1. A method of monitoring and evaluating the status of a tumor undergoing treatment, comprising the steps of: (a) monitoring in vivo at least one physiological parameter associated with a tumor in a subject undergoing treatment with an in situ sensor unit; (b) transmitting data associated with the at least one monitored physiological parameter from the in situ positioned sensor unit to a receiver located external to the subject; (c) analyzing the transmitted data to determine a condition of the tumor; (d) repeating steps (a), (b), and (c) periodically at a plurality of sequential points in time; and (e) evaluating a tumor treatment strategy.