Former 'ER' star Maura Tierney is to have surgery to remove a tumour from her breast.
The actress has said that doctors have told her that her condition is "very treatable".
On Friday NBC, which is making Tierney's new series 'Parenthood', postponed production on the show, which was scheduled to premiere in the autumn.
In a statement NBC said that Tierney was undergoing a "medical evaluation".
The 44-year-old actress said in her own statement that NBC's announcement had "unfortunately caused some confusion and undue alarm".
"I have discovered a tumor in my breast which requires surgery," she said.
"I will not know either my exact diagnosis or course of treatment until that surgery is performed.
"My doctors have all assured me this is a very treatable condition.
"I'm very optimistic as to the outcome and want to thank everyone who has sent positive thoughts and support.
"I look forward to going back to work soon."
