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

Helical tomotherapy craniospinal irradiation in primary brain tumours: Toxicities and outcomes in a peadiatric and adult population

Objective

As craniospinal irradiation (CSI) is delivered more frequently by helical tomotherapy (HT) with few reports about late effects, we analysed all patients treated in our centre over an 11-year period.

Methods and materials

Our study included all patients that underwent CSI by HT, between September 2009 and January 2020, in the Department of Radiation Oncology of the Toulouse Cancer Institute. Acute radiotherapy toxicities were reported and medium- to long-term outcomes analysed.

Results

Among the 79 patients included, 70.9 % were younger than 18 years at diagnosis, the median age was 13 (range: 1-52) at the time of radiation therapy, 67.1 % of patients had medulloblastoma. Half of them (49.4 %) had a metastatic disease at diagnosis. The median dose of CSI was 36 Gy (range, 18-36). Seventy-seven patients received a radiation boost to the original location of the primary tumour (97.5 %), 32 patients also received a boost to their metastatic sites (40.5 %). Median follow-up was 55.5 months (95 %CI = [41.2; 71.8]). The 3-year event-free survival rate was 66.3 % (95 %CI = [54.2; 75.9]). Most patients presented with acute haematological toxicities during CSI (85.9 %), predominantly severe thrombocytopenia (39.7 %). Among the 64 patients assessed for medium- and long-term outcomes, 52 survived and 47 were alive and disease-free at the latest follow-up visit on record. There were 3.8 % secondary tumours: two meningiomas and one diffuse intrinsic pontine glioma. Adult and paediatric patients respectively presented with secondary cataract (4.3 % vs 22.0 %), persistent hearing disorders (26.1 % vs 29.3 %), pulmonary or cardiac late effects (4.3 % vs 2.4 %), hormonal pituitary gland deficiencies (30.0 % vs 56.8 %) and psycho-cognitive disorders (56.5 % vs 53.7 %).

Conclusion

CSI dispensed by HT, did not result in any additional acute or late toxicities when compared to 3D-CSI. There was no increase in the secondary tumour rate compared to that reported in the literature.

Tomotherapy for Cranio-Spinal Irradiation

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Tomotherapy is safe and effective for cranio-spinal irradiation, both in paediatric patients and in adults, with similar disease-specific outcomes and toxicities as other techniques such as 3DCRT or IMRT/VMAT.

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Tomotherapy offers several technical advantages when compared to other radiotherapy techniques such as higher target conformity and better dose homogeneity.

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Helical Tomotherapy provides good organ-at-risk sparing for several structures, especially the vertebrae, parotids, and optic system.

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Reported treatment time/ beam-on-time is longer with helical Tomotherapy compared to other techniques.

Tomotherapy is a method of delivering rotational IMRT offering various advantages, notably for complex and large targets such as the cranio-spinal axis. This systematic literature review reports on main clinical outcomes and toxicities in patients with various cancer types that received whole craniospinal axis irradiation (CSI) using Tomotherapy and offers a comprehensive comparison between Tomotherapy and other radiotherapy delivery techniques. Databases including PubMed, PubMed Central, Embase, and Cochrane were searched using the keywords “tomotherapy” AND “craniospinal”. Fifty-six papers were included in the review. Patient population was adult in 9 papers, paediatric in 26 papers and mixed in 14 papers. Patients treated with helical Tomotherapy had similar disease-specific clinical outcomes and toxicities as patients treated using other techniques. Compared to any other technique, Tomotherapy provides better target coverage, homogeneity, and conformity in 23, 34 and 22 reports. Tomotherapy showed better organ-at-risk sparing for the thyroid, parotids, cochlea, eyes, heart and esophagus. Beam-On-Time (BOT) was reported to be longer for Tomotherapy in most studies (Median BOT: HT = 11 min, VMAT = 5.49 min, 3DCRT = 1.46 min). In conclusion, Tomotherapy offers good cranio-spinal axis coverage with improved homogeneity and conformity compared to other techniques, but with a considerably longer treatment time. Clinical outcome and toxicities suggest using Tomotherapy for CSI is efficient and safe.

FLASH irradiation induces lower levels of DNA damage ex vivo, an effect modulated by oxygen tension, dose, and dose rate

OBJECTIVE

FLASH irradiation reportedly produces less normal tissue toxicity, while maintaining tumour response. To investigate oxygen's role in the 'FLASH effect', we assessed DNA damage levels following irradiation at different oxygen tensions, doses and dose rates.

METHODS

Samples of whole blood were irradiated (20 Gy) at various oxygen tensions (0.25-21%) with 6 MeV electrons at dose rates of either 2 kGy/s (FLASH) or 0.1 Gy/s (CONV), and subsequently with various doses (0-40 Gy) and intermediate dose rates (0.3-1000 Gy/s). DNA damage of peripheral blood lymphocytes (PBL) were assessed by the alkaline comet assay.

RESULTS

Following 20 Gy irradiation, lower levels of DNA damage were induced for FLASH, the difference being significant at 0.25% (p < 0.05) and 0.5% O2 (p < 0.01). The differential in DNA damage at 0.5% O2 was found to increase with total dose and dose rate, becoming significant for doses ≥20 Gy and dose rates ≥30 Gy/s.

CONCLUSION

This study shows, using the alkaline comet assay, that lower levels of DNA damage are induced following FLASH irradiation, an effect that is modulated by the oxygen tension, and increases with the total dose and dose rate of irradiation, indicating that an oxygen related mechanism, e.g. transient radiation-induced oxygen depletion, may contribute to the tissue sparing effect of FLASH irradiation.

ADVANCES IN KNOWLEDGE

This paper is first to directly show that FLASH-induced DNA damage is modulated by oxygen tension, total dose and dose rate, with FLASH inducing significantly lower levels of DNA damage for doses ≥20 Gy and dose rates ≥30 Gy/s, at 0.5% O2.

In vitro assays for investigating the FLASH effect

FLASH radiotherapy is a novel technique that has been shown in numerous preclinical in vivo studies to have the potential to be the next important improvement in cancer treatment. However, the biological mechanisms responsible for the selective FLASH sparing effect of normal tissues are not yet known. An optimal translation of FLASH radiotherapy into the clinic would require a good understanding of the specific beam parameters that induces a FLASH effect, environmental conditions affecting the response, and the radiobiological mechanisms involved. Even though the FLASH effect has generally been considered as an in vivo effect, studies finding these answers would be difficult and ethically challenging to carry out solely in animals. Hence, suitable in vitro studies aimed towards finding these answers are needed. In this review, we describe and summarise several in vitro assays that have been used or could be used to finally elucidate the mechanisms behind the FLASH effect.

Hematological Changes Following Low Dose Radiation Therapy and Comparison to Current Standard of Care Cancer Treatments

Cancer is the second leading cause of mortality worldwide accounting for almost 10 million deaths in 2020. Current standard of care treatment varies depending on the type and stage of disease, but commonly includes surgery, chemotherapy, and/or radiation therapy. There is evidence that whole- and half-body exposure to low dose ionizing radiation can also be an effective therapeutic due to its stimulation of anti-cancer immunity. One of the limiting factors for past clinical trials using low dose radiation therapy has been adverse hematological events. However, similar hematological changes are also frequently reported following standard of care treatments in oncology. This review summarizes the effects of various cancer therapies on hematologic toxicity through the evaluation of complete blood count reports. The reviewed literature elucidates hematological trends in patients undergoing chemotherapy, and both high and low dose radiation therapy. In general, high dose radiation and chemotherapy can result in widespread changes in blood counts, with the most severe effects related to leukopenia. Overall, compared to standard of care treatments, low dose radiation results in similar, yet more mild hematological changes. Taken together, hematological toxicities should not be a limiting factor in the applicability of low dose radiation as a cancer therapeutic.

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.

A systematic review of craniospinal irradiation for leptomeningeal disease: past, present, and future

PURPOSE

Leptomeningeal disease (LMD) is a rare but deadly complication of cancer in which the disease spreads to the cerebrospinal fluid and seeds the meninges of the central nervous system (CNS). Craniospinal irradiation (CSI) involves treatment of the entire CNS subarachnoid space and is occasionally used as a last-resort palliative therapy for LMD.

METHODS

This review examined literature describing the role of CSI for LMD from solid and hematologic malignancies in adults. A search for studies published until September 1, 2020 was conducted using PubMed database.

RESULTS

A total of 262 unique articles were identified. Thirteen studies were included for analysis in which a total of 275 patients were treated with CSI for LMD. Median age at time of irradiation was 43 years, and most patients had KPS score of 70 and higher. The most common cancers resulting in LMD were acute lymphocytic leukemia, breast cancer, and acute myelogenous leukemia. Median CSI dose was 30 Gy and 18% of patients were treated with proton radiation. 52% of patients had stable-to-improved neurologic symptoms. Median overall survival for the entire cohort was 5.3 months. Patients treated with marrow-sparing proton radiation had median OS of 8 months. The most common treatment toxicities were hematologic and gastrointestinal events.

CONCLUSIONS

Despite advances in systemic and radiation therapies, LMD remains a devastating end-stage complication of some malignancies. Treatment-related toxicities can be a significant barrier to CSI delivery. In select patients with LMD, marrow-sparing proton CSI may provide safer palliation of symptoms and prolong survival.

Evaluating the positional uncertainty of intrafraction, adjacent fields, and daily setup with the BrainLAB ExacTrac system in patients who are receiving craniospinal irradiation

Purpose

To investigate the daily setup, interfraction motion, variability in the junction areas, and dosimetric effect in craniospinal irradiation (CSI) patients.

Methods

Fifteen CSI patients who had undergone split‐field IMRT were followed in the study. Previous, middle, and posttreatment, each target volume position was evaluated using the ExacTrac system. Interfraction and intrafraction motions, the margin of the junction in adjacent targets volumes, and the dosimetric effect of the longitudinal residual error were analyzed.

Results

The lowest attainment rate within the tolerance of the initial setup error was 66.79% in six directions. The values of the initial error were within 15 mm (SD 4.5 mm) in the translation direction and 5° (SD 1.3°) in the rotation direction after the transposition of the treatment isocenter. With the guidance of the ExacTrac system, the interfraction and intrafraction residual errors were almost within the tolerance after correction, the margin of CTV‐to‐PCTV was in the range of target expansion criteria. The residual longitudinal errors resulted in only slight changes in the mean doses of PGTV and PCTV, while the maximum dose of the spinal cord increased by 16.1%. The patients did not exhibit any side‐effects by the overall treatment during the follow‐up period.

Conclusions

Position correction is necessary after setup and the transposition of the treatment isocenter. Intra‐fraction motion in the lateral direction should be monitored throughout treatment. The position errors in junction areas are almost within the tolerance after correction. The patients did not exhibit any side‐effects by the overall treatment.

Craniospinal irradiation(CSI) in patients with leptomeningeal metastases: risk-benefit-profile and development of a prognostic score for decision making in the palliative setting

BACKGROUND

The aim of our study was to assess the feasibility and oncologic outcomes in patients treated with spinal (SI) or craniospinal irradiation (CSI) in patients with leptomeningeal metastases (LM) and to suggest a prognostic score as to which patients are most likely to benefit from this treatment.

METHODS

Nineteen patients treated with CSI at our institution were eligible for the study. Demographic data, primary tumor characteristics, outcome and toxicity were assessed retrospectively. The extent of extra-CNS disease was defined by staging CT-scans before the initiation of CSI. Based on outcome parameters a prognostic score was developed for stratification based on patient performance status and tumor staging.

RESULTS

Median follow-up and overall survival (OS) for the whole group was 3.4 months (range 0.5-61.5 months). The median overall survival (OS) for patients with LM from breast cancer was 4.7 months and from NSCLC 3.3 months. The median OS was 7.3 months, 3.3 months and 1.5 months for patients with 0, 1 and 2 risk factors according to the proposed prognostic score (KPS < 70 and the presence of extra-CNS disease) respectively. Nonhematologic toxicities were mild.

CONCLUSION

CSI demonstrated clinically meaningful survival that is comparable to the reported outcome of intrathecal chemotherapy. A simple scoring system could be used to better select patients for treatment with CSI in this palliative setting. In our opinion, the feasibility of performing CSI with modern radiotherapy techniques with better sparing of healthy tissue gives a further rationale for its use also in the palliative setting.

Outcome and prognostic factors following palliative craniospinal irradiation for leptomeningeal carcinomatosis

Background

Leptomeningeal carcinomatosis (LC) is a severe complication of metastatic tumor spread to the central nervous system. Prognosis is dismal with a median overall survival (OS) of ~10–15 weeks. Treatment options include radiotherapy (RT) to involved sites, systemic chemo- or targeted therapy, intrathecal chemotherapy and best supportive care with dexamethasone. Craniospinal irradiation (CSI) is a more aggressive radiotherapeutic approach, for which very limited data exists. Here, we report on our 10-year experience with palliative CSI of selected patients with LC.

Patients and methods

Twenty-five patients received CSI for the treatment of LC at our institution between 2008 and 2018. Patients were selected individually for CSI based on clinical performance, presenting symptoms and estimated benefit. Median patient age was 53 years (IQR: 45–59), and breast cancer was the most common primary. Additional brain metastases were found in 18 patients (72.0%). RT was delivered at a TomoTherapy machine, using helical intensity-modulated radiotherapy (IMRT). The most commonly prescribed dose was 36 Gy in 20 fractions, corresponding to a median biologically equivalent dose of 40.8 Gy (IQR: 39.0–2.5). Clinical performance and neurologic function were assessed before and in response to therapy, and deficits were retrospectively quantified on the 5-point neurologic function scale (NFS). A Cox proportional hazards model with univariate and multivariate analyses was fitted for survival.

Results

Twenty-one patients died and four were alive at the time of analysis. Median OS from LC diagnosis was 19.3 weeks (IQR: 9.3–34.0, 95% CI: 11.0–32.0). In univariate analysis, a Karnofsky performance scale index (KPI) ≥70% (P=0.001), age ≤55 years at LC diagnosis (P=0.022), cerebrospinal fluid (CSF) protein <100 mg/dL (P=0.018) and no more than mild or moderate neurologic deficits (NFS ≤2; P=0.007) were predictive of longer OS. So were the neurologic response to treatment (P=0.018) and the application of systemic therapy after RT completion (P=0.029). The presence of CSF flow obstruction was predictive of shorter OS (P=0.026). In multivariate analysis, age at LC diagnosis (P=0.018), KPI (P<0.001) and neurologic response (P=0.037) remained as independent prognostic factors for longer OS. Treatment-associated toxicity was manageable and mostly grades I and II according to the Common Terminology Criteria for Adverse Events v4.0. Eight patients (32%) developed grade III myelosuppression. Neurologic symptom stabilization could be achieved in 40.0% and a sizeable improvement in 28.0% of all patients.

Conclusion

CSI for the treatment of LC is feasible and may have therapeutic value in carefully selected patients, alleviating symptoms or delaying neurologic deterioration. OS after CSI was comparable to the rates described in current literature for patients with LC. The use of modern irradiation techniques such as helical IMRT is warranted to limit toxicity. Patient selection should take into account prognostic factors such as age, clinical performance, neurologic function and the availability of systemic treatment options.

Late effects of craniospinal irradiation for medulloblastomas in paediatric patients

Along with surgery, radiation therapy (RT) remains an essential option to cure patients suffering from medulloblastoma. However, its long-term adverse effects, particularly due to craniospinal irradiation (CSI), which is necessary to eradicate microscopic spread, are a limiting factor. The most frequent sequelae involve neurocognitive and endocrine impairment, which occurs in nearly all patients. Recent progress achieved through genetic and molecular biology offers the possibility to better stratify patients according to risk factors such as age, post-resection tumour residue and metastasis. Thus, new therapeutic studies assess the possibility to reduce radiation dose and/or radiation field size for patients with the most favourable prognosis. New radiotherapy techniques are also used such as Intensity-Modulated Radiotherapy (IMRT), tomotherapy and proton therapy, which aim at reducing the dose delivered to normal tissue. Conventional photon-based therapy has a relatively high exit dose in contrast with proton therapy which causes less damage to surrounding healthy tissue. It is noteworthy that each technique requires a long follow-up in order to prove that late effects could be reduced without compromising survival rates. Dosimetric comparison theoretically suggests that proton therapy may be the superior method for CSI in terms of late effects, but further research is needed to firmly establish this. Whatever the technique used, the great complexity of CSI requires discipline and expertise along with an external quality control online before the first RT session.

Case Report of Bone Marrow-Sparing Proton Therapy Craniospinal Irradiation for Central Nervous System Myelomatosis

Central nervous system (CNS) involvement is rare but it is an increasingly recognized complication of the multiple myeloma. The craniospinal radiotherapy is a standard treatment option, however, it may be challenging to deliver due to hematologic toxicity in the patients with multiple prior systemic therapies. We report a case of CNS myelomatosis in a patient with prior stem cell transplant multiple systemic therapies treated with bone marrow-sparing proton therapy craniospinal irradiation, with the dramatic clinical response and minimal hematologic toxicity.

Pediatric craniospinal irradiation with conventional technique or helical tomotherapy: impact of age and body volume on integral dose

PURPOSE

The use of helical tomotherapy (HT) for craniospinal irradiation (CSI) in pediatric patients remains an issue of discussion. In this study, we evaluated the integral dose (ID) to organs at risk (OARs) and to the whole body delivered with conventional 3-dimensional conformal radiotherapy (3D-CRT) and HT for pediatric patients and made a comparison according to different whole body volumes.

METHODS

We selected 10 pediatric patients with different body volumes and of different ages undergoing CSI. Plans for 3D-CRT and HT were developed for each patient. The ID to OARs and to the whole body were compared and statistical analyses were performed to determine differences.

RESULTS

We noticed that variations of ID depend on the different anatomical location of the organs relatively to the target, with lower ID to OARs opposed to the target and increased ID to lateral organs: ID tomotherapy/3D-CRT ratio was higher in lungs, kidneys, and mammary region, while it was lower in heart, liver, thyroid, and esophagus. The ID of the body increased with large volumes both in HT and in 3D-CRT plans, but in tomotherapy plans ID increased significantly more with large volumes than with small ones.

CONCLUSIONS

While there are no differences in using tomotherapy or 3D-CRT with small body volumes, we found a difference with large volumes (≥20,000 mL vs ≤20,000 mL). Therefore, for very small patients, the use of intensity-modulated radiotherapy provided with tomotherapy to reduce the dose to OARs can be reconsidered.

Dosimetric results in treatments of neuroblastoma and neuroendocrine tumors with (131)I-metaiodobenzylguanidine with implications for the activity to administer

PURPOSE

The aim was to investigate whole-body and red marrow absorbed doses in treatments of neuroblastoma (NB) and adult neuroendocrine tumors (NETs) with (131)I-metaiodobenzylguanidine and to propose a simple method for determining the activity to administer when dosimetric data for the individual patient are not available.

METHODS

Nine NB patients and six NET patients were included, giving in total 19 treatments as four patients were treated twice. Whole-body absorbed doses were determined from dose-rate measurements and planar gamma-camera imaging. For six NB and five NET treatments, red marrow absorbed doses were also determined using the blood-based method.

RESULTS

Dosimetric data from repeated administrations in the same patient were consistent. In groups of NB and NET patients, similar whole-body residence times were obtained, implying that whole-body absorbed dose per unit of administered activity could be reasonably well described as a power function of the patient mass. For NB, this functional form was found to be consistent with dosimetric data from previously published studies. The whole-body to red marrow absorbed dose ratio was similar among patients, with values of 1.4 ± 0.6-1.7 ± 0.7 (1 standard deviation) in NB treatments and between 1.5 ± 0.6 and 1.7 ± 0.7 (1 standard deviation) in NET treatments.

CONCLUSIONS

The consistency of dosimetric results between administrations for the same patient supports prescription of the activity based on dosimetry performed in pretreatment studies, or during the first administration in a fractionated schedule. The expressions obtained for whole-body absorbed doses per unit of administered activity as a function of patient mass for NB and NET treatments are believed to be a useful tool to estimate the activity to administer at the stage when the individual patient biokinetics has not yet been measured.

Prospective study on dosimetric comparison of helical tomotherapy and 3DCRT for craniospinal irradiation - A single institution experience

AIM

This prospective study aims to assess feasibility of helical tomotherapy (HT) for craniospinal irradiation (CSI) and perform dosimetric comparison of treatment plans for both HT and 3D conformal radiotherapy (3DCRT).

BACKGROUND

CSI is a challenging procedure. Large PTV size requires field matching due to technical limitations of standard linear accelerators, which cannot irradiate such volumes as a single field. HT could help to avoid these limitations as irradiation of long fields is possible without field matching.

MATERIALS AND METHODS

Three adults were enrolled from 2009 to 2010. All patients received radiochemotherapy. Treatment plans in prone position for 3DCRT and in supine position for HT were generated. The superior plan was used for patients' irradiation. Plans were compared with the application of DVH, Dx parameters - where x represents a percentage of the structure volume receiving a normalized dose and homogeneity index (HI).

RESULTS

All patients received HT irradiation. The treatment was well tolerated. The HT plans resulted in a better dose coverage and uniformity in the PTV: HI were 5.4, 7.8, 6.8 for HT vs. 10.3, 6.6, 10.4 for 3DCRT. For most organs at risk (OARs), the D(V80) was higher for HT than for 3DCRT, whereas D(V5) was lower for HT.

CONCLUSIONS

HT is feasible for CSI, and in comparison with 3DCRT it improves PTV coverage. HT reduces high dose volumes of OARs, but larger volumes of normal tissue receive low radiation dose. HT requires further study to establish correlations between dosimetrical findings and clinical outcomes, especially with regard to late sequelae of treatment.

A template for writing radiotherapy protocols

BACKGROUND

Well-specified and unambiguous treatment protocols are essential both for current practice and for the future development of radiation therapy. In order to provide assistance for writing good protocols, irrespective of treatment intention and complexity, up-to-date guidelines are highly desirable.

METHODS

We have analysed the radiotherapy work-flow, including clinical and physical aspects, such as preparatory imaging, treatment planning, delivery and evaluation, with the aim to outline a consistent framework covering the entire radiotherapy process.

RESULTS

Based on the analysis, a recipe-style template for specifying the description of the radiotherapy process has been designed. The template is written in a general format, which allows for modified phrasing, and should be customised for the specific clinical situation and diagnosis, as well as facility resources.

CONCLUSIONS

The template can be used as a tool to ensure a consistent and comprehensive description of the radiotherapy section of clinical guidelines, care programmes and clinical trial protocols.