Influence of Respiratory Motion on Dose Distribution in Gastric Mucosa-associated Lymphoid Tissue Lymphoma Radiotherapy

BACKGROUND/AIM

The present study investigated the effect of respiratory motion on planned radiotherapy (RT) dose for gastric mucosa-associated lymphoid tissue (MALT) lymphoma using four-dimensional dose (4D-dose) accumulation.

PATIENTS AND METHODS

4D-computed tomography (4D-CT) images of 10 patients with gastric MALT lymphomas were divided into 10 respiratory phases. Further, the 3D-dose was calculated using 3D conformal RT (3D-CRT) and volumetric modulated arc therapy (VMAT) plans based on the average intensity projection (AIP) images. Then, both plans were recalculated according to each phase image. Moreover, the dose distributions in each phase were transferred to the AIP images using deformable image registration. The 4D-dose distribution was calculated by summing the doses of each phase, and it was compared with the dosimetric parameters of the 3D-dose distribution.

RESULTS

For 3D-CRT, the D95 and D99 of the 4D-dose in the planning target volume (PTV) were significantly lower than those of the 3D-dose, with mean differences of 0.2 (p=0.009) and 0.1 Gy (p=0.021), respectively. There were no significant differences in the other PTV and organ-at-risk dosimetric parameters of 3D-CRT or in any dosimetric parameters of VMAT between the 3D- and 4D-dose distributions.

CONCLUSION

The effect of respiratory motion on the planned 3D-CRT and VMAT dose distributions for gastric MALT lymphoma is minimal and clinically negligible.

Prevalence and risk factors for retropharyngeal and retro-styloid lymph node metastasis in hypopharyngeal carcinoma

BACKGROUND

We evaluated the prevalence and identified the risk factors for retropharyngeal and retro-styloid lymph node metastasis (LNM) in patients with hypopharyngeal carcinoma (HPC). This was achieved using a combination of magnetic resonance (MR) and [18 F]-fluoro-2-deoxy-D-glucose (FDG)-positron emission tomography (PET)/computed tomography (CT) images.

METHODS

Two board-certified radiation oncologists retrospectively reviewed pretreatment FDG-PET/CT images and contrast-enhanced thin-slice CT and MR images of 155 patients with HPC who underwent radiotherapy. Fisher's exact tests and logistic regression analyses were performed to assess the risk factors for LNM.

RESULTS

Retropharyngeal LNM (RPLNM) was confirmed in 20 (13%) patients. Posterior wall (PW) tumors (odds ratio [OR]: 4.128, 95% confidence interval [CI]: 1.339-12.727; p = 0.014) and bilateral or contralateral cervical LNM (OR: 11.577, 95% CI: 2.135-62.789; p = 0.005) were significantly correlated with RPLNM. The RPLNM was found in 9 (32%) of the 28 patients with PW tumors. Of these 9 patients, 2 (7%) had ipsilateral RPLNM, 3 (11%) had contralateral RPLNM, and 4 (14%) had bilateral RPLNM. The PW tumors were significantly associated with contralateral RPLNM (p < 0.001). Retro-styloid LNM (RSLNM) was confirmed in two (1%) patients, both of whom had ipsilateral RSLNM with lymph nodes (LNs) of ≥ 15 mm in the upper limit of ipsilateral level II. A significant association was found between LNs of ≥ 15 mm in the upper limit of ipsilateral level II and ipsilateral RSLNM (p = 0.001).

CONCLUSIONS

The RPLNM was identified in 13% of patients with HPC. The PW tumors and bilateral or contralateral cervical LNM were risk factors for RPLNM; particularly, PW tumors were a specific risk factor for contralateral RPLNM. Although the RSLNM was rare, LNs of ≥ 15 mm in the upper limit of ipsilateral level II were a risk factor for ipsilateral RSLNM.

Impact of metal artifact reduction algorithm on gross tumor volume delineation in tonsillar cancer: reducing the interobserver variation

Background

Patients with tonsillar cancer (TC) often have dental fillings that can significantly degrade the quality of computed tomography (CT) simulator images due to metal artifacts. We evaluated whether the use of the metal artifact reduction (MAR) algorithm reduced the interobserver variation in delineating gross tumor volume (GTV) of TC.

Methods

Eighteen patients with TC with dental fillings were enrolled in this study. Contrast-enhanced CT simulator images were reconstructed using the conventional (CT_CONV) and MAR algorithm (CT_MAR). Four board-certified radiation oncologists delineated the GTV of primary tumors using routine clinical data first on CT_CONV image datasets (GTV_CONV), followed by CT_CONV and CT_MAR fused image datasets (GTV_MAR) at least 2 weeks apart. Intermodality differences in GTV values and Dice similarity coefficient (DSC) were compared using Wilcoxon’s signed-rank test.

Results

GTV_MAR was significantly smaller than GTV_CONV for three observers. The other observer showed no significant difference between GTV_CONV and GTV_MAR values. For all four observers, the mean GTV_CONV and GTV_MAR values were 14.0 (standard deviation [SD]: 7.4) cm³ and 12.1 (SD: 6.4) cm³, respectively, with the latter significantly lower than the former (p < 0.001). The mean DSC of GTV_CONV and GTV_MAR was 0.74 (SD: 0.10) and 0.77 (SD: 0.10), respectively, with the latter significantly higher than that of the former (p < 0.001).

Conclusions

The use of the MAR algorithm led to the delineation of smaller GTVs and reduced interobserver variations in delineating GTV of the primary tumors in patients with TC.

Implementation of 99mTc-GSA SPECT Image-guided Inverse Planning into Palliative Radiotherapy for Diffuse Liver Metastases: A Novel Approach

BACKGROUND/AIM

This is a report of the first clinical implementation of ^99mTc-labeled diethylene triamine pentaacetate-galactosyl human serum albumin (^99mTc-GSA) single-photon emission computed tomography (SPECT) image-guided inverse planning into palliative radiotherapy (RT) for diffuse liver metastases.

CASE REPORT

A 48-year-old man developed chemo-refractory diffuse liver metastases from thymic carcinoma characterized by abdominal pain and distension. Palliative RT was performed with a total dose of 20 Gy in five fractions using double arc volumetric modulated arc therapy to reduce the dose to functional liver defined by ^99mTc-GSA SPECT images. His symptoms were immediately relieved after RT and did not experience radiation-induced liver disease. Both Functional Assessment of Cancer Therapy (FACT)-G and FACT-Hep total scores improved after 2 weeks of RT initiation and did not become worse than baseline scores.

CONCLUSION

The ^99mTc-GSA SPECT image-guided palliative RT is an effective and safe treatment for patients with diffuse liver metastases.

A prospective comparison of adaptive and fixed boost plans in radiotherapy for glioblastoma

Purpose

To analyze the efficacy of adaptive radiotherapy (ART) for glioblastoma.

Methods

Sixty-one glioblastoma patients who received ART were prospectively evaluated. The initial clinical target volume (CTVinitial) was represented by T2 hyperintensity on postoperative MRIs (pre-RT MRI [MRIpre])plus 10 mm. The initial planning target volume (PTVinitial) was the CTVinitial plus a 5-mm margin. The PTVinitial received 40 Gy. An MRI and a second planning CT were performed during radiotherapy (MRImid). Two types of boost CTVs (the resection cavity and residual tumor on enhanced T1-weighted MRI plus 10 mm) were created based on the MRIpre and MRImid (CTVboost-pre and -mid). The boost PTV (PTVboost) was the CTVboost plus 5 mm. Two types of boost plans (fixed and adaptive boost plans in the first and second planning CT, respectively) of 20 Gy were created. The PTV based on the post-RT MRI (PTVboost-post) was created, and the dose-volume histograms of the PTVboost-post in the fixed and adaptive boost plans were compared. Additionally, the conformity indices (CIs) of the fixed and adaptive boost plans were compared.

Results

The median V95 of the PTVboost-post of the fixed and adaptive boost plans (V95pre and V95mid) were 95.6% and 98.3%, respectively (P < 0.01). The median V95pre and V95mid of patients after gross total resection (GTR) were 97.4% and 98.8%, respectively (P = 0.41); in contrast, the median values of patients after non-GTR were 91.9% and 98.2%, respectively (P < 0.01). The median CIs of the fixed and adaptive boost plans in all patients were 1.45 and 1.47, respectively (P = 0.31). The median CIs of the fixed and adaptive boost plans in patients after GTR were 1.61 and 1.48, respectively (P = 0.01); in contrast, those in patients after non-GTR were 1.36 and 1.44, respectively (P = 0.13).

Conclusion

ART for glioblastoma improved the target coverage and dose reduction for the normal brain. By analyzing the results according to the resection rate, we can expect a decrease in normal brain dose in patients with GTR and an increase in coverage in those with partial resection or biopsy.

Concurrent Chemoradiotherapy With Docetaxel, Cisplatin, and 5-Fluorouracil for T3 N0 Glottic Carcinoma Without Vocal Cord Fixation

BACKGROUND/AIM

We retrospectively evaluated the efficacy and toxicity of concurrent chemoradiotherapy (CCRT) with docetaxel, cisplatin, and 5-fluorouracil (TPF) for T3 N0 glottic carcinoma without vocal cord fixation.

PATIENTS AND METHODS

Twenty-five patients underwent TPF-CCRT without elective nodal irradiaion (ENI). After the RT of 40 Gy, five patients (20%) without tumor regression underwent surgery. Others underwent RT with a median total dose of 66 Gy.

RESULTS

Of the five patients who underwent surgery after the RT of 40 Gy, two showed residual carcinoma pathologically and the other three were confirmed to have complete pathological response to the treatment. The 5-year local control rate was 87%. No patients exhibited regional failure. No acute toxicities of grade 5 or late toxicities ≥grade 3 were observed.

CONCLUSION

TPF-CCRT provides excellent tumor control with acceptable toxicities. CCRT while omitting ENI is a reasonable approach for T3 N0 glottic carcinoma without vocal cord fixation.

Palliative radiotherapy for painful lymph node metastases

BACKGROUND

There is limited evidence concerning radiotherapy for painful lymph node metastases (PLM). We evaluated the effectiveness of radiotherapy for PLM using the International Consensus Endpoint in a subgroup analysis of a prospective observational study.

METHODS

In the primary study, 302 patients received radiotherapy for painful tumors. Among them, those treated with palliative radiotherapy for PLM were analyzed in the present study. We used the Brief Pain Inventory short form to evaluate the intensity of pain and the pain interference in patient's life. We collected the Brief Pain Inventory and analgesic data at baseline and at 1, 2, and 3 months after the start of radiotherapy. Pain response was assessed using the International Consensus Endpoint. Patients were diagnosed with a predominance of other pain (POP) if non-index pain of a malignant or unknown origin was present and had a greater 'worst pain' score than the index pain.

RESULTS

Radiotherapy for PLM was performed on 25 patients. In total, 15 (60%) patients experienced a pain response. The pain response rates for evaluable patients were 66%, 67%, and 57% at 1-, 2-, and 3-month follow-ups, respectively. At baseline and at 1, 2, and 3 months, the median index pain scores were 7, 2, 0, and 0.5, respectively. At 1 month, all pain interference scores were significantly reduced from baseline. Four (16%) patients experienced POP within three months.

CONCLUSION

Radiotherapy for PLM improved pain intensity and pain interference. Palliative radiotherapy may be a viable treatment option for PLM.

Plan Quality Comparisons Between 3D-CRT, IMRT, and VMAT Based on 4D-CT for Gastric MALT Lymphoma

BACKGROUND/AIM

We compared three-dimensional conformal RT (3D-CRT), intensity-modulated radiotherapy (IMRT), and volumetric modulated arc therapy (VMAT) for gastric mucosa-associated lymphoid tissue (MALT) lymphoma using four-dimensional computed tomography (4D-CT) images.

PATIENTS AND METHODS

Three treatment plans of 3D-CRT, IMRT, and VMAT with 30 Gy were created based on 4D-CT images of seven patients. We calculated D95, homogeneity index (HI), and conformity index (CI) of planning target volume, and organs at risk doses.

RESULTS

There was no significant difference among the three plans in D95. HI of the IMRT plan was significantly better than that of the VMAT (p=0.047) and 3D-CRT (p=0.047) plans. CIs of the IMRT and VMAT plans were significantly better than those of the 3D-CRT plan (p=0.047 and p=0.047, respectively). D_mean of the liver for 3D-CRT was significantly higher than that for the IMRT (p=0.047) and VMAT (p=0.047) plans.

CONCLUSION

The IMRT plan yields the best plan quality for gastric MALT lymphoma.

Influence of pain duration on pain outcomes following palliative radiotherapy for painful tumors: the sooner the irradiation, the better?

PURPOSE

The influence of pre-radiotherapy pain duration on post-treatment outcomes was assessed.

METHODS

Patients that received palliative radiotherapy were analyzed in a prospective observational study investigating curative and palliative radiotherapy. Brief Pain Inventory data were acquired at baseline and 1, 2, and 3 months after commencing irradiation. The pain response in terms of the index pain (i.e., pain caused by the irradiated tumors) was assessed using the International Consensus Endpoint. Patients were diagnosed with predominance of other pain (POP) if non-index pain of malignant or unknown origin was present and showed a higher pain score than the index pain. Competing risk analyses were performed in which deaths without the pain endpoints were considered as competing events.

RESULTS

Of 229 patients analyzed, 123 (54%) experienced a pain response and 43 (19%) experienced POP. Multivariable analyses using the Fine-Gray model revealed that patients with shorter pain duration (< 1 month) had higher cumulative incidence of pain response (subdistribution hazard ratio, 2.43; 95% confidence interval [CI], 1.35-4.38) and POP (subdistribution hazard ratio, 4.22; 95% CI, 1.30-13.70) compared with patients with longer pain duration (≥ 4 months). For patients with a pain duration of less than 1 month, cumulative incidence of pain response was estimated to be 69% (95% CI, 53-85%) and cumulative incidence of POP was estimated to be 15% (95% CI, 3-28%) at 1‑month follow-up.

CONCLUSION

Commencing palliative radiotherapy earlier may improve the probability of patients achieving a pain response, although POP may be more frequent.

Impact of four-dimensional cone-beam computed tomography on target localization for gastric mucosa-associated lymphoid tissue lymphoma radiotherapy: reducing planning target volume

Background

Radiotherapy of gastric mucosa-associated lymphoid tissue (MALT) lymphoma should be delivered to the entire stomach with planning target volume (PTV) that accounts for variations in stomach volume, respiratory movement, and patient set-up error. In this study, we evaluated whether the use of four-dimensional cone-beam computed tomography (4D-CBCT) reduces the PTV.

Methods

Eight patients underwent radiotherapy with 15 fractions of gastric MALT lymphoma using 4D-CBCT. PTV structures of 5–30 mm margins (5 mm intervals) from the clinical target volume (CTV) delineated based on the 4D-CT images (CTV-4D) were generated. For the target localization, we performed matching based on skin marking (skin matching), bone anatomy (bone matching), and stomach anatomy (4D soft-tissue matching) based on registration between planning CT and 4D-CBCT images from 10 phases. For each patient, we calculated the covering ratio (CR) of the stomach with variable PTV structures, based on the 4D-CBCT images, with a total of 150 phases [CR (%) = (number of covering phases/150 phases) × 100], for three target localization methods. We compared the CR values of the different target localization methods and defined the PTV with an average CR of ≥ 95% for all patients.

Results

The average CR for all patients increased from 17.9 to 100%, 19.6 to 99.8%, and 33.8 to 100%, in the skin, bone, and 4D soft-tissue matchings, respectively, as the PTV structures increased from 5 to 30 mm. The CR obtained by 4D soft-tissue matching was superior to that obtained by skin (P = 0.013) and bone matching (P = 0.008) for a PTV structure of 15 mm margin. The PTV required an additional margin of 20 mm (average CR: 95.2%), 25 mm (average CR: 99.1%), and 15 mm (average CR: 98.0%) to CTV-4D for the skin, bone, and 4D soft-tissue matchings, respectively.

Conclusions

This study demonstrates that the use of 4D-CBCT reduces the PTV when applying 4D soft-tissue matching, compared to skin and bone matchings. Additionally, bone matching does not reduce the PTV as compared with traditional skin matching.

QUAD shot: an effective cyclical hypofractionated palliative radiotherapy for salivary gland carcinoma

Surgery with or without post-operative radiotherapy is the mainstay treatment for salivary gland carcinoma (SGC); however, palliative radiotherapy or supportive observation is considered for elderly patients. An 87-year-old female who was diagnosed with SGC in the left parotid gland, with a clinical stage T4aN2bM0 Stage IVA, underwent the Radiation Therapy Oncology Group 8502 “QUAD shot” regimen (14.8 Gy/4 fractions, twice-daily treatment with a 6 h interval, on 2 consecutive days), which were repeated every 4 weeks 3 times using volumetric modulated arc therapy. During and after the treatment, she experienced no acute toxicity but had Grade 1 xerostomia. At 4 months after completion of the treatment, [¹⁸F]-fluoro-2-deoxy-D-glucose positron emission tomography/CT revealed a complete metabolic response to the treatment. She is still alive without any evidence of recurrence 9 months after completion of the treatment. The Radiation Therapy Oncology Group 8502 “QUAD shot” regimen using VMAT may be an effective palliative treatment for SGC with minimal toxicity.

Hypofractionated palliative volumetric modulated arc radiotherapy with the Radiation Oncology Study Group 8502 "QUAD shot" regimen for incurable head and neck cancer

BACKGROUND

To review a single institutional experience of the Radiation Therapy Oncology Group (RTOG) 8502 "QUAD shot" regimen using volumetric modulated arc radiotherapy (VMAT) for incurable head and neck cancer (HNC).

METHODS

Thirty-four consecutive patients with HNC were treated with at least one cycle of the RTOG 8502 regimen. Treatment plans included the use of VMAT with 6 MV photons generated by a linear accelerator. Two daily fractions of 3.7 Gy were delivered with an interval of at least 6 h for 2 consecutive days, totaling 14.8 Gy over 4 fractions. This was repeated every 3-4 weeks for a total of three cycles. No concurrent systemic therapy was performed.

RESULTS

The number of completed cycles was 1 in 6 (18%) patients, 2 in 5 (15%), and 3 in 23 (68%). Tumor response was achieved in 29 (85%) patients and symptom relief in 20 (77%) of 26 patients. Overall response (tumor response or symptom relief) was achieved in 32 (94%) patients. All patients who received 2 or more treatment cycles achieved overall response. Median overall survival (OS) was 5.7 months. Multivariate analysis revealed that completion of all three treatment cycles was significantly associated with better OS (P = 0.002). Grade 2 toxicity was observed in four (12%) patients, but no acute Grade ≥ 3 or late toxicity was observed.

CONCLUSIONS

The RTOG 8502 "QUAD shot" regimen using VMAT is effective for incurable HNC with highly reduced toxicity. Treatment with multiple cycles is recommended for better treatment response and/or survival.

High Spatial Resolution Digital Positron Emission Tomography Images With Dedicated Source-to-background Algorithm for Radiotherapy Planning

BACKGROUND/AIM

To evaluate the utility of high spatial resolution digital positron emission tomography images with the source-to-background ratio (SBR) algorithm for gross tumour volume (GTV) delineation.

MATERIALS AND METHODS

The bowl and spheres (10-37 mm) were filled with fluoro-2-deoxy-D-glucose to achieve 4-16 times background radioactivity. The images were reconstructed using three isotropic voxel sizes. The SBR and percentage threshold (TH) to SUV_max were calculated. The plots between SBR and TH were fitted using a regression equation. The contoured volumes (CVs) of the spheres were calculated by applying TH.

RESULTS

TH was 38.6+75.0/SBR for 4 mm voxel size; 39.6+37.0/SBR for 2 mm; and 38.8+35.2/SBR for 1 mm. The mean relative errors between CV and true volume for 4, 2, and 1 mm voxel sizes were 15%, 7%, and 7%, respectively.

CONCLUSION

The present technique is useful for GTV delineation with reduced contouring error.

Diagnostic Value of FDG-PET/CT for the Identification of Extranodal Extension in Patients With Head and Neck Squamous Cell Carcinoma

BACKGROUND/AIM

We evaluated the diagnostic value of functional imaging with [¹⁸F]-fluoro-2-deoxy-D-glucose (FDG)-positron emission tomography/computed tomography (PET/CT) for the identification of extranodal extension (ENE) in patients with head and neck squamous cell carcinoma (HNSCC).

PATIENTS AND METHODS

In this study, 94 patients with HNSCC who underwent FDG-PET/CT were enrolled. We recorded the maximum standardized uptake value (SUV_max), compared the results with pathologic findings, and evaluated the diagnostic performance of using a SUV_max cut-off value for ENE.

RESULTS

Of the 566 dissected levels examined, 53 (9.4%) exhibited ENE. The mean SUV_max of LN with and without ENE were 6.67 and 1.64, respectively (p<0.001). A receiver operating characteristics (ROC) curve analysis for SUV_max showed an area under the ROC curve of 0.913. A SUV_max cut-off of 3.0 achieved diagnostic performance for identifying ENE with sensitivity, specificity, and accuracy of 81.1%, 94.3% and 93.1%, respectively.

CONCLUSION

FDG-PET/CT findings using a SUV_max cut-off of 3.0 provides appropriate diagnostic value in identifying ENE.

Impact of hybrid FDG-PET/CT on gross tumor volume definition of cervical esophageal cancer: reducing interobserver variation

Intensity-modulated radiation therapy is being increasingly used to treat cervical esophageal cancer (CEC); however, delineating the gross tumor volume (GTV) accurately is essential for its successful treatment. The use of computed tomography (CT) images to determine the GTV produces a large degree of interobserver variation. In this study, we evaluated whether the use of [18F]-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET)/CT fused images reduced interobserver variation, compared with CT images alone, to determine the GTV in patients with CEC. FDG-PET/CT scans were obtained for 10 patients with CEC, imaged positioned on a flat tabletop with a pillow. Five radiation oncologists independently defined the GTV for the primary tumors using routine clinical data; they contoured the GTV based on CT images (GTVCT), followed by contouring based on FDG-PET/CT fused images (GTVPET/CT). To determine the geometric observer variation, we calculated the conformality index (CI) from the ratio of the intersection of the GTVs to their union. The interobserver CI was compared using Wilcoxon's signed rank test. The mean (±SD) interobserver CIs of GTVCT and GTVPET/CT were 0.39 ± 0.15 and 0.58 ± 0.10, respectively (P = 0.005). Our results suggested that FDG-PET/CT images reduced interobserver variation when determining the GTV in patients with CEC. FDG-PET/CT may increase the consistency of the radiographically determined GTV in patients with CEC.

Impact of 99mTc-GSA SPECT Image-Guided Inverse Planning on Dose-Function Histogram Parameters for Stereotactic Body Radiation Therapy Planning for Patients With Hepatocellular Carcinoma: A Dosimetric Comparison Study

Purpose:

To evaluate the impact of ^99mTc-labeled diethylene triamine pentaacetate-galactosyl human serum albumin (^99mTc-GSA) single-photon emission computed tomography (SPECT) image-guided inverse planning on the dose–function histogram (DFH) parameters for stereotactic body radiation therapy planning in patients with hepatocellular carcinoma (HCC).

Methods:

Eleven patients were enrolled in this study. The functional liver structure (FLS) was derived from SPECT thresholds of 60% to 80% of the maximum pixel value. Two treatment plans optimized without FLS (plan C) and with FLS (plan F) were designed for 50 Gy to the planning target volume (PTV). The DFH parameters were calculated as follows: Fx = (sum of the counts within the liver volume receiving a dose >x Gy/sum of the counts within the whole liver volume) × 100. Other parameters for the PTV included D₉₅, mean dose, conformity index (CI), and homogeneity index (HI).

Results:

Compared with plan C, plan F significantly reduced DFH parameters of F₅ to F₄₀ (P < .05). There were no significant differences in the parameters of the PTV of D₉₅, mean dose, CI, and HI and organs at risks (stomach, duodenum, spinal cord, and kidneys) between plans C and F.

Conclusion:

DFH analyses revealed that ^99mTc-GSA SPECT image-guided inverse planning provided dosimetric benefits related to sparing of liver function and may reduce hepatic toxicities.

Spleen Dose-Volume Parameters as a Predictor of Treatment-related Lymphopenia During Definitive Chemoradiotherapy for Esophageal Cancer

AIM

Our study sought to identify dosimetric predictors of treatment-related lymphopenia during chemoradiotherapy for esophageal cancer.

MATERIALS AND METHODS

Patients with esophageal cancer who had received definitive chemoradiotherapy at our Institution were retrospectively assessed. The absolute volume of the spleen, body, and bone marrow that had received 5, 10, 20, and 30 Gy and the mean splenic dose were recorded.

RESULTS

Multivariate linear regression analysis revealed that docetaxel use and spleen dose-volume parameters (V5, V10, V20, V30, and mean splenic dose) were significant independent factors negatively influencing the absolute lymphocyte count at nadir. An increase of 1 Gy in mean splenic dose predicted a 2.9% decrease in nadir absolute lymphocyte count. Univariable logistic regression analysis showed that the mean splenic dose was a significant predictor of grade 4 lymphopenia. None of the body or bone marrow dose-volume parameters significantly predicted lymphopenia.

CONCLUSION

Higher spleen dose-volume parameters were associated with severe lymphopenia during chemoradiotherapy.

Improvement in pain interference after palliative radiotherapy for solid and hematologic painful tumors: a secondary analysis of a prospective observational study

Background

We previously demonstrated that patients with painful hematologic tumors were more likely to experience pain response after palliative radiotherapy (RT) than those with painful solid tumors. However, it is unknown whether change in pain interference differs between these two tumor types. In the present study, we carried out a secondary analysis of our previous prospective observational study to investigate this matter.

Methods

From patients undergoing palliative RT to treat painful tumors, Brief Pain Inventory data were collected at the start of RT and at the 1-, 2-, and 3- month follow-ups. The Mann-Whitney U test was used to compare changes in pain interference score from baseline between the two groups.

Results

Of the 237 patients, 203 (86%) had solid and 34 (14%) had hematologic index tumors planned to receive RT. At baseline, the groups did not differ significantly in terms of pain score, analgesic use, or pain interference score. At the 1-, 2-, and 3-month follow-ups, the changes in pain interference score from baseline did not differ significantly between the two groups. In both groups, all seven pain interference items, other than sleep in patients with hematologic tumors at the 2-month follow-up, were significantly improved (P < 0.05).

Conclusions

The two groups showed comparable benefit from RT in terms of improvement in pain interference. Patients with tumor-related pain should be offered the option of palliative RT, irrespective of whether the painful tumor is solid or hematologic.

Predictors of the Predominance of NonIndex Pain After Palliative Radiation Therapy for Painful Tumors

Purpose

Even when index pain (pain caused by the irradiated tumor) is palliated after radiation therapy (RT), patients may not derive the full benefits of RT in the presence of another, more intense pain. In this case-control study with prospectively collected data, we sought to identify predictors of the predominance of nonindex pain after palliative RT.

Methods and Materials

Brief Pain Inventory data were collected from patients who received RT for painful tumors. The treating radiation oncologists prospectively evaluated the intensity and origin of nonindex pain. Patients were diagnosed with predominance of other pain (POP) if nonindex pain of malignant or unknown origin was present and had a greater worst pain score than the index pain at the 1- or 2-month follow-up. Changes in pain interference from baseline to follow-up were compared between the 2 groups using Mann-Whitney U tests. Using variables that were identified as significant in a multivariable logistic regression analysis, we developed a prediction model for POP.

Results

Of the 170 patients who were evaluable at the 2-month follow-up, 24 (14%) were diagnosed with POP. At the 2-month follow-up examination of the patients with POP, none of the items of the pain interference scores were reduced from baseline; in contrast, patients without POP experienced significant reductions in all items. Multivariable analysis using the backward elimination method indicated that age ≤65 years, the presence of nonindex pain of malignant or unknown origin at baseline, and no opioid analgesic use at baseline were significant independent predictors of POP. As the number of the risk factors increased, the proportion of patients with POP increased.

Conclusions

We identified three predictors of POP. For patients likely to have POP, careful follow-up is important, and new palliative RT or analgesics should be used when needed.

A neuropathic pain component as a predictor of improvement in pain interference after radiotherapy for painful tumors: A secondary analysis of a prospective observational study

•

A neuropathic component was related to worse pain interference scores at baseline.

•

A neuropathic component predicted a greater reduction in pain interference.

•

Older patients and male patients tended to have a neuropathic component.

Background and purpose

We previously demonstrated that patients with a tumor-related neuropathic pain component were more likely to experience a pain response after radiotherapy (RT) than those without. It is unknown whether the presence of a neuropathic component also favorably influences pain interference. In a secondary analysis of our previous prospective observational study, we investigated if the presence of a neuropathic component of the index pain caused by the irradiated tumors predicts greater reduction in pain interference.

Material and methods

For patients scheduled for RT for painful tumors, Brief Pain Inventory data were collected at initiation of RT and 1, 2, and 3 months thereafter. Multivariable linear regression analyses were performed to investigate the effects of the presence of a neuropathic component on the changes in pain interference scores (i.e., follow-up minus baseline). We used 10 covariates as potential confounders.

Results

Of the 302 analyzable patients, 93 (31%) were diagnosed as having a neuropathic component of the index pain. Multivariable linear regression analyses revealed that all the point estimates of regression coefficients at 1-, 2-, and 3-month follow-up were negative values; some were statistically significant. At 2-month follow-up, patients with a neuropathic component experienced greater reductions in their pain interference scores for walking ability (p = 0.048), normal work (p = 0.021), sleep (p = 0.001), and enjoyment of life (p = 0.010) than those without it.

Conclusions

The presence of a neuropathic pain component predicted a greater reduction in pain interference after RT. Patients with neuropathic tumor-related pain should be offered the option of receiving palliative RT.

Dose-function Histogram Evaluation Using 99mTc-GSA SPECT/CT Images for Stereotactic Body Radiation Therapy Planning for Hepatocellular Carcinoma Patients: A Dosimetric Parameter Comparison

BACKGROUND/AIM

We evaluated the influence of previous treatments on the parametric discrepancies between dose-volume histograms (DVHs) and dose-function histograms (DFHs) generated based on ^99mTc-GSA SPECT images of hepatocellular carcinoma (HCC) patients treated with stereotactic body radiation therapy (SBRT).

PATIENTS AND METHODS

Twelve patients underwent SBRT at 30-40 Gy. Registration between planning CT and SPECT/CT images was performed, and DFH parameters were calculated as follows: Fx=(sum of the counts within the liver volume receiving a dose of more than x Gy/sum of the counts within the whole liver volume) ×100. The discrepancy between Fx and Vx (Dx) was also calculated.

RESULTS

The number of previous treatments for lesions other than SBRT-treated lesions (≥2 vs. <2) exhibited a significant influence on the absolute values of D₁₀, D₁₅, and D₂₀ (p<0.05).

CONCLUSION

Previous treatment significantly influences the parametric discrepancy between DFH and DVH.

Four-dimensional cone-beam computed tomography-guided radiotherapy for gastric lymphoma

PURPOSE

We describe a treatment method with four-dimensional cone-beam computed tomography (4D-CBCT)-guided radiotherapy for gastric lymphoma.

MATERIALS AND METHODS

We performed image-guided radiotherapy (IGRT) with 15 fractions for a gastric mucosa-associated lymphoid tissue lymphoma patient, using 4D-CBCT. The stomach was delineated based on 4D-CT images. For image guidance, an automatic registration between planning CT and 4D-CBCT images was performed based on the bony anatomy (bone matching), followed by manual registration based on the stomach in 4D-CBCT images of all 10 phases (4D matching). We calculated the covering ratio (CR) with variable stomach-to-planning target volume (PTV) margins, based on the images of all phases [CR (%) = the number of covering phases/all 150 phases × 100].

RESULTS

The patient underwent radiotherapy (RT) as scheduled, without any significant adverse effects. The appropriate PTV margins (CR ≥ 95%) were 25 mm (CR 99.3%) and 15 mm (CR 98.7%) for bone and 4D matching, respectively.

CONCLUSION

4D matching using 4D-CBCT is appropriate for IGRT of gastric lymphomas.

An endothelin B receptor-selective antagonist: IRL 1038, [Cys11-Cys15]-endothelin-1(11-21)

In the inhibition of specific binding of [125I]endothelins (ETs) to membrane from various tissues of rats, guinea pigs, pigs and humans, [Cys11-Cys15]-ET-1(11-21), IRL 1038, has a much higher affinity for ETB receptors (Ki = 6-11 nM) than for ETA receptors (Ki = 0.4-0.7 microM). In contraction assays, with ET-3 as a stimulant, 3 microM IRL 1038 antagonized the ETB receptor-mediated contraction of guinea pig ileal and tracheal smooth muscle without any significant agonistic activity, but did not effect the ETA receptor-mediated contraction of rat aortic smooth muscle. IRL 1038 is therefore, considered to be the first antagonist selective to the ETB receptor.

A reversible radioligand specific for the ETB receptor: [125I]Tyr13-Suc-[Glu9,Ala11,15]-endothelin-1(8- 21), [125I]IRL 1620

Suc-[Glu9,Ala11,15]-endothelin(ET)-1(8-21), IRL 1620, is a linear ET-analog specific for the ET-isopeptide-nonselective ETB receptor. The radio-iodinated analog, [125I]IRL 1620, showed a single class of saturable binding to the ETB receptors in porcine lung membranes with a Kd of 18 pM and a Bmax of 930 fmol/mg protein, which are almost comparable to the values obtained with [125I]ET-3 (6 pM and 900 fmol/mg protein). In competitive binding assays with [125I]IRL 1620, unlabeled ET-1, ET-3, IRL 1620 and [monoiodo-Tyr13]-IRL 1620 showed almost identical displacement curves with Ki of 8 to 16 pM. However, [125I]IRL 1620 was dissociated from the binding sites by addition of an excess amount (100 nM) of any of these unlabeled peptides, each with the same t1/2 of 100 min. This was in marked contrast to [125I]ET-3 which was hardly dissociated from the binding sites.

A potent and specific agonist, Suc-[Glu9,Ala11,15]-endothelin-1(8-21), IRL 1620, for the ETB receptor

A series of C-terminal linear peptides of endothelin (ET)-1 and their N alpha-succinyl (Suc) analogs were synthesized and their binding affinities for the two subtypes of ET receptor, ETA and ETB, in porcine lung membranes were examined. Among the synthetic analogs, Suc-[Glu9,Ala11,15]-ET-1(8-21), IRL 1620, was the most potent and specific ligand for the ETB receptor (KiETA/KiETB approximately equal to 120,000) as judged by the Ki values for ETA (1.9 microM) and ETB (16 pM) receptors. IRL 1620 was 60 times more selective for the ETB receptor than ET-3 (KiETA/KiETB approximately equal to 1,900). IRL 1620 (10(-9)-10(-7) M) induced contractions of the guinea pig trachea with a comparable potency to those of ET-1 or ET-3, suggesting that IRL 1620 is a potent ETB receptor agonist.

Endothelin stimulates both cAMP formation and phosphatidylinositol hydrolysis in cultured embryonic bovine tracheal cells

Embryonic bovine tracheal (EBTr) cells were found to possess receptors for endothelin (ET) of ET-1-selective (ETA) subtype with a Kd for ET-1 of 114 pM and a Bmax of 12.9 fmol/10(5) cells. Stimulation of EBTr cells with 100 pM to 100 nM ET-1 increased the contents of both inositol phosphates and cAMP in a concentration-dependent manner, indicating that the receptors are coupled to both phosphatidylinositol hydrolysis and cAMP formation in EBTr cells.