with DCMAT achieved high conformity and delivered adequate doses within the PTV. The median dose covering 95% of the PTV was consistent with the prescribed dose. V(20) can be estimated using the tumor diameter and normal lung volume. DCMAT was thus both a feasible and a reproducible method of SBRT delivery.

Prediction of seed migration after transperineal interstitial prostate brachytherapy with I-125 free seeds

PURPOSE

The present study was undertaken to determine the incidence and predictors of seed migration after transperineal interstitial prostate brachytherapy using I-125 free seeds.

METHODS AND MATERIALS

Between September 2004 and November 2007, 158 patients who underwent transperineal interstitial prostate brachytherapy as monotherapy for clinical T1/T2 carcinoma of the prostate gland were reviewed. Implants had been performed with standard techniques. All 158 patients underwent followup radiographs (orthogonal chest radiographs, a kidney-ureter-bladder radiograph, and a posteroanterior pelvic radiograph) to assess the presence of seed migration at 3 months after transperineal interstitial prostate brachytherapy. Patient characteristics and treatment status were recorded. Univariate and multivariate analyses were performed to identify predictors of seed migration.

RESULTS

Seed migration occurred in 35 of 158 patients (22.2%). Univariate analyses revealed that preoperative prostate volume estimated by transrectal ultrasound, the number of needles, the number of seeds implanted, and the presence or absence of pubic arch interference (PAI) were significantly associated with seed migration. These results indicated that larger prostate glands were more likely to have seed migration. However, the absolute difference in prostate size was not overly impressive (22.4 vs. 26.3cm(3)). Multivariate analysis revealed that the number of seeds implanted and the presence or absence of PAI were significant predictors of seed migration.

CONCLUSION

The number of seeds implanted and the presence or absence of PAI provide the most predictive information on seed migration.

Weekly low-dose docetaxel-based chemoradiotherapy for locally advanced oropharyngeal or hypopharyngeal carcinoma: a retrospective, single-institution study

PURPOSE

To retrospectively assess the efficacy, toxicity, and prognostic factors of weekly low-dose docetaxel-based chemoradiotherapy for Stage III/IV oropharyngeal or hypopharyngeal carcinoma.

METHODS AND MATERIALS

Between 2001 and 2005, 72 consecutive patients with locally advanced oropharyngeal or hypopharyngeal carcinoma were treated with concurrent chemoradiotherapy (CCR; radiation at 60 Gy plus weekly docetaxel [10 mg/m(2)]). Thirty of these patients also received neoadjuvant chemotherapy (NAC; docetaxel, cisplatin, and 5-fluorouracil) before concurrent chemoradiotherapy. Survival was calculated according to the Kaplan-Meier method. The prognostic factors were evaluated by univariate and multivariate analyses.

RESULTS

The median follow-up was 33 months, with overall survival, disease-free survival, and locoregional control rates at 3 years of 59%, 45%, and 52%, respectively. Thirty-six patients (50%) experienced more than one Grade 3 to 4 acute toxicity. Grade 3 mucositis occurred in 32 patients (44%), Grade 4 laryngeal edema in 1 (1%). Grade > or =3 severe hematologic toxicity was observed in only 2 patients (3%). Grade 3 dysphagia occurred as a late complication in 2 patients (3%). Multivariate analyses identified age, T stage, hemoglobin level, and completion of weekly docetaxel, but not NAC, as significant factors determining disease-free survival.

CONCLUSIONS

Docetaxel is an active agent used in both concurrent and sequential chemoradiotherapy regimens. Mucositis was the major acute toxicity, but this was well tolerated in most subjects. Anemia was the most significant prognostic factor determining survival. Further studies are warranted to investigate the optimal protocol for integrating docetaxel into first-line chemoradiotherapy regimens, as well as the potential additive impact of NAC.

Practical management of well differentiated thyroid carcinoma in Korea

OBJECTIVES

The optimal extent of surgery and postoperative management of patients with well differentiated thyroid carcinoma (WDTC) vary among countries and institutions. We assessed the practical management of WDTC in Korea by questionnaire and compared these results with those obtained in similar surveys of members of the Japanese Society of Thyroid Surgery (JSTS) and the International Association of Endocrine Surgeons (IAES).

MATERIALS AND METHODS

Questionnaires were sent by mail or e-mail to 266 members of the Korean Association of Endocrine Surgeons (KAES). Ninety members (33.8%) completed the questionnaire; their responses were compared with those of the JSTS and IAES surveys.

RESULTS

Total thyroidectomy was more prevalent in the KAES and IAES than in the JSTS, irrespective of tumor size in the low-risk group. Patients with papillary microcarcinoma were more likely to undergo aggressive central compartment node dissection in the KAES than in the IAES or JSTS. Thyroid stimulating hormone suppression therapy was administered to a higher proportion of patients and for longer times in the KAES and IAES than in the JSTS. Postoperative radioactive iodine treatment was more prevalent in the KAES than in the JSTS. There were no differences between the KAES and the JSTS in the treatment of patients with locally advanced thyroid carcinoma. External irradiation and radioactive iodine treatment for recurrent papillary thyroid carcinoma were favored more by the KAES than the IAES and JSTS.

CONCLUSIONS

The actual practices of members of the KAES were almost similar to those of the IAES, but differed from those in Japan in some aspects. In general, however, members of the KAES favored more aggressive treatment of WDTC than did physicians in other countries.

Long-term follow-up of allogeneic hematopoietic stem cell transplantation for de novo acute myelogenous leukemia with a conditioning regimen of total body irradiation and granulocyte colony-stimulating factor-combined high-dose cytarabine

We retrospectively evaluated the efficacy and safety of total body irradiation (TBI) and granulocyte colony-stimulating factor (G-CSF)-combined high-dose cytarabine as a conditioning regimen for allogeneic hematopoietic stem cell transplantation (HSCT) in patients with de novo acute myelogenous leukemia (AML). The conditioning regimen consisted of 12 Gy of TBI followed by high-dose cytarabine (3 g/m(2)) every 12 hours for 4 days in combination with the continuous administration of G-CSF. Stem cell sources included bone marrow or peripheral blood stem cells (PBSC) from human leukocyte antigen (HLA)-identical siblings (n = 24), or bone marrow from HLA serologically matched unrelated donors (n = 26). Fifty patients (median age, 38 years) were evaluated. At HSCT, 35 patients were in the first or second complete remission (CR1/2), and 15 patients were not in remission (n = 14) or in the third CR (n = 1). Thirty-six of 50 patients are currently alive, with a median follow-up period of 5.6 years (range: 1.1-12.1 years). The 5-year estimated overall survival (OS) and disease-free survival (DFS) rates were 85.5% (95% confidence interval [CI], 73.7%-97.3%) and 82.1% (95% CI, 69.0%-95.2%) in patients with AML in the first or second CR, 46.7% (95% CI, 21.4%-72.0%), and 40.0% (95% CI, 15.3%-64.7%) in patients with AML in other stages. The 2-year cumulative incidence of treatment-related mortality (TRM) of all patients was 10.4% (95% CI, 1.8%-18.6%). The only factors affecting the OS and DFS were disease status at transplant and cytogenetics by multivariate analysis. These results suggest that G-CSF-combined high-dose cytarabine could be a promising component of the conditioning regimen for allogeneic HSCT for AML, providing a high DFS and low TRM.

Effects of single or repeated administrations of methamphetamine on immune response in mice

The present study aimed to clarify the connection between immune responses and the administration frequency of methamphetamine (MAP) in male and female mice. Male and female ddY mice were given single or multiple (repeated for 10 days) intraperitoneal injections of MAP (5.0 mg/kg/day). The following immune parameters were examined; the number of leukocytes in peripheral blood and the proliferative activity (phytohemagglutinin;PHA, lipopolysaccharide; LPS response) and natural killer (NK) cell activity in splenic lymphocytes. Further, the differences in metabolic function in the spleen in response to MAP (and its metabolite amphetamine) in male and female mice were measured by gas chromatography. The results of the present study were that; 1) single and repeated MAP injections reduced leukocytes; 2) single MAP injection increased the proliferative response of splenic lymphocytes to PHA stimulation in only male mice, but the response to LPS stimulation was slightly increased in both male and female mice; 3) single and repeated MAP injections reduced NK cell activity of splenic lymphocytes, and especially in female mice with 5 injections of MAP; 4) with 10 MAP injections the NK cell activity and leukocytes recovered to the level of controls; and 5) the metabolic activity of MAP was reduced in female mice treated acutely with MAP in comparison to male mice. These results appear to indicate that immune responses to MAP were involved in the different results shown for administration frequency, sex difference and metabolic process of MAP.

Possible Misinterpretation of Demarcated Solid Patterns of Radiation Fibrosis on CT Scans as Tumor Recurrence in Patients Receiving Hypofractionated Stereotactic Radiotherapy for Lung Cancer

PURPOSE

To retrospectively analyze opacity changes near primary lung cancer tumors irradiated by using hypofractionated stereotactic radiotherapy (HSRT) to determine the presence or absence of tumor recurrence.

METHODS AND MATERIALS

After review-board approval for a retrospective study, we examined data from 50 patients treated with curative intent for proven or highly suspected localized peripheral-lung cancer and followed up for at least 12 months. All patients had received 50 Gy in five fractions (80% isodose) and were followed up monthly with chest X-ray until clinical and X-ray findings stabilized. Follow-up computed tomography scans were performed 1 and 3 months after HSRT and thereafter at 3-month intervals during the first 2 years.

RESULTS

Median follow-up was 30.4 months (range, 12.0-73.8 months). Abnormal opacities that were suspicious for recurrent tumor appeared in 20 patients at a median of 20.7 months (range, 5.9-61.4 months). Only 3 patients were finally found to have recurrence; 14 were recurrence free but were suspected to have fibrosis, and findings for the other 3 patients were considered equivocal because of a short follow-up period (<or=6 months).

CONCLUSION

Radiation fibrosis, which may occur 1 year or longer after completion of HSRT, is difficult to distinguish from tumor recurrence. Even when opacities increase on follow-up radiologic scans, recurrence cannot be diagnosed conclusively based on image findings; biopsy occasionally is warranted.

Hypofractionated stereotactic radiotherapy with and without transarterial chemoembolization for small hepatocellular carcinoma not eligible for other ablation therapies: Preliminary results for efficacy and toxicity

AIM

To investigate the efficacy and toxicity of hypofractionated stereotactic radiotherapy for the treatment of patients presenting with hepatocellular carcinoma (HCC) in a single institutional setting.

METHODS

Sixteen patients who presented with solitary HCC, including two patients with a tumor thrombus of the portal veins, were treated with stereotactic radiotherapy with or without transarterial chemoembolization. The criteria for stereotactic radiotherapy were existence of technical difficulties for other ablation therapies, inoperable disease or refusal to undergo surgery, tumor staged as Grade A or B according to the Child-Pugh classification, and solitary tumor distant from the gastrointestinal tract and kidney with a tumor volume <100 cm(3). In 14 of 16 patients, a total dose of 35- 50 Gy was delivered in 5-7 fractions over 5-9 days.

RESULTS

At the end of a mean follow-up of 612 days (median 611 days; range 244-994 days), all patients were alive. Eight of 16 patients had complete responses and seven others were judged as stable with lipiodol accumulation. In one patient, local recurrence developed after 489 days. Intrahepatic recurrences developed outside the treated volume in six patients and no extrahepatic metastases developed during follow-up. No serious treatment-related toxic manifestations developed.

CONCLUSIONS

Stereotactic radiotherapy for HCC with or without transarterial chemoembolization is feasible therapy and provides good local control with a short treatment period. Stereotactic radiotherapy may be of clinical benefit in patients who are inoperable or for whom there are difficulties in other ablation therapies.

Phase II study of chemoradiotherapy with S-1 and low-dose cisplatin for inoperable advanced gastric cancer

PURPOSE

The results of a pilot study using S-1/low-dose cisplatin/radiotherapy led us to hypothesize that the initial chemoradiotherapy regimen would induce a 70% efficacy rate with a 10% pathologic complete response rate.

PATIENTS AND METHODS

Only patients with unresectable or incurable advanced gastric cancer were eligible. The patients received induction S-1 and cisplatin therapy with radiotherapy followed by chemotherapy alone.

RESULTS

Of the 30 patients recruited and assessed, 29 were eligible for clinical evaluation of measurable lesions. The response rate was 65.5%, with 19 with a partial response, 8 with no change, and 2 with progressive disease of 29 patients. Of the 30 patients recruited, 10 (33.3%) underwent stomach resection and D2 LN dissections. The pathologic complete response rate was 13.3% (4 patients), and the R0 resection rate was 100% (10 patients). The survival analysis showed a median survival time of 25 months. Grade 3 toxicity occurred in 66.7% for leukocytopenia, 33.3% for thrombocytopenia, 23.3% for nausea and appetite loss, and 6.7% for anemia, diarrhea, and renal dysfunction. Although all the patients had been hospitalized with a poor performance status with a giant tumor, 97% (29 of 30) could be discharged after the first cycle, resulting in an improvement in quality of life.

CONCLUSION

Chemoradiotherapy could be a powerful regimen for controlling tumor progression in advanced gastric cancer, improving patients' quality of life with tolerable toxicity. A complete histologic response rate of >10% would be expected, even for large tumors with metastatic lesions.

[External radiation therapy for thyroid disease]

The external beam irradiation plays a very important role in the treatment of some thyroid diseases, such as primary cancers (papillary, follicular, medullary and anaplastic), malignant lymphoma and bone metastasis. The treatment policies, the irradiation techniques and the treatment results of these diseases are described from our experiences and the literature. The recent improvements of irradiation techniques are also explained.

Comparison of intraoperative ultrasound with postimplant computed tomography--dosimetric values at Day 1 and Day 30 after prostate brachytherapy

PURPOSE

To compare the results of intraoperative dosimetry with those of postimplant computed tomography (CT)-based dosimetry after (125)I prostate brachytherapy.

METHODS AND MATERIALS

We treated 412 prostate cancer patients with (125)I prostate brachytherapy, with or without external beam radiotherapy at our institution. Neoadjuvant hormone therapy was administered to 331 patients (80.3%). Implantation was performed using an intraoperative interactive technique. Postimplant dosimetry was performed on Day 1 and Day 30 using CT imaging. The dosimetric results for the prostate, urethra, and rectum were compared among intraoperative ultrasound, and CT scans of Day 1 and Day 30.

RESULTS

The mean intraoperative minimal dose received by 90% of the prostate volume (D(90)) was 118.8% of the prescribed dose vs. 106.4% for Day 1 (p < 0.01) and 119.2% for Day 30 (p = 0.25). There were no significant correlations between the intraoperative D(90) and the postimplant D(90) values (intraclass correlation coefficients=0.42 and 0.33 for Day 1 and Day 30, respectively). Prostatic edema at Day 1 had the largest effect on the Day 1 D(90) (p < 0.01). The factor significantly affecting the Day 30 D(90) was neoadjuvant hormone therapy (p < 0.01). The mean Day 30 D(90) for the hormone-treated patients was 117.9%, compared with 124.6% for those who remained hormone naïve. The intraoperative and postimplant dosimetric values differed significantly for the urethra and rectum.

CONCLUSIONS

Our results demonstrate that there are no significant differences between the D(90) assessments obtained intraoperatively and at Day 30 postoperatively. Furthermore, there are no definite correlations between intra- and postimplantation dosimetric values. Other D(90) values differed significantly between the intraoperative and postimplant dosimetry. This study suggests that dosimetry has negligible clinical utility for informing patients, at discharge, of whether or not their implants are adequate.