Introduction: The Rising Discovery of Intestinal Polyps
With the continuous advancement and accessibility of endoscopic technologies, the detection of intestinal polyps during routine examinations has significantly increased. While many regard polyps as mere benign “small bumps” in the intestine, concerns about their potential to turn malignant are widespread. Understanding which polyps harbor the highest cancer risk and when they warrant removal is essential for both patients and clinicians.
Why Do Polyps Develop in an Otherwise Healthy Intestine?
Clinical research indicates that approximately 80%-90% of colorectal cancers progress through a multistep transformation: from normal mucosa to inflammatory cell proliferation, then adenoma formation, and finally adenoma-to-carcinoma progression. A low-grade, chronic inflammatory state often underlies this sequence. Inflammation injures the intestinal mucosa, leading to mucosal protrusions that manifest as polyps if not treated timely.
Most polyps themselves are harmless, but certain lifestyle factors can drive mutation in polyp cells. High consumption of fatty and sugary foods, smoking, heavy alcohol intake, prolonged sedentary life, and genetic predisposition contribute to this risk.
Who Is at Higher Risk for Developing Intestinal Polyps?
Several groups show an increased susceptibility to intestinal polyps:
– Individuals Over 50 Years Old: Aging slows intestinal mucosal metabolism and leads to cumulative chronic inflammation and gene mutations. Statistics reveal about 30% of those over 50 have colonic polyps, increasing to 40%-50% in people over 60.
– Poor Dietary Habits: Diets high in fat and sugar but low in fiber increase polyps incidence. High fat raises bile acid concentrations, irritating the mucosa, while low fiber reduces bowel motility, prolonging exposure to harmful substances.
– Family History of Colorectal Cancer: Genetic factors significantly raise risk if first-degree relatives have histories of polyps or colorectal malignancy.
– Metabolic Syndrome Patients: Conditions such as obesity, hyperlipidemia, type 2 diabetes, and hypertension closely correlate with polyp occurrence.
– Chronic Intestinal Diseases: Diseases like chronic colitis, ulcerative colitis, and Crohn’s disease cause persistent mucosal inflammation, dramatically increasing polyp risk.
When Should Polyps Be Removed? Evaluating Size, Shape, and Histology
The duration for a polyp to develop into invasive colorectal cancer can range from 5 to 10 years. Initial polyps are typically asymptomatic and often identified via screening. Once polyps exceed 10 millimeters, symptoms such as constipation, diarrhea, abdominal pain, occult blood in stool, weight loss, or anemia may occur.
Medical decisions about removal depend on:
1. Size:
– Polyps ≥5 mm in diameter are generally recommended for endoscopic removal.
– Polyps ≤5 mm that are non-adenomatous, especially multiple ones in the sigmoid colon or rectum, may not require removal if biopsy confirms benign nature.
– Small polyps with depressed, flat, serrated, or villous characteristics should be removed regardless of size.
2. Morphology:
– Polyps with smooth, rounded, flat edges tend to be benign and may be monitored if ≤5 mm.
– Rough-surfaced polyps with ulcers, bleeding, necrosis, or characteristic openings increase suspicion for malignancy necessitating removal.
3. Pathology:
– Non-neoplastic polyps include hyperplastic, inflammatory, and hamartomatous types, mostly benign with hyperplastic polyps least likely to undergo malignant change.
– Neoplastic polyps include adenomatous types—tubular, villous, and tubulovillous adenomas—along with serrated lesions and genetic polyp syndromes, showing predominantly malignant potential.
Although only about 5% of adenomatous polyps become cancerous, they are implicated in 85%-90% of colorectal cancers. In China, adenomatous polyps are discovered in at least 25% of men and 15% of women undergoing colonoscopy, with rates exceeding 40% in individuals over 60.
Hence, adenomatous polyps should be removed irrespective of size. Patients with familial adenomatous polyposis have nearly 100% risk of malignant transformation, making early removal crucial. Serrated and villous components on pathology strongly suggest malignancy potential and mandate excision.
The Role of Colonoscopy: The Gold Standard for Detection and Removal
Colonoscopy remains the most reliable tool for detecting intestinal polyps. Guidelines recommend that adults aged over 40, especially those with a family history of colorectal cancer, obesity, high-fat diets, or heavy smoking and drinking habits, undergo colonoscopy every 3 to 5 years.
Most polyps can be removed during the endoscopic procedure, which is typically painless and associated with rapid recovery.
Case Study: Mr. John Williams’ Journey
John Williams, a 55-year-old man with a family history of colorectal cancer, underwent a routine colonoscopy after experiencing subtle changes in bowel habits. The procedure identified a 7-mm tubular adenoma in his sigmoid colon. The polyp was successfully removed endoscopically without complications. Subsequent pathology confirmed low-grade dysplasia with no malignancy. John was advised regular surveillance colonoscopies every three years. His early detection and treatment likely prevented progression to cancer.
Summary and Recommendations
Intestinal polyps are common, especially as age advances, and while most are benign, adenomatous polyps carry significant malignant potential. Understanding risk factors—including age, diet, genetic predisposition, and chronic inflammation—is essential for early identification.
Endoscopic removal based on polyp size, morphology, and pathology is critical to prevent progression to colorectal cancer. Regular colonoscopic surveillance is especially important for high-risk populations. By adhering to recommended screening and preventive strategies, colorectal cancer risk can be substantially reduced.
References
1. Fearon ER, Vogelstein B. A genetic model for colorectal tumorigenesis. Cell. 1990;61(5):759-767.
2. Rex DK, Boland CR, Dominitz JA, et al. Colorectal cancer screening: Recommendations for physicians and patients from the U.S. Multi-Society Task Force on Colorectal Cancer. Gastroenterology. 2017;153(1):307-323.
3. Lieberman DA, Rex DK, Winawer SJ, et al. Guidelines for colonoscopy surveillance after screening and polypectomy: a consensus update by the US Multi-Society Task Force on Colorectal Cancer. Gastroenterology. 2012;143(3):844-857.
4. Cancer Genome Atlas Network. Comprehensive molecular characterization of human colon and rectal cancer. Nature. 2012;487(7407):330-337.
5. Wong MCS, Huang J, Huang JLW, et al. Global incidence and mortality of colorectal cancer and association with Human Development Index: a systematic review and meta-analysis. Clin Transl Gastroenterol. 2020;11(9):e00222.
