Actor Adan Canto died of appendiceal cancer at age 42. Here's what to know about the disease.

On Jan. 8, Designated Survivor actor Adan Canto died at age 42. The cause of death was appendiceal cancer, a rare disease that occurs when a tumor forms in the appendix. According to the Cleveland Clinic, appendiceal cancer affects about 1 to 2 people out of every 1 million in the U.S. Here’s what to know about it.

What is appendiceal cancer?

Appendiceal cancer is a type of cancer that originates in the appendix, a small pouch located in the abdomen. The appendix is part of the digestive system, although its exact function is not entirely clear, with some people theorizing it may play a role in immune function.

Around 50% of appendix cancers are known as carcinoid tumors, per the Cleveland Clinic. These tumors affect neuroendocrine cells, specialized cells in the body that release hormones that act as messengers to regulate various functions between the nervous system and the endocrine system. Generally, carcinoid tumors tend to grow slowly.

Appendiceal adenocarcinoma is a type of cancer that originates in the tissue that lines the inside of the appendix. There are different subtypes of appendiceal adenocarcinoma, each with unique characteristics. For example, colonic-type adenocarcinoma, which develops near the base of the appendix, often causes the patient to develop symptoms similar to colorectal cancer.

How is appendiceal cancer diagnosed?

Though it’s unclear how Canto was diagnosed specifically, appendiceal cancer is typically difficult to identify based on symptoms alone because many people don’t present with symptoms in its early stages.

"Unfortunately, there is no screening test," says Dr. Christopher Chen, a specialist in oncology and hematology at Stanford University School of Medicine. "Many cases are diagnosed unexpectedly when patients are taken for an appendectomy due to symptoms of acute appendicitis, like abdominal pain, nausea or bloating."

Appendicitis itself can be a warning sign of appendiceal cancer.

This type of cancer may also be found if the cancer spreads from the appendix to the abdomen, leading to more noticeable symptoms. These symptoms can include abdominal pain, bloating and bowel obstructions, or general cancer-related symptoms like unexplained weight loss and fatigue.

"Unfortunately, many patients present with late symptoms and are found to have advanced or metastatic disease," Dr. Alex Kim, a surgical oncologist who specializes in gastrointestinal cancers at the Ohio State University Comprehensive Cancer Center, tells Yahoo Life. "In these settings, we recommend for biopsy, which usually confirms the diagnosis of appendiceal cancer."

Dr. Kiran Turaga, Yale Cancer Center researcher and division chief of surgical oncology in Yale’s department of surgery, tells Yahoo Life that "currently, there is no screening test for it and often these are missed on colonoscopy." However, Turaga says there is a lot of evolving research in the use of liquid biopsy to help with screening for cancer in general, including appendix cancer.

How rare is it to be diagnosed with appendiceal cancer at 42?

Appendiceal cancer is rare, but it is most common among people ages 50 to 55, according to the National Institute of Cancer. It’s worth noting that certain types of cancer are rising rapidly among people younger than 50, and appendix cancer is one of them.

Turaga says it's not unheard of for someone to be diagnosed at age 42. "This disease occurs in young adults, and in fact we are seeing a fair number of cases in younger patients," he says. "It is still common for people in their 50s, but certain subtypes — like goblet cell adenocarcinoma — occurs in younger folks."

What are the risk factors?

Scientists do not know exactly why appendiceal cancer forms. However, Turaga says that recent research shows about 10% of patients have genetic mutations that can be related to appendix cancer. Some patients also seem to have autoimmune diseases that might be related to developing appendix cancer. Although experts say that both men and women can be affected by the disease, Johns Hopkins says that appendiceal cancer is more common in women than men.

Unlike some other types of cancer, appendiceal cancer does not tend to run in families. However, there are certain potential risk factors, such as smoking, that are associated with multiple types of cancer. Certain health conditions, including pernicious anemia and atrophic gastritis, which affects the stomach’s ability to produce acid, may also increase your risk for appendix cancer, according to Johns Hopkins Medicine.