09/11/2009 at 08:00 AM EDT
Having revealed in July she was undergoing surgery
for removal of a breast tumor, Maura Tierney has now withdrawn from her upcoming series Parenthood
, say trade reports.
The star's spokeswoman told the Hollywood Reporter
that the former ER
actress, 44, is "deeply disappointed" not to be participating in the NBC show, and that "Ms. Tierney and her doctors remain confident that the outcome of her treatments will be positive."
On the show, which is based on the 1989 movie that starred Steve Martin and Mary Steenburgen, Tierney was to have played a sister-in-law role, which Dianne Wiest performed in the movie. The TV version will star Peter Krause, Erika Christensen, Dax Shepard, Bonnie Bedelia and Craig T. Nelson.
Tierney's operation had already pushed back the series' original fall debut date, and Parenthood
will now be offered mid-season.
In a network's statement, NBC said, "While we are saddened that Maura Tierney won't be able to continue in her current role in Parenthood
, our main concern is for her quick and full recovery. Our thoughts and best wishes are with her."
Through her spokesperson, Tierney thanked the executive producer and NBC "for their patience and support."
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