The Australian Broadcasting Corp., which has been without a headquarters in Queensland for a year and a half after abandoning it following reports of an unusual number of breast cancer cases among its staff, has now been forced to abandon plans to build a new headquarters after the discovery of possible radioactive contamination at the proposed site. The ABC had been in the process of conducting due diligence on a deal to acquire 42,000 square feet of land in Newstead but said it had canceled the contract after the discovery of elevated levels of radiation there.