Seventy-eight per cent of workers voted to reject the employer's last offer and now the union has extended an invitation to SAHO to work with a mediator to help sort out the issues to solve the bargaining impasse.
The union has been calling for binding arbitration, but so far, the government has refused.
Key issues include full retroactivity for nurses and binding arbitration for future rounds of bargaining so that disputes can be settled without strike action.
Currently, staff are refusing to work voluntary overtime at the agency in an effort to put pressure on the government and SAHO.
Cancer agency workers have been without a contract since December 2009.