Challenges with hippocampal MR spectroscopy as a surrogate for pre-radiotherapy assessment of neurocognitive impairment in patients with brain metastasis.

AIM: Patients with multiple brain metastases (BM) benefit from hippocampal-avoiding whole brain radiotherapy (HA-WBRT), the challenging and less available form of WBRT. This study explores potential of pre-radiotherapy (pre-RT) hippocampal magnetic resonance spectroscopy (MRS) measuring hippocampal neuronal density as an imaging surrogate and predictive tool for assessing neurocognitive functions (NCF). METHODS: 43 BM patients underwent pre-RT hippocampal MRS. N-acetyl aspartate (NAA) concentration, a marker for neuronal density (weighted by creatine (Cr) and choline (Cho) concentrations), and neurocognitive function (NCF) tests (HVLT and BVMT) performed by certified psychologists were evaluated. Clinical variables and NAA concentrations were correlated with pre-RT NCFs. RESULTS: HVLT and BVMT subtests showed pre-RT deterioration except for BVMT recognition. Significantly better NCFs were observed in women in HVLT subsets. Significantly higher NAA/Cr + Cho was measured in women (median 0.63 vs. 0.55; P=0.048) in the left hippocampus (no difference in the right hippocampus). In men, a positive correlation (0.51, P=0.018) between total brain volume and HVLT-TR, between left hippocampal NAA/Cr + Cho and HVLT-R (0.45, P=0.063), and between right hippocampal NAA/Cr + Cho and BVMT-recognition (0.49, P=0.054) was observed. In women, a borderline significant negative correlation was observed between left hippocampal NAA/Cr + Cho and BVMT-TR (-0.43, P=0.076) and between right NAA/Cr + Cho and HVLT-DR (-0.42, P=0.051). CONCLUSION: Borderline statistically significant correlations were observed with speculative interpretation underlying the challenges of hippocampal MRS as a surrogate for neurocognitive impairment. Further studies need to be done to ascertain the opportunities for imaging predictors of benefit from memory sparing radiotherapy.

Hippocampal subfield volumetric changes after radiotherapy for brain metastases.

Background: Changes in the hippocampus after brain metastases radiotherapy can significantly impact neurocognitive functions. Numerous studies document hippocampal atrophy correlating with the radiation dose. This study aims to elucidate volumetric changes in patients undergoing whole-brain radiotherapy (WBRT) or targeted stereotactic radiotherapy (SRT) and to explore volumetric changes in the individual subregions of the hippocampus. Method: Ten patients indicated to WBRT and 18 to SRT underwent brain magnetic resonance before radiotherapy and after 4 months. A structural T1-weighted sequence was used for volumetric analysis, and the software FreeSurfer was employed as the tool for the volumetry evaluation of 19 individual hippocampal subregions. Results: The volume of the whole hippocampus, segmented by the software, was larger than the volume outlined by the radiation oncologist. No significant differences in volume changes were observed in the right hippocampus. In the left hippocampus, the only subregion with a smaller volume after WBRT was the granular cells and molecular layers of the dentate gyrus (GC-ML-DG) region (median change -5 mm3, median volume 137 vs. 135 mm3; P = .027), the region of the presumed location of neuronal progenitors. Conclusions: Our study enriches the theory that the loss of neural stem cells is involved in cognitive decline after radiotherapy, contributes to the understanding of cognitive impairment, and advocates for the need for SRT whenever possible to preserve cognitive functions in patients undergoing brain radiotherapy.

Small RNA Sequencing Identifies a Six-MicroRNA Signature Enabling Classification of Brain Metastases According to their Origin.

BACKGROUND/AIM: Brain metastases (BMs) are the most frequent intracranial tumors in adults and one of the greatest challenges for modern oncology. Most are derived from lung, breast, renal cell, and colorectal carcinomas and melanomas. Up to 14% of patients are diagnosed with BMs of unknown primary, which are commonly characterized by an early and aggressive metastatic spread. It is important to discover novel biomarkers for early identification of BM origin, allowing better management of patients with this disease. Our study focused on microRNAs (miRNAs), which are very stable in frozen native and FFPE tissues and have been shown to be sensitive and specific diagnostic biomarkers of cancer. We aimed to identify miRNAs with significantly different expression in the five most frequent groups of BMs and develop a diagnostic classifier capable of sensitive and specific classification of BMs. MATERIALS AND METHODS: Total RNA enriched for miRNAs was isolated using the mirVana miRNA Isolation Kit from 71 fresh-frozen histopathologically confirmed BM tissues originating in 5 cancer types. Sequencing libraries were prepared using the QIAseq miRNA Library Kit and sequenced on the NextSeq 500 platform. MiRNA expression was further validated by RT-qPCR. RESULTS: Differential analysis identified 373 miRNAs with significantly different expression between 5 BM groups (p<0.001). A classifier model was developed based on the expression of 6 miRNAs (hsa-miR-141-3p, hsa-miR-141-5p, hsa-miR-146a-5p, hsa-miR-194-5p, hsa-miR-200b-3p and hsa-miR-365b-5p) with the ability to correctly classify 91.5% of samples. Subsequent validation confirmed both significantly different expression of selected miRNAs in 5 BM groups as well as their diagnostic potential. CONCLUSION: To date, our study is the first to analyze miRNA expression in various types of BMs using small RNA sequencing to develop a diagnostic classifier and, thus, to help stratify BMs of unknown primary. The presented results confirm the importance of studying the dysregulated expression of miRNAs in BMs and the diagnostic potential of the validated 6-miRNA signature.

Neoadjuvant Chemotherapy of Triple-Negative Breast Cancer: Evaluation of Early Clinical Response, Pathological Complete Response Rates, and Addition of Platinum Salts Benefit Based on Real-World Evidence.

Pathological complete response (pCR) achievement is undoubtedly the essential goal of neoadjuvant therapy for breast cancer, directly affecting survival endpoints. This retrospective study of 237 triple-negative breast cancer (TNBC) patients with a median follow-up of 36 months evaluated the role of adding platinum salts into standard neoadjuvant chemotherapy (NACT). After the initial four standard NACT cycles, early clinical response (ECR) was assessed and used to identify tumors and patients generally sensitive to NACT. BRCA1/2 mutation, smaller unifocal tumors, and Ki-67 ≥ 65% were independent predictors of ECR. The total pCR rate was 41%, the achievement of pCR was strongly associated with ECR (OR = 15.1, p < 0.001). According to multivariable analysis, the significant benefit of platinum NACT was observed in early responders ≥45 years, Ki-67 ≥ 65% and persisted lymph node involvement regardless of BRCA1/2 status. Early responders with pCR had a longer time to death (HR = 0.28, p < 0.001) and relapse (HR = 0.26, p < 0.001). The pCR was achieved in only 7% of non-responders. However, platinum salts favored non-responders' survival outcomes without statistical significance. Toxicity was significantly often observed in patients with platinum NACT (p = 0.003) but not for grade 3/4 (p = 0.155). These results based on real-world evidence point to the usability of ECR in NACT management, especially focusing on the benefit of platinum salts.

Targeted Radiotherapy of the Tumor Cavity after Surgical Resection of Aggressive Recurrent Brain Metastasis: A Case Report.

Postoperative management of patients with brain metastases is controversial. Besides local control, cognitive function and quality of life are the most important outcomes of postoperative radiotherapy. In this case report, we introduce a patient with aggressive recurred solid metastasis treated with repeated surgery and an individual radiotherapy approach in order to highlight that close mutual collaboration leads to a clear benefit for our patients. The local targeted radiotherapy with 35 Gy in 10 fractions was performed with the volumetric modulated arc technique, leading to more than 2.5 years of local control and survival without any of the side effects usually attributed to whole brain radiotherapy.

In silico study of pseudoprogression in glioblastoma: collaboration of radiologists and radiation oncologists in the estimation of extent of high dose RT region.

BACKGROUND AND AIM: Oncologists play a vital role in the interpretation of radiographic results in glioblastoma patients. Molecular pathology and information on radiation treatment protocols among others are all important for accurate interpretation of radiology images. One important issue that may arise in interpreting such images is the phenomenon of tumor "pseudoprogression"; oncologists need to be able to distinguish this effect from true disease progression.Exact knowledge about the location of high-dose radiotherapy region is needed for valid determination of pseudoprogression according to RANO (Response Assessment in Neuro-Oncology) criteria in neurooncology. The aim of the present study was to evaluate the radiologists' understanding of a radiotherapy high-dose region in routine clinical practice since radiation oncologists do not always report 3-dimensional isodoses when ordering follow up imaging. METHODS: Eight glioblastoma patients who underwent postresection radiotherapy were included in this study. Four radiologists worked with their pre-radiotherapy planning MR, however, they were blinded to RT target volumes which were defined by radiation oncologists according to current guidelines. The aim was to draw target volume for high dose RT fields (that is the region, where they would consider that there may be a pseudoprogression in future MRI scans). Many different indices describing structure differences were analyzed in comparison with original per-protocol RT target volumes. RESULTS: The median volume for RT high dose field was 277 ccm (range 218 to 401 ccm) as defined per protocol by radiation oncologist and 87 ccm (range 32-338) as defined by radiologists (median difference of paired difference 31%, range 15-112%). The Median Dice index of similarity was 0.46 (range 0.14 - 0.78), the median Hausdorff distance 25 mm. CONCLUSION: Continuing effort to improve education on specific procedures in RT and in radiology as well as automatic tools for exporting RT targets is needed in order to increase specificity and sensitivity in response evaluation.