Susan Wojcicki, YouTube CEO, died at 56 from a type of lung cancer that is often diagnosed late

Susan Wojcicki, the former CEO of YouTube, died from lung cancer on Friday. She was 56.

In a Facebook post, her husband, Dennis Troper, said that Wojcicki died “after 2 years of living with non small cell lung cancer.”

Non-small cell lung cancer is the most common type of lung cancer, accounting for 85% of 230,000 diagnosed lung cancer cases each year, according to Yale Medicine.

Non-small cell lung cancer is often diagnosed late

There are two types of lung cancer: small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). In NSCLC, the cancer cells are larger, according to Cleveland Clinic.

Symptoms can include a persistent cough, coughing up blood, chest pain, wheezing, fatigue, appetite loss, and face swelling.

Because some non-small cell lung cancer symptoms can resemble other illnesses like bronchitis, about 80% of cases are diagnosed at later stages, making it harder to treat once the cancer has spread to other parts of the body, according to Yale Medicine.

Smoking is the biggest risk factor, even if you quit

According to Cleveland Clinic, the biggest risk factor for NSCLC is smoking. Other risks include exposure to asbestos, metal and mineral dust, air pollution, radon, and radiation therapy. Some infections and diseases, like HIV/AIDS and Chronic obstructive pulmonary disease, also increase risks.

Most guidelines recommend annual NSCLC screenings for people ages 50-80 who smoked at least 20 packs of cigarettes per year and have either quit or continued to smoke within the last 15 years.