A colonoscopy does not detect stomach cancer. Stomach (gastric) cancer and colorectal cancer occur in different parts of the digestive tract and require distinct screening methods. Understanding the anatomy covered by each procedure is necessary for appropriate cancer detection and prevention.
What a Colonoscopy Examines
A colonoscopy is a medical procedure designed to examine the lower portion of the gastrointestinal tract. This procedure uses a long, flexible tube called a colonoscope, equipped with a light and a small video camera at its tip. The scope is inserted through the rectum and navigated through the entire large intestine, also known as the colon.
The colon is the primary focus of this examination. The colonoscopy permits a thorough inspection of the internal lining of the colon wall and the rectum. Its main function is to screen for and prevent colorectal cancer.
During the procedure, the physician looks for small growths called polyps, which are common and can sometimes develop into cancer. If a polyp or any suspicious area is found, the instruments passed through the colonoscope allow for immediate removal or a biopsy, which is then sent for laboratory analysis. This makes the colonoscopy the standard method for detecting and treating early-stage colorectal cancer.
The Correct Procedure for Stomach Cancer Screening
Detecting stomach cancer (gastric cancer) requires a different procedure, known as an Upper Endoscopy or Esophagogastroduodenoscopy (EGD). This examination uses a flexible tube, the endoscope, but it is routed through the mouth and down the throat.
The EGD allows the doctor to view the lining of the upper digestive tract, which includes the esophagus, the stomach, and the duodenum (the first section of the small intestine). This procedure is the definitive method for diagnosing stomach cancer by visually inspecting the stomach lining for abnormal areas. If a suspicious lesion is observed, the endoscope allows for a biopsy to check for cancer cells.
In the United States, upper endoscopy is typically reserved for individuals who are at a higher risk of developing gastric cancer. This includes people with a family history of the disease or those with chronic conditions, such as long-term inflammation of the stomach. The procedure is considered the standard for diagnosing gastric cancer in these high-risk populations.
Key Differences in Symptoms and Risk Factors
The different locations of these cancers mean they present with distinct warning signs. Symptoms that may indicate a need for a colonoscopy involve changes in the lower digestive system, such as persistent changes in bowel habits, rectal bleeding, or blood in the stool. Other signs include unexplained weight loss, fatigue, or lower abdominal pain.
Warning signs that point toward potential stomach issues, requiring an EGD, often relate to the upper digestive process. These symptoms include persistent indigestion, chronic nausea, vomiting, or difficulty swallowing. A feeling of fullness after eating only a small amount of food (early satiety) is associated with gastric cancer.
The risk factors for each cancer type also differ, guiding a physician’s suspicion toward the appropriate screening. For stomach cancer, a major risk factor is chronic infection with the bacterium Helicobacter pylori (H. pylori). Other factors include diets high in salted, smoked, or processed foods, a family history of gastric cancer, and long-term stomach inflammation.
Risk factors for colorectal cancer are often linked to lifestyle, including a diet low in fiber and high in red or processed meat, physical inactivity, and obesity. Age is also a factor, with screening recommended for average-risk individuals starting at age 45. Consulting a physician about any persistent or concerning changes is the most effective way to determine which screening procedure is appropriate.