Only a small minority of all polyps become cancerous. That includes sessile polyps. However, sessile polyps are a greater cancer risk because they’re tricky to find and may be overlooked for years. Their flat appearance hides them in the thick mucus membranes that line the colon and stomach.

Of these categories, the sessile serrated polyp is the most challenging to identify, hardest to remove, and most likely to develop into cancer. Sessile serrated polyps are common and tend to carry a low risk of becoming cancerous as long as they do not contain major cellular changes.

What does it mean if I have an adenoma (adenomatous polyp), such as a sessile serrated adenoma or traditional serrated adenoma? These types of polyps are not cancer, but they are pre-cancerous (meaning that they can turn into cancers).

Some evidence suggests that the sessile serrated polyp-to-cancer sequence takes 10 to 20 years, the same time frame generally accepted for the conventional adenoma-to-cancer sequence.

Depending on their size and location in the colon, serrated polyps may become cancerous. Small, serrated polyps in the lower colon, also known as hyperplastic polyps, are rarely malignant. Larger serrated polyps, which are typically flat (sessile), difficult to detect and located in the upper colon, are precancerous.

Serrated polyposis syndrome has a heterogeneous genetic underpinning with BRAF and KRAS mutations being the most common, with an incidence of ~70%.

The ‘WHO Criteria’ for the Serrated Polyposis Syndrome (SPS) include any of the following: At least five serrated polyps proximal to the sigmoid colon, two of which are greater than 10mm in diameter. Any number of serrated polyps occurring proximal to the sigmoid colon in an individual who has a first-degree relative with serrated polyposis More than 20 serrated polyps of any size distributed throughout the colon.