Our Experts

Our management team brings together highly experienced and trusted individuals in healthcare who have successful track records of managing and growing oncology centers nationwide.

Josh Johnson

Chief Executive Officer

Josh Johnson is the Chief Executive Officer of Integrated Oncology Network, LLC (ION). Previously, Mr. Johnson was the Senior Vice President, Chief Operating Officer and Chief Development Officer for e+CancerCare which was acquired by ION in June of 2019. He was responsible for overall operations, analyzing and developing plans to drive growth, nurturing existing and new business opportunities as well as partner relationships. In addition, he led the company’s corporate development function, with responsibility for acquisitions, mergers and joint ventures while overseeing sales and marketing. He assisted with the development of programs supporting organizational strategy and objectives, both short and long range. Previously, Josh was the Chief Operating Officer for Accurate Healthcare and worked for AmSurg, a leading, outpatient surgery company, where his focus entailed financial management and operational assistance. Mr. Johnson brings over fifteen (15) years of healthcare experience with a keen focus on oncology service line leadership.

Josh Johnson

Chief Executive Officer

Stuart M. Bitting

EVP, Chief Financial Officer

Stuart leads the company’s finance, accounting, revenue cycle, planning and IT functions. Previously, he was Executive Vice President and CFO of e+CancerCare which was acquired by ION in June 2019. Prior to e+CancerCare, he was the CFO of HarperCollins Christian Publishing, which comprises Thomas Nelson Inc. and Zondervan. Stuart has over 30 years of broad financial, strategic, operational, and merger and acquisition experience across multiple business segments with companies including Frito-Lay, Inc. (a division of PepsiCo), Centex Homes (now part of Pulte Group, Inc.), David Weekley Homes, CompX International Inc., NCH Corporation and Atlas Powder Company. Stuart earned a B.A. in Accounting from St. Ambrose University and a Finance Certificate from Southern Methodist University and is a licensed CPA and CGMA.

Stuart M. Bitting

EVP, Chief Financial Officer

Robbie Rhymer

EVP Human Resources & Chief Clinical Operations Officer

Robbie Rhymer is the Executive Vice President of Human Resources & Chief Clinical Operations Officer of Integrated Oncology Network, LLC. Prior to ION, Mr. Rhymer was the Chief Clinical Operations Officer and Chief Compliance Officer for e+ CancerCare, responsible for overall clinical operations, human resources, compliance and physician relationships. e+ CancerCare was acquired by ION in June, 2019. He assisted in the start-up of e+ in 2003, at which time the company started as a PET/CT company & then expanded to a full, outpatient, oncology service line in 2008. Previously, Robbie was a Regional Vice President at Symbion, a leading, for-profit ambulatory surgery center company, where he managed the Southeastern regional market and was keenly instrumental in the incremental growth of the division, service, quality and various financial aspects. He possesses a strong leadership and clinical background (critical care, surgery and oncology) having held various positions at academic and for-profit companies, including both Tenet Healthcare and HCA. Mr. Rhymer has a graduate degree from Duke University and has more than thirty (30) years’ experience in healthcare.

Robbie Rhymer

EVP Human Resources & Chief Clinical Operations Officer

Ryan E. White

EVP, Chief Compliance Officer

Ryan White is the Executive Vice President, Corporate Compliance Officer of ION. Prior to ION, Mr. White was the Compliance Officer for DaVita Health Plan of California. Mr. White has extensive audit, compliance, investigations, privacy and regulatory experience and is skilled in the implementation of global compliance programs, risk assessments, policies, internal control procedures, and the comprehensive analysis of exposure issues related to internal and government audits and investigations.

Previously, Mr. White served as the Senior Director of DaVita HealthCare Partners National compliance program. Mr. White has also worked in senior compliance and legal roles at Allergan Inc. and McKesson Corp. Mr. White has a Bachelor’s Degree from Vassar College in Biopsychology.

Ryan E. White

EVP, Chief Compliance Officer

Mark Ahern

Mark Ahern

Chief Development Officer

Prior to ION, Mr. Ahern spent 14 years in executive leadership roles and as Chief Development Officer at Vantage Oncology, and subsequently with McKesson / US Oncology, upon its acquisition of Vantage in April 2016. In these roles, Mark led teams which acquired and integrated medical oncology, radiation therapy and comprehensive cancer care centers for physicians and hospitals. Prior to Vantage Oncology, Mark was President, Global Operations for First Circle Medical, a hepatitis C biotech initiative, prior to which he was a Founding Member and Senior VP of Corporate Development for The US Oncology Network. Mark began his professional career as Vice President of Corporate Development & Strategy for Caremark. Mark received his B.A. in Marketing from the University of Arizona and attended The Wharton School’s Organizational Leadership programs.

Mark Ahern

Chief Development Officer

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