Overview: Stomach, liver, & Colon

The stomach is a reservoir for food and aids in digestion after food enters from the esophagus. Distally, it connects to the small intestine at the duodenum. Cancers of the stomach typically grow slowly and develop over many years. Most cancers are classified and adenocarcinomas.

The liver is the largest solid organ in the body, located in the upper right quadrant of the abdomen. The most common type of primary liver cancer is hepatocellular carcinoma. Most tumors of the liver are secondary or metastasis from other sites. The common cancers that spread to the liver are from the pancreas, colon, rectum, breast, and lung. The gallbladder is surrounded by the liver and aids in the digestion of fatty foods. Cancers here are rare and most are adenocarcinomas.

The colon (large bowel) consists of eight regions: the cecum, ascending colon, descending colon, splenic flexure, hepatic flexure, transverse colon, sigmoid, and rectum. The cecum, transverse colon, and sigmoid sections are located intraperitoneally and can be surgically removed unless the tumor is invading adjacent structures. The ascending colon, descending colon, hepatic flexures, and splenic flexures are located retroperitoneally or outside the peritoneum. Due to their location and lack of mesenteric support, cancers found in these portions of the colon commonly spread outside the bowel wall to adjacent soft tissues, like the kidney and pancreas. Lymphatic drainage along the colon is extremely rich and dependent upon the section of the colon. Most colon cancers are adenocarcinomas.

Patient simulation & Special Considerations: Stomach, liver, & Colon

Stomach: The role of radiation therapy in stomach cancers is typically used adjuvant to surgery and chemotherapy. The most common treatment options are 3D-CRT or IMRT. According to The World Journal of Gastroenterology’s article, the radiation dose for these treatments would be 60 Gy in 1.5-2.0 Gy fractions for unresectable gastric cancer. Another trial at the Mayo Clinic treated unresectable gastric cancer with or without 5-FU chemo during the first three days of radiation and treated with 35-37.5 Gy in 4-5 weeks.

Liver & Gallbladder: For liver metastasis, 20-30 Gy in 13-29 fractions is delivered to the whole organ to relieve painful hepatomegaly. Another option is 20-25 Gy to in 2-3 weeks. For lesions <5 cm, SBRT is the treatment of choice, giving 45-54 Gy in 3-5 fractions. For more information about SBRT treatments, review the Treatment Volume Localization: SBRT section.

The treatment regimen for gallbladder lesions is chemoradiation. This tends to have more potent side effects but is more effective, especially for nodal involvement. The gallbladder was historically treated with a field arrangement like a pancreatic tumor or through AP/PA fields. The target includes the primary lesion, adjacent tissues, and any involved regional nodes. The dose fractionation for inoperable gallbladder disease is 54 Gy in 20 fractions with a 15 Gy IORT boost. Another fractionation option is 35-55 Gy EBRT and 15 Gy in 3 fractions using brachytherapy.

Colon: The treatment of choice for rectal cancer is the surgical removal of the primary tumor and primary nodal drainage. Neoadjuvant Radiation Therapy, decreases the viability of tumor cells that could spread at the time of surgery, improving the ability to resect large tumors and reducing small bowel complications by radiating in a nonsurgical area. Adjuvant Radiation Therapy, has the advantage of better selection of patients for treatment based on the surgical and pathologic findings.

Emerging Technologies & Treatments: Stomach, liver, & Colon

Treatment advances and technologies available for the stomach, liver, and colon are the same as those described in the Emerging Technologies & Treatments: Abdomen section.