Doctors are warning of a mysterious rise in appendix cancer cases among young adults — after actor Adan Canto died from the disease at the age of 42.
The cancer is very rare, with fewer than 1,000 cases diagnosed in the US every year — equivalent to one to three per million people.
But studies show the disease is starting to become more common, with rates rising 200 percent among under-50s over the last two decades.
Appendix cancer is easily dismissed in the early stages, with its symptoms — including bloating and abdominal pain — written off as down to other causes, raising the risk of the cancer only being diagnosed in later stages when it is harder to treat.
Doctors are not sure of the cause behind the rise, but link it to an unexplained uptick also being detected in colon cancer — with more cases being recorded among young people.
Read on for everything you need to know about appendix cancer:
The above graphic shows the symptoms of appendicial, or appendix, cancer. Doctors are detecting a mysterious rise in cases of the disease
Adan Canto, pictured above in 2016 participating in a triathalon in Malibu, California, died from the cancer at the age of 42 years following a private battle with the disease
What is appendiceal cancer?
Appendiceal cancer, or appendix cancer, is a type of cancer that grows from cells in the appendix — a small finger-shaped pouch at the end of the large intestine.
Doctors are unsure of the function of the appendix, with some experts saying it may act as a storehouse for good bacteria while others brand is an evolutionary leftover from a time when human ancestors ate more plants.
But the organ, like others in the body, can develop cancer.
There are two types of appendiceal cancer: epithelial appendiceal cancer and neuroendocrine appendiceal cancer.
Epithelial appendiceal cancer grows from cells that make up the lining of the appendix. This leads to a buildup of mucin, a jelly-like substance that protects the lining of the stomach, intestines, and appendix.
When mucin accumulates too much, it leads to the appendix rupturing.
Neuroendocrine appendiceal cancer — the most common form of the disease — grows from enterochromaffin cells, which are involved in digestion and movement in the intestines.
What are the symptoms?
A challenge of appendiceal cancer is that its symptoms are vague and can be mistaken for more common conditions.
According to the National Cancer Institute (NCI), most appendiceal cancers do not cause symptoms at first.
But as tumors grow, the cancer can cause appendicitis — or inflammation of the appendix.
There is also a risk it could trigger ascites — or fluid in the abdomen — as well as bloating, abdominal pain, an increased waistline, changes in bowel movements and infertility.
Some patients may also experience nausea, vomiting and a feeling of being full shortly after eating.
The lack of symptoms in early stages mean the disease is often only detected at this time by accident — if someone comes to have their appendix removed or a scan for a separate condition.
How common is appendiceal cancer?
Appendiceal cancer is very rare, affecting just one or two per million Americans every year, according to the NCI — equivalent to 1,000 people.
The cancer is most common among those aged 50 to 55 years old, but rates have risen exponentially in the past couple of years — particularly among younger adults.
A 2020 study published in the journal Gastroenterology found that while the rate of people getting appendectomies — removal of the appendix — has remained steady over the years, cases of appendiceal cancer have risen.
The researchers found that between 2000 and 2016, rates of appendiceal cancer have increased by 232 percent.
The team noted that the sharpest increase was in patients under age 50.
They said this could be due to it being mistaken as more common disorders, like appendicitis, as well as colon cancer, which is also on the rise in under-50s.
Doctors are largely unsure what is behind the rise in young people suffering cancers like colon cancer, though some experts have blamed increases in diabetes and obesity, fungal infections, and overuse of antibiotics.
Lead researcher Dr Andreana Holowatyj of Vanderbilt University Medical Center said: ‘The potential misclassification of appendiceal cancer as colon cancer is a barrier to discovering disease-specific risk factors and tumor biomarkers, which would have implications for risk assessment, screening, surveillance and treatment.’
What causes appendiceal cancer?
Doctors are largely unsure what causes appendiceal cancer.
According to Moffitt Cancer Center in Florida, smoking is one risk factor for appendiceal cancer.
Additionally, the center cited a family history of multiple endocrine neoplasia type 1 (MEN1) syndrome as a potential risk factor. MEN1 causes tumors to form along the endocrine glands, which produce hormones.
Appendiceal is not known to run in families, the NCI says.
Other causes include obesity, which is linked to a range of health problems, and lifestyle factors such as not exercising often.
But doctors are still searching for an explanation as to what may cause the cancer among more healthy individuals.
What is the prognosis for appendiceal cancer?
Studies show that between 67 and 97 percent of patients diagnosed with neuroendocrine tumors — the most common form — live more than five years after their diagnosis.
But for patients whose cancer is spotted in later stages, and when it has spread to other areas of the body, the rate is lower.
Experts say that the rarity of the cancer makes it difficult to calculate the five-year survival rate.