Vestibular schwannomas: Accuracy of tumor volume estimated by ice cream cone formula using thin-sliced MR images

Response prediction of vestibular schwannoma after gamma-knife radiosurgery using pretreatment dynamic contrast-enhanced MRI: a prospective study

OBJECTIVES

There are few known predictive factors for response to gamma-knife radiosurgery (GKRS) in vestibular schwannoma (VS). We investigated the predictive role of pretreatment dynamic contrast-enhanced (DCE)-MRI parameters regarding the tumor response after GKRS in sporadic VS.

METHODS

This single-center prospective study enrolled participants between April 2017 and February 2019. We performed a volumetric measurement of DCE-MRI-derived parameters before GKRS. The tumor volume was measured in a follow-up MRI. The pharmacokinetic parameters were compared between responders and nonresponders according to 20% or more tumor volume reduction. Stepwise multivariable logistic regression analyses were performed, and the diagnostic performance of DCE-MRI parameters for the prediction of tumor response was evaluated by receiver operating characteristic curve analysis.

RESULTS

Ultimately, 35 participants (21 women, 52 ± 12 years) were included. There were 22 (62.9%) responders with a mean follow-up interval of 30.2 ± 5.7 months. K^trans (0.036 min^-1 vs. 0.057 min^-1, p = .008) and initial area under the time-concentration curve within 90 s (IAUC90) (84.4 vs. 143.6, p = .003) showed significant differences between responders and nonresponders. K^trans (OR = 0.96, p = .021) and IAUC90 (OR = 0.97, p = .004) were significant differentiating variables in each multivariable model with clinical variables for tumor response prediction. K^trans showed a sensitivity of 81.8% and a specificity of 69.2%, and IAUC90 showed a sensitivity of 100% and a specificity of 53.8% for tumor response prediction.

CONCLUSION

DCE-MRI (particularly K^trans and IAUC90) has the potential to be a predictive factor for tumor response in VS after GKRS.

KEY POINTS

•Pretreatment prediction of gamma-knife radiosurgery response in vestibular schwannoma is still challenging. •Dynamic contrast-enhanced MRI could have predictive value for the response of vestibular schwannoma after gamma-knife radiosurgery.

Synthetic and immunological studies on the OCT4 immunodominant motif antigen-based anti-cancer vaccine

Objective: Cancer stem cell is one of the important causes of tumorigenesis as well as a drug target in the treatment of malignant tumor. However, at present, there is no immune vaccine targeting these cells. Octamer-binding transcription factor 4 (OCT4), a marker of embryonic stem cells and germ cells, often highly expresses in the early stages of tumorigenesis and is therefore a good candidate for cancer vaccine development.

Methods: To identify the optimal carrier and adjuvant combination, we chemically synthesized and linked three different OCT4 epitope antigens to a carrier protein, keyhole limpet hemocyanin (KLH), combined with Toll-like receptor 9 agonist (TLR9).

Results: Immunization with OCT4-3 + TLR9 produced the strongest immune response in mice. In prevention assays, significant tumor growth inhibition was achieved in BABL/c mice treated with OCT4-3 + TLR9 (P < 0.01). Importantly, the results showed that cytotoxic T lymphocyte activity and the inhibition of tumor growth were enhanced in mice immunized with OCT4-3 combined with TLR9. Meanwhile, multiple cytokines [such as interferon (IFN)-γ (P < 0.05), interleukin (IL)-12 (P < 0.05), IL-2 (P < 0.01), and IL-6 (P < 0.05)] promoting cellular immune responses were shown to be greatly enhanced in mice immunized with OCT4-3 + TLR9. Moreover, we considered safety considerations in terms of the composition of the vaccines to help facilitate the development of effective next-generation vaccines.

Conclusions: Collectively, these experiments demonstrated that combination therapy with TLR9 agonist induced a tumor-specific adaptive immune response, leading to the suppression of primary tumor growth in testis embryonic carcinoma.

Volumetric tumor response assessment is inefficient without overt clinical benefit compared to conventional, manual veterinary response assessment in canine nasal tumors

Accurate assessment of tumor response to therapy is critical in guiding management of veterinary oncology patients and is most commonly performed using response evaluation criteria in solid tumors criteria. This process can be time consuming and have high intra- and interobserver variability. The primary aim of this serial measurements, secondary analysis study was to compare manual linear tumor response assessment to semi-automated, contoured response assessment in canine nasal tumors. The secondary objective was to determine if tumor measurements or clinical characteristics, such as stage, would correlate to progression-free interval. Three investigators evaluated paired CT scans of skulls of 22 dogs with nasal tumors obtained prior to and following radiation therapy. The automatically generated tumor volumes were not useful for canine nasal tumors in this study, characterized by poor intraobserver agreement between automatically generated contours and hand-adjusted contours. The radiologist's manual linear method of determining response evaluation criteria in solid tumors categorization and tumor volume is significantly faster (P < .0001) but significantly underestimates nasal tumor volume (P < .05) when compared to a contour-based method. Interobserver agreement was greater for volume determination using the contour-based method when compared to response evaluation criteria in solid tumors categorization utilizing the same method. However, response evaluation criteria in solid tumors categorization and percentage volume change were strongly correlated, providing validity to response evaluation criteria in solid tumors as a rapid method of tumor response assessment for canine nasal tumors. No clinical characteristics or tumor measurements were significantly associated with progression-free interval.

Current Volumetric Models Overestimate Vestibular Schwannoma Size Following Stereotactic Radiosurgery

OBJECTIVE

Accurate volume assessment is essential for the management of vestibular schwannoma after stereotactic radiosurgery (SRS). A cuboidal approximation for volume is the standard surveillance method; however, this may overestimate tumor volume. We sought to evaluate several volumetric models and their suitability for post-SRS surveillance.

STUDY DESIGN

Retrospective cohort study.

SETTING

Tertiary referral center.

PATIENTS

We evaluated 54 patients with vestibular schwannoma before and after SRS.

INTERVENTION(S)

Gold-standard volumes were obtained by a radiation oncologist using contouring software. Volume was also calculated by cuboidal, ellipsoidal, and spherical formulae using tumor diameters obtained by a neuroradiologist.

MAIN OUTCOME MEASURE(S)

Percent error (PE) and absolute percent error (APE) were calculated. Paired t test evaluated bias, and the Bland-Altman method evaluated reproducibility. Linear regression evaluated predictors of model error.

RESULTS

All models overestimated volume compared with the gold standard. The cuboidal model was not reproducible before SRS (p < 0.001), and no model was reproducible after SRS (cuboidal p < 0.001; ellipsoidal p = 0.02; spherical p = 0.02). Significant bias was present before SRS for the cuboidal model (p < 0.001), and post-SRS for all models [cuboidal (p < 0.001), ellipsoidal (p < 0.02), and spherical (p = 0.005)]. Model error was negatively associated with pretreatment volume for the cuboidal (PE p = 0.03; APE p = 0.03), ellipsoidal (PE p = 0.03; APE p = 0.04), and spherical (PE p = 0.02; APE p = 0.03) methods and lost linearity post-SRS.

CONCLUSIONS

The standard cuboidal practice for following vestibular schwannoma tumor volume after SRS overestimates size. Ellipsoidal and spherical estimations have improved performance but also overestimate volume and lack reliability post-SRS. The development of other volumetric models or application of contouring software should be investigated.

Seizures and Blurred Vision as Initial Presentation of Intracerebral Schwannoma: A Rare Tumor of the Brain

Schwannomas are the most common tumor of peripheral nerves which are arising from Schwann cells and are benign in their nature. Intracranial schwannoma accounts for between 5 and 8% of intracranial tumors, whereas intracerebral schwannoma, a rare disease, accounts for <1% of intracranial schwannomas. Intracerebral schwannoma has no specific clinical manifestation, and it is not classified by age. Here, we are reporting a case of an 18-year-old male who presented with attacks of seizures. MR imaging studies were done and showed right parieto-occipital cortical and subcortical mass lesion with intense enhancement and significant vasogenic oedema with mass effect on the subjacent sulci. The tumor was surgically removed through a right occipital craniotomy. Histological findings confirmed the diagnosis of schwannoma.