PERSPECTIVE AND PATTERNS OF SPREAD
The digestive system anatomy with its multiple-layered walls determines the TNM staging and is the model for staging other hollow viscera and structures.
PERSPECTIVE AND PATTERNS OF SPREAD
Gastrointestinal tract (GIT) neoplasms are among the most common cancers. Colorectal cancers are the third-most-common cancers in both men and women. Cancer of the colon and rectum affects as many as 150,000 Americans annually; almost one third of this group dies from it. Research stimulating screening and early detection of polyps appears to be reducing mortality rates. Gastric cancers are quite prevalent in some parts of the world, such as Japan, but they are decreasing in incidence for unexplained reasons in the United States. Because of the accommodating nature of the GIT, most cancers are insidious in onset and can manifest as subtle changes in digestive and bowel habits or appetite. Unfortunately, the usual presentations of bowel obstruction, ulceration, and bleeding or perforation are signs of considerable advancement.
The digestive system is the longest anatomic structure, characterized by the infradiaphragmatic GIT as a hollow tubular organ, which is largely glandular in nature and gives rise to adenocarcinomas (Table 22.1). The lumen of the small intestines is lined by a single layer of columnar epithelial cells that form an apical membrane of enterocytes that contains numerous microvilli. The villi become less numerous as one transits from the jejunum to the ileum and become more mucous producing and rich in goblet cells in the colon. Polyposis secondary to inflammatory disease or an inherited familial disorder is often the forerunner to frank malignancy. The apocryphal model of genetic instability and gene modifications for the progression of in situ cellular changes from a benign polyp to a locally invasive cancer and then to metastatic behavior was first described by Vogelstein in bowel (Figure 22.1). This multistep paradigm has been more widely adopted as the molecular biologic basis for carcinogenesis.
As the benign polyp transforms into an adenocarcinoma it invades the wall of the bowel and spreads in the direction of the muscular layers (Fig. 22.2). First, it encircles the lumen following circular muscles and then is propelled longitudinally with peristalsis by the longitudinal muscle layer. It is important to note that with depth of wall invasion there is propulsion of the cancer by peristalsis in other directions and dimensions.
Pain arising from a viscus (organ) varies from dull to severe but is poorly localized. It radiates to the part of the body supplied by somatic sensory fibers associated with the same spinal ganglion and segment of the spinal cord that receive visceral sensory (autonomic) fibers from the viscus concerned. The pain is interpreted by the brain as though the irritation occurred in the area of skin supplied by the dorsal roots of the affected segments. This is called visceral referred pain.
Figure 22.1 | A model for genetic changes and progression in colon cancer.
Figure 22.2 | A. Patterns of spread of gastrointestinal cancers and major digestive organ tumors. Color coded for T stage: Tis, yellow; T1, green; T2, blue; T3, purple; and T4, red. B. Approximate spinal cord segments and spinal sensory ganglia involved in sympathetic and visceral afferent (pain) innervation of abdominal viscera. C. Anterior view: visceral referred pain. D. Posterior view: visceral referred pain.
TNM STAGING CRITERIA
CLASSIFICATION AND STAGING
TNM Staging Criteria
Gastrointestinal Tract
The pattern of hollow viscous invasion varies with the anatomic location or site of origin of the cancer in the GIT. The size of the lumen and the proximity of the tumor to sphincters determine whether obstruction is an early expression of malignant activity or a sign of an extensive tumor. Adjacent structures are invaded first, particularly those in direct proximity. The bowel loops with mesenteries are more mobile than those that are fixed and can spread their cancer cells intraperitoneally more readily. Tumor behavior is a function of the anatomy and physiology at each of the major sites in the alimentary tract. The GIT is a hollow tubular organ. The cancer's depth of penetration of the wall of bowel is the commonality for staging at all sites, T1, T2, T3, and T4—mucosal, muscularis, serosa, and adjacent viscera, respectively (Fig. 22.3). This is also the rule for most other hollow organs in other systems—for example, gallbladder and bile ducts (Table 22.2). Staging in solid organs (pancreas and liver) is based on tumor size T1, T2 and capsular invasion T3 and major vessels invasion is T4.
The lymphoid drainage of the digestive system and that of major digestive glands (MDGs) overlap and reflect both the arterial blood supply and venous drainage, which are not always parallel. The small intestine is a major extranodal site with its Peyer patches, and the appendix is an analog for the bursa of Fabricius, the origin for B cells in lower vertebrates. The mesenteric nodes are not acknowledged in the lymphoma staging as a node-bearing region. The para-aortic and paracaval locations for lymph nodes relate to the roots of origin of visceral arteries as the celiac, superior, and inferior mesenteric arteries. Smooth metastatic nodules in the pericolic and perirectal fat are considered lymph node metastases and counted in N staging. Irregular nodules are considered as vascular invasion and are either V1 (microscopic) or V2 (macroscopic) when viewed histopathologically.
The sentinel lymph nodes for each primary site are also noted.
When the visceral vessels drain into the inferior vena cava, the retroperitoneal lymph nodes cluster along the abdominal aorta and inferior vena cava vessels. When these nodes are involved, they are juxtaregional and can be considered metastatic nodes. The staging of nodes in the gastrointestinal region is extremely varied, and one can only speculate as to the lack of more uniform criteria in the sixth edition AJCC. At most major primary sites, there is only an N1 designation independent of size and number of nodes involved. Thus, N1 is simply a positive node and applies to esophagus, small intestine, liver, pancreas, gallbladder, extrahepatic ducts, and ampulla of Vater. The colon and rectum are similar to the breast in that N1 is one to three nodes and N2 is more than four nodes. The stomach was the most distinct site, with an elaborate nodal classification: N1, 1 to 6 nodes; N2, 7 to 15 nodes; and N3, ≤15 nodes. This has been revised in the seventh edition.
Major Digestive Glands and Ducts
The major feature in staging cancer of the liver and pancreas is size of the cancer(s) and venous invasion or entrapment of major arteries and veins that render such malignancies unresectable with conventional radical surgery. However, the increasing use of liver transplantation and/or liver–pancreas transplants with their connecting extrahepatic ducts may require the criteria of unresectability to be revamped. For the liver a size of 5 cm and for the pancreas a size of 2 cm divides lesions between early (T1) and advanced (T2, T3; Fig. 22.3). The gallbladder and extrahepatic duct cholangiocarcinomas, and the rare cancer of the hepatopancreatic ampulla (of Vater) masquerade as gallstones, presenting with obstructive jaundice. If detected when those duct cancers are contained within their walls, it is T1 or T2, and the possibility of resection and cure is real. However, once their walls are penetrated by cancer (T3) or enter and invade adjacent and surrounding organs (T4), their resectability decreases and their patient's survival is compromised.
SUMMARY OF CHANGES
Generally, there is no overarching principle or context design for the digestive system (GIT) or MDG as to stage groupings. For gastrointestinal system and major digestive glands there are no overarching rules as to stage groups and definitions of nodal categories. The T categories are consistent for hollow tubular multilayered digestive system sites, i.e., T1 mucosa, T2 submucosa, T3 muscularis, T4 serosa. N1 is the only nodal category in 7 of 10 sites but is variously assigned from stage I to stage III. Stage subgroups A/B are variously assigned in stage I, II, III, IV with an occasional C. The major basis for stage subgroups are supportive survival data, justifying the amalgams of T and N. The color code for progression of stage groups generally defines resectable (purple) versus unresectable (red) cancers and black is reserved for metastatic. Stages are frequently expanded to six by subdividing a stage into A and B. The T and N categories are assigned to a stage grouping, specifically for division of a stage into a (A) more favorable versus a (B) less favorable grouping. This occurs at different stages for different sites. N1 is the only nodal category in 7 of 10 sites but is variously assigned from I, II, III, and IV. There is an anatomic basis for T-stage assignment to N, as a function of primary tumor extent, that is, the T stage progression and depth of invasion is equal to where nodes are located.
Figure 22.3 | TNM staging criteria. Hollow organ prototype. Tis (mucosa), yellow; T1 (submucosa), green; T2 (muscularis externa), blue; T3 (serosa), purple; and T4 (perforates into another organ), red. Solid organ (pancreas). T1, green; T2, blue; T3, purple; and T4, red.
OVERVIEW OF HISTOGENESIS
The digestive system (alimentary tract) is a long, hollow, tubular organ with multilayered walls and numerous sphincters. Once the upper digestive system passes the esophagus, the mucosa that gives rise to adenocarcinomas is similar for stomach, small intestine, colon, and rectum. The mucosa—the innermost layer—is covered with simple columnar epithelium and has specific variation in villus size, which decreases in size and cell kinetic turnover time as one descends from stomach to rectum. Figure 22.4A shows a diagram of the general organization of the wall structure for each segment, and Table 22.1 lists the derivative cell and respective cancer to which it gives rise in the various sections of the digestive system:
• Esophagus (Fig. 22.4B): Stratified squamous with islands of gastric mucosa.
• Stomach (Fig. 22.4C): Gastric gland: Active divisions are in the neck with its short isthmus compared to the deep pits with mucous (blue), parietal (red), and chief (violaceous) cells.
• Small intestine (Fig. 22.4D): The small intestinal mucosa is marked with feathery villi and shallow pits, with active division in the neck of the gland with its columnar absorptive cells on the villus and into the pit. The primary function of enterocytes is absorption; goblet cells produce mucin; and Paneth cells maintain mucosal immunity with their antimicrobial secretions. Each villus has a central lacteal, a capillary, and venule.
• Colon (Fig. 22.4E): The colon has a smooth mucosa without villi or pits. It has shallow glands lined with a simple columnar epithelium that contains goblet cells, absorptive cells, and enteroendocrine cells with active division in its crypts.
• Liver (Fig. 22.4F): The liver is a compound tubular gland; each portal triad has its own bile duct, portal vein, and hepatic artery segment.
• Pancreas (Fig. 22.4G): The pancreas consists of centroacinar and pancreatic acinar cells with pancreatic islets of ±, >, and × cells.
The gastrointestinal canal includes that portion of the digestive tract that extends from the stomach to the anus. It is housed within the abdominopelvic cavity, which extends from the thoracic diaphragm to the pelvic diaphragm caudally. The abdominal cavity is lined by peritoneum—an areolar membrane covered with a single layer of mesothelial cells. The peritoneal cavity is a physiologically complex structure containing fluid secretions, which bathe and lubricate the bowel surfaces, and anatomically consists of numerous sacs and folds. Normally, the fluid is absorbed, but when it accumulates as ascites, malignancy with peritoneal seeding is a concern clinically. A double layer of peritoneum connects the stomach with the lesser omentum (from the lesser curvature) and with the greater omentum (from the greater curvature). The numerous peritoneal folds consist of mesenteries for gut, arteries, and veins, although some do not contain tubes. Peritoneal fossae, recesses, and gutters determine initial pathways of tumor spread both for bowel cancer and ovarian cancer. In addition to the omental bursae, there is a duodenal fossa, a cecal fossa, an intersigmoid fossa, a pelvic fossa, and a paracolic fossa.
Figure 22.4 | Overview of histogenesis. Histologic structural differences throughout gastrointestinal and major digestive organ systems. A. Primary site isocenters. B. Esophagus. C. Liver. D. Small intestine. E. Stomach. F.Pancreas. G. Colon.
T-ONCOANATOMY
THREE-PLANAR ONCOANATOMY
Orientation of T-oncoanatomy
There are 11 primary cancer sites, including the 7 GIT hollow structures: esophagus, stomach, small intestine, appendix (new), colon, rectum, and anus. In addition, there are 7 primary sites arising in the MDG: liver, intrahepatic bile ducts (new), gallbladder, extrahepatic bile ducts (hilar and distal), the ampulla of Vater, and pancreas. There are 2 major anatomic sectors and 11 major primary cancer sites. The abdomen is divided into two sectors based on the peritoneum, that is, the structures are intraperitoneal or extraperitoneal. With the exception of the pancreas, lower rectum, and anus, all major primary sites are intraperitoneal except for that portion of the bowel that is directly attached to the posterior wall of the abdomen and has no mesentery.
The abdomen superiorly extends under the diaphragm into the lower third of the thorax and inferiorly extends into the pelvis. The GIT and the MDG are the frequent sites of adenocarcinomas. To interweave these 11 primary sites, which are largely intraperitoneal, a multiplanar orientation follows (Fig. 22.5A, B). The presentation of primary site isocenters starts at T11 and T12 near the diaphragmatic insertion and progresses to L1 to L5 and then onto the pelvis S1, S2, and S3.
• Esophagus: The gastroesophageal junction is at the diaphragmatic level, and islands of Barrett mucosa can occur. The ectopic location of gastric mucosa in the distal esophagus is vulnerable for forming adenocarcinomas. The cardioesophageal junction has become increasingly notorious for adenocarcinomas that spread into the thorax as well as the epigastrium.
• Stomach: The stomach is divided into three regions: upper, middle, and lower third. To delineate these regions, the lesser and greater curves of the stomach are divided; the upper third is the cardiac area and fundus, the middle third is the body, and the lower third is the antrum. Gastric cancers can become large before they produce obstructive symptoms. Avid and aggressive screening in at-risk populations (Japan) has led to detection of early gastric cancers.
• Small intestine: The small intestine extends from the pylorus of the stomach to the ileocecal valve. It is approximately 25 feet long and is divided into three sections: the duodenum, jejunum, and ileum. The duodenum is essentially a midline structure approximately 1 foot long. It provides some of the most complex anatomy in the upper abdomen as it conforms to and surrounds the head of the pancreas. The small intestine, despite its length, gives rise to few cancers. Instead, a large variety of neoplastic syndromes occur, and unusual tumors is its hallmark.
• Colon: The large intestine is the most prevalent site for cancer, particularly with its numerous (eight) subsites at high risk. The large intestine or colon picture frames the abdominal content and is 60 cm long and is divided into an ascending, transverse, descending, and sigmoid colon with a hepatic flexure on the right and splenic flexure on the left. Favored subsites for malignancy include the cecum, sigmoid, and rectum. The colon is vulnerable to polyposis and chronic inflammatory disease, which can lead to carcinomas.
• Rectum: The rectum is the most common site in GIT for malignancies. It is about 12 cm long and extends from a point opposite the third sacral vertebra down to the apex of the prostate in the male and to the apex of the perineal body in the female, that is, to a point 4 cm anterior to the tip of the coccyx. It may be arbitrarily defined as the distal 10 cm of the large intestine, as measured by preoperative sigmoidoscopy from the anal verge. The rectum has no epiploic appendages, no haustrations, and no taeniae. It is covered by peritoneum in front and on both sides in its upper third and on the anterior wall only in its middle third; there is no peritoneal covering in the lower third.
• Anus: About 4 cm long, the anal canal courses downward and backward from the apex of the prostate or the perineal body. The anocutaneous line, or white line of Hilton, at the base of the rectal columns marks the site of the original anal membrane that separated the endodermal gut from the ectodermal proctoderm. With the high incidence of anal viral infection—both human papilloma virus and human immunodeficiency virus—the risk of anal cancers is increasing in the homosexual population.
The MDG constitute seven more primary sites, a number of which are quite uncommon cancers (Table 22.2):
• Liver: By virtue of its weight, the liver is the largest organ in the body. When filled with cancerous nodules, it is often the greatest repository of neoplastic disease, exceeding the primary tumors in the quantity of malignant cells. To understand the anatomy of the liver, it is important to be aware of its internal structure as a gland of compound tubular design. Each lobule is shaped like a cylinder or tubule, with a central vein that drains a rich anatomic sinusoidal network derived from the fine hepatic arterioles and portal vessels. The hepatocyte elaborates both an external/exocrine secretion and an internal/endocrine secretion of enzymes into the blood. The former is referred to as bile and is collected by biliary canaliculi.
• Intrahepatic bile ducts: cholangiocarcinomas is new.
• Gallbladder: The gallbladder is a small, saccular organ located inferior to the liver in its own fossa. It is a harbinger for gallstones and it can undergo dysplastic and then neoplastic changes. As a hollow, pear-shaped organ it simulates bowel, with an epithelial mucosa, smooth muscle layer, and serosa. In contrast to the intestine, there is no submucosa, and there is only one muscle layer, muscularis externa.
• Extrahepatic bile ducts: The extrahepatic bile ducts are a continuation of the intrahepatic ducts. The confluence of right and left hepatic ducts is the site of most cholangiocarcinomas and has been added as a new site. Symptoms of obstructive jaundice are invariably present.
• Ampulla of Vater: The ampulla of Vater is another confluence junction of both the pancreatic duct and extrahepatic bile ducts as it enters the second part of the duodenum. This is perhaps the least common malignancy of the MDG.
• Pancreas: The pancreas is a long, lobulated structure that lies transversely in the posterior abdomen located retroperitoneally in the concavity of the duodenum on its right end and touching the spleen on its left end. The shape of the pancreas may be compared with the letter J placed sideways. It is divisible into a head with an uncinate process, neck, body, and tail. Each of these sites, when afflicted with cancer, produces a specific set of characteristic signs and symptoms.
Figure 22.5 | Orientation of three-planar Toncoanatomy. Anatomic isocenter of multiple GIT primary sites. A. Sagittal lateral. B. Coronal anterior. A cephalad-to-caudad GIT and MDG tabulation of the cancers, the vertebral levels, and the adjacent anatomic structures to be aware of at the transverse axial level assists in presenting the classification and staging process of the digestive tract cancers. Most GIT and MDG organs occupy many vertebral levels; the three planar views and the axial vertebral assignment is designed to be at the anatomic isocenter of the structure. The anatomic isocenters (Fig. 22.5) for the gastrointestinal tract are displayed in sections transversely at a specific vertebral levels, recognizing there is a variability.
N-ONCOANATOMY AND M-ONCOANATOMY
Orientation of N-oncoanatomy
The coronal planar oncoanatomy of lymph nodes will present the arrays of regional lymph nodes (Fig. 22.6). The lymphoid drainage of the digestive system and major digestive glands (MDG) overlap and reflect both the arterial blood supply and venous drainage, which are not always parallel. The small intestine is a major extranodal site with its Peyer patches and the appendix is an analog for the bursa of Fabricius, the origin for B cells in lower vertebrates. The mesenteric nodes are not acknowledged in the lymphoma staging as a node-bearing region. The para-aortic and paracaval location for lymph nodes relate to the roots of origin of visceral arteries as the celiac, superior, and inferior mesenteric arteries. Smooth metastatic nodules in the pericolic and perirectal fat are considered lymph node metastases and counted in N staging. Irregular nodules are considered as vascular invasion and are either V1 (microscopic) or V2 (macroscopic) when viewed histopathologically.
The lymphatics and major lymph node stations of the digestive tract are rich and directly related to the vascular arcades that characterize the extensive arterial and venous network. In the upper abdomen, the celiac axis of arteries supplies the stomach along its lesser and greater curvatures and the hepatic and pancreaticosplenic arteries, liver, and pancreas along with its ductal systems. The major lymphatic collecting trunks are parallel with the left gastric artery, splenic artery, and hepatic artery.
The major first station nodes are along the lesser gastropyloric, suprapyloric, pancreatoduodenal, celiac, splenic, and hepatic lymph nodes. The second station nodes include the para-aortic nodes. However, it is the superior and inferior mesenteric arterial and venous arcades that one associates with the GIT's rich lymphatics and lymph nodes. The intestinal wall is impregnated with Peyer patches and a rich network of lacteals in villi that provide robust drainage of chyme into the cisterna chili and then onto the thoracic duct. Each of these regional lymph nodes is discussed separately with the GIT/MDG organ of interest. The sentinel nodes for each site are listed in Table 22.3. The spleen can function as a major systemic lymph node and plays an important immunologic role.
Figure 22.6 | Orientation of N-oncoanatomy. A. Stomach and small intestine. B. Large intestine. C. Liver and gallbladder. D. Spleen and pancreas. E. Drainage from lumbar and intestinal lymphatic trunks. Lymph from the abdominal nodes drains into the cistern chyli, origin of the inferior end of the thoracic duct. The thoracic duct receives all lymph that forms inferior to the diaphragm and left upper quadrant (thorax and left upper limb) and empties into the junction of the left subclavian and left internal jugular veins.
Orientation of M-oncoanatomy
The entire portal circulation should be considered as a unit in regard to the venous anatomy of the GIT below the diaphragm (Fig. 22.7A.) The two major trunks are the inferior mesenteric and superior mesenteric veins. The inferior mesenteric vein drains the left colon and sigmoid colon tributaries, which covers the vascular drainage to the left of the midline originating from the superior rectal veins. On the right side, the superior mesenteric vein originates from the tributaries draining the ileum, jejunum, and ileocolic and right colic veins. The inferior mesenteric vein usually joins the splenic vein, which coalesces with the superior mesenteric vein and forms the portal vein. The splenic vein, which is a major tributary of the portal system in addition, drains much of the stomach along its greater curvature and includes the short gastric veins and left gastroepiploic and right gastric epiploic veins. The right gastroepiploic also flows into the superior mesenteric vein. The entire drainage of the lesser curvature of the stomach, including the left and right gastric veins, drains directly into the portal vein. Because the portal vein then drains directly into the liver, it is the target metastatic organ and the most commonly involved organ in hematogenous spread pattern from the venous system of the GIT as compared with other parts of the body, where the drainage is directly into the lung by way of the caval system (Fig. 22.7; Table 22.4).
THE ABDOMINAL PERITONEAL CAVITY
The abdominal cavity is lined by peritoneum, an areolar membrane covered with a single layer of mesothelial cells. The peritoneal cavity is a physiologically complex structure containing fluid secretions, which bathe and lubricate the bowel surfaces, and anatomically consists of numerous sacs and folds. Normally, the fluid is absorbed, but when it accumulates as ascites, malignancy with peritoneal seeding is a concern clinically. A double layer of peritoneum connects the stomach with the lesser omentum (from the lesser curvature) and with the greater omentum (from the greater curvature). The numerous peritoneal folds consist of mesenteries for gut, arteries, and veins, although some do not contain tubes. Peritoneal fossae, recesses, and gutters determine initial pathways of tumor spread both for bowel cancer and ovarian cancer. In addition to the omental bursae, there is a duodenal fossa, a cecal fossa, an intersigmoid fossa, a pelvic fossa, and a paracolic fossa (Figure 22.7B,C).
The origin of the abdominal cavity and the gastrointestinal contents is essential to understand metastatic seeding in the abdomen. Embryologically, the gastrula folds into a tube with a foregut, midgut, and hindgut, suspended by a dorsal mesentery into the abdominal cavity lined by a simple squamous parietal peritoneal lining over the abdominal wall and a visceral peritoneum over the gut. As the gut rotates clockwise, the viscera are suspended by “ligaments” that create separate pockets, that is, lesser and greater peritoneal sacs, as well as the omentum.
The diaphragm develops from the septum transversum that partitions the thoracic and abdominal cavities; its muscle, derived from cervical somite myotones, carries with it the phrenic nerve, that is, referring abdominal inflammation to the shoulder and neck. The infradiaphragmatic lymphatics drain the peritoneal fluid, which is secreted with flow patterns determined by visceral movement and ligamentous attachments.
Once gastrointestinal cancer penetrates the gut wall serosa, it can do the following:
• Seed out into the abdominal cavity and lead to the omental or visceral deposits of cancer.
• Form masses; a dramatic illustration is stomach-seeding ovarian masses—Krukenberg tumors.
• Lead to peritoneal fluid formation, resulting in ascites, that is, mucinous peritoneal due to goblet cell proliferations.
• Cause diaphragmatic lymphatic obstruction, resulting in serous exudates or, if the cisternachyli is invaded, a chylous ascites.
• Lead to omental cakes, which can lead to mass formation that in turn invades the abdominal wall.
• Directly invade another segment of the small intestine and colon, resulting in stricture and bowel obstruction.
• Lead to perforation of visceral peritoneum, which can lead to fistula and to abscess formation localized to the cancer site or migrate leading to subdiaphragmatic abscess.
• Lead to acute peritonitis with an acute abdomen: air accumulating under the diaphragm due to ulceration and perforation.
Figure 22.7 | Orientation of M-oncoanatomy. A. Portal venous system. B. Peritoneal cavity without viscera. C. Peritoneal cavity with viscera.
STAGING WORKUP
RULES FOR CLASSIFICATION AND STAGING
Clinical Staging and Imaging
Most of the digestive system and MDG are inaccessible to physical examination to detect and diagnose cancer formation and invasion. Endoscopic viewing provides the diagnosis, but to probe and biopsy the wall carries the hazard of perforation. The role and importance of sophisticated imaging are essential to staging. Endoscopic ultrasound can visualize the multilayered wall as rings of hyperechoic and hypoechoic bands and their signal distortion by tumor invasion. Virtual endoscopy, like colonoscopy, is an improving modality with more accurate computer displays and reconstructions. Computed tomography (CT) and magnetic resonance imaging (MRI) are valuable for assessing solid organs such as liver and pancreas, as well as adenopathy. Three-planar viewing is widely adopted and available for staging the primary tumor and regional nodes. Hepatic metastases are the greatest concern for all GIT and MDG sites, and CT and MRI are excellent modes for searching and identifying lesions. Positron emission tomographic scanning is a sensitive means to total body scan for occult dissemination (Table 22.5). Endorectal ultrasounds is useful in defining depth of wall invasion (Fig. 22.8). The arterial phase can be useful to determine tumor blood supply in various abdominal organs (Fig. 22.9A, B).
Pathologic Staging
The surgically resected portion of the GIT and associated lymph nodes removed are noted, numbered, and assessed for tumor. Tumor extension and location of both primary and nodes should be documented. Residual cancer can be R1, microscopic, or R2, macroscopic.
Figure 22.8 | Schematic representation of endoscopic ultrasound appearance of the typical five-layered wall pattern and the histologic correlation.
PROGNOSIS AND CANCER SURVIVAL
CANCER STATISTICS AND SURVIVAL
The majority of digestive systems neoplasms are successfully treated with multimodal treatment. The number of new patients with cancers are 275,000 of which 50% (140,000) survive. The incidence is slightly greater in males than females 54% vs. 46% i.e., 150,000 vs. 1260,000. The death rates over the past five decades have most dramatically decreased in stomach and colon rectum cancers and are unchanged for pancreas and liver. The deaths are also greater in males than females: 56% vs. 44% i.e. 80,000 vs. 60,000.
An overview of digestive system cancers and their incidence of new patients and their death rates are tabulated according to ACS Cancer Facts and Figures 2010 (Tables 22.6 and 22.7).
The largest gains in survival are in colon and rectum, followed by stomach. The poorest results are those in pancreas and liver. The gains other sites vary depending on early detection of cancer in a localized stage in esophago-gastric junction or where chemoradiation is very effective i.e. anal cancers.
Figure 22.9 | A. Arterial phase coronal maximum intensity projection image. 1. left renal art 2. right renal art 3. left common iliac art. A, abdominal aorta; AC, ascending colon; DC, descending colon; Liv, liver; LK, left kidney; RK, right kidney; Spl, spleen; Stom, stomach. B. Coronal abdomen. 1. left iliac bone 2. main portal vein 3. inferior vena cava 4. ascending colon 5. descending colon. A, abdominal aorta; Liv, liver; Ps, psoas muscle; Spl, spleen; Stom, stomach; UB, urinary bladder.
Figure 22.10 | Five-year survival graphs for abdominal cancers. (Data from Edge SB, Byrd DR, and Compton CC, et al, AJCC Cancer Staging Manual, 7th edition. New York: Springer, 2010.)