Phantosmia during proton radiation and differences in frequency of phantosmia rates based on proton craniospinal irradiation technique for pediatric brain tumor patients

BACKGROUND

Unusual olfactory perception, often referred to as "phantosmia" or "cacosmia" has been reported during brain radiotherapy (RT), but is infrequent and does not typically interfere with the ability to deliver treatment. We seek to determine the rate of phantosmia for patients treated with proton craniospinal irradiation (CSI) and identify any potential clinical or treatment-related associations.

METHODS

We performed a retrospective review of 127 pediatric patients treated with CSI, followed by a boost to the brain for primary brain tumors in a single institution between 2016 and 2021. Proton CSI was delivered with passive scattering (PS) proton technique (n = 53) or pencil beam scanning technique (PBS) (n = 74). Within the PBS group, treatment delivery to the CSI utilized a single posterior (PA) field (n = 24) or two posterior oblique fields (n = 50). We collected data on phantom smell, nausea/vomiting, and the use of medical intervention.

RESULTS

Our cohort included 80 males and 47 females. The median age of patients was 10 years (range: 3-21). Seventy-one patients (56%) received concurrent chemotherapy. During RT, 104 patients (82%) developed worsening nausea, while 63 patients (50%) reported episodes of emesis. Of those patients who were awake during CSI (n = 59), 17 (29%) reported phantosmia. In the non-sedated group, we found a higher rate of phantosmia in patients treated with PBS (n = 16, 42%) than PS (n = 1, 4.7%) (p = .002). Seventy-eight patients (61%) required medical intervention after developing nausea/vomiting or phantosmia during RT. Two patients required sedation due to the malodorous smell during CSI. We did not find any significant difference in nausea/vomiting based on treatment technique.

CONCLUSION

Proton technique significantly influenced olfactory perception with greater rates of phantosmia with PBS compared to PS. Prospective studies should be performed to determine the cause of these findings and determine techniques to minimize phantosmia during radiation therapy.

Craniospinal irradiation for CNS leukemia: rates of response and durability of CNS control

PURPOSE

Management of CNS involvement in leukemia may include craniospinal irradiation (CSI), though data on CSI efficacy are limited.

METHODS

We retrospectively reviewed leukemia patients who underwent CSI at our institution between 2009 and 2021 for CNS involvement. CNS local recurrence (CNS-LR), any recurrence, progression-free survival (PFS), CNS PFS, and overall survival (OS) were estimated.

RESULTS

Of thirty-nine eligible patients treated with CSI, most were male (59%) and treated as young adults (median 31 years). The median dose was 18 Gy to the brain and 12 Gy to the spine. Twenty-five (64%) patients received CSI immediately prior to allogeneic hematopoietic cell transplant, of which 21 (84%) underwent total body irradiation conditioning (median 12 Gy). Among 15 patients with CSF-positive disease immediately prior to CSI, all 14 assessed patients had pathologic clearance of blasts (CNS-response rate 100%) at a median of 23 days from CSI start. With a median follow-up of 48 months among survivors, 2-year PFS and OS were 32% (95% CI 18-48%) and 43% (95% CI 27-58%), respectively. Only 5 CNS relapses were noted (2-year CNS-LR 14% (95% CI 5-28%)), which occurred either concurrently or after a systemic relapse. Only systemic relapse after CSI was associated with higher risk of CNS-LR on univariate analysis. No grade 3 or higher acute toxicity was seen during CSI.

CONCLUSION

CSI is a well-tolerated and effective treatment option for patients with CNS leukemia. Control of systemic disease after CSI may be important for CNS local control. CNS recurrence may reflect reseeding from the systemic space.

Subtyping of Group 3/4 medulloblastoma as a potential prognostic biomarker among patients treated with reduced dose of craniospinal irradiation: a Japanese Pediatric Molecular Neuro-Oncology Group study

BACKGROUND

One of the most significant challenges in patients with medulloblastoma is reducing the dose of craniospinal irradiation (CSI) to minimize neurological sequelae in survivors. Molecular characterization of patients receiving lower than standard dose of CSI therapy is important to facilitate further reduction of treatment burden.

METHODS

We conducted DNA methylation analysis using an Illumina Methylation EPIC array to investigate molecular prognostic markers in 38 patients with medulloblastoma who were registered in the Japan Pediatric Molecular Neuro-Oncology Group and treated with reduced-dose CSI.

RESULTS

Among the patients, 23 were classified as having a standard-risk and 15 as high-risk according to the classic classification based on tumor resection rate and presence of metastasis, respectively. The median follow-up period was 71.5 months (12.0-231.0). The median CSI dose was 18 Gy (15.0-24.0) in both groups, and 5 patients in the high-risk group received a CSI dose of 18.0 Gy. Molecular subgrouping revealed that the standard-risk cohort included 5 WNT, 2 SHH, and 16 Group 3/4 cases; all 15 patients in the high-risk cohort had Group 3/4 medulloblastoma. Among the patients with Group 3/4 medulloblastoma, 9 of the 31 Group 3/4 cases were subclassified as subclass II, III, and V, which were known to an association with poor prognosis according to the novel subtyping among the subgroups. Patients with poor prognostic subtype showed worse prognosis than that of others (5-year progression survival rate 90.4% vs. 22.2%; p < 0.0001). The result was replicated in the multivariate analysis (hazard ratio12.77, 95% confidence interval for hazard ratio 2.38-99.21, p value 0.0026 for progression-free survival, hazard ratio 5.02, 95% confidence interval for hazard ratio 1.03-29.11, p value 0.044 for overall survival).

CONCLUSION

Although these findings require validation in a larger cohort, the present findings suggest that novel subtyping of Group 3/4 medulloblastoma may be a promising prognostic biomarker even among patients treated with lower-dose CSI than standard treatment.

Genetic susceptibility to cognitive decline following craniospinal irradiation for pediatric central nervous system tumors

BACKGROUND

Survivors of pediatric central nervous system (CNS) tumors treated with craniospinal irradiation (CSI) exhibit long-term cognitive difficulties. Goals of this study were to evaluate longitudinal effects of candidate and novel genetic variants on cognitive decline following CSI.

METHODS

Intelligence quotient (IQ), working memory (WM), and processing speed (PS) were longitudinally collected from patients treated with CSI (n = 241). Genotype-by-time interactions were evaluated using mixed-effects linear regression to identify common variants (minor allele frequency > 1%) associated with cognitive performance change. Novel variants associated with cognitive decline (P < 5 × 10-5) in individuals of European ancestry (n = 163) were considered replicated if they demonstrated consistent genotype-by-time interactions (P < .05) in individuals of non-European ancestries (n = 78) and achieved genome-wide statistical significance (P < 5 × 10-8) in a meta-analysis across ancestry groups.

RESULTS

Participants were mostly males (65%) diagnosed with embryonal tumors (98%) at a median age of 8.3 years. Overall, 1150 neurocognitive evaluations were obtained (median = 5, range: 2-10 per participant). One of the five loci previously associated with cognitive outcomes in pediatric CNS tumors survivors demonstrated significant time-dependent IQ declines (PPARA rs6008197, P = .004). Two variants associated with IQ in the general population were associated with declines in IQ after Bonferroni correction (rs9348721, P = 1.7 × 10-5; rs31771, P = 7.8 × 10-4). In genome-wide analyses, we identified novel loci associated with accelerated declines in IQ (rs116595313, meta-P = 9.4 × 10-9), WM (rs17774009, meta-P = 4.2 × 10-9), and PS (rs77467524, meta-P = 1.5 × 10-8; rs17630683, meta-P = 2.0 × 10-8; rs73249323, meta-P = 3.1 × 10-8).

CONCLUSIONS

Inherited genetic variants involved in baseline cognitive functioning and novel susceptibility loci jointly influence the degree of treatment-associated cognitive decline in pediatric CNS tumor survivors.

Outcomes of Infants and Young Children With Relapsed Medulloblastoma After Initial Craniospinal Irradiation-Sparing Approaches: An International Cohort Study

PURPOSE

Infant and young childhood medulloblastoma (iMB) is usually treated without craniospinal irradiation (CSI) to avoid neurocognitive late effects. Unfortunately, many children relapse. The purpose of this study was to assess salvage strategies and prognostic features of patients with iMB who relapse after CSI-sparing therapy.

METHODS

We assembled a large international cohort of 380 patients with relapsed iMB, age younger than 6 years, and initially treated without CSI. Univariable and multivariable Cox models of postrelapse survival (PRS) were conducted for those treated with curative intent using propensity score analyses to account for confounding factors.

RESULTS

The 3-year PRS, for 294 patients treated with curative intent, was 52.4% (95% CI, 46.4 to 58.3) with a median time to relapse from diagnosis of 11 months. Molecular subgrouping was available for 150 patients treated with curative intent, and 3-year PRS for sonic hedgehog (SHH), group 4, and group 3 were 60%, 84%, and 18% (P = .0187), respectively. In multivariable analysis, localized relapse (P = .0073), SHH molecular subgroup (P = .0103), CSI use after relapse (P = .0161), and age ≥ 36 months at initial diagnosis (P = .0494) were associated with improved survival. Most patients (73%) received salvage CSI, and although salvage chemotherapy was not significant in multivariable analysis, its use might be beneficial for a subset of children receiving salvage CSI < 35 Gy (P = .007).

CONCLUSION

A substantial proportion of patients with relapsed iMB are salvaged after initial CSI-sparing approaches. Patients with SHH subgroup, localized relapse, older age at initial diagnosis, and those receiving salvage CSI show improved PRS. Future prospective studies should investigate optimal CSI doses and the role of salvage chemotherapy in this population.

High dose craniospinal irradiation as independent risk factor of permanent alopecia in childhood medulloblastoma survivors: cohort study and literature review

PURPOSE

Our aim was to determine the main risk factors related to the occurrence of permanent alopecia in childhood medulloblastoma (MB) survivors.

METHODS

We retrospectively analyzed the clinical features of all consecutive MB survivors treated at our institute. We divided the patients into 3 groups depending on the craniospinal irradiation (CSI) dose received and defined permanent alopecia first in terms of the skin region affected (whole scalp and nape region), then on the basis of the toxicity degree (G). Any relationship between permanent alopecia and other characteristics was investigated by a univariate and multivariate analysis and Odds ratio (OR) with confidence interval (CI) was reported.

RESULTS

We included 41 patients with a mean10-year follow-up. High dose CSI resulted as an independent factor leading to permanent hair loss in both groups: alopecia of the whole scalp (G1 p-value 0.030, G2 p-value 0.003) and of the nape region (G1 p-value 0.038, G2 p-value 0.006). The posterior cranial fossa (PCF) boost volume and dose were not significant factors at multivariate analysis neither in permanent hair loss of the whole scalp nor only in the nuchal region.

CONCLUSION

In pediatric patients with MB, the development of permanent alopecia seems to depend only on the CSI dose ≥ 36 Gy. Acute damage to the hair follicle is dose dependent, but in terms of late side effects, constant and homogeneous daily irradiation of a large volume may have a stronger effect than a higher but focal dose of radiotherapy.

Randomized Phase II Trial of Proton Craniospinal Irradiation Versus Photon Involved-Field Radiotherapy for Patients With Solid Tumor Leptomeningeal Metastasis

PURPOSE

Photon involved-field radiotherapy (IFRT) is the standard-of-care radiotherapy for patients with leptomeningeal metastasis (LM) from solid tumors. We tested whether proton craniospinal irradiation (pCSI) encompassing the entire CNS would result in superior CNS progression-free survival (PFS) compared with IFRT.

PATIENTS AND METHODS

We conducted a randomized, phase II trial of pCSI versus IFRT in patients with non-small-cell lung cancer and breast cancers with LM. We enrolled patients with other solid tumors to an exploratory pCSI group. For the randomized groups, patients were assigned (2:1), stratified by histology and systemic disease status, to pCSI or IFRT. The primary end point was CNS PFS. Secondary end points included overall survival (OS) and treatment-related adverse events (TAEs).

RESULTS

Between April 16, 2020, and October 11, 2021, 42 and 21 patients were randomly assigned to pCSI and IFRT, respectively. At planned interim analysis, a significant benefit in CNS PFS was observed with pCSI (median 7.5 months; 95% CI, 6.6 months to not reached) compared with IFRT (2.3 months; 95% CI, 1.2 to 5.8 months; P < .001). We also observed OS benefit with pCSI (9.9 months; 95% CI, 7.5 months to not reached) versus IFRT (6.0 months; 95% CI, 3.9 months to not reached; P = .029). There was no difference in the rate of grade 3 and 4 TAEs (P = .19). In the exploratory pCSI group, 35 patients enrolled, the median CNS PFS was 5.8 months (95% CI, 4.4 to 9.1 months) and OS was 6.6 months (95% CI, 5.4 to 11 months).

CONCLUSION

Compared with photon IFRT, we found pCSI improved CNS PFS and OS for patients with non-small-cell lung cancer and breast cancer with LM with no increase in serious TAEs.

Proton therapy for adult medulloblastoma: Acute toxicity and disease control outcomes

PURPOSE

We report disease control, survival outcomes, and treatment-related toxicity among adult medulloblastoma patients who received proton craniospinal irradiation (CSI) as part of multimodality therapy.

METHODS

We reviewed 20 adults with medulloblastoma (≥ 22 years old) who received postoperative proton CSI ± chemotherapy between 2008 and 2020. Patient, disease, and treatment details and prospectively obtained patient-reported acute CSI toxicities were collected. Acute hematologic data were analyzed.

RESULTS

Median age at diagnosis was 27 years; 45% of patients had high-risk disease; 75% received chemotherapy, most (65%) after CSI. Eight (40%) patients received concurrent vincristine with radiotherapy. Median CSI dose was 36GyE with a median tumor bed boost of 54GyE. Median duration of radiotherapy was 44 days. No acute ≥ grade 3 gastrointestinal or hematologic toxicities attributable to CSI occurred. Grade 2 nausea and vomiting affected 25% and 5% of patients, respectively, while 36% developed acute grade 2 hematologic toxicity (36% grade 2 leukopenia and 7% grade 2 neutropenia). Those receiving concurrent chemotherapy with CSI had a 38% rate of grade 2 hematologic toxicity compared to 33% among those not receiving concurrent chemotherapy. Among patients receiving adjuvant chemotherapy (n = 13), 100% completed ≥ 4 cycles and 85% completed all planned cycles. With a median follow-up of 3.1 years, 4-year actuarial local control, disease-free survival, and overall survival rates were 90%, 90%, and 95%, respectively.

CONCLUSIONS

Proton CSI in adult medulloblastoma patients is very well tolerated and shows promising disease control and survival outcomes. These data support the standard use of proton CSI for adult medulloblastoma.

Impact of lifetime attributable risk of radiation-induced secondary cancer in proton craniospinal irradiation with vertebral-body-sparing for young pediatric patients with medulloblastoma

We used the method proposed by Schneider et al. Theor Biol Med Model 2011;8:27, to clarify how the radiation-induced secondary cancer incidence rate changes in patients after proton craniospinal irradiation (CSI) without and with vertebral-body-sparing (VBS). Eight patients aged 3-15 years who underwent proton CSI were enrolled in the study. For each case, two types of plan without and with VBS in the target were compared. The prescribed doses were assumed to be 23.4 Gy relative biological effectiveness (RBE) and 36 Gy (RBE). Using the dose-volume histograms of the two plans, the lifetime attributable risk (LAR) was calculated by both methods for each patient based on the dose data calculated using an XiO-M treatment planning system. Eight organs were analyzed as follows: lung, colon, stomach, small intestine, liver, bladder, thyroid and bone. When the prescribed dose used was 23.4 Gy (RBE), the average LAR differences and the average number needed to treat (NNT) between proton CSI without and with VBS were 4.04 and 24.8, respectively, whereas the average LAR difference and the average NNT were larger at 8.65 and 11.6, respectively, when the prescribed dose of 36 Gy (RBE) was used. The LAR for radiation-induced secondary cancer was significantly lower in proton CSI with VBS than without VBS in pediatric patients, especially for the colon, lung, stomach and thyroid. The results of this study could serve as reference data when considering how much of vertebral bodies should be included when performing proton CSI according to age in clinical settings.

Clinical trial of proton craniospinal irradiation for leptomeningeal metastases

BACKGROUND

Leptomeningeal metastases (LM) are associated with limited survival and treatment options. While involved-field radiotherapy is effective for local palliation, it lacks durability. We evaluated the toxicities of proton craniospinal irradiation (CSI), a treatment encompassing the entire central nervous system (CNS) compartment, for patients with LM from solid tumors.

METHODS

We enrolled patients with LM to receive hypofractionated proton CSI in this phase I prospective trial. The primary endpoint was to describe treatment-related toxicity, with dose-limiting toxicity (DLT) defined as any radiation-related grade 3 non-hematologic toxicity or grade 4 hematologic toxicity according to the Common Terminology Criteria for Adverse Events that occurred during or within 4 weeks of completion of proton CSI. Secondary endpoints included CNS progression-free survival (PFS) and overall survival (OS).

RESULTS

We enrolled 24 patients between June 2018 and April 2019. Their median follow-up was 11 months. Twenty patients were evaluable for protocol treatment-related toxicities and 21 for CNS PFS and OS. Two patients in the dose expansion cohort experienced DLTs consisted of grade 4 lymphopenia, grade 4 thrombocytopenia, and/or grade 3 fatigue. All DLTs resolved without medical intervention. The median CNS PFS was 7 months (95% CI: 5-13) and the median OS was 8 months (95% CI: 6 to not reached). Four patients (19%) were progression-free in the CNS for more than 12 months.

CONCLUSION

Hypofractionated proton CSI using proton therapy is a safe treatment for patients with LM from solid tumors. We saw durable disease control in some patients.

Treatment of children under 4 years of age with medulloblastoma and ependymoma in the HIT2000/HIT-REZ 2005 trials: Neuropsychological outcome 5 years after treatment

Young children with brain tumours are at high risk of developing treatment-related sequelae. We aimed to assess neuropsychological outcomes 5 years after treatment. This cross-sectional study included children under 4 years of age with medulloblastoma (MB) or ependymoma (EP) enrolled in the German brain tumour trials HIT2000 and HIT-REZ2005. Testing was performed using the validated Wuerzburg Intelligence Diagnostics (WUEP-D), which includes Kaufman-Assessment-Battery, Coloured Progressive Matrices, Visual-Motor Integration, finger tapping “Speed”, and the Continuous Performance Test. Of 104 patients in 47 centres, 72 were eligible for analyses. We assessed whether IQ was impacted by disease extent, disease location, patient age, gender, age at surgery, and treatment (chemotherapy with our without craniospinal irradiation [CSI] or local radiotherapy [LRT]). Median age at surgery was 2.3 years. Testing was performed at a median of 4.9 years after surgery. Patients with infratentorial EPs (treated with LRT) scored highest in fluid intelligence (CPM 100.9±16.9, mean±SD); second best scores were achieved by patients with MB without metastasis treated with chemotherapy alone (CPM 93.9±13.2), followed by patients with supratentorial EPs treated with LRT. In contrast, lowest scores were achieved by patients that received chemotherapy and CSI, which included children with metastasised MB and those with relapsed MB M0 (CPM 71.7±8.0 and 73.2±21.8, respectively). Fine motor skills were reduced in all groups. Multivariable analysis revealed that type of treatment had an impact on IQ, but essentially not age at surgery, time since surgery or gender. Our results confirm previous reports on the detrimental effects of CSI in a larger cohort of children. Comparable IQ scores in children with MB treated only with chemotherapy and in children with EP suggest that this treatment strategy represents an attractive option for children who have a high chance to avoid application of CSI. Longitudinal follow-up examinations are warranted to assess long-term neuropsychological outcomes.

Clinical experience of craniospinal intensity-modulated spot-scanning proton therapy using large fields for central nervous system medulloblastomas and germ cell tumors in children, adolescents, and young adults

The outcomes of intensity-modulated proton craniospinal irradiation (ipCSI) are unclear. We evaluated the clinical benefit of our newly developed ipCSI system that incorporates two gantry-mounted orthogonal online X-ray imagers with a robotic six-degrees-of-freedom patient table. Nine patients (7-19 years old) were treated with ipCSI. The prescribed dose for CSI ranged from 23.4 to 36.0 Gy (relative biological effectiveness) in 13-20 fractions. Four adolescent and young adult (AYA) patients (15 years or older) were treated with vertebral-body-sparing ipCSI (VBSipCSI). Myelosuppression following VBSipCSI was compared with that of eight AYA patients treated with photon CSI at the same institution previously. The mean homogeneity index (HI) in the nine patients was 0.056 (95% confidence interval: 0.044-0.068). The mean time from the start to the end of all beam delivery was 37 min 39 s ± 2 min 24 s (minimum to maximum: 22 min 49 s - 42 min 51 s). The nadir white blood cell, hemoglobin, and platelet levels during the 4 weeks following the end of the CSI were significantly higher in the VBSipCSI group than in the photon CSI group (P = 0.0071, 0.0453, 0.0024, respectively). The levels at 4 weeks after the end of CSI were significantly higher in the VBSipCSI group than in the photon CSI group (P = 0.0023, 0.0414, 0.0061). Image-guided ipCSI was deliverable in a reasonable time with sufficient HI. Using VBSipCSI, AYA patients experienced a lower incidence of serious acute hematological toxicity than AYA patients treated with photon CSI.

Retrospective estimation of heart and lung doses in pediatric patients treated with spinal irradiation

BACKGROUND AND PURPOSE

The purpose of this study was to investigate whether treatment information from medical records can be used to estimate radiation doses to heart and lungs retrospectively in pediatric patients receiving spinal irradiation with conventional posterior fields.

MATERIAL AND METHODS

An algorithm for retrospective dosimetry in children treated with spinal irradiation was developed in a cohort of 21 pediatric patients with available CT-scans and treatment plans. We developed a multivariable linear regression model with explanatory variables identifiable in case note review for retrospective estimation of minimum, maximum, mean and V10%-V80% doses to the heart and lungs. Doses were estimated for both linear accelerator (Linac) and 60Co radiation therapy modalities.

RESULTS

Age and spinal field width were identified as statistically significant predictors of heart and lung doses in multivariable analyses (p < 0.01 in all models). Models showed excellent predictive performance with R2 = 0.70 for mean heart dose and 0.79 for mean lung dose, for Linac plans. In leave-one-out cross-validation analysis the average difference between predicted and actual mean heart dose was 6.7% and 7.6% of the prescription dose for Linac and 60Co plans, respectively, and 5.2% and 4.9% for mean lung dose. Due to the small sample size and large inter-patient variation in heart and lung dose, prospective studies validating these findings are highly warranted.

CONCLUSIONS

The models presented here provide retrospective estimates of heart and lung doses for historical cohorts of pediatric patients, thus facilitating studies of long-term adverse effects of radiation.

Quality of life and chronic health conditions in childhood acute leukaemia survivors

BACKGROUND

Survival of childhood acute lymphoblastic leukaemia involves an increasing risk of long-term morbidities. Due to the impact of cancer treatment and comorbidities, AL survivors may experience a decrease in their health-related quality of life.

OBJECTIVE

We aimed to describe the long-term comorbidities, related quality of life and their development predictors in these survivors.

METHODS

cross-sectional study of 54 survivors aged ≥18 and who have a survival rate of more than 10 years. Quality of life was assessed by personal interview using SF-36 questionnaire.

RESULTS

53.7% of AL survivors developed more than one comorbidity (24.7% hypothyroidism; 20.3% obesity; 14.8% metabolic syndrome; 18.5% subclinical cardiac dysfunction); 20.3% of them were severe. 73.3% of high-risk leukaemias and 66.6% of patients treated with radiotherapy or stem cells transplantation reported long-term comorbidity, P<.05. Global quality of live score was: 86.3 (14) (classified as very good). Patients with high-risk acute leukaemia (83.2 vs. 89.5), severe long-term comorbidities (80.4 vs. 89.7) and females (81.8 vs. 89.9), reported worse quality of life, P<.05. Physical summary score was worse in: obese (80 vs. 92) and hypothyroid (84.9 vs. 92.4) and radiotherapy-treated survivors (82.3 vs. 87.5); mental summary was worse in survivors with hypogonadism (68.2 vs. 86.3) and trasplanted patients (77.2 vs. 83.1), P<.05.

CONCLUSIONS

Acute leukaemia survivors reported an increase prevalence of chronic comorbidities, related to cancer-treatment. Despite a decrease in scores for certain physical or mental items, global quality of life was very good in all acute leukaemia survivors, even better than compared with the general population.

Craniospinal irradiation prior to stem cell transplant for hematologic malignancies with CNS involvement: Effectiveness and toxicity after photon or proton treatment

PURPOSE/OBJECTIVE(S)

Craniospinal irradiation (CSI) improves local control of leukemia/lymphoma with central nervous system (CNS) involvement; however, for adult patients anticipating stem cell transplant (SCT), cumulative treatment toxicity is a major concern. We evaluated toxicities and outcomes for patients receiving proton or photon CSI before SCT.

METHODS AND MATERIALS

We identified 37 consecutive leukemia/lymphoma patients with CNS involvement who received CSI before SCT at our institution. Photon versus proton toxicities during CSI, transplant, and through 100 days posttransplant were compared using Fisher exact and Wilcoxon rank sum tests. Long-term neurotoxicity, disease response, and overall survival were analyzed.

RESULTS

Thirty-seven patients (23 photon, 14 proton) underwent CSI for CNS involvement of acute lymphoblastic leukemia (49%), acute myeloblastic leukemia (22%), chronic lymphocytic leukemia (3%), chronic myelocytic leukemia (14%), lymphoma (11%), and myeloma (3%). CSI was used for consolidation (30 patients, 81%) and gross disease treatment (7 patients, 19%). Median radiation dose (interquartile range) was 24 Gy (23.4-24) for photons and 21.8 Gy (21.3-23.6) for protons (P = .03). Proton CSI was associated with lower rates of Radiation Therapy Oncology Group grade 1-3 mucositis during CSI (7% vs 44%, P = .03): 1 grade 3 with protons versus 5 grade 1, 3 grade 2, and 2 grade 3 with photons. During CSI, other toxicities (infection, gastrointestinal symptoms) did not differ. Allogeneic stem cell transplant (SCT) was used in 95% of patients, with 53% of patients in remission before SCT. Myeloablative conditioning was used for 76%. During SCT admission and 100 days post-SCT, toxicities did not differ by CSI technique. Successful engraftment occurred in 95% of patients (P = .67). Progression or death occurred for 47% of patients, with only 1 CNS relapse.

CONCLUSION

In our cohort, CSI offered excellent local control for CNS-involved hematologic malignancies in the pre-SCT setting. Acute mucositis occurred less frequently with proton CSI with comparable peritransplant/long-term toxicity profile, suggesting the need to further explore the benefit/toxicity profile of this technique.

Impact of acute hematological toxicity on treatment interruptions during cranio-spinal irradiation in medulloblastoma: a tertiary care institute experience

To analyze treatment interruptions due to acute hematological toxicity in patients of medulloblastoma receiving cranio-spinal irradiation (CSI). Prospectively collected data from case records of 52 patients of medulloblastoma treated between 2011 and 2014 was evaluated. Blood counts were monitored twice a week during CSI. Spinal irradiation was interrupted for patients with ≥grade 2 hematological toxicity and resumed after recovery to grade 1 level (TLC >3000; platelet count >75,000). Treatment interruptions and hematological toxicity were analyzed. Median age was 11 years. All patients received adjuvant CSI of 36 Gy, followed by boost of 18 Gy to posterior fossa, at 1.8 Gy per fraction. Concurrent chemotherapy was not given. Adjuvant chemotherapy was given after CSI for high risk patients. Spinal fields were interrupted in 73.1% of patients. Cause of first interruption was leucopenia in 92.1%, thrombocytopenia in 2.6%, and both in 5.3%. Median number of fractions at first interruption was 8, with 25% of interruptions in first week. Median duration for hematological recovery after nadir was 5 days for leucopenia and 3 days for thrombocytopenia. Half of the patients had at least 2 interruptions, and 19% subsequently developed grade 3 toxicity. On multivariate analysis, significant correlation with duration of delay was observed for pre-treatment haemoglobin, number of fractions at first interruption, grade and duration of recovery of leucopenia. Acute hematological toxicity with CSI is frequently under-reported. Patients with low pre-treatment hemoglobin, early onset leucopenia, profound leucopenia and prolonged recovery times are at a higher risk of having protracted courses of irradiation. Frequent monitoring of blood counts and timely interruption of spinal fields of irradiation at grade 2 level of hematological toxicity minimizes the risk of grade 3 and grade 4 toxicity, while reducing the interruptions in irradiation of the gross tumour bed.

Craniospinal irradiation using helical tomotherapy for central nervous system tumors

The aim of this study was to describe early and late toxicity, survival and local control in 45 patients with primary brain tumors treated with helical tomotherapy craniospinal irradiation (HT-CSI). From 2006 to 2014, 45 patients with central nervous system malignancies were treated with HT-CSI. The most common tumors were medulloblastoma in 20 patients, ependymoma in 10 patients, intracranial germinoma (ICG) in 7 patients, and primitive neuroectodermal tumor in 4 patients. Hematological toxicity during treatment included leukopenia Grades 1-4 (6.7%, 33.3%, 37.8% and 17.8%, respectively), anemia Grades 1-4 (44.4%, 22.2%, 22.2% and 0%, respectively) and thrombocytopenia Grades 1-4 (51.1%, 15.6%, 15.6% and 6.7%, respectively). The most common acute toxicities were nausea, vomiting, fatigue, loss of appetite, alopecia and neurotoxicity. No Grade 3 or higher late toxicity occurred. The overall 3- and 5-year survival rates were 80% and 70%, respectively. Survival for the main tumor entities included 3- and 5-year survival rates of 80% and 70%, respectively, for patients with medulloblastoma, 70% for both in patients with ependymoma, and 100% for both in patients with ICG. Relapse occurred in 11 patients (24.4%): 10 with local and 1 with multifocal relapse. One patient experienced a secondary cancer. M-status and the results of the re-evaluation at the end of treatment were significantly related to survival. Survival after HT-CSI was in line with the existing literature, and acute treatment-induced toxicity resolved quickly. Compared with conventional radiotherapy, HT offers benefits such as avoiding gaps and junctions, sparing organs, and better and more homogeneous dose distribution and coverage of the target volume.

Craniospinal irradiation with concomitant and adjuvant temozolomide--a feasibility assessment of toxicity in patients with glioblastoma with a PNET component

There is no standard treatment for glioblastoma with elements of PNET (GBM-PNET). Conventional treatment for glioblastoma is surgery followed by focal radiotherapy with concurrent temozolomide. Given the increased propensity for neuroaxial metastases seen with GBM-PNETs, craniospinal irradiation (CSI) with temozolomide (TMZ) could be a feasible treatment option but little is known regarding its toxicity. The clinical records of all patients treated at two UK neuro-oncology centres with concurrent CSI and TMZ were examined for details of surgery, radiotherapy, chemotherapy and toxicities related to the CSI-TMZ component of their treatment. Eight patients were treated with CSI-TMZ, the majority (6/8) for GBM-PNET. All patients completed radiotherapy to the craniospinal axis 35-40 Gy in 20-24 daily fractions with a focal boost to the tumour of 14-23.4 Gy in 8-13 daily fractions. Concurrent TMZ was administered at 75 mg/m(2) for seven of the cohort, with the other patient receiving 50 mg/m(2). The most commonly observed non-haematological toxicities were nausea and vomiting, with all patients experiencing at least grade 2 symptoms of either or both. All patients had at least grade 3 lymphopaenia. Two patients experience grade 4 neutropaenia and grade 3 thrombocytopaenia. Three of the eight patients required omission of TMZ for part of their chemoradiotherapy and 3/8 required hospital admission at some point during chemoradiotherapy. The addition of TMZ to CSI did not interrupt radiotherapy. Principal toxicities were neutropaenia, lymphopaenia, thrombocytopaenia, nausea and vomiting. Treatment with CSI-TMZ merits further investigation and may be suitable for patients with tumours at high-risk of metastatic spread throughout the CNS who have TMZ-sensitive pathologies.

Combined Neurotrauma Models: Experimental Models Combining Traumatic Brain Injury and Secondary Insults

Patients with severe traumatic brain injury (TBI) frequently present with concomitant injuries that may cause secondary brain injury and impact outcomes. Animal models have been developed that combine contemporary models of TBI with a secondary neurologic insult such as hypoxia, shock, long bone fracture, and radiation exposure. Combined injury models may be particularly useful when modeling treatment strategies and in efforts to map basic research to a heterogeneous patient population. Here, we review these models and their collective contribution to the literature on TBI. In addition, we provide protocols and notes for two well-characterized models of TBI plus hemorrhagic shock.

Visualization of risk of radiogenic second cancer in the organs and tissues of the human body

BACKGROUND

Radiogenic second cancer is a common late effect in long term cancer survivors. Currently there are few methods or tools available to visually evaluate the spatial distribution of risks of radiogenic late effects in the human body. We developed a risk visualization method and demonstrated it for radiogenic second cancers in tissues and organs of one patient treated with photon volumetric modulated arc therapy and one patient treated with proton craniospinal irradiation.

METHODS

Treatment plans were generated using radiotherapy treatment planning systems (TPS) and dose information was obtained from TPS. Linear non-threshold risk coefficients for organs at risk of second cancer incidence were taken from the Biological Effects of Ionization Radiation VII report. Alternative risk models including linear exponential model and linear plateau model were also examined. The predicted absolute lifetime risk distributions were visualized together with images of the patient anatomy.

RESULTS

The risk distributions of second cancer for the two patients were visually presented. The risk distributions varied with tissue, dose, dose-risk model used, and the risk distribution could be similar to or very different from the dose distribution.

CONCLUSIONS

Our method provides a convenient way to directly visualize and evaluate the risks of radiogenic second cancer in organs and tissues of the human body. In the future, visual assessment of risk distribution could be an influential determinant for treatment plan scoring.

A comparative study on the risks of radiogenic second cancers and cardiac mortality in a set of pediatric medulloblastoma patients treated with photon or proton craniospinal irradiation

PURPOSE

To compare the risks of radiogenic second cancers and cardiac mortality in 17 pediatric medulloblastoma patients treated with passively scattered proton or field-in-field photon craniospinal irradiation (CSI).

MATERIAL/METHODS

Standard of care photon or proton CSI treatment plans were created for all 17 patients in a commercial treatment planning system (TPS) (Eclipse version 8.9; Varian Medical Systems, Palo Alto, CA) and prescription dose was 23.4 or 23.4 Gy (RBE) to the age specific target volume at 1.8 Gy/fraction. The therapeutic doses from proton and photon CSI plans were estimated from TPS. Stray radiation doses were determined from Monte Carlo simulations for proton CSI and from measurements and TPS for photon CSI. The Biological Effects of Ionization Radiation VII report and a linear model based on childhood cancer survivor data were used for risk predictions of second cancer and cardiac mortality, respectively.

RESULTS

The ratios of lifetime attributable risk (RLARs) (proton/photon) ranged from 0.10 to 0.22 for second cancer incidence and ranged from 0.20 to 0.53 for second cancer mortality, respectively. The ratio of relative risk (RRR) (proton/photon) of cardiac mortality ranged from 0.12 to 0.24. The RLARs of both cancer incidence and mortality decreased with patient's age at exposure (e), while the RRRs of cardiac mortality increased with e. Girls had a significantly higher RLAR of cancer mortality than boys.

CONCLUSION

Passively scattered proton CSI provides superior predicted outcomes by conferring lower predicted risks of second cancer and cardiac mortality than field-in-field photon CSI for all medulloblastoma patients in a large clinically representative sample in the United States, but the magnitude of superiority depends strongly on the patients' anatomical development status.

Proton beam therapy reduces the incidence of acute haematological and gastrointestinal toxicities associated with craniospinal irradiation in pediatric brain tumors

BACKGROUND

The benefits of proton beam craniospinal irradiation (PrBCSI) in children have been extensively reported in dosimetric studies. However, there is limited clinical evidence supporting the use of PrBCSI. We compared the acute toxicity of PrBCSI relative to that of conventional photon beam CSI (PhBCSI) in children with brain tumours.

MATERIAL AND METHODS

We prospectively evaluated the haematological and gastrointestinal toxicities in 30 patients who underwent PrBCSI between April 2008 and December 2012. As a reference group, we retrospectively evaluated the medical records of 13 patients who underwent PhBCSI between April 2003 and April 2012. The median follow-up time from starting CSI was 22 months (range 2-118 months). The mean irradiation dose was 32.1 Gy (range 23.4-39.6 Gy) and 29.4 CGE (cobalt grey equivalents; range 19.8-39.6), in the PrBCSI and PhBCSI groups, respectively (p = 0.236).

RESULTS

There was no craniospinal fluid space relapse after curative therapy in either group of patients. Thrombocytopenia was less severe in the PrBCSI group than in the PhBCSI group (p = 0.012). The recovery rates of leukocyte and platelet counts measured one month after treatment were significantly greater in the PrBCSI group than in the PhBCSI group (p = 0.003 and p = 0.010, respectively). Diarrhoea was reported by 23% of patients in the PhBCSI group versus none in the PrBCSI group (p = 0.023).

CONCLUSIONS

The incidence rates of thrombocytopenia and diarrhoea were lower in the PrBCSI group than in the PhBCSI group. One month after completing treatment, the recovery from leukopenia and thrombocytopenia was better in patients treated with PrBCSI than in those treated with PhBCSI.

Estimated risk of radiation-induced cancer following paediatric cranio-spinal irradiation with electron, photon and proton therapy

BACKGROUND

Improvement in radiotherapy during the past decades has made the risk of developing a radiation-induced secondary cancer as a result of dose to normal tissue a highly relevant survivorship issue. Important factors expected to influence secondary cancer risk include dose level and dose heterogeneity, as well as gender and type of tissue irradiated. The elevated radio-sensitivity in children calls for models particularly tailored to paediatric cancer patients.

MATERIAL AND METHODS

Treatment plans of six paediatric medulloblastoma patients were analysed with respect to secondary cancer risk following cranio-spinal irradiation (CSI), using either: 1) electrons and photons combined; 2) conformal photons; 3) double-scattering (DS) protons; or 4) intensity-modulated proton therapy (IMPT). The relative organ equivalent dose (OED) concept was applied in three dose-risk scenarios: a linear response model, a plateau response and an organ specific linear-exponential response. Life attributable risk (LAR) was calculated based on the BEIR VII committee's preferred models for estimating age- and site-specific solid cancer incidence. Uncertainties in the model input parameters were evaluated by error propagation using a Monte Carlo sampling procedure.

RESULTS

Both DS protons and IMPT achieved a significantly better dose conformity compared to the photon and electron irradiation techniques resulting in a six times lower overall risk of radiation-induced cancer. Secondary cancer risk in the thyroid and lungs contributed most to the overall risk in all compared modalities, while no significant difference was observed for the bones. Variations between DS protons and IMPT were small, as were differences between electrons and photons.

CONCLUSION

Regardless of technique, using protons decreases the estimated risk of secondary cancer following paediatric CSI compared to conventional photon and electron techniques. Substantial uncertainties in the LAR estimates support relative risk comparisons by OED.

Haematological toxicity in adult patients receiving craniospinal irradiation--indication of a dose-bath effect

BACKGROUND AND PURPOSE

The purpose of this study was to investigate the correlation between the haematological toxicity observed in patients treated with craniospinal irradiation, and the dose distribution in normal tissue, specifically the occurrence of large volumes exposed to low dose.

MATERIALS AND METHODS

Twenty adult male patients were included in this study; eight treated with helical tomotherapy (HT), and twelve with three-dimensional conformal radiation therapy. The relative volume of red bone marrow and body that was exposed to low dose (i.e. the so-called dose bath) was evaluated and correlated with nadir blood values during treatment, i.e. the severity of anaemia, leukopaenia, and thrombocytopaenia. The correlation was tested for different dose levels representing the dose bath using the Pearson product-moment correlation method.

RESULTS

We found a significant correlation between the volume of red bone marrow exposed to low dose and the severity of thrombocytopaenia during treatment. Furthermore, for the HT patients, a significant correlation was found between the relative volume of the body exposed to low dose and the severity of anaemia and leukopenia.

CONCLUSIONS

The severity of haematological toxicity correlated with the fraction of red bone marrow or body that was exposed to low dose.

The predicted relative risk of premature ovarian failure for three radiotherapy modalities in a girl receiving craniospinal irradiation

In girls and young women, irradiation of the ovaries can reduce the number of viable ovarian primordial follicles, which may lead to premature ovarian failure (POF) and subsequently to sterility. One strategy to minimize this late effect is to reduce the radiation dose to the ovaries. A primary means of reducing dose is to choose a radiotherapy technique that avoids irradiating nearby normal tissue; however, the relative risk of POF (RRPOF) due to the various therapeutic options has not been assessed. This study compared the predicted RRPOF after craniospinal proton radiotherapy, conventional photon radiotherapy (CRT) and intensity-modulated photon radiotherapy (IMRT). We calculated the equivalent dose delivered to the ovaries of an 11-year-old girl from therapeutic and stray radiation. We then predicted the percentage of ovarian primordial follicles killed by radiation and used this as a measure of the RRPOF; we also calculated the ratio of the relative risk of POF (RRRPOF) among the three radiotherapies. Proton radiotherapy had a lower RRPOF than either of the other two types. We also tested the sensitivity of the RRRPOF between photon and proton therapies to the anatomic position of the ovaries, i.e., proximity to the treatment field (2 ≤ RRRPOF ≤ 10). We found that CRT and IMRT have higher risks of POF than passive-scattering proton radiotherapy (PRT) does, regardless of uncertainties in the ovarian location. Overall, PRT represents a lower RRPOF over the two other modalities.

Comparison of risk of radiogenic second cancer following photon and proton craniospinal irradiation for a pediatric medulloblastoma patient

Pediatric patients who received radiation therapy are at risk of developing side effects such as radiogenic second cancer. We compared proton and photon therapies in terms of the predicted risk of second cancers for a 4 year old medulloblastoma patient receiving craniospinal irradiation (CSI). Two CSI treatment plans with 23.4 Gy or Gy (RBE) prescribed dose were computed: a three-field 6 MV photon therapy plan and a four-field proton therapy plan. The primary doses for both plans were determined using a commercial treatment planning system. Stray radiation doses for proton therapy were determined from Monte Carlo simulations, and stray radiation doses for photon therapy were determined from measured data. Dose-risk models based on the Biological Effects of Ionization Radiation VII report were used to estimate the risk of second cancer in eight tissues/organs. Baseline predictions of the relative risk for each organ were always less for proton CSI than for photon CSI at all attained ages. The total lifetime attributable risk of the incidence of second cancer considered after proton CSI was much lower than that after photon CSI, and the ratio of lifetime risk was 0.18. Uncertainty analysis revealed that the qualitative findings of this study were insensitive to any plausible changes of dose-risk models and mean radiation weighting factor for neutrons. Proton therapy confers lower predicted risk of second cancer than photon therapy for the pediatric medulloblastoma patient.

Delayed central nervous system irradiation effects in rats--part 2: aggravation of experimental autoimmune encephalomyelitis

BACKGROUND

Central nervous system (CNS) irradiation has detrimental effects which become evident within hours to few days and after a long latency of months and years. However, the delayed effect of irradiation on neuroimmune diseases has not been thoroughly examined.

OBJECTIVES

We evaluated the delayed effects of irradiation on the course of experimental autoimmune encephalomyelitis (EAE), which is used as a model for neuroimmune inflammation and multiple sclerosis.

METHODS

Adult male rats were exposed to a dose of 15 Gy given to the thoracolumbar spinal cord. Six months later, EAE was induced by inoculation of rat spinal cord homogenate in complete Freund's adjuvant (CFA). The disease was evaluated by clinical, histopathological and immunological parameters.

RESULTS

Irradiated rats developed clinical signs of EAE earlier than the control group and their disease was much more severe. Unlike the control group, all rats in the EAE-irradiated group died within 5 days after the onset of clinical signs. Sections taken from irradiated rats showed diffuse and large hemorrhagic infiltrates of lymphocytes and granulocytes. In contrast, control rats displayed fewer infiltrates, which were less prominent and not hemorrhagic.

CONCLUSIONS

CNS irradiation has a delayed effect that caused a marked aggravation of the clinical and pathological signs of EAE. The severity of the disease may be a consequence of the effect of irradiation on the CNS vascular bed and impaired blood-brain barrier.

Life years lost--comparing potentially fatal late complications after radiotherapy for pediatric medulloblastoma on a common scale

BACKGROUND

The authors developed a framework for estimating and comparing the risks of various long-term complications on a common scale and applied it to 3 different techniques for craniospinal irradiation in patients with pediatric medulloblastoma.

METHODS

Radiation dose-response parameters related to excess hazard ratios for secondary breast, lung, stomach, and thyroid cancer; heart failure, and myocardial infarction were derived from large published clinical series. Combined with age-specific and sex-specific hazards in the US general population, the dose-response analysis yielded excess hazards of complications for a cancer survivor as a function of attained age. After adjusting for competing risks of death, life years lost (LYL) were estimated based on excess hazard and prognosis of a complication for 3-dimensional conformal radiotherapy (3D CRT), volumetric modulated arc therapy (VMAT), and intensity-modulated proton therapy (IMPT).

RESULTS

Lung cancer contributed most to the estimated LYL, followed by myocardial infarction, and stomach cancer. The estimates of breast or thyroid cancer incidence were higher than those for lung and stomach cancer incidence, but LYL were lower because of the relatively good prognosis. Estimated LYL ranged between 1.90 years for 3D CRT to 0.28 years for IMPT. In a paired comparison, IMPT was associated with significantly fewer LYL than both photon techniques.

CONCLUSIONS

Estimating the risk of late complications is associated with considerable uncertainty, but including prognosis and attained age at an event to obtain the more informative LYL estimate added relatively little to this uncertainty.

Supine craniospinal irradiation in children: patient position modification, dose uniformity and early adverse effects

BACKGROUND

Different craniospinal irradiation techniques are complex. The homogeneity of the dose to the target and the normal tissues at risk affect both the control rate and the level of adverse effects.

PATIENTS AND METHODS

Thirty one patients were treated with CSI in the supine position. Custom-made Styrofoam was tailored for each patient to straighten the convexity and concavity of the spinal axis allowing better dose distribution uniformity during CSI technique. In the first 6 patients, CT simulation were performed twice: one time with the patient lying directly on the vacuum mattress without the foam (the conventional way) and the second while lying on the foam. Dose distribution was calculated using a 3D conformal planning. The gap between the fields was determined using isodose alignment method. All treatment portals were verified during the first 3 treatment sessions and once weekly thereafter using either cone-beam or portal image device. Weekly feathering (shifting of the junction between the 2 adjacent radiation fields) was routinely performed.

RESULTS

The 95% dose distribution had better coverage with the foam (p=0.042) while the hot volume of 110% and 105% dosage were significantly lesser than conventional technique (both p=0.028). The organs at risk received nearly similar radiation doses in the 2 positions. The CSI led to minimal immediate adverse effects that were reversible. Weight loss was experienced by 55% of patients.

CONCLUSION

This modified technique of CSI is simple, ensuring better dose distribution to CSI target without increasing the dose to the surrounding organs at risk. It is tolerable and safe to apply.