The sessile serrated polyp1, also known as a sessile serrated lesion (SSL), is one of the precursors for colorectal cancer. It is notorious as significantly hard to visualize under colonoscopy, difficult to be removed completely (frequent regrowth), and can rapidly progress to colon cancer without detection. Unfortunately, it has been estimated to contribute up to 20-30% of colorectal cancer worldwide2. Despite its notorious fame and premalignant nature, few studies are available to investigate the risk factors for developing SSP. Recently, a study3 in China investigated the clinical risk factors of SSL and compared them with colorectal adenomas targeting the population of Chinese individuals.
The study3 included a total of 2295 patients, among which 459 with SSL, 918 with adenoma, and 918 with normal colonoscopy reports. The researchers evaluated the following independent risk factors known for colon cancer:
- Smoking status (current/ex-smoker or non-smoker)
- Alcohol intake (current/ex-drinker with more than two drinks per week or non-drinker)
- Diabetes mellitus (DM)
- Hypertension
- Dyslipidaemia
The characteristics of patients with each condition are summarised in the table below:
The proportion of patients with DM in the SSL group (19.4%) and adenomas group (15.8%) was significantly higher than that in the normal colonoscopy group (11.7%). As for hypertension, the proportion in the SSL group (13.3%) and adenomas group (13.0%) was also significantly higher than in the normal colonoscopy group (9.2%). Alcohol intake only showed differences between subjects with adenomas and those with normal colonoscopy. Smoking status did not differ significantly among these three groups. However, a comparison between the SSL group and the adenomas group did not identify any significant difference in these risk factors.
On univariate analysis, dyslipidaemia and DM were significantly associated with SSLs, comparing subjects with only SSLs versus normal colonoscopy. And by logistic regression, they both remained independent risk factors for developing SSLs. The researchers acknowledged that many other studies have observed an association between SSLs and smoking status, which in this case might have been limited by the retrospective nature of this study with possible missing data.
On another aspect, this study indicated that SSLs tended to be in the proximal colon, whereas the tubulovillous/villous adenomas group tended to occur in the distal colon. SSLs were more likely to occur as a single polyp, whereas those with tubulovillous/villous adenomas were more likely to have synchronous multiple lesions.
In conclusion, the study suggested that dyslipidaemia and DM were independent risk factors for SSLs, which tend to happen in the proximal colon. Further investigations could focus on other metabolic risk factors such as BMI and serum triglyceride level to further propose screening tools for early detection of SSL.
Reference
- Obuch JC, Pigott CM, Ahnen DJ. Sessile Serrated Polyps: Detection, Eradication, and Prevention of the Evil Twin. Current Treatment Options in Gastroenterology. 2015 Jan 28;13(1):156–70.
- Makkar R, Pai RK, Burke CA. Sessile serrated polyps: cancer risk and appropriate surveillance. Cleveland Clinic journal of medicine [Internet]. 2012 [cited 2019 Dec 9];79(12):865–71.
- Zhang R, Ni Y, Guo CL, Lui RN, Wu WK, Sung JJ, et al. Risk factors for sessile serrated lesions among Chinese patients undergoing colonoscopy. Journal of Gastroenterology and Hepatology. 2023 May.
