Perihippocampal Meningeal Carcinomatosis Following Hippocampal Avoidance Prophylactic Cranial Irradiation in Small Cell Lung Cancer: A Case Report.

Prophylactic cranial irradiation (PCI) for limited disease small cell lung cancer is the standard of care for curative treatment of this disease. However, neurocognitive dysfunction is one of the late adverse events of PCI and is often problematic. Recently, hippocampal avoidance prophylactic cranial irradiation (HA-PCI) is sometimes performed to prevent neurocognitive dysfunction after PCI. In HA-PCI, the question is whether or not metastases appear around the hippocampus that were not irradiated. We have experienced a case of perihippocampal meningeal carcinomatosis after HA-PCI. We also draw attention to the potential risks of performing HA-PCI based on this experience.

Clinical Experience of Intra-tumoral Central-Dose Escalated Volumetric Modulated Arc Therapy for Lymph Node Metastases in Patients With Advanced Cancer.

Background Lymph node metastases (LN mets) are radioresistant, and high-dose irradiation is preferred for their control. The volumetric-modulated arc therapy technique makes it possible to perform intra-tumoral dose escalation without increasing the total prescribed dose of fractionated irradiation. We report its clinical experiences with intra-tumoral central-dose escalated volumetric-modulated arc therapy (ICE-VMAT) for LN mets. Materials and methods This study retrospectively evaluated 31 patients with 50 LN mets from stage III and IV advanced cancers who received ICE-VMAT. The total described dose was 50 Gy, and the median intra-tumoral central dose was 66 Gy (range, 54-79 Gy). Results The median follow-up period was 21 months. The two-year local control and overall survival (OS) rates were 95% and 56%, whereas univariate analysis revealed that the KPS ≥ 80 group had a significantly better OS compared to the KPS < 80 group. Conclusion ICE-VMAT was effective for LN mets. Patients with good KPS may benefit from therapeutic intervention with ICE-VMAT, even if they have multiple distant LN mets.

Characteristics of microSilicon diode detector for electron beam dosimetry.

A microSilicon™ (PTW type 60023), a new unshielded diode detector succeeding Diode E (model 60017, PTW), was characterized for electron beam dosimetry and compared with other detectors. Electron beams generated from a TrueBeam linear accelerator were measured using the microSilicon, Diode E, and microDiamond synthetic single-crystal diamond detector. Positional accuracy of microSilicon was measured by data collected in air and water. The percent depth dose (PDD), off-center ratio (OCR), dose-response linearity, dose rate dependence, and cone factors were evaluated. The PDDs were compared with data measured using a PPC40 plane-parallel ionization chamber. The maximum variations of depth of 50% and 90% of the maximum dose, and practical depth among all detectors and energies were 0.9 mm. The maximum variations of the bremsstrahlung dose among all detectors and energies were within 0.3%. OCR showed good agreement within 1% for the flat and tail regions. The microSilicon detector showed a penumbra width similar to microDiamond, whereas Diode E showed the steepest penumbra shape. All detectors showed good dose-response linearity and stability against the dose rate; only Diode E demonstrated logarithmic dose rate dependency. The cone factor measured with microSilicon was within ±1% for all energies and cone sizes. We demonstrated that the characteristics of microSilicon is suitable for electron beam dosimetry. The microSilicon detector can be a good alternative for electron beam dosimetry in terms of providing an appropriate PDD curve without corrections, high spatial resolution for OCR measurements and cone factors.

Characterization of a microSilicon diode detector for small-field photon beam dosimetry.

This study characterized a new unshielded diode detector, the microSilicon (model 60023), for small-field photon beam dosimetry by evaluating the photon beams generated by a TrueBeam STx and a CyberKnife. Temperature dependence was evaluated by irradiating photons and increasing the water temperature from 11.5 to 31.3°C. For Diode E, microSilicon, microDiamond and EDGE detectors, dose linearity, dose rate dependence, energy dependence, percent-depth-dose (PDD), beam profiles and detector output factor (OFdet) were evaluated. The OFdet of the microSilicon detector was compared to the field output factors of the other detectors. The microSilicon exhibited small temperature dependence within 0.4%, although the Diode E showed a linear variation with a ratio of 0.26%/°C. The Diode E and EDGE detectors showed positive correlations between the detector reading and dose rate, whereas the microSilicon showed a stable response within 0.11%. The Diode E and microSilicon demonstrated negative correlations with the beam energy. The OFdet of microSilicon was the smallest among all the detectors. The maximum differences between the OFdet of microSilicon and the field output factors of microDiamond were 2.3 and 1.6% for 5 × 5 mm2 TrueBeam and 5 mm φ CyberKnife beams, respectively. The PDD data exhibited small variations in the dose fall-off region. The microSilicon and microDiamond detectors yielded similar penumbra widths, whereas the other detectors showed steeper penumbra profiles. The microSilicon demonstrated favorable characteristics including small temperature and dose rate dependence as well as the small spatial resolution and output factors suitable for small field dosimetry.

Feasibility of virtual starshot analysis providing submillimeter radiation isocenter accuracy: A long-term multi-institutional analysis.

PURPOSE: We developed a technique to calculate the offset between room lasers and the radiation isocenter using a digital Winston-Lutz (WL) test with a starshot technique. We have performed isocenter localization quality assurance (QA) with submillimeter accuracy for a long period. Here we evaluated the feasibility and accuracy of this virtual starshot (VS) analysis for isocenter localization QA. METHODS: A 6-MV photon beam with a square multileaf collimator field was used to irradiate a WL sphere positioned at the intersection of the room lasers. Images were acquired using an electronic portal imaging device. A four-field WL test was performed, and the path of each beam was calculated from the offset between the beam and sphere. Virtual starshot analysis was used to analyze the radiation isocenter, which calculates the center of the beam paths by using a least-squares method, similar to the starshot analysis. Then, eight coplanar and 12 noncoplanar beams were irradiated to evaluate isocenter localization accuracy. RESULTS: Several VS analyses, using different WL spheres, were performed at three institutions, and the calculated accuracies were within 0.1 mm at all institutions. Long-term analysis showed that the isocenter localization accuracy was appropriately managed with three-dimensional accuracy within ± 0.5 mm for 90 months after the first laser adjustments. The offset between each beam and the room laser was within 0.6 mm and within 1.0 mm for eight coplanar and 12 noncoplanar beams, respectively, for 90 months. Cone-beam computed tomography images, acquired after verification beams, showed that the offset between the radiation isocenter and the imaging center was within 0.66 mm for 90 months. The isocenter localization accuracy within 1 mm was kept for long period at other four institutions. CONCLUSIONS: Long-term analysis showed the feasibility of VS analysis for isocenter localization QA, including room laser re-alignment, noncoplanar irradiation verification, and image guidance accuracy.

Preventing Complications from High-Dose Rate Brachytherapy when Treating Mobile Tongue Cancer via the Application of a Modular Lead-Lined Spacer.

PURPOSE: To point out the advantages and drawbacks of high-dose rate brachytherapy in the treatment of mobile tongue cancer and indicate the clinical importance of modular lead-lined spacers when applying this technique to patients. METHODS: First, all basic steps to construct the modular spacer are shown. Second, we simulate and evaluate the dose rate reduction for a wide range of spacer configurations. RESULTS: With increasing distance to the source absorbed doses dropped considerably. Significantly more shielding was obtained when lead was added to the spacer and this effect was most pronounced on shorter (i.e. more clinically relevant) distances to the source. CONCLUSIONS: The modular spacer represents an important addition to the planning and treatment stages of mobile tongue cancer using HDR-ISBT.

Efficacy and safety of nedaplatin-based concurrent chemoradiotherapy for FIGO Stage IB2-IVA cervical cancer and its clinical prognostic factors.

Cisplatin-based concurrent chemoradiotherapy (CCRT) is a standard treatment for cervical cancer, but nedaplatin-based CCRT is not routinely administered. We evaluated the efficacy and safety of nedaplatin-based CCRT (35 mg/m(2) weekly) and analyzed prognostic factors for survival among 52 patients with International Federation of Gynecology and Obstetrics (FIGO) Stage IB2-IVA cervical cancer treated from 1999 to 2009. Patients were treated with a combination of external beam radiotherapy of 40-56 Gy (in 20-28 fractions) and 13.6-28.8 Gy (in 2-4 fractions) of high-dose-rate (HDR) intracavitary brachytherapy or 18 Gy (in 3 fractions) of HDR interstitial brachytherapy. Overall survival (OS), progression-free survival (PFS), and local control (LC) were estimated using the Kaplan-Meier method. The Cox proportional hazard model was used for multivariate analysis. Acute and late toxicities were evaluated using the Common Terminology Criteria for Adverse Events version 4.0. The median follow-up period was 52 months. The median patient age was 63 years. The 5-year OS, PFS and LC rates were 78%, 57% and 73%, respectively. Multivariate analysis showed that histologic type, maximum tumor diameter, and pretreatment hemoglobin level were independent risk factors for PFS. Regarding adverse effects, 24 patients (46%) had acute Grade 3-4 leukopenia and 5 (10%) had late Grade 3 gastrointestinal toxicities. No patient experienced renal toxicity. Nedaplatin-based CCRT for FIGO Stage IB2-IVA cervical cancer was efficacious and safe, with no renal toxicity. Histologic type, maximum tumor diameter, and pretreatment hemoglobin level were statistically significant prognostic factors for PFS.

Treatment outcomes using CyberKnife for brain metastases from lung cancer.

We investigated the clinical outcomes following treatment using stereotactic radiosurgery (SRS) and fractionated stereotactic radiotherapy (SRT) for brain metastases from lung cancer. A total of 67 patients with 109 brain metastases from lung cancer treated using CyberKnife between 1998 and 2011 were retrospectively analyzed. SRS (median dose, 24 Gy) was used to treat 79 lesions, and 3-fraction SRT (median dose, 30 Gy) was used to treat 30 lesions. The median follow-up time was 9.4 months (range, 0.4-125 months). The 1-year local control rate was 83.3%, and the 1-year distant brain failure rate was 30.1%. The median survival time was 13.1 months, and the 1- and 3-year overall survival (OS) rates were 54.8% and 25.9%, respectively. On multivariate analysis, three factors were found to be statistically significant predictors of OS: (i) presence of uncontrolled primary disease [hazard ratio (HR) = 3.04; P = 0.002]; (ii) Brinkman index (BI) ≥ 1000 (HR = 2.75; P = 0.007); and (iii) pulmonary metastases (HR = 3.54; P = 0.009). Radionecrosis and worsening of neurocognitive function after radiosurgery were observed in 5 (7%) and 3 (4%) patients, respectively. Our results indicated that SRS/SRT for brain metastases from lung cancer was effective. Uncontrolled primary disease, high BI, and pulmonary metastases at treatment were significant risk factors for OS.

Hypofractionated stereotactic radiotherapy using CyberKnife as a boost treatment for head and neck cancer, a multi-institutional survey: impact of planning target volume.

AIM: To evaluate the role of hypofractionated stereotactic radiotherapy (hSRT) as a boost treatment for head and neck cancer. PATIENTS AND METHODS: We conducted a multi-institutional retrospective review for the outcome of boost irradiation using CyberKnife for head and neck cancer patients from the charts of four Institutes. Twenty-five patients were treated with hSRT boost for primary site with a median follow-up of 28 months. Treatment sites were 11 nasopharynx, 7 oropharynx, one hypopharynx, 3 nasal cavity or paranasal sinus and three oral cancers. All patients underwent preceding conventional radiotherapy of 35 to 72 Gy (median, 50 Gy) in 1.2- to 2 Gy-fractions. The dose and fractionation scheme of the Cyberknife SRT boost was individualized and the prescribed dose ranged from 12 Gy to 35 Gy in 1 to 5 fractions (median, 15 Gy in 3 fractions). RESULTS: There were 18 complete responses, 6 partial responses and one progressive disease, resulting in 96% (24/25) response rate. Local control (LC) rates at 2- and 5-years were 89% and 71%, respectively. Progression-free survival (PFS) and overall survival (OS) at 2- and 5-years were 70%/ 83% and 70%/ 70%, respectively. Planning target volume (PTV) at boost treatment planning and initial response were predisposing factors for PFS and OS. Patients with PTV ≤ 20 cm(3) showed better PFS (92%) and OS (100%) than those with a PTV > 20 cm(3) (PFS, 61% and OS, 47%). Good initial response predicts better outcome in LC, PFS and OS. CONCLUSION: The results of the present study showed potential benefits of the CyberKnife hSRT boost. Smaller PTV and good initial response predict good outcome.

Comparison of the prognoses of FIGO stage I to stage II adenosquamous carcinoma and adenocarcinoma of the uterine cervix treated with radical hysterectomy.

OBJECTIVES: To evaluate the significance of adenosquamous carcinoma (ASC) compared with adenocarcinoma (AC) in the survival of surgically treated early-stage cervical cancer. METHODS: We retrospectively reviewed the medical records of 163 patients with International Federation of Gynecology and Obstetrics stage IA2 to stage IIB cervical cancer who had been treated with radical hysterectomy with or without adjuvant radiotherapy between January 1998 and December 2008. The patients were classified according to the following: (1) histological subtype (ASC group or AC group) and (2) pathological risk factors (low-risk or intermediate/high-risk group). Survival was evaluated using the Kaplan-Meier method and compared using the log-rank test. Multivariate analysis of progression-free survival (PFS) was performed using the Cox proportional hazards regression model to investigate the prognostic significance of histological subtype. RESULTS: Clinicopathological characteristics were similar between the ASC and AC histology groups. Patients with the ASC histology displayed a PFS rate similar to that of the patients with the AC histology in both the low-risk and intermediate/high-risk groups. Neither the recurrence rate nor the pattern of recurrence differed between the ASC group and the AC group. Univariate analysis revealed that patients with pelvic lymph node metastasis and parametrial invasion achieved significantly shorter PFS than those without these risk factors. CONCLUSIONS: Characteristics of the patients and the tumors as well as survival outcomes of ASC were comparable to adenocarcinoma of early-stage uterine cervix treated with radical hysterectomy. Our results in part support that the management of ASC could be the same as the one of AC of the uterine cervix.