Early Versus Delayed Fractionated Stereotactic Radiotherapy for Nonfunctioning Pituitary Adenoma

BACKGROUND

Fractionated stereotactic radiotherapy (FSRT) is a common modality used to treat pituitary adenomas with good control rates. It is not known whether FSRT should be performed early or delayed until progression occurs. We compared FSRT in treating nonfunctional pituitary adenomas (NFPA) as an adjuvant (ADJ) or on-progression (PRG) therapy.

METHODS

A retrospective review of patients who underwent FSRT for an NFPA between January 2004 and December 2022 at a single institution was performed. We compared endocrinologic, ophthalmologic, and radiographic outcomes in FSRT delivered as ADJ and PRG treatment.

RESULTS

Seventy-five patients were analyzed, with a median follow-up of 53 months. FSRT was administered to 35 and 40 patients as ADJ and PRG, with a median time to treatment of 5.5 and 40 months, respectively. The tumor control rate was 94.3% for ADJ and 95.0% for PRG. Treatment resulted in 4 (11.4%) versus 7 (17.5%) new endocrinopathies and 2 (5.7%) versus 1 (2.5%) new visual deficits for ADJ versus PRG. A survival analysis of time to new endocrinopathy showed no difference between the 2 cohorts. The median time from surgery to new endocrinopathy was significantly different between ADJ and PRG, at 15.5 and 102.0 months, respectively.

CONCLUSIONS

FSRT is effective in treating NFPA for residual and progressive tumors, with excellent tumor control rates and a low risk of developing new endocrinopathies and visual deficits. Delaying treatment delayed the development of new endocrinopathies, suggesting that observation with FSRT on tumor progression may delay the onset of hypopituitarism and maintain similar effectiveness in tumor control.

Institutional Validation Study Inferring 2% MGMT Methylation Positive Impact on Survival in Newly Diagnosed Glioblastoma (GBM) Patients

PURPOSE/OBJECTIVE(S)

O6-methylguanine DNA methyltransferase (MGMT) MATERIALS/METHODS: is a well-established prognostic factor in patients with newly diagnosed glioblastoma (GBM). However, there is no consensus on a standardized method of threshold for MGMT testing. Previous studies have reported levels of as little as 1-3% to confer better prognosis. This study reports a single institutional experience of determining methylation status via methylation-sensitive high-resolution melting (MS-HRM). Previous literature suggests 10% cutoff for MGMT methylation using MS-HRM. We hereby report clinical outcomes using a lower threshold of 2%.

MATERIALS/METHODS

GBM patients treated at our institution retrospectively reviewed between the years 2013 and 2022 were included in the study. Patients who received hypofractionated radiation (<60 Gy) were excluded. All patients had MS-HRM test for MGMT methylation status. A real-time PCR assay was used to amplify a 62 base-pair region of MGMT for both methylated and unmethylated alleles. PCR products underwent HRM analysis and the fraction of methylated DNA was determined by comparison with a standard curve. Clinical data were collected retrospectively. Kaplan-Meier and log-rank tests were performed to compare survival.

RESULTS

A total of 181 patients with newly diagnosed GBM were initially included in this study. 42 patients treated with hypofractionated radiation were excluded. All patients received concurrent and maintenance temozolomide. Median age was 61.5 years. A total of 84 patients had MGMT methylation levels <2%, and 55 patients had MGMT methylation level ≥ 2% with a median methylation level of 28.5% (Range 0.8%-100%). Patients with MGMT methylation level ≥ 2% had an improved median overall survival (25.1 vs 16.0 months; p = 0.006) and improved median progression free survival (11.3 vs 7.9 months; p = 0.017). In a multivariable mode that included age, use of tumor-treating fields, KPS, sex, and BMI, only age, KPS, and MGMT remained significant.

CONCLUSION

Our institutional review confirmed low level of MGMT hypermethylation (≥ 2%) predicts improved outcome in patients with newly diagnosed GBM. Further investigation on optimal cut off level for MGMT methylation is still warranted.

Body Mass Index (BMI) at Time of Diagnosis as a Prognostic Indicator in Patients with Newly Diagnosed Glioblastoma (GBM)

PURPOSE/OBJECTIVE(S)

Glioblastoma (GBM) is the most common primary brain cancer in adults with very poor prognosis. Metabolic drivers of tumorigenesis are highly relevant within the central nervous system, where glucose is the sole source of energy. The impact of obesity on survival outcomes in patients with GBM has not been well reported and some initial results are inconsistent. This study investigates the factor of body mass index (BMI) in patients diagnosed with GBM. This study evaluated the prognostic association of BMI with survival outcomes in patients with newly diagnosed GBM.

MATERIALS/METHODS

Patientswith newly diagnosed GBM at our institution from 2015-2022 were included in this study. All patients were >18 years of age and received 60 Gy of radiation therapy with concurrent and adjuvant temozolomide following maximal safe resection. Through retrospective chart review, patient BMI at the time of diagnosis and overall survival (OS) were recorded. Analysis was done between patient groups of underweight/normal weight (BMI <25) and overweight/obese (BMI ≥ 25.00). The subgroup of overweight patients was also divided into subgroups of overweight (BMI 25.00-29.99) and obese (BMI≥30.00). A difference in clinical outcomes of overall survival was evaluated between the groups using Gehan-Breslow-Wilcoxon and log-rank tests.

RESULTS

Atotal of 393 patients met inclusion criteria. Median age 57.3 years, range 18.8-92.7. 185 female and 208 were male. 120 patients had a BMI <25 and 273 had a BMI ≥ 25.00. Median survival in patients with BMI <25 was 24.90 months and in patients with BMI ≥ 25.00, 18.20 months (p = 0.0001; HR 0.6552, 95% CI 0.5299-0.8101). We further divided patients with BMI ≥ 25.00 to 25-29.99 (n = 152) and BMI≥30.00 (n = 121). Both groups' OS were significantly worse than patients with BMI < 25 (p = 0.006). There was no difference in survival outcomes between patients with a BMI 25.00-29.99 and BMI≥30.00, with median OS 19.0 months and 18.1 months, respectively.

CONCLUSION

Patient baseline BMI <25 appears to be a prognostic indicator and correlates to improves overall survival for patients with newly diagnosed GBM. This study adds to the existing literature supporting overweight/obesity is associated with worse survival for GBM patients. Additional studies are warranted for further analysis of BMI and survival outcomes in GBM patients across patient demographics.

Multifocal Ectopic Recurrence of a C2 Chordoma

Background  Chordomas are histologically benign but locally aggressive tumors with a high propensity to recur. Our case highlights the importance of long-term vigilance in patients who have undergone chordoma resection. Case Report  We report the case of a 47-year-old man with a cervical chordoma who developed multiple musculoskeletal ectopic recurrences in the left supraclavicular region, the proximal right bicep, and the left submandibular region without recurrence in the primary tumor site. Primary tumor resection was achieved via a combination of surgery, adjuvant radiation therapy, and imatinib. All recurrences were successfully resected and confirmed via pathology to be ectopic chordoma. Discussion  Ectopic recurrence of cervical chordoma is rare and lung is the most common site of distant spread. Chordoma recurrence in skeletal muscle is particularly rare, with only 10 cases described in the literature. A plausible mechanism of distant metastatic disease in chordoma patients suggests that tumor cells escape the surgical tract via a combination of cytokine release, vasodilation, and microtrauma induced during resection. Conclusion  Cervical chordoma with ectopic recurrence in skeletal muscle has not been previously described in the literature. Skull base surgeons should be aware of the phenomenon of chordoma ectopic recurrence in the absence of local recurrence.

Differences in clinical outcomes based on molecular markers in glioblastoma patients treated with concurrent tumor-treating fields and chemoradiation: exploratory analysis of the SPARE trial

BACKGROUND

Glioblastoma (GBM) is the most common primary malignant brain tumor in adults. Despite enormous research efforts, GBM remains a deadly disease. The standard-of-care treatment for patients with newly diagnosed with GBM as per the National Cancer Comprehensive Cancer Network (NCCN) is maximal safe surgical resection followed by concurrent chemoradiation and maintenance temozolomide (TMZ) with adjuvant tumor treating fields (TTF). TTF is a non-pharmacological intervention that delivers low-intensity, intermediate frequency alternating electric fields that arrests cell proliferation by disrupting the mitotic spindle. TTF have been shown in a large clinical trial to improve patient outcomes when added to radiation and chemotherapy. The SPARE trail (Scalp-sparing radiation with concurrent temozolomide and tumor treating fields) evaluated adding TTF concomitantly to radiation and chemotherapy.

METHODS

This study is an exploratory analysis of the SPARE trial looking at the prognostic significance of common GBM molecular alterations, namely MGMT, EGFR, TP53, PTEN and telomerase reverse transcriptase (TERT), in this cohort of patients treated with concomitant TTF with radiation and chemotherapy.

RESULTS

As expected, MGMT promoter methylation was associated with improved overall survival (OS) and progression-free survival (PFS) in this cohort. In addition, TERT promoter mutation was associated with improved OS and PFS in this cohort as well.

CONCLUSIONS

Leveraging the molecular characterization of GBM alongside advancing treatments such as chemoradiation with TTF presents a new opportunity to improve precision oncology and outcomes for GBM patients.

RADT-19. CHEMORADIATION (CRT) TREATMENT WITH OR WITHOUT CONCURRENT TUMOR-TREATING FIELDS (TTFIELDS) IN PATIENTS WITH NEWLY DIAGNOSED GLIOBLASTOMA (GBM)

OBJECTIVES

Standard of care for newly diagnosed glioblastoma after resection includes concurrent temozolomide (TMZ) and radiation therapy followed by adjuvant TTF with maintenance TMZ. Preclinical studies suggest TTF and radiotherapy work synergistically. We evaluate the benefit of concurrent TTF with CRT vs adjuvant TTF with TMZ after CRT.

METHODS

Concurrent TTF with CRT patients were enrolled in a single-arm pilot study (clinicaltrials.gov Identifier: NCT03477110). For the comparison control of adjuvant TTF, adult patients with newly diagnosed GBM that had a KPS ≥ 60 who received treatment with CRT and adjuvant TMZ + TTF from three institutions were included. The adjuvant TTF cohort excluded patients who progressed during CRT or did not receive TMZ. PFS and OS were compared between groups.

RESULTS

A total of 87 patients were included in this study, of which 30 received concurrent TTF with CRT. Median patient age was 58 in the concurrent TTF group and 59 in the adjuvant TTF group. The median KPS in both groups was. MGMT methylation was present in 33.3% of the concurrent TTF and 32.0% in the adjuvant TTF group. 40% received GTR in the concurrent group and 38% received GTR in the adjuvant group. Multifocal disease was appreciated in 40% of patients in the concurrent TTF group. There was no significant difference in median OS (p=0.38) or PFS (p=0.76).

CONCLUSIONS

There was no difference in OS or PFS between concurrent or adjuvant TTF treatment groups. However, the adjuvant TTF group is expected to be a better prognosis due to the elimination of patients that progressed or declined after initial CRT. The current study suggested concurrent TTF treatment achieved outcomes to that of a better prognosis group. The survival benefit of concurrent TTF with CRT vs adjuvant TTF is being tested in the phase 3 TRIDENT EF-32 clinical trial (NCT04471844).

INNV-09. IMPACT OF MOLECULAR MARKERS ON TREATMENT OUTCOME OF GLIOBLASTOMA PATIENTS TREATED WITH CONCURRENT TUMOR-TREATING FIELDS (TTF) AND CHEMORADIATION: SECONDARY ANALYSIS OF SPARE TRIAL

OBJECTIVES

SPARE trial (Scalp-sparing radiation with concurrent temozolomide and tumor treating fields; NCT03477110) is a single-arm pilot study that evaluated the safety and feasibility of concurrent TTF with chemoradiation for adult patients with newly diagnosed GBM. The current study is a secondary analysis evaluating the impact of molecular markers (PTEN, TP53, EGFR, and TERT) on overall survival (OS) and progression-free survival (PFS) of the patients in the trial.

METHODS

Molecular markers of histologically-confirmed, IDH-wildtype GBM patients age ≥ 18 years old with a KPS ≥ 60 who received concurrent chemoradiation and TTF followed by maintenance TMZ + TTF were evaluated. Molecular profile was evaluated with next-generation sequencing. Impact of mutations in PTEN, TP53, EGFR, and TERT on OS and PFS was evaluated using a multivariable backward model.

RESULTS

A total of 30 patients were enrolled in the SPARE trial, and 1 patient with IDH-mutant was excluded from the current analysis. All patients underwent concurrent TTF and chemoradiation. The median age is 58 and KPS was 90. 9 patients had methylated MGMT promotor. 14 patients were found to have PTEN mutation, 9 patients with EGFR, 7 with TP53 mutation, and 23 patients with TERT mutated. MGMT methylation remained statistically significant for an increased OS (p=0.032; HR 7.18). TERT mutation had a statistically significant improvement in PFS (P=0.003) and OS (p=0.012). However, neither EGFR, TP53, nor PTEN showed any association of PFS or OS for patients who received concurrent TTF and CRT.

CONCLUSIONS

In this secondary analysis, patients with MGMT methylation showed better PFS and OS as expected. Neither EGRF, TP53, or PTEN mutation showed any association with PFS or OS. Patients with TERT mutant showed improved OS of patients treated with concurrent TTF with chemoradiation. A TERT mutation may be a new molecular biomarker in the described treatment approach.