Dr. Maithel is an expert in hepatopancreatobiliary surgery including the Whipple procedure and minimally invasive laparoscopic pancreatectomy. His clinical interests include surgical treatment of hepatobiliary tumors, or cancer of the liver (metastatic and primary) and bile ducts, and other gastrointestinal malignancies such as cancer of the pancreas, stomach, colon, and small intestine.

Dr. Maithel has a variety of research interests. He has worked in clinical investigation and outcomes analysis of patients treated for tumors of the liver, biliary tract, pancreas, and stomach. He also leads the translational research program in the Division of Surgical Oncology, which focuses on identifying tumor specific molecular biomarkers as predictors of outcome and chemotherapeutic response for tumors of the liver, biliary tract, pancreas, and stomach (including colorectal liver metastases and pancreas cancer). Dr. Maithel uses the diverse learning opportunities provided by his highly active laboratory to mentor postdoctoral research fellows, residents, and medical students, allowing them to develop their academic portfolios.

As chair of the Gastrointestinal Surgery Working Group of the Eastern Cooperative Oncology Group and the American College of Radiology Imaging Network Cancer Research Group, Dr. Maithel evaluates the production of forward-looking clinical trials that focus on biomarker-driven cancer investigations.

His appointment to the Executive Committee of the International Cholangiocarcinoma Research Network allows him to oversee the global collaborations of renowned research groups that are working to improve knowledge about cholangiocarcinoma. He also serves as co-chair of the Adjuvant Therapy for Biliary Tract Cancers Expert Panel of the American Society of Clinical Oncology's Clinical Practice Guidelines Committee.

Dr. Maithel provided the medical direction and voice-over narration for the "Surgical Anatomy of the Liver" app. Intended for trainees, medical students, instructors, and professionals, this highly comprehensive interactive 3D app allows users to mentally map the anatomy of the liver in ways that were never before possible with print illustrations or imaging studies.