The "Home Alone" and “Schitt’s Creek" star died of a pulmonary embolism, which affects the lungs, and she also had rectal cancer, according to her death certificate.

Catherine O’Hara died at age 71 from a pulmonary embolism, with cancer as the underlying cause. A Los Angeles County death certificate issued Monday lists the pulmonary embolism as the immediate cause of the actor's Jan. 30 death. Rectal cancer was the long-term cause.

People who lead a sedentary lifestyle, are on hormone replacement therapy, birth control, or have cancer are all at higher risk for developing blood clots.

Once Jansson was transferred to Dubai’s Rashid Hospital, a wave of tests began. Finally came the diagnosis: she had suffered from a massive bilateral saddle pulmonary embolism — in other words, a massive blood clot in both of her lungs.