Once known as a disease of old age, cancer is now striking young and even healthy individuals. According to experts, many kinds of cancers—including colon, breast, stomach, and pancreatic cancers—are now hitting those younger than 40 years old. A new study, published in the journal Annals of Internal Medicine, focusing on a relatively rare cancer—appendiceal cancer—has found that its rates are extremely high, especially among millennials.

Scientists from Vanderbilt University Medical Center specifically tracked appendix cancer, which for many years was misclassified as colorectal cancer since the appendix sits at the start of the large intestine. Recent research has shown an increase in this cancer, and scientists feel there are generational effects that could help put the pieces together.

Experts feel there is no single factor but the interaction of several that contribute to increased cancer risk in the young age group—like rising rates of obesity and metabolic syndrome as well as environmental exposures. “The challenging thing now is to disentangle not only what these exposures are, but what molecular changes these exposures cause, and what the consequences of those changes are on our cells that may end up increasing the risk of carcinogenesis,” said Andreana Holowatyji, assistant professor of hematology and oncology at Vanderbilt University Medical Center.

Appendix cancer is a rare disease that occurs when the cells in your appendix mutate and grow out of control. Your appendix is part of your digestive system, being a small tube-like pouch located on the lower right side of your abdomen, near the junction of your large and small intestines.

As of now, scientists do not know for sure what your appendix does. However, some believe it helps your immune system function well.

Doctors say many benign and malignant tumours develop in your appendix. Malignant, or cancerous, ones have the potential to grow and spread. Experts classify malignant appendix tumours based on the type of cell where the cancer starts. The two types include:

• Appendiceal adenocarcinoma
• Neuroendocrine tumors

What are the early signs and symptoms of appendix cancer?

Experts say you can have appendix cancer without developing symptoms, or sometimes you may not even notice the symptoms until the tumour has spread. Appendix cancer symptoms vary from person to person and may include:

Many times, appendix cancer also occurs alongside a rare condition known as pseudomyxoma peritoneum—in which cancer cells secrete jelly-like mucin that can cause your appendix to swell.

There are many factors that may increase your risk of appendix cancer, including:

Appendix cancer can occur at any age, but it is more likely to develop in people between 40 and 60 years of age.

More women are likely to develop neuroendocrine tumours in their appendix.

Tobacco use can increase your chances of all cancers, including appendix cancer.

Certain health conditions like atrophic gastritis, pernicious anemia and Zollinger–Ellison syndrome do increase your risk for this cancer.

Studies say some people with appendix cancer inherit genes that increase their cancer risk.