US TV
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The 45-year-old has already filmed scenes for the show's upcoming seventh season, reports TV Guide. She will reprise the role of Kelly McPhee.
The cast and crew are currently filming season six and season seven back to back.
Tierney left Rescue Me after landing a lead role in NBC's Parenthood. She had to drop out of that series last year to undergo treatment for breast cancer.
"[Tierney] has finished treatment and is doing very well and is happy to move forward with the next phase of her life," said Christina Papadopoulos, Tierney's representative.
Rescue Me returns to FX with new episodes in June.
More: Maura Tierney, US TV
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