What to know about appendiceal cancer, the rare disease that killed actor Adan Canto

Adan Canto, a Mexican-American actor known for his roles in "X-Men: Days of Future Past," "Designated Survivor” and “The Cleaning Lady,” died of cancer on Monday, his publicist told outlets on Tuesday.

Canto's quiet battle was with a lesser-known form of cancer: appendiceal or appendix cancer, a very rare form that is often discovered and diagnosed during other procedures, such as treatment for appendicitis.

Because it is so rare, research on appendiceal cancer is sparse, but recent studies have found that diagnoses are on the rise. A 2020 study published in the American Cancer Society journal called "Cancer" found that diagnosed incidences of malignant appendiceal tumors grew by 232% in the United States from 2000 to 2016.

While doctors and scientists are still trying to figure out why this is, there are certain symptoms and risk factors anyone concerned with developed can look out for. Here's what to know.

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What is appendiceal or appendix cancer?

Appendiceal cancer is a rare form of cancer that affects the appendix, a thin pouch attached to the large intestine. Part of the gastrointestinal tract, the appendix is believed to function as part of the immune system in young people, though it ceases to have a clear function in adulthood, according to Johns Hopkins Medicine.

As with other cancers, appendiceal cancer is caused by cells in that organ changing and growing at an abnormal rate. Because it is so uncommon, appendix cancer is most often discovered during treatment for other conditions, such as appendicitis or other abdominal procedures.

There are four types of appendix cancer, according to Johns Hopkins. These are:

• Carcinoid tumors: A rare and cancerous tumor that grows slowly, meaning many people can go years without knowing it's there.
• Mucinous neoplasms: Generally benign tumors that include lesions with precancerous potential. If the lesions rupture, they can cause pseudomyxoma peritonei, a condition caused by cancerous cells that can disrupt organ function and digestion.
• Appendix adenocarcinoma: Tumors that begin as cells lining the inside of the appendix. This form of tumor is treated similarly to colorectal cancer.
• Goblet cell carcinomas/adenocarcinoids: An aggressive cancer featuring adenocarcinomas, cancer that develops in the glands that line your organs, and carcinoids, a type of slow-growing tumor.

How common is appendiceal cancer?

Appendiceal cancer is very rare, annually occurring in only 1 or 2 people per 1 million in the U.S., according to the National Cancer Institute. However, studies have found it is becoming more common, especially among people aged between 50 and 55.

In comparison, American women have a 1 in 8 or about 13% chance of developing breast cancer in their lifetime. Likewise, 1 in 5 Americans will develop skin cancer by age 70, according to the Skin Cancer Foundation.

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Who is most likely to get appendiceal cancer?

People over the age of 50 are more likely to develop appendix cancer, with women being at higher risk than men.

Other risk factors include lifestyle and genetic factors, such as tobacco use/smoking, a family history of appendix cancer or multiple endocrine neoplasia type 1, and patients with a medical history that includes certain conditions, such as atrophic gastritis or pernicious anemia, according to Johns Hopkins.

What are the symptoms of appendiceal cancer?

Appendiceal cancer is most commonly diagnosed in the process of treating other conditions, as symptoms aren't always present. However, according to the Cleveland Clinic, some common symptoms include:

• Appendicitis (inflammation or infection of the appendix).
• Bloating.
• Abdominal pain.
• Pelvic pain.
• Fluid buildup in the abdomen (ascites).
• Changes in bowel function.
• Nausea and vomiting.
• Increase in waist size.
• Fertility problems.

What is the treatment for appendiceal cancer?

If your doctor suspects you may have appendiceal cancer, they may perform imaging testing, a biopsy, laparoscopy and/or blood tests.

Appendix cancer is mostly commonly treated through surgery, either through the direct removal of smaller tumors or further procedures such as the removal of part of the colon.

According to Johns Hopkins, some common surgeries to treat appendix cancer include:

• Appendectomy: Removal of the appendix.
• Hemicolectomy: removal of the portion of the colon that is next to your appendix.
• Cytoreductive surgery: Cytoreductive surgery is often recommended for more contained tumors that have yet to spread. This surgery entails the removal of the tumor and surrounding fluid that may cause inflammation.
• Peritonectomy: This more extensive surgery may be recommended if cancer has spread beyond the colon and entails the removal of the lining of the abdomen, called the peritoneum.

Traditional chemotherapy and Hyperthermic intraperitoneal chemotherapy (HIPEC) are also options, though they are less often used in the treatment of this specific type of cancer.

Who was Adan Canto?

Adan Canto was a Mexican actor known for his roles in "Designated Survivor,"  "X-Men: Days of Future Past," and "The Cleaning Lady."

Canto, who was born in Mexico and raised in Texas, died Monday at the age of 42 after a private battle with appendiceal cancer.

Canto made American media debut in 2013 (alongside Kevin Bacon, nonetheless) when he played Paul Torres in the first season of the TV drama, "The Following."

Before that, Canto left his home in Ciudad Acuña, Coahuila, Mexico as a teenager and moved to Mexico City to become a singer-songwriter. In 2009, he landed his first role in the Mexican series “Estado de Gracia.”

"X-Men" co-star Halle Berry posted about Canto's death on Tuesday, writing: "I don’t have the words just yet…. but my dear sweet friend Adan just gained his wings. Forever, forever in my heart."