About Us

Backus Physicians

Backus Physician Services LLC, a practice affiliated with The William W. Backus Hospital, offers a wide range of minimally invasive surgeries for patients.

Four surgeons practice in the Norwichtown Medical Office Building at 12 Case St., Suite 313 – Sergio Casillas, MD, specializing in colon and rectal surgery as well as general surgery; Michael Deren, MD, specializing in thoracic surgery; and Mark Tousignant, MD, specializing in general surgery.

Photo of Sergio  Casillas-Romero, MD

Sergio Casillas-Romero, MD

Medical School: LaSalle University
Residency: SUNY Upstate Medical University at Syracuse
Fellowship: The Cleveland Clinic
Internship: SUNY Upstate Medical University at Syracuse

Photo of Michael  Deren, MD

Michael Deren, MD

Undergraduate: Georgetown University
Medical School: Georgetown University School of Medicine
Residency: Yale-New Haven Hospital
Internship: Hartford Hospital,