The report lists O’Hara’s immediate cause of death as pulmonary embolism, with rectal cancer as the underlying cause.

The much-loved star’s death on January 30 shocked fans worldwide, having been working steadily until her passing and set to begin filming for Season 2 of The Studio before her health took a turn.

Fans began to suspect a change as the star sparked concerns over her health with some of her final public appearances, noticeably skipping the Golden Globes, for which she was nominated for her role in the Apple TV show.

O’Hara looked dramatically thinner than fans were used to seeing her when she appeared at the Emmy Awards back in September, and looked even more frail in what was to be her final public appearance at the Angel Awards in Los Angeles the following month.

A guest at that ceremony told the Daily Mail that the actress “looked very slender,” noting, “It was noticeable.”

“Her face was almost gaunt, but she still looked very pretty,” the insider added, “She is a striking-looking woman and she had a touch of glam going on. She hid her figure in a bulky green pinstriped suit.”

“She seemed to be in great spirits, however, and was very friendly and upbeat and lovely,” the source continued.

Sudden, drastic weight loss is a common symptom of rectal cancer.

According to TMZ, O’Hara suffered a medical emergency at her Los Angeles home in the early hours of January 30, with dispatch audio revealing she was having difficulty breathing.

The Los Angeles Fire Department confirmed that it had responded to a call at O’Hara’s property at 4.48am local time before transporting her to the hospital in a “serious” condition – just hours later, she passed away.

As well as the medical issues that caused her death, O’Hara suffered from Situs inversus, an extremely rare condition in which all of a person’s organs appear on the opposite of their body than typical.

It’s generally considered harmless, but can cause complications with diagnosis of subsequent medical issues.

The beloved actress and two-time Emmy winner enjoyed a life with her husband of 33 years, production designer Bob Welch, and their two sons, Matthew, 31, and Luke, 29.

O’Hara starred as the iconic Kate McCallister in the 1990 Christmas classic Home Alone, the eccentric Delia Deetz in Beetlejuice (1998), and a wealth of other projects across film and television.

Macaulay Culkin, who played Catherine’s mischievous son, Kevin, in both Home Alone flicks, shared a heartwarming message to his on-screen mother after her death.

“Mama. I thought we had time. I wanted more. I wanted to sit in a chair next to you. I heard you, but I had so much more to say,” the actor wrote on social media.