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

Comparison of lifetime attributable risk of post-irradiation secondary cancer of boron neutron capture therapy, proton beam therapy, and X-ray therapy for pediatric and adolescent and young adult patients

Background and purpose

This study aimed to compare the post-irradiation secondary cancer rates of boron neutron capture therapy (BNCT), proton beam therapy (PBT), and X-ray therapy (XT) in pediatric and Adolescent and Young Adult (AYA) patients with intracranial lesions.

Materials and methods

BNCT, PBT, and XT plans were optimized for nine pediatric and AYA patients with intracranial lesions. The BNCT dose calculation results were biologically effective dose converted. Lifetime attributable risk (LAR) was calculated using a calculation model proposed by Schneider et al. Statistical analysis was performed using log-linear model with mixed effects. Organs included in the radiation field were the brain, bones, and soft tissue. The difference in LAR between the three treatments for each organ and the number needed to treat (NNT), as an indicator of the number of cases required to achieve the effect of suppressing the occurrence of secondary cancers, was calculated and evaluated.

Results

Statistically significant differences between BNCT vs PBT and XT were confirmed for the brain, bone, soft tissue, and cumulative (P < 0.0001). Significant differences were also observed in PBT and XT, with P < 0.0001 for brain and cumulative, P = 0.0002 for bone, and P = 0.0281 for soft tissue. The cumulative NNT for BNCT vs. PBT, BNCT vs. XT, and PBT vs. XT were 162, 78.6, and 153, respectively.

Conclusion

BNCT had a significantly lower LAR compared to PBT and XT. These findings suggest the usefulness of BNCT in pediatric and AYA patients with brain tumors from the perspective of post-irradiation secondary cancer.

Delivery of re-irradiation and complex palliative radiotherapy using proton therapy in pediatric cancer patients

BACKGROUND

The intent of this study is to characterize indications for pediatric palliative-intent proton radiation therapy (PIPRT).

PROCEDURE

We retrospectively reviewed patients 21 years and younger who received PIPRT. We defined PIPRT as radiotherapy (RT) aimed to improve cancer-related symptoms/provide durable local control in the non-curative setting. Mixed proton/photon plans were included. Adjacent re-irradiation (reRT) was defined as a reRT volume within the incidental dose cloud of a prior RT target, whereas direct reRT was defined as in-field overlap with prior RT target. Acute toxicity during RT until first inspection visit was graded according to the Common Terminology Criteria for Adverse Events. The Kaplan-Meier method, measured from last PIPRT fraction, was used to assess progression-free survival (PFS) and overall survival (OS).

RESULTS

Eighteen patients underwent PIPRT between 2014 and 2020. Median age at treatment start was 10 years [2-21]. Median follow-up was 8.2 months [0-48]. Treatment sites included: brain/spine [10], abdomen/pelvis [3], thorax [3], and head/neck [2]. Indications for palliation included: durable tumor control [18], neurologic symptoms [4], pain [3], airway compromise [2], and great vessel compression [1]. Indications for protons included: reRT [15] (three adjacent, 12 direct), craniospinal irradiation [4], reduction of dose to normal tissues [3]. Sixteen experienced grade (G) 1-2 toxicity; two G3. There were no reports of radionecrosis. Median PFS was 5.3 months [95% confidence interval (CI): 2.7-16.3]. Median OS was 8.3 months [95% CI: 5.5-26.3].

CONCLUSIONS

The most common indication for PIPRT was reRT to provide durable tumor control. PIPRT appears to be safe, with no cases of high-grade toxicity.

Global metabolomics study on the pathogenesis of pediatric medulloblastoma via UPLC- Q/E-MS/MS

Medulloblastoma is one of the most frequent malignant brain tumors in infancy and childhood. Early diagnosis and treatment are quite crucial for the prognosis. However, the pathogenesis of medulloblastoma is still not completely clarified. High-resolution mass spectrometry has enabled a comprehensive investigation on the mechanism of disease from the perspective of metabolism. Herein, we compared the difference of metabolic profiles of serum between medulloblastoma (n = 33) and healthy control (HC, n = 16) by using UPLC-Q/E-MS/MS. Principal component analysis and orthogonal projections to latent structures discriminant analysis (OPLS-DA) intuitively revealed the significantly distinct metabolic profiles between medulloblastoma and HC (p < 0.01 for permutation test on OPLS-DA model). Total of 25 significantly changed metabolites were identified. ROC analysis reported that six of them (Phosphatidic acid (8:0/15:0), 3'-Sialyllactose, Isocoproporphyrin, Acetylspermidine, Fructoseglycine and 3-Hydroxydodecanedioate) showed high specificity and precision to be potential diagnosis biomarkers (AUC > 0.98). Functional analysis discovered that there are four pathways notably perturbed for medulloblastoma. These pathways are related with the dysfunction of arachidonic acid metabolism, steroid hormone biosynthesis, and folate-related metabolism. The target intervention on these pathways may reduce the mortality of medulloblastoma.