About the Society of Interventional Oncology The Board of Directors of WCIO, a non-profit association that supports and promotes the field of interventional oncology (IO), announces the establishment of the Society of Interventional Oncology (SIO), effective January 17, 2017. The society’s annual IO conference will maintain its name of WCIO. SIO's mission is to establish, nurture, and support Interventional Oncology (IO) as the fourth pillar of cancer therapy alongside medical, surgical, and radiation oncology worldwide.