Management Team

21st Century Oncology is the largest, physician-led provider of integrated cancer care services, dedicated to providing patients with the best technologies available. Founded by a group of dedicated physicians, the vision of the company remains to be the industry leader in cancer care. Our first radiation treatment center opened in 1983. Through our growth from a single radiation center to an international network, we have successfully developed an operating model that enables us to consistently deliver the highest quality, most compassionateand cost effective patient care.

Click below to learn more about the 21st Century Oncology management team.

Executive Officers

Kimberly J. Commins-Tzoumakas

Chief Executive Officer

Kimberly J. Commins-Tzoumakas has served as a member of 21st Century Oncology’s executive team, as an advisor to the board, and as General Counsel since November 2014. Before that, she served in an executive legal role with Carondelet Health Network and was a key founder of the Michigan office and a board member of Hall Render, a national health care law firm.

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Constantine A. Mantz, MD

Chief Policy Officer / Radiation Oncologist

Dr. Constantine “Connie” Mantz joined 21st Century Oncology in 2000 and has served in his current capacity as Chief Policy Officer since February 2018 and formerly as Chief Medical Officer and Senior Vice President of Clinical Operations. Dr. Mantz is Board Certified in Radiation Oncology by the American Board of Radiology. At 21st Century Oncology, as an area expert, he leads the company’s focus on the study and treatment of prostate and breast cancer.

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Arie Dosoretz, MD, MBA

Chief of Clinical Operations and Quality / Radiation Oncologist

Dr. Arie Dosoretz joined 21st Century Oncology in 2015 and has served in his current capacity of Chief of Clinical Operations and Quality since February 2018. In this role, he is devoted to quality initiatives for the company and works closely with the operations team to ensure a patient and physician focus in all operational decisions. He continues to provide clinical services in addition to this administrative role.

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Gustavo Olivera

Chief Technical Officer

Gustavo Olivera is 21st Century Oncology's Chief Technical Officer. In this role, he oversees all aspects of the physics department and ensures adherence to Medical Physics quality requirements, accreditation requirements and administration, physics vendor management, and applicable state and federal laws. He is also responsible for strategic development of the physics/technology department.

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Lenny Brunson

Chief Information Officer

Lenny Brunson leads the Information Technology team and oversees the Company's information strategy and operations. With more than 29 years of experience in information technology, Mr. Brunson joined the 21st Century Oncology team in 2016.

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Barry Axelrod

Chief Information Security Officer

Barry Axelrod leads the information security team and oversees the company’s information security risk management program, which is focused on protecting the confidentiality, integrity, and availability of all information systems and data.

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Steven Graham

Chief Accounting Officer

Steven Graham joined the 21st Century Oncology team in 2017 as Chief Accounting Officer. In this role, Mr. Graham is responsible for the core accounting, finance, and business functions. His background includes full responsibility for geographically-dispersed, broad-brand accounting and compliance teams.

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Betta Sherman

Chief Compliance Officer

Betta Sherman leads the corporate and regional compliance team, implementing a program that is consistent with guidelines issued by the Office of Inspector General of the U.S. Department of Health and Human Services. Ms. Sherman has been working with 21st Century Oncology since 2015.

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Juli Wessel

Chief Privacy Officer

Juli Wessel joined 21st Century Oncology in 2017 as the Chief Privacy Officer. In this role, she is responsible for the development, implementation, and maintenance of privacy policies and training. She manages the company’s privacy monitoring program, including investigating and tracking privacy incidents, and ensuring compliance with federal and state breach notification rules. She also oversees the company’s compliance with use and disclosure requirements and patients’ rights with respect to protected health information (PHI).

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Ravi Patel

Senior Vice President, United States Operations

Ravi Patel currently serves as the Senior Vice President of US Operations. In that role, he is responsible for US operations and Corporate and Business Development.

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Timothy D. Shafman, MD

Senior Vice President, National Medical Director

Dr. Timothy D. Shafman joined 21st Century Oncology in June 2004 and has served as National Medical Director since 2014. In this role, he is involved in clinical and operational management and development for radiation therapy services throughout the company. Formerly, Dr. Shafman was the Medical Director of our Rhode Island and Massachusetts regional networks and he now sees patients in Port Charlotte, Florida.

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Mark Zickel

Senior Vice President of Payer Contracting and Relations

Mark Zickel joined the 21st Century Oncology team in 2017 as Senior Vice President of Payer Contracting and Relations. Mr. Zickel is responsible for managing relationships with national, regional and local payers across the United States.

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