Definitive Surgery after Neoadjuvant Chemotherapy for Locally Advanced Oral Cavity Cancers: Experience from a Tertiary Care Center

Mansi AgrawalVidya KonduruBackground  Oral cavity cancers require definitive surgical resection as the primary treatment, but with advanced T stage, complete resection with pathologically negative margins might be difficult to achieve. Induction chemotherapy helps achieve the balance between resection and morbidity in locally advanced technically unresectable tumors. The aim of this study was to analyze the impact of surgery in locally advanced, technically unresectable oral cavity cancers after neoadjuvant chemotherapy (NACT). Materials and Methods  A retrospective analysis of patients with borderline resectable, locally advanced oral cavity cancers who were given NACT between February 2017 and December 2021 was conducted. Data regarding clinical and pathological characteristics, NACT, surgery, adjuvant therapy, and recurrences was analyzed. Results  Of the 69 patients in the study, 69.6% had tongue cancer, rest were gingivobuccal complex cancers. All tumors were resected based on the post-NACT tumor volume and clear margins were achieved in 42% of cases. About 85.4% of the tongue cancers required a lesser resection than anticipated, thereby following the concept of organ and functional preservation post-NACT as proposed by Licitra et al. About 30.4% had ypT0 and 17.4% had ypN0. Recurrence and survival rates noted in our study were comparable to those reported in literature. Lymph node density of more than or equal to 0.07 was found in all recurrent cases. Conclusions  Induction chemotherapy offers a chance of achieving adequate surgical resection while reducing morbidity and improving functional outcomes for patients with technically unresectable oral cavity cancers. Nodal disease may not respond to chemotherapy as well as the primary tumor. There is a need for comprehensive evaluation of prognostic factors, which could help identify the patients who will most benefit with NACT.

A New Experiment for Investigating Evaporation and Condensation of Cryogenic Propellants

Passive and active technologies have been used to control propellant boil-off, but the current state of understanding of cryogenic evaporation and condensation in microgravity is insufficient for designing large cryogenic depots critical to the long-term space exploration missions. One of the key factors limiting the ability to design such systems is the uncertainty in the accommodation coefficients (evaporation and condensation), which are inputs for kinetic modeling of phase change. A novel, combined experimental and computational approach is being used to determine the accommodation coefficients for liquid hydrogen and liquid methane. The experimental effort utilizes the Neutron Imaging Facility located at the National Institute of Standards and Technology (NIST) in Gaithersburg, Maryland to image evaporation and condensation of hydrogenated propellants inside of metallic containers. The computational effort includes numerical solution of a model for phase change in the contact line and thin film regions as well as an CFD effort for determining the appropriate thermal boundary conditions for the numerical solution of the evaporating and condensing liquid. Using all three methods, there is the possibility of extracting the accommodation coefficients from the experimental observations. The experiments are the first known observation of a liquid hydrogen menisci condensing and evaporating inside aluminum and stainless steel cylinders. The experimental technique, complimentary computational thermal model and meniscus shape determination are reported. The computational thermal model has been shown to accurately track the transient thermal response of the test cells. The meniscus shape determination suggests the presence of a finite contact angle, albeit very small, between liquid hydrogen and aluminum oxide.