Difference in failure patterns after stereotactic body radiotherapy for lung cancer according to clinical T stage based on 4D computed tomography

PURPOSE

Stereotactic body radiotherapy (SBRT) is a treatment option for early-stage lung cancer. We aimed to examine the differences in failure patterns after SBRT according to the clinical T stage.

METHODS

A total of 120 patients with early-stage lung cancer (T1-3N0M0) who underwent SBRT were analysed. The clinical stage in patients whose tumours were in contact with the chest wall was confirmed using four-dimensional computed tomography (4D-CT). Local failure, regional node metastasis, and distant metastasis were confirmed from clinical charts.

RESULTS

Median follow-up time was 27.5 months (range 7-122) after SBRT. Thirteen patients were restaged from clinical T2 with visceral pleural invasion to T3 with chest wall invasion using 4D-CT analysis. Thirty-seven patients developed recurrences. The median progression-free survival (PFS) and overall survival (OS) were 38.1 and 53.8 months, respectively. The 3‑year PFS and OS rates were 50.7% and 60.3%, respectively. A significant difference was observed in PFS according to the clinical T stage (p = 0.001). No significant differences were observed in OS according to the clinical T stage (p = 0.213). The proportion of locoregional failures relative to distant metastasis decreased with progression from T1 to T3. The pleural dissemination rate was significantly higher in T3 tumours than in T1 and T2 tumours (p = 0.010).

CONCLUSION

Clinical T stage is associated with PFS after SBRT for lung cancer. There were differences in the failure patterns according to T stage. 4D-CT might provide significant information for assessing chest wall invasion associated with unfavourable PFS.

Escalated Maximum Dose in the Planning Target Volume Improves Local Control in Stereotactic Body Radiation Therapy for T1-2 Lung Cancer

Stereotactic body radiotherapy (SBRT) is a treatment option for early-stage lung cancer. The purpose of this study was to investigate the optimal dose distribution and prognostic factors for local control (LC) after SBRT for lung cancer. A total of 104 lung tumors from 100 patients who underwent SBRT using various treatment regimens were analyzed. Dose distributions were corrected to the biologically effective dose (BED). Clinical and dosimetric factors were tested for association with LC after SBRT. The median follow-up time was 23.8 months (range, 3.4-109.8 months) after SBRT. The 1- and 3-year LC rates were 95.7% and 87.7%, respectively. In univariate and multivariate analyses, pathologically confirmed squamous cell carcinoma (SQ), T2 tumor stage, and a Dmax < 125 Gy (BED10) were associated with worse LC. The LC rate was significantly lower in SQ than in non-SQ among tumors that received a Dmax < 125 Gy (BED10) (p = 0.016). However, there were no significant differences in LC rate between SQ and non-SQ among tumors receiving a Dmax ≥ 125 Gy (BED10) (p = 0.198). To conclude, SQ, T2 stage, and a Dmax < 125 Gy (BED10) were associated with poorer LC. LC may be improved by a higher Dmax of the planning target volume.

Risk factors for radiation pneumonitis after rotating gantry intensity-modulated radiation therapy for lung cancer

The risk factors for severe radiation pneumonitis (RP) in patients with lung cancer who undergo rotating gantry intensity-modulated radiation therapy (IMRT) using volumetric modulated arc therapy (VMAT) or helical tomotherapy (HT) are poorly understood. Fifty-two patients who received rotating gantry IMRT for locally advanced lung cancer were included in this retrospective study. In total, 31 and 21 patients received VMAT and HT, respectively. The median follow-up duration was 14 months (range, 5.2–33.6). Twenty (38%) and eight (15%) patients developed grade ≥ 2 and ≥ 3 RP, respectively. In multivariate analysis, lung V5 ≥ 40% was associated with grade ≥ 2 RP (P = 0.02), and past medical history of pneumonectomy and total lung volume ≤ 3260 cc were independently associated with grade ≥ 3 RP (P = 0.02 and P = 0.03, respectively). Rotating gantry IMRT was feasible and safe in patients with lung cancer undergoing definitive radiotherapy. Reducing lung V5 may decrease the risk of symptomatic RP, and care should be taken to avoid severe RP after radiotherapy in patients with a past medical history of pneumonectomy and small total lung volume.

Neoadjuvant Modified Short-Course Radiotherapy Followed by Delayed Surgery for Locally Advanced Rectal Cancer

Simple Summary

Both short- and long-course neoadjuvant radiotherapy (NA-RT) followed by surgery have been adopted as standard treatments for locally advanced rectal cancer (LARC). We hypothesized that a modified short-course radiotherapy (mSC-RT) using an accelerated hyperfractionated regimen, with a dose of 2.5 Gy twice daily up to a total dose of 25 Gy in 10 fractions, can provide a favorable therapeutic ratio in comparison with the conventional regimens. Ninety-seven consecutive LARC patients undergoing mSC-RT followed by delayed surgery were analyzed in this retrospective study. Additionally, potential prognostic factors for overall survival (OS) were also assessed. The results showed that mSC-RT followed by delayed surgery achieved equivalent anti-tumor efficacy and acute toxicity that were comparable with long- and short-course NA-RT, respectively. A neutrophil-to-lymphocyte ratio (NLR) ≥ 1.83 was independently associated with poor OS in LARC patients receiving mSC-RT. Thus, mSC-RT can be a promising alternative to both standard long- and short-course NA-RT regimens.

Abstract

This study aimed to assess the clinical outcomes and predictive factors of neoadjuvant modified short-course radiotherapy (mSC-RT) for locally advanced rectal cancer (LARC). Data from 97 patients undergoing mSC-RT followed by radical surgery for LARC were retrospectively analyzed. A 2.5 Gy dose twice daily up to a total dose of 25 Gy in 10 fractions was administered through mSC-RT, and this was delivered with oral chemotherapy in 95 (97.9%) patients. Radical surgery was performed 6 (range, 3–13) weeks after mSC-RT. The median follow-up among surviving patients was 43 (8–86) months. All patients completed neoadjuvant radiotherapy with no acute toxicity grade ≥ 3. Three- and five-year local control rates were 96.3% and 96.3%, respectively. Three- and five-year overall survival (OS) rates were 92.7% and 79.8%, respectively. Univariate analyses revealed that poor OS was associated with no concurrent administration of capecitabine, C-reactive-protein-to-albumin ratio ≥ 0.053, carcinoembryonic antigen ≥ 3.4 ng/mL, and neutrophil-to-lymphocyte ratio (NLR) ≥ 1.83 (P = 0.045, 0.001, 0.041, and 0.001, respectively). Multivariate analyses indicated that NLR ≥ 1.83 was independently associated with poor OS (p = 0.018). mSC-RT followed by delayed surgery for LARC was deemed feasible and resulted in good clinical outcomes, whereas poor OS was associated with high NLR.

A first report of tumour-tracking radiotherapy with helical tomotherapy for lung and liver tumours: A double case report

There are only a limited number of previous reports on clinical cases using tumour tracking with tomotherapy. Therefore, we present two cases of patients treated with tumour tracking with tomotherapy. First, a 74-year-old man with an inoperable lung cancer type T1bN0M0 underwent stereotactic body radiotherapy at a total dose of 48 Gy in four fractions. Second, a 68-year-old man with hepatocellular carcinoma with a portal venous tumour thrombosis and history of liver stereotactic body radiotherapy with fiducial marker implantation received radiotherapy at a total dose of 48 Gy in 20 fractions. The results of patient-specific quality assurance and tracking radiotherapy were sufficient to irradiate tumours. Tumour tracking with tomotherapy successfully delivered radiation in a total of 24 treatment fractions in both patients. Tumour tracking with tomotherapy is feasible in lung and liver cancer treatment. This study's findings suggest the clinical use of tumour tracking with tomotherapy.

New clinical data on human spinal cord re-irradiation tolerance

Purpose

To provide additional clinical data about the re-irradiation tolerance of the spinal cord.

Methods

This was a retrospective bi-institutional study of patients re-irradiated to the cervical or thoracic spinal cord with minimum follow-up of 6 months. The maximum dose (Dmax) and dose to 0.1cc (D0.1cc) were determined (magnetic resonance imaging [MRI]-defined cord) and expressed as equivalent dose in 2‑Gy fractions (EQD2) with an α/β value of 2 Gy.

Results

All 32 patients remained free from radiation myelopathy after a median follow-up of 12 months. Re-irradiation was performed after 6–97 months (median 15). In 22 cases (69%) the re-irradiation spinal cord EQD2 Dmax was higher than that of the first treatment course. Forty-eight of 64 treatment courses employed fraction sizes of 2.5 to 4 Gy to the target volume. The median cumulative spinal cord EQD2 Dmax was 80.7 Gy, minimum 61.12 Gy, maximum 114.79 Gy. The median cumulative spinal cord D0.1cc EQD2 was 76.1 Gy, minimum 61.12 Gy, maximum 95.62 Gy. Besides cumulative dose, other risk factors for myelopathy were present (single-course Dmax EQD2 ≥51 Gy in 9 patients, single-course D0.1cc EQD2 ≥51 Gy in 5 patients).

Conclusion

Even patients treated to higher cumulative doses than previously recommended, or at a considerable risk of myelopathy according to a published risk score, remained free from this complication, although one must acknowledge the potential for manifestation of damage in patients currently alive, i.e., still at risk. Individualized decisions to re-irradiate after appropriate informed consent are an acceptable strategy, including scenarios where low re-irradiation doses to the spinal cord would compromise target coverage and tumor control probability to an unacceptable degree.

Intensity-modulated radiation therapy administered to a previously irradiated spine is effective and well-tolerated

PURPOSE

This study sought to discern the clinical outcomes of intensity-modulated radiation therapy (IMRT) administered to the spine in patients who had undergone previous radiotherapy.

METHODS

A total of 81 sites of 74 patients who underwent previous radiotherapy administered to the spine or peri-spine and subsequently received IMRT for the spine were analyzed in this study. The prescribed dose of 80 Gy in a biologically effective dose (BED) of α/β = 10 (BED₁₀) was set as the planning target volume. The constraint for the spinal cord and cauda equine was D_0.1 cc ≤ 100 Gy and ≤ 150 Gy of BED for re-irradiation alone and the total irradiation dose, respectively.

RESULTS

The median follow-up period was 10.1 (0.9-92.1) months after re-irradiation, while the median interval from the last day of the previous radiotherapy to the time of re-irradiation was 15.6 (0.4-210.1) months. Separately, the median prescript dose of re-irradiation was 78.0 (28.0-104.9) of BED₁₀. The median survival time in this study was 13.9 months, with 1-, 3-, and 5-year overall survival rates of 53.7%, 29.3%, and 26.6%, respectively. The 1-, 3-, and 5-year local control rates were 90.8%, 84.0%, and 84.0%, respectively. Neurotoxicity was observed in two of 72 treatments (2.8%) assessed after re-irradiation.

CONCLUSION

Re-irradiation for the spine using IMRT seems well-tolerated. Definitive re-irradiation can be a feasible treatment option in patients with the potential for a good prognosis.

Experimental Animal Model of Re-irradiation to Evaluate Radiation-induced Damage in the Normal Intestine

BACKGROUND/AIM

We aimed to elucidate the pathological findings following acute and late re-irradiation in a preclinical model.

MATERIALS AND METHODS

Mice were divided into five treatment groups: sham-irradiation (Sham-IR), 10-12 Gy (Single IR Acute), 15 Gy (Single IR Late), 15 Gy followed by 10-12 Gy re-irradiation 7 days later (Re-IR Acute), or 15 Gy followed by 10-12 Gy re-irradiation 12 weeks later (Re-IR Late). Mice were sacrificed after either single irradiation or re-irradiation for pathological assessment.

RESULTS

The Re-IR Late group had significantly lower numbers of crypts with apoptotic cells than those observed in mice in the Single IR Acute group. There were no significant differences between the Single IR Acute and re-IR Acute groups in cell proliferation or in a crypt survival assay.

CONCLUSION

Re-irradiation with a long interval after the first irradiation may cause similar acute biological effects in normal intestine as observed following irradiation without re-irradiation.

Impact of preoperative chemoradiotherapy using concurrent S-1 and CPT-11 on long-term clinical outcomes in locally advanced rectal cancer

BACKGROUND

Preoperative chemoradiotherapy regimens using a second drug for locally advanced rectal cancer are still under clinical investigation.

AIM

To investigate the clinical outcomes of patients with locally advanced rectal cancer treated with preoperative chemoradiotherapy using tegafur/gimeracil/oteracil (S-1) plus irinotecan (CPT-11).

METHODS

This was a single-center retrospective study of 82 patients who underwent radical surgery for rectal cancer after chemoradiotherapy with S-1 (80 mg/m²/d), CPT-11 (60 mg/m²/d), and radiation (total 45 Gy) between 2009 and 2016. The median follow-up was 51 mo (range: 17–116 mo).

RESULTS

Twenty-nine patients (35.4%) had T3 or T4 rectal cancer with mesorectal fascia invasion, 36 (43.9%) had extramural vascular invasion, 24 (29.8%) had N2 rectal cancer and eight (9.8%) had lateral lymph node swelling. The relative dose intensity was 90.1% for S-1 and 92.9% for CPT-11. Seventy-nine patients (96.3%) underwent R0 resection. With regard to pathological response, 13 patients (15.9%) had a pathological complete response and 52 (63.4%) a good response (tumor regression grade 2/3). The 5-year local recurrence-free survival, relapse-free survival and overall survival rates were 90.1%, 72.5% and 91.3%, respectively. We analyzed the risk factors for local recurrence-free survival by Cox regression analysis and none were detected. Previously described risk factors such as T4 stage, mesorectal fascia invasion or lateral lymph node swelling were not detected as negative factors for local recurrence-free survival.

CONCLUSION

We demonstrated good compliance and favorable tumor regression in patients with locally advanced rectal cancer treated with preoperative S-1 and CPT-11.

Patterns of bone metastases from head and neck squamous cell carcinoma

OBJECTIVE

To report clinical features of bone metastases (BM) from head and neck squamous cell carcinoma (HNSCC).

METHODS

Among 772 patients with HNSCC diagnosed at our hospital over 9 years, 30 patients (3.9%) had clinical evidence of BM (24 men and 6 women; mean age: 63 years). We assessed the time interval from the primary diagnosis to BM development, symptoms attributable to BM, presence of distant metastases to other organs, number of BM, sites of BM, morphologic changes on computed tomography (CT) images, treatment for BM, and overall survival (OS).

RESULTS

BM at the initial stage were found in 9 patients with HNSCC (30%), and in 21 patients (70%) with HNSCC during the course of the disease. In the later patients, the median time interval from the primary diagnosis was 11.5 months. Nineteen patients (63%) did not have BM-related symptoms, 6 (20%) had pain, 3 (10%) had neurologic symptoms resulting from vertebral or skull metastases, and 2 (7%) had hypercalcemia. Seventeen patients (57%) showed bone-exclusive metastases, and 13 (43%) had distant metastases in other organs. Eleven patients (37%) had monostotic metastases (solitary BM), and 19 patients (63%) had polyostotic metastases (multiple BM). When combined, 9 patients (30%) showed bone-exclusive and monostotic metastases. The most commonly affected site was the thoracolumbar spine, accounting for 34% of total BM, followed by the pelvis (24%), shoulder and thorax (21%), and the extremities (17%). Notably, metastases to bones above the clavicle (craniofacial bones and cervical spine) accounted for only 3% of all bone lesions. CT images showed variable morphologic patterns with osteolytic type in 17 patients (57%), intertrabecular in 7 (23%), osteoblastic in 4 (13%), and mixed in 2 (7%). Systematic chemotherapy for BM was performed in 19 patients and radiotherapy in 18. The median survival time for patients with bone-exclusive and monostotic metastases was significantly longer than that for patients with multi-organ metastases or polyostotic metastases at 18.2 months vs. 5.7 months (p=0.02). Neither chemotherapy nor radiotherapy extended OS.

CONCLUSION

Thirty percent of BM cases from HNSCC showed bone-exclusive and monostotic metastases. These patients tended to show a more favorable prognosis than patients with multi-organ metastases or polyostotic metastases.

Neutrophil-to-Lymphocyte Ratio Predicts Survival After Whole-brain Radiotherapy in Non-small Cell Lung Cancer

AIM

This study aimed to identify prognostic factors for response to whole-brain radiotherapy (WBRT) in patients with brain metastases (BMs) from non-small cell lung cancer (NSCLC).

PATIENTS AND METHODS

This study retrospectively evaluated 100 patients who underwent WBRT for BMs from NSCLC between December 2012 and October 2017. Clinical factors were tested for associations with overall survival after WBRT.

RESULTS

The median follow-up time was 134 days (range=14-1,395 days), the median survival time was 143 days, and the 1-year survival rate was 30.4%. Univariate and multivariate analyses revealed that better survival was independently associated with expression of programmed death-ligand 1 (PD-L1), no previous treatment for BMs, no extracranial disease, and a neutrophil-to-lymphocyte ratio (NLR) of <5.0.

CONCLUSION

A low NLR and positive PD-L1 expression independently predict better prognosis in patients with BMs from NSCLC after WBRT. These findings suggest that the potential immune response may influence survival among patients with BMs.

Stereotactic body radiotherapy in patients with chronic obstructive pulmonary disease and interstitial pneumonia: a review

Stereotactic body radiation therapy (SBRT) can yield excellent local tumor control, as well as survival benefit comparable to that of surgery for early-stage lung cancer. However, in terms of toxicity, SBRT might lead to fatal radiation pneumonitis. Lung diseases, such as chronic obstructive pulmonary disease (COPD) and interstitial lung disease (ILD), are major risk factors for lung cancer. However, these patients are typically not candidates for the gold-standard treatment option, lobectomy, because of the perioperative risks. In addition, patients with poor respiratory function can be excluded in prospective clinical trials. Thus, SBRT for patients with pulmonary diseases is still challenging, but there appears to be a clinical role for this modality as an alternative treatment. However, there are few well-documented review articles on SBRT for patients with pulmonary diseases. Therefore, we aimed to review SBRT in the context of important patient-related factors, including COPD and ILD. SBRT is an acceptable alternative treatment option for patients with lung cancer who also have COPD with an equivalent risk of radiation pneumonitis to normal lung. However, latent ILD should be detected prior to treatment. The indication for SBRT should be decided by carefully considering the risks and benefit for patients with ILD.

Serum lactate dehydrogenase predicts survival in small-cell lung cancer patients with brain metastases that were treated with whole-brain radiotherapy

This study aimed to identify factors that predict prognosis after radiotherapy for brain metastases (BMs) from small-cell lung cancer (SCLC). This study retrospectively evaluated 48 consecutive patients who underwent whole-brain radiotherapy (WBRT) for BMs from SCLC between February 2008 and December 2017. WBRT was delivered at a median dose of 30 Gy (range: 30-40 Gy) in 10 fractions (range: 10-16 fractions). Clinical factors were tested for associations with overall survival after WBRT. The median survival and 1-year overall survival rate after WBRT treatment were 232 days and 34.4%, respectively. Univariate analyses revealed that longer survival was associated with Eastern Cooperative Oncology Group performance status of 0-1, asymptomatic BMs, lactate dehydrogenase (LDH) in the normal range, Radiation Therapy Oncology Group-recursive partitioning analysis class 2, and a graded prognostic assessment score of ≥1.5 (P < 0.01, P < 0.01, P < 0.01, P < 0.01 and P < 0.05, respectively). In the multivariate analyses, longer survival was independently associated with asymptomatic BMs [hazard ratio for death (HR), 0.32; 95% confidence interval (CI), 0.12-0.79; P < 0.05] and LDH in the normal range (HR, 0.42; 95% CI, 0.21-0.83; P < 0.05). The presence of symptoms due to BMs and LDH values independently predicted prognosis after WBRT for BMs from SCLC. Elevated LDH may provide valuable information for identifying patients with BMs who could have poor survival outcomes.

Clinical T staging is superior to fluorodeoxyglucose positron emission tomography for predicting local outcomes after intra-arterial infusion chemoradiotherapy for maxillary sinus squamous cell carcinoma

Concomitant intra-arterial infusion chemoradiotherapy (IA-CRT) has been used to treat locally advanced maxillary sinus squamous cell carcinoma (MSSCC) with positive outcomes. However, an optimal predictive prognostic factor for MSSCC treated with IA-CRT remains elusive. The aim of the present study was to assess the feasibility of 18F-fluorodeoxyglucose positron emission tomography (FDG-PET), including volumetric parameters, to predict the prognosis of MSSCC treated with IA-CRT. Twenty-four patients with newly diagnosed MSSCC receiving FDG-PET imaging before IA-CRT treatment were analyzed in this retrospective study. All patients underwent radiotherapy with a total tumor dose of 60–66 Gy in a conventional fractionation schedule, using three-dimensional conformal radiation therapy or intensity-modulated radiation therapy. Radiotherapy was performed concurrently with concurrent intra-arterial infusion chemotherapy (cisplatin). The IA-CRT response rate was 83.33%. The 1- and 3-year survival rates were 81.30% and 64.34%, respectively. The 1- and 3-year local failure-free rates were 57.21% and 40.96%, respectively. Local failure was significantly associated with poor survival (P = 0.0152). Further, clinical T staging clearly stratified local control outcomes among patients with clinical T3 or less, T4a, and T4b (P = 0.0312). Moreover, patients with stage T4b showed a significantly poorer local control compared with T3 or less (P = 0.0103). However, FDG-PET parameters provided no significant predictive information regarding treatment outcome. To conclude, pretreatment T stage predicts local control by IA-CRT, which is associated with survival.

Definitive re-irradiation using intensity-modulated radiation therapy in cancers of the head and neck, focusing on rare tumors

PURPOSE

To analyze the outcomes following re-irradiation for local recurrence of rare head and neck tumors.

MATERIAL AND METHODS

We retrospectively analyzed 11 patients who had received intensity-modulated radiation therapy (IMRT) for recurrent tumors in the head and neck except for laryngopharynx.

RESULTS

Primary tumor sites included the maxillary sinus, nasal cavity, and external ear canal in six, three, and two patients, respectively. The median follow-up times were 13 (range, 3-54) months. The median survival time was 17 months with 1- and 2-year survival rates of 63.64 and 39.77%, respectively. Among 11 patients, five experienced local failure in the follow-up period. The 1- and 2-year local control rates were 58 and 47%, respectively. Patients who had received a radiation dose of ≥3 Gy per fraction showed significantly better local control than those receiving less (p = .0419). One patient experienced Grade 3 facial pain as acute toxicity. Late toxicities included radiographic findings of partial central nervous system necrosis in three patients and Grade 3 osteonecrosis and Grade 3 facial nerve disorder in one patient.

CONCLUSIONS

Re-irradiation of rare head and neck tumors using IMRT for loco-regional recurrence may be an acceptable treatment option.

Stereotactic Body Radiation Therapy for Liver Tumors: Current Status and Perspectives

Surgical resection is the standard therapy for solitary primary or metastatic liver tumors. However, liver tumors are often unresectable at diagnosis and hepatectomy is invasive. Local therapies, such as radiofrequency ablation, are used instead, which can be challenging. Recent advances in modern radiotherapy, including stereotactic body radiation therapy (SBRT), have increased the use of radiotherapy as a curative modality. SBRT delivers ablative high doses of irradiation in small volumes. SBRT for liver tumors provided local control with potential survival benefits in patients with inoperable status. However, the following issues remain: primary vs. metastatic liver cancers; SBRT-related toxicity and prevention; pathological features of liver cancers; and potential SBRT strategies. We summarized a literature review to summarize the effectiveness of SBRT and patient tolerance and present the current status and future perspective of SBRT for liver tumors. SBRT is a potential game changer for multimodal therapy.

Clinical Implications of a Novel, Iron-containing Fiducial Marker in Radiotherapy for Liver Tumors: An Initial Experience

A 0.5%-iron-containing fiducial marker, Gold Anchor^TM (Naslund Medical AB, Huddinge, Sweden), has been recently developed. Herein, we report our initial experiences with the clinical use of the Gold Anchor^TM (GA) in radiotherapy for liver tumors. Data of four consecutive patients with liver tumors, including two liver metastases and two hepatocellular carcinomas, were retrospectively analyzed. The GA was percutaneously placed under local anesthesia, close to the tumor. Gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid-enhanced magnetic resonance imaging (MRI) was performed after the placement of the GA. Radiotherapy was designed using the volumetric modulated arc therapy technique. All procedures for placement of the GA were successfully performed with no complications. The GA exhibited various forms in the liver in the four patients. All of the GAs were well-detected on MRI, planned computed tomography (CT), and cone-beam CT. Additionally, the tadpole-like shape of the GA showed better detectability than the uptake of lipiodol emulsion and could be used for three-dimensional correlation during setup in daily image-guided radiotherapy. GA was a useful tool in image registration of radiotherapy with a high applicability. Additionally, the tadpole-like shape can be recommended for liver radiotherapy. Our findings suggest that the GA will indeed be useful in clinical practice.

Effect of primary tumor location and tumor size on the response to radiotherapy for liver metastases from colorectal cancer

Metastatic liver tumors (MLTs) from colorectal cancer (CRC) are often treated with stereotactic body radiation therapy (SBRT). The present study aimed to examine the predictive factors for response of MLTs to SBRT. A total of 39 MLTs from 24 patients with CRC were retrospectively analyzed. Radiotherapy for MLT was typically performed with a prescribed dose equivalent to a biologically effective dose (BED)10 of 100 Gy. The median follow-up period was 16 months (range, 5-64 months). The median prescribed dose and total BED10 were 56 Gy (range, 45-72 Gy) and 97.5 Gy (range, 71.7-115.5 Gy), respectively, in a median of 8 fractions (range, 4-33 fractions). The 1- and 2-year local control rates were 67.2 and 35.9%, respectively. For patients with MLT treated with ablative SBRT (BED10 ≥100 Gy in ≤5 fractions), the 1- and 2-year local control rates were 83.3 and 62.5%, respectively. Univariate analysis showed that primary tumor location (left-sided colon), maximum tumor diameter (≤30 mm) and ablative SBRT (BED10 ≥100 Gy in ≤5 fractions) were significantly associated with improved local control (P=0.0058, P=0.0059 and P=0.0268, respectively). Multivariate analysis showed that tumor diameter was significantly associated with improved local control (P=0.0314). In addition, patients who received ablative SBRT had significantly prolonged overall survival times compared with those treated with non-ablative SBRT (P=0.0261). To conclude, tumors ≤30 mm that can be treated with ablative SBRT are associated with good local control rates. The primary tumor location may affect the radiosensitivity of MLTs.

Validation of the liver mean dose in terms of the biological effective dose for the prevention of radiation-induced liver damage

AIM

The purpose of this study was to determine the optimal mean liver biologically effective dose (BED) to prevent radiation-induced liver disease (RILD) in stereotactic body radiation therapy (SBRT).

BACKGROUND

The actual mean doses appropriate for liver irradiation in modern radiotherapy techniques have not been adequately investigated, although SBRT is sometimes alternatively performed using fractionated regimens.

MATERIALS AND METHODS

SBRT treatment plans for liver tumors in 50 patients were analyzed. All distributions of the physical doses were transformed to BED₂ using the linear-quadratic model. The relationship between physical doses and the BED₂ for the liver were then analyzed, as was the relationship between the mean BED₂ for the liver and the planning target volume (PTV).

RESULTS

A significantly positive correlation was observed between the mean physical dose for the background liver and the mean BED₂ for the whole liver (P < 0.0001, r = 0.9558). Using the LQ model, a mean BED₂ of 73 and 16 Gy for the whole liver corresponded to the hepatic tolerable mean physical dose of 21 and 6 Gy for Child-Pugh A- and B-classified patients, respectively. Additionally, the PTV values were positively correlated with the BEDs for the whole liver (P < 0.0001, r = 0.8600), and the background liver (P < 0.0001, r = 0.7854).

CONCLUSION

A mean BED₂ of 73 and 16 Gy for the whole liver appeared appropriate to prevent RILD in patients with Child-Pugh classes A and B, respectively. The mean BED₂ for the liver correlated well with the PTV.

Utility of intraoral stents in external beam radiotherapy for head and neck cancer

AIM

This study aimed to assess the utility and stability of intraoral stent during intensity-modulated radiation therapy (IMRT).

BACKGROUND

The benefits of intraoral stents in radiotherapy are unclear.

MATERIALS AND METHODS

We analyzed 386 setup errors in 12 patients who received IMRT for head and neck cancers without intraoral stents (intraoral stent [-]) and 183 setup errors in 6 patients who received IMRT with intraoral stents (intraoral stent [+]). All patients were matched according to the immobilization method (masks and boards). Setup errors were measured as the distance from the initial setup based on the marking on the skin and mask to the corrected position based on bone matching on cone beam computed tomography.

RESULTS

The mean interfractional setup errors in the right-left, craniocaudal, anterior-posterior (AP), and three-dimensional (3D) directions were -0.33, 0.08, -0.25, and 2.75 mm in the intraoral stent (-) group and -0.37, 0.24, -0.63, and 2.42 mm in the intraoral stent (+) group, respectively (P = 0.50, 0.65, 0.01, and 0.02, respectively). The systematic errors for the same directions were 0.89, 1.46, 1.15, and 0.88 mm in the intraoral stent (-) group and 0.62, 1.69, 0.68, and 0.56 mm in the intraoral stents (+) group, respectively. The random errors were 1.43, 1.43, 1.44, and 1.22 mm in the intraoral stent (-) group and 1.06, 1.11, 1.05, and 0.92 mm in the intraoral stents (+) group, respectively.

CONCLUSION

Setup errors can be significantly reduced in the AP and 3D-directions by using intraoral stents.

Pravastatin reduces radiation-induced damage in normal tissues

Pravastatin is an inhibitor of 3-hydroxy-3-methyl- glutaryl-coenzyme A reductase that has been reported to have therapeutic applications in a range of inflammatory conditions. The aim of the present study was to assess the radioprotective effects of pravastatin in an experimental animal model. Mice were divided into two groups: The control group received ionizing radiation with no prior medication, while the pravastatin group received pravastatin prior to ionizing radiation. Pravastatin was administered orally at 30 mg/kg body weight in drinking water at 24 and 4 h before irradiation. Intestinal crypt epithelial cell survival and the incidence of apoptosis in the intestine and lung were measured post-irradiation. The effect of pravastatin on intestinal DNA damage was determined by immunohistochemistry. Finally, the effect of pravastatin on tumor response to radiotherapy was examined in a mouse mesothelioma xenograft model. Pravastatin increased the number of viable intestinal crypts and this effect was statistically significant in the ileum (P<0.0001). The pravastatin group showed significantly lower apoptotic indices in all examined parts of the intestine (P<0.0001) and tended to show reduced apoptosis in the lung. Pravastatin reduced the intestinal expression of ataxia-telangiectasia mutated and gamma-H2AX after irradiation. No apparent pravastatin-related differences were observed in the response of xenograft tumors to irradiation. In conclusion, pravastatin had radioprotective effects on the intestine and lung and reduced radiation-induced DNA double-strand breaks. Pravastatin may increase the therapeutic index of radiotherapy.

Threshold doses and prediction of visually apparent liver dysfunction after stereotactic body radiation therapy in cirrhotic and normal livers using magnetic resonance imaging

The purpose of the present study was to investigate the threshold dose for focal liver damage after stereotactic body radiation therapy (SBRT) in cirrhotic and normal livers using magnetic resonance imaging (MRI). A total of 64 patients who underwent SBRT for liver tumors, including 54 cirrhotic patients with hepatocellular carcinoma (HCC) and 10 non-cirrhotic patients with liver metastases, were analyzed. MRI was performed 3-6 months after SBRT, using gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid-enhanced T1-weighted sequences. All MRI datasets were merged with 3D dosimetry data. All dose distributions were corrected to the biologically effective dose using the linear-quadratic model with an assumed α/β ratio of 2 Gy. The development of liver dysfunction was validly correlated with isodose distribution. The median biologically effective dose (BED2) that provoked liver dysfunction was 57.3 (30.0-227.9) and 114.0 (70.4-244.9) Gy in cirrhotic and normal livers, respectively (P = 0.0002). The BED2 associated with a >5% risk of liver dysfunction was 38.5 in cirrhotic livers and 70.4 Gy in normal livers. The threshold BED2 for liver dysfunction was not significantly different between Child-Pugh A and B patients (P = 0.0719). Moreover, the fractionation schedule was not significantly correlated with threshold BED2 for liver dysfunction in the cirrhotic liver (P = 0.1019). In the cirrhotic liver, fractionation regimen and Child-Pugh classification did not significantly influence the threshold BED2 for focal liver damage after SBRT. We suggest that the threshold BED2 for liver dysfunction after SBRT is 40 and 70 Gy in the cirrhotic and normal liver, respectively.