Precancerous conditions of the pancreas

Precancerous conditions of the pancreas are changes to pancreatic cells that make them more likely to develop into cancer. These conditions are not yet cancer. But if they aren’t treated, there is a chance that they will become pancreatic cancer.

Pancreatic intraepithelial neoplasia (PanIN) is the most common type of precancerous condition of the pancreas. It occurs when cells of the epithelium lining the inside of the pancreatic ducts (ductal cells) become abnormal (called dysplasia) . PanIN causes very small, usually flat growths that can only be seen under a microscope. It is usually diagnosed in the lab when looking at pancreatic tissue that was removed during surgery or a biopsy done for another reason.

PanIN is more common in older people and people with obesity.

PanIN is divided into low grade and high grade based on how the cells look under a microscope and the patterns of gene expression compared to normal ductal cells. Low-grade PanIN can become high-grade PanIN if the epithelial cells become less differentiated over time. High-grade PanIN is more likely to become cancer.

Most cases of pancreatic ductal adenocarcinoma (PDAC) start as PanIN. Sometimes, high-grade PanIN is considered carcinoma in situ.

Pancreatic cysts are abnormal growths that form inside or on the surface of the pancreas. They can be hollow or fluid-filled. There are over 20 kinds of pancreatic cysts. Up to half of Canadians will develop pancreatic cysts at some point during their lifetime. Only about 30% of all pancreatic cysts are precancerous.

Pancreatic cysts can be caused by many conditions including:

• von Hippel-Lindau (VHL) syndrome
• inflammation of the pancreas (called pancreatitis)
• injury to the abdomen, such as from a car accident

Most cysts cause no symptoms and are only found during an abdominal MRI or CT scan that is done for another reason.

Only some types of pancreatic cysts can become cancer. The following are the most common types of precancerous pancreatic cysts.

Intraductal papillary mucinous neoplasms (IPMNs) are the second most common precancerous tumour of the pancreas. Like PanIN, IPMN is a form of ductal cell dysplasia. IPMNs are cysts filled with mucus (mucin) that form in the epithelium that lines the inside of the pancreatic ducts. It more commonly occurs in the smaller branches of the pancreatic ducts.

IPMN is more common in middle-aged to older adults.

Mucinous cystic neoplasms (MCNs) are large cysts made up of many small mucin-filled compartments that are separated by thin walls called septations. This makes MCNs look like they are multiple cysts clumped together. MCN occurs in the exocrine tissue around pancreatic ducts, usually in the body or tail of the pancreas.

Most cases of MCN occur in women. It is rare in men.

Solid pseudopapillary neoplasms (SPNs) are large cysts that have mucin-filled pockets within sections of solid tissue. They form in the exocrine tissue around the pancreatic ducts, usually in the body or tail of the pancreas.

SPN is more common in young to middle-aged women.

Treatment options for precancerous conditions of the pancreas include:

• surgery, such as the Whipple procedure or a pancreatectomy (removal of part or all of the pancreas)
• active surveillance

Whether your healthcare team recommends surgery depends on specific features (for example, large size or growth) of the precancerous cyst or growth and whether it is causing symptoms of pancreatic cancer. Certain symptoms may be a sign that the condition has become cancer and should be removed. Most precancerous conditions can be removed entirely through surgery.

If you have active surveillance, your healthcare team will monitor you for any changes. If you develop any signs that your condition has become cancerous, your healthcare team may recommend surgery.