Gastrointestinal Cancer Types and
Radio Therapy Treatment Options

Colorectal Cancer

Cancer of the large bowel is second only to lung cancer as a cause of cancer death in the United States: 136,000 new cases occurred in 2016 and more than 50,000 deaths were caused to colorectal cancer. Risk factors include: diet, smoking, alcohol, lack of physical activity, family history of colon cancer and colon polyps, presence of colon polyps, race, and even diseases such as diabetes and obesity.

Most colorectal cancers arise from adenomatous polyps. A polyp is a grossly visible protrusion from the mucosa of the colon into the lumen of the gut. They can be classified as hyperplastic polyps which are benign, or adenomatous polyps which have the potential to become cancers. Most polyps produce no symptoms and remain clinically undetected.

Colorectal Cancer Screening

• Digital rectal exam
• Fecal occult blood exams
• Radiographic studies such as barium enemas or CT colonography
• Colonoscopy

Occult blood in the stool is found in 5% of the patients with these polyps. The probability of an adenomatous polyp to become cancerous depends on the gross appearance of the lesion, its histology and its size. The likelihood that any polyp contains cancer is relative to the size of the polyp, being negligible (<2%) in lesions smaller than 1.5 cm, intermediate (2-10%) in lesions from 1.5-2.5 cm and substantial (>10%) in lesions larger than 2.5 cm in size.

Although colonic polyps can be detected by using X-rays such as Barium Enemas or CT-colonography, most polyps in the United States are detected using colonoscopy. The advantages of colonoscopy over X-rays are that at the time of detection the polyp can be resected. At that time, the histologic nature of the polyp can be ascertained and most of the times no further therapy is needed. However, following detection of an adenomatous polyp the entire large bowel should be visualized endoscopically because other synchronous lesions are noted in 1/3 of patients.

Colonoscopy should then be repeated periodically because such patients are at a higher than average risk of developing colorectal cancer. Adenomatous polyps are thought to require more than 5 years of growth before becoming clinically significant; for that reason colonoscopy does not have to be repeated more frequently than every 3 years for the great majority of patients.

Colonoscopy should then be repeated periodically because such patients are at a higher than average risk of developing colorectal cancer. Adenomatous polyps are thought to require more than 5 years of growth before becoming clinically significant; for that reason colonoscopy does not have to be repeated more frequently than every 3 years for the great majority of patients.

Colon cancer screening is beneficial at detecting precancerous changes and small early tumors in the large intestine and rectum. For adults who are at average risk of colon and rectal cancer, it is recommended to begin screening at age 50. Adults who are classified at higher risk may begin screening earlier at the recommendation of their doctor. Remember that even if you are not experiencing symptoms of colon or rectal cancer, you should always follow your doctor’s screening recommendations, including:

​Eating a well-balanced diet is advantageous for many reasons. A diet rich in fruits and vegetables and low in animal fats reduces your risk of some types of gastrointestinal cancer. In addition, eating a well-balanced diet reduces obesity, which has been recognized as a significant risk factor for many types of cancer.

Colorectal Cancer Treatment

Treatment for gastrointestinal cancer depends on the type of cancer, stage, and other general health factors. Common methods of treating gastrointestinal cancer include surgery, chemotherapy and radiation. Sometimes a combination of all methods are used, this is commonly called multidisciplinary management.

Role of Radiation Therapy in Colorectal Cancer

Radiation therapy to the pelvis is recommended for patients with rectal cancer because it reduces the 20-25% probability of regional recurrences following complete surgical resection of stage II or II tumors, especially if they have penetrated through the serosa. This alarmingly high rate of local disease recurrence is believed to be due to the fact that the contained anatomic space within the pelvis limits the extent of the resection and because the rich lymphatic network of the pelvic side wall immediately adjacent to the rectum facilitates the early spread of malignant cells into surgically inaccessible tissue.