Article continues below advertisementCatherine O'Hara secretly battled rectal cancer before her death at 71. On Monday, February 9, the Los Angeles County Medical Examiner's Office confirmed that while a pulmonary embolism was the immediate cause of her death, rectal cancer was an underlying factor.Article continues below advertisementSudden PassingSource: megaCatherine O'Hara privately battled rectal cancer before her death at age 71.The death certificate notes that O'Hara was cremated, and her remains were given to her husband, Robert "Bo" Welch, according to TMZ.