Dr. Lancaster is a cardiologist practicing at Bridgeport Hospital in Bridgeport, Connecticut. He is the director of the hospital's non-invasive cardiology testing laboratory and a consultant on heart patients in the hospital and at an affiliated outpatient clinic. In addition to his clinical work, Dr. Lancaster teaches medical students, medical residents and cardiology fellows and is an Associate Clinical Professor of Medicine at the Yale University School of Medicine.

During the early days of the 2008 presidential elections, Dr. Lancaster co-founded Healthcare Professionals for Healthcare Reform (HPfHR), a non-partisan group that understood the need for healthcare professionals’ input in designing bona fide healthcare system reform. He was the lead author of the group’s EMBRACE proposal published in the Annals of Internal Medicine in 2009, and has lectured extensively on healthcare reform.