Brief Summary: This study investigates a device that closely monitors vital signs, as well as a smartphone application (app) that allows patients to respond to different questions and tests that will monitor for new symptoms. This study may help researchers understand if wearing the device is a better tool than standard vital sign assessment tools done only while at the doctor's office or hospital, and if using the smartphone app is a better tool than standard assessment tools used while in the doctor's office or hospital.

Detailed Description: PRIMARY OBJECTIVES: I. Develop patient-specific algorithms to predict the trajectory of cytokine release syndrome (CRS) and or neurotoxicity and time to escalation of medical intervention is needed. (Arm 1) II. Establish the validity for the use of mobile technology to assess neurologic symptoms remotely. (Arm 1) III. Compare the time to escalation of potential medical intervention between remote monitoring (RM) and standard care (SC) based on retrospective analysis of clinical trial data. (Arm 1) IV. Establish the feasibility for the use of wearable device for continuous, remote monitoring of physiologic parameters by quantifying false alerts and downstream clinical actions. (Arm 1) V. Define the range of physiologic variables associated with receipt of radiation and chemotherapy. (Arm 2) VI. Correlate PROs and physician rated CTCAE to biologic parameters. (Arm 2) VII. Establish the feasibility for the use of wearable device for continuous, remote monitoring of physiologic parameters by quantifying false alerts and downstream clinical actions. (Arm 2) OUTLINE: ARM 1: Patients undergoing CAR-T therapy use the Biofourmis wearable device(s) and smartphone app to answer a series of questions about health and neurologic symptoms a few times a day for 5 weeks. ARM 2: Patients undergoing radiation therapy (RT) for head and neck, lung, or gastrointestinal cancers use the Biofourmis wearable device(s) for 60 to 90 days after completion of RT. Patients also use the smartphone app to answer a series of questions about health and neurologic symptoms before start of RT, after completion of RT, 3 months after completion of RT, and 1 year after completion of RT. In addition, patients complete weekly questionnaires regarding side effects and tolerance of the device.