The 44-year-old actress issued a statement Monday after NBC announced her new TV series "Parenthood" would be delayed next season while Tierney addressed a health concern.
"In an effort to guard my privacy, it seems that the wording of NBC's press release has unfortunately caused some confusion and undue alarm about my health," Tierney said in a statement issued to People magazine.
"I have discovered a tumor in my breast which requires surgery. 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," the statement read. "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."
Tierney is best known for her work on TV's "NewsRadio" and "ER." She has also appeared in the films "Forces of Nature," "Semi-Pro" and "Baby Mama."