Citations

3520 Background: Duration of adjuvant FOLFOX or CAPOX for stage III CC is being guided by pt stratification into low (T1-3N1) and high (T4 or N2) risk groups based on the IDEA study. We determined the relative contributions of clinical and molecular features for prediction of time-to-recurrence (TTR) and survival after recurrence (SAR) within each risk group. Methods: Stage III CC (N=5,430) from 2 trials of adjuvant FOLFOX ± cetuximab with similar outcome by study arm [NCCTG N0147 (Alliance), PETACC-8] were used. Tumors were analyzed for mismatch repair (dMMR vs pMMR), mutations in KRAS (exon 2) and BRAFV600E. Median pt follow-up was 83.4 months. Relative contributions to predicting outcome were assessed using χ2 (Harrell’s rms) based on multivariable (MV) Cox models. Results: N (50.8%) and T (31.8%) stage were the top two contributors to prediction of TTR which supports risk grouping. High risk (n=2566) vs low risk (n=2774) pts had poorer TTR (HR 2.7, 95% CI, 2.4-3.0) and SAR [HR 1.6 (1.4-1.9)], both p<.0001. TTR: KRAS contributed the most to predicting TTR among high (58.6%) and low (51.1%) risk pts (Table). Contribution of MMR (16%) to predicting TTR was limited to low risk pts. Contribution of BRAFV600E to TTR was nearly 3-fold increased in high vs low risk pts. SAR: BRAFV600E contributed the most to predicting SAR, especially in high vs low risk pts (2-fold increase). Tumor sidedness and performance status (PS) were key contributors to SAR, but not TTR. MV associations: TTR: low risk, KRAS [HR 1.7 (1.4-2.3], MMR [HR 0.55 (.35-.87), gender (M/F) [HR 1.3 (1.0-1.5)], all p<.04]; high risk: BRAF [HR 1.3 (1.1-1.7)], sidedness (R vs L) [HR 1.14 (1.0-1.3)], KRAS [HR 1.4 (1.2-1.6)], all p<.04]. SAR: BRAF, sidedness, PS (all p<.05). Conclusions: KRAS mutation was the strongest predictor of shorter TTR in both risk groups whereas BRAFV600E was the primary driver of SAR, especially in high risk pts. Support: U10CA180821, U10CA180882, U24CA196171; BMS, Pfizer, Sanofi. NCT00079274.[Table: see text]

Abstract BACKGROUND Stereotactic radiosurgery (SRS) is a common treatment modality for vestibular schwannoma (VS), with a role in primary and recurrent/progressive algorithms. At our institution, routine magnetic resonance imaging (MRI) is obtained at 6 and 12 mo following SRS for VS. OBJECTIVE To analyze the safety and financial impact of eliminating the 6-mo post-SRS MRI in asymptomatic VS patients. METHODS A prospectively maintained SRS database was retrospectively reviewed for VS patients with 1 yr of post-treatment follow-up, 2005 to 2015. Decisions at 6-mo MRI were binarily categorized as routine follow-up vs clinical action —defined as a clinical visit, additional imaging, or an operation as a direct result of the 6-mo study. RESULTS A total of 296 patients met screening criteria, of whom 53 were excluded for incomplete follow-up and 8 for NF-2. Nine were reimaged prior to 6 mo due to clinical symptoms. Routine 6-mo post-SRS MRI was completed by 226 patients (76% of screened cohort), following from which zero instances of clinical action occurred. When scaled using national insurance database-derived financials—which estimated the mean per-study charge for MRI of the brain with and without contrast at $1767—the potential annualized national charge reduction was approximated as $1 611 504. CONCLUSION For clinically stable VS, 6-mo post-SRS MRI does not contribute significantly to management. We recommend omitting routine MRI before 12 mo, in patients without new or progressive neurological symptoms. If extrapolated nationally to the more than 100 active SRS centers, thousands of patients would be spared an inconvenient, nonindicated study, and national savings in health care dollars would be on the order of millions annually.

Abstract The suprameatal tubercle is a variable prominence of the posterior aspect of the petrous part of the temporal bone located above the internal acoustic meatus. An enlarged suprameatal tubercle (EST) may present an obstacle during posterior fossa operations, including microvascular decompression (MVD). In this video we present the case of a 55-yr-old woman with 2 yr of medically refractory left V2-3 typical trigeminal neuralgia. Magnetic resonance imaging (MRI) was suspicious for a compressive superior cerebellar artery (SCA) loop, and negative for any other pathological findings. A left retrosigmoid craniotomy was performed, and upon initial exploration, only the most proximal, superior aspect of the trigeminal nerve was unobscured by an EST. The EST was subsequently removed using the ultrasonic aspirator with bone cutting attachment, allowing full visualization of the nerve from root entry zone (REZ) to Meckel's cave. Inferiorly, a small EST remnant was left to protect the VII-VIII complex. An MVD was performed using Teflon felt to elevate the SCA loop off the REZ and nerve, which was then fully explored, to ensure complete decompression. The patient recovered well with resolved trigeminal neuralgia and no new deficit. EST is a rare anatomic variant, with potentially significant implications for visualization of structures superior and deep to the internal acoustic canal, including the trigeminal REZ and nerve. Resection of the tubercle is safe, and recommended where it markedly obstructs the operative corridor. Care should be taken to wax the drilled surface of the petrous temporal bone and minimize incumbent risk of cerebrospinal fluid leak. Informed consent was appropriately documented and verified as outlined by our institutional guidelines.