Catherine O'Hara's death certificate reveals rectal cancer diagnosis. What to know.

What symptoms indicate rectal cancer?

Why is rectal cancer leading cause of death under 50?

What treatment options exist for rectal cancer?

What are Chloe Kim's immigrant family origins?

Catherine O'Hara died from a pulmonary embolism, but her death certificate also revealed she was diagnosed with rectal cancer.

O'Hara's death certificate was obtained by USA TODAY on Feb. 9. TMZ was first to report the news.

Rectal cancer is a type of cancer that starts in the rectum, which is the last several inches of the large intestine, according to Mayo Clinic.

Since rectal and colon cancers are similar in many ways, they're often referred to together as colorectal cancer. But treatments are quite different, the clinic adds.

Here's what to know about the diagnosis.

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Rectal cancer symptoms

Rectal cancer symptoms usually happen when the disease is advanced, according to Mayo Clinic, and may include:

• Bowel movement changes

• Feeling like the bowel doesn't empty completely

• Abdominal pain

• Rectal bleeding

• Narrow stool

• Weight loss

• Weakness or fatigue

• A lump in the rectum

"Generally, bleeding related to hemorrhoids is bright red and happens during or after bowel movements, while bleeding related to cancer may be dark or bright red and happen at any time," the clinic notes, but adds it's important to get any bleeding evaluated by a healthcare professional to determine what's going on.

If someone indeed has rectal cancer, there may be shame or stigma around discussing it. It's important to look into resources, like the Colorectal Cancer Alliance, that advise how to combat such feelings.

More details: Catherine O'Hara cause of death revealed after 'Home Alone' star died at 71

Rectal cancer risk factors and prevention

Risk factors for rectal cancer are the same as those for colon cancer, the American Cancer Society notes, which include:

• Age, as risk of colorectal cancer goes up as you get older

• Racial and ethnic background, since American Indians, Alaska Natives and African Americans have the highest rates in the United States.

• A personal history of colorectal polyps or inflammatory bowel disease

• Previous radiation to the abdomen or pelvis

• A family history or certain inherited syndromes

While these risk factors are unavoidable, there are others that can be changed or improved through lifestyle including excess body weight, smoking, alcohol use, Type 2 diabetes and diets low in vegetables and high in red, processed meats, the organization adds.

According to the ACS Cancer Facts & Figures 2024 report, around 55% of colorectal cancers might be traced to these preventable risk factors like diet, weight, tobacco use and lack of exercise.

What is a pulmonary embolism? Catherine O'Hara's cause of death, explained

Rectal cancer treatment

Colorectal cancer is now the leading cause of cancer-related death among people under 50 in the United States, according to new evidence from the ACS published in January.

But the good news is rectal cancer is often curable, especially when found early, according to the Mayo Clinic.

"Treatment may begin with surgery to remove the cancer. If the cancer grows larger or spreads to other parts of the body, treatment might start with medicine and radiation instead," the clinic notes, adding a treatment plan may also include chemotherapy, targeted therapy drugs, immunotherapy or palliative care.

Depending on the stage of the cancer and other factors, the ACS says different types of treatment may be combined at the same time or used after one another.