The American Association for Cancer Research called off its annual meeting in Toronto as a result of the outbreak of the mysterious illness known as severe acute respiratory syndrome, or SARS.

More than 12,000 cancer researchers, as well as 16,000 attendees, including cancer patients, were expected to attend the event, which is one of the most anticipated events in the pharmaceutical sector. The association didn't announce a future date for its 2003 conference, which had been scheduled to take place April 5 to 9.

SARS has been blamed for 78 deaths and has infected more than 2,200 people in 22 countries as of Wednesday, according to the World Health Organization. Seventy cases were confirmed in the U.S., while Toronto has reported 160 possible cases and six deaths.

"We believe this is the most prudent course of action at this time," the group said Wednesday. "The decision reflects the growing concern of many ... that we must minimize the risk of spreading SARS, especially for those whose immune system is already compromised from their fight with cancer."