Malignant tumors of the esophagus are carcinomas and gastrointestinal stromal tumors (GISTs). Sarcomas, lymphomas, and metastases are less common. Esophageal cancer is the third most common cancer of the GIT, with an overall 5-year survival rate less than 10 %. There are two histologic variants: squamous cell carcinoma and adenocarcinoma, evenly distributed between the middle and lower third of esophagus, where nearly three quarters of all esophageal cancers are located.

Predisposing factors to squamous cell carcinoma are achalasia, stenosis from caustics, previous head and neck cancers, Plummer-Vinson syndrome, radiation, and tylosis; with adenocarcinoma, progression to dysplasia and cancer in Barrett esophagus is known.

Dysphagia is the most frequent symptom in patients with esophageal cancer. Less common presenting symptoms include odynophagia, anorexia, weight loss, chest pain on swallowing due to mediastinal structures infiltration, and ­anemia related to chronic oozing of blood; hematemesis is a rare occurrence in case of aortoesophageal fistula. Some patients may have hoarseness due to direct infiltration of the larynx or recurrent laryngeal nerve. Cough, when present, should raise the suspicion of trachea-esophageal or esophago-bronchial fistula. It seems evident that these are nonspecific symptoms often present in elderly patients as consequences of functional disorders occurring with age or as expression of cerebrovascular diseases (Green et al. 2002).

The staging of esophageal cancer is assessed with the TNM system as developed by the American Joint Committee on Cancer (AJCC); the histologic types of esophageal cancer are not taken into account (Fleming et al. 1997). The esophagus is divided into four anatomic regions for classification, reporting, and staging purposes. The cervical portion extends from the cricoid cartilage to the thoracic inlet. The thoracic esophagus extends from the thoracic inlet to the gastroesophageal junction and is divided into upper, mid, and lower. The upper thoracic esophagus extends from the thoracic inlet to the carina, the mid-thoracic esophagus from the carina to the gastroesophageal junction, and the lower thoracic and abdominal esophagus, which measures approximately 8 cm in length, including the intra-abdominal portion of the gastroesophageal junction.

Treatment strategy depends on the depth of parietal infiltration: patients with T1 or T2 tumors may be candidates for surgical therapy, whereas patients with T3 or T4 tumors are frequently offered preoperative chemotherapy or combined chemotherapy and radiation therapy.

According to the current AJCC classification system, locoregional lymph nodes are defined on the basis of the location of the primary esophageal tumor. The identification of metastases is important in treatment planning. According to the AJCC, distant metastases are subdivided into M1a and M1b subcategories, with M1a indicating metastases to cervical or celiac axis lymph nodes and M1b indicating metastases to distant sites.

Endoscopic ultrasound is considered the most accurate imaging modality currently available for primary tumor staging (T staging) in patients with esophageal cancer. The esophageal wall is visualized as five alternating layers of differing echogenicity. The first layer is hyperechoic and represents the interface between balloon and superficial mucosa. The second layer is hypoechoic and represents the lamina propria and muscularis mucosae. The third layer is hyperechoic and represents the submucosa. The fourth layer is hypoechoic and represents the muscularis propria. The fifth layer is hyperechoic and represents the interface between the serosa and surrounding tissues. Recently, endoscopic ultrasound performed with high-frequency ultrasound probes has shown promising results in helping distinguish mucosal (T1m) from submucosal (T1sm) invasion. The tumor is recognized as a heterogeneous hypoechoic mass, which disrupts the normal stratification of the wall. Only a limited number of metastatic lymph nodes can be recognized with endoscopic ultrasound (Lightdale and Kulkarni 2005).

The double-contrast barium X-ray is considered the best technique for identifying early cancer, with a limit of non-differentiation between T2 and T3. The early lesion may present with different aspects: nodular, plaque, polypoid, and ulcerated. In the advanced stage, lesions may appear as diffuse infiltrating, polypoid, ulcerative, or varicose. Infiltrating lesions are characterized by irregular narrowing with stenosis of the esophageal lumen, whereas the overlying mucosa may be ulcerated or nodular with proximal and distal sharp edges. The polypoid tumor appears as a large mass projecting into the lumen inducing esophageal obstruction; the ulcerated surface is expressive of tumor necrosis. In the ulcerated form, a large well-defined ulcer replaces the mass. In the varicoid lesion, the vector growth is submucosal, resulting in a thickening of the folds, which appear irregular and tortuous. In the double-contrast barium X-ray, extrinsic footprints on esophagus, expression of nodal metastases, and fistulas within the bronchial tree are found (Berger and Scott 2004).

The normal esophageal wall is usually less than 3 mm thick at double-contrast CT when the esophagus is distended. Asymmetric thickening of the esophageal wall is a primary but nonspecific CT finding of esophageal cancer. CT is unable to adequately help differentiate between T1, T2, and T3 diseases, whereas it is possible to differentiate between T3 and T4, a distinction that is important when considering the use of neoadjuvant chemotherapy and radiation therapy. The CT criteria for T4 identification include loss of fat planes between the tumor and adjacent structures in the mediastinum and displacement or indentation of other mediastinal structures (Fig. 31.2). Aortic invasion is suggested if 90° or more of the aorta is in contact with the tumor or if there is obliteration of the triangular fat space between the esophagus, aorta, and spine adjacent to the primary tumor. A tracheobronchial fistula or tumor extension into the airway lumen is a definite sign of tracheobronchial invasion. Displacement of the trachea or bronchus or indentation of the posterior wall of the trachea or bronchus by the tumor has been proved accurate in predicting tracheobronchial invasion. Pericardial invasion is suspected if pericardial thickening or pericardial effusion is seen. In cachectic patients, especially after neoadjuvant therapy, the cleavage planes of the fat may not be reliable, with a real difficulty in staging. An important limitation of CT in staging esophageal cancer is its lack of sensitivity for detecting lymph node metastases, since even a normal-sized lymph node might contain microscopic metastatic foci that are beyond the level of detection offered by CT. CT has an established role in the detection of distant organ metastases (M1b) (Kim et al. 2009; Kwon et al. 2005). CT plays a key role in follow-up after surgery and in planning and follow-up of implants, thanks to the MPR and 3D reconstructions in various planes (Fig. 31.3a, b).

The long execution time of MRI is a limiting factor in patients with reduced compliance. This method visualizes the primary tumor as an abnormal and asymmetric wall thickening of the esophagus. The superior contrast resolution achieved with MRI would suggest that the technique is likely to be useful in differentiating tumors abutting surrounding structures (stage T3) from direct invasion of tumor into the surrounding tissues (stage T4), and, thanks to ­innovative diffusion-weighted sequences, it has greater sensitivity than CT in identifying metastatic lymphadenopathy (Riddell et al. 2007).

Although PET has been shown to have a higher sensitivity than CT in the detection of primary esophageal cancer, it is of limited value in assessing T stage because it provides little information on the depth of tumor invasion. The sensitivity and specificity for the detection of locoregional metastases are low (51 and 84 %, respectively). Intense uptake of FDG by the primary tumor commonly complicates interpretation by obscuring the adjacent regional lymph node basins. In contrast, sensitivities as high as 90 % have been reported in the detection of metastatic lymph nodes at distant sites (M1a) and distant metastases (M1b). The differentiation between FDG uptake by peritumoral lymph nodes and that by the ­primary tumor might be improved with PET-CT, which, at present, is the best imaging modality for the evaluation of therapeutic response to neoadjuvant treatment (Bruzzi et al. 2007).

Stomach cancer remains the second most common cancer worldwide. While benign forms have no predilection for age, diagnosis at an advanced age is an expression of a missed diagnosis. Carcinoma is recognized as a neoplasm of the elderly, with a peak incidence in the seventh decade of life. However in this group of patients, compared to younger people, the tumor is a distinct clinical pathologic entity with some peculiar elements. In both the non-endemic and endemic lesions, in patients older than 65 years, there is a preponderance of women (male to female ratio of 1.6:1–2.4:1). The site is in the middle and lower third of the stomach; the macroscopic appearance is type IIc (46 %) followed by types I and IIa for early gastric cancer and type III for advanced cancer. Regardless of the stage, several studies have demonstrated that in elderly patients gastric cancer is often a well-differentiated form ­(papillary and tubular adenocarcinoma), while the poorly differentiated forms represent only 10 % of all cases.

The well-differentiated intestinal-type adenocarcinoma is more frequent in the elderly and usually tends to spread to the liver, while peritoneal carcinomatosis is uncommon.

In advanced forms, the locoregional lymph node involvement is no different than in young patients (high incidence), while in early gastric cancer lymph node involvement is less common than in the young (Saif et al. 2010).

Gastric cancer in aged people is often a hidden injury, responsible for iron-deficiency anemia, expression of chronic oozing blood, associated with a state of malnutrition; these symptoms are nonspecific and are very common in the elderly; they are epiphenomena of a myriad of clinical entities not necessarily related to the location and extent of the cancer. The tumor may not be clinically evident until it reaches a considerable size, causing a mechanical obstruction with involvement of perivisceral loose connective tissue (T4), lymph node, and distant metastasis (Arai et al. 2004).

Therefore, the diagnosis is not easy, especially in non-endemic areas where there is no screening strategy.

Endoscopic ultrasound is considered to be the most accurate imaging modality currently available for primary tumor staging (T staging). The double-contrast barium X-ray is considered the best technique for identifying early cancer, despite its low specificity. CT plays a key role in the staging and during and after medical therapy and surgery. PET, in particular PET-CT, is the best imaging modality for evaluation of therapeutic response to treatment.

MRI has the same advantages as CT but the long execution time is a limiting factor in patients with reduced compliance.

Although the small intestine alone includes more than 90 % of the mucosal surface of the entire GIT, tumors are rare; only about 3–6 % of all gastrointestinal primary tumors, more “common” but often unrecognized, are the metastases. The most common benign tumor in the elderly is the adenoma, whereas malignancies have a peak incidence between the sixth and seventh decades and are represented by adenocarcinoma (45 %), lymphoma (15 %), and stromal tumors (10 %), including GIST and carcinoid. It is more common in men than in women. The diagnosis is difficult and represents a challenge for the clinician and the radiologist.

Neoplasms are often asymptomatic and if there are any symptoms, they are frequently aspecific (anorexia, weight loss, iron-deficiency anemia, dyspepsia) and in 60–75 % of cases indicative of malignancies. Commonly, the ­clinical manifestation of cancer is an acute abdominal massive bleeding, perforation, and mechanical ileus (Grassi et al. 2004; Ruiz-Tovar et al. 2009).

Inadequate radiograph or incorrect interpretation of radiographic signs contributes to diagnostic delay. Although endoscopy, videocapsule, and traditional enteroclysis are routine procedures, their usefulness is limited to the study of wall lesions (Albert et al. 2005). In addition, the poor tolerability, due to the long execution time and to the intrinsic difficulties of the procedures, reduces the use in elderly patients.

Ultrasound is often the first exam when the symptoms are nonspecific. The major limitation is the small lesions of the bowel wall which can be disregarded, and to the difficulty of defining the organ of origin in big expansive processes. Ultrasound has a role in the identification of intussusception, noting that primary or secondary wall lesions can be a locus of intussusception. Therefore, in neoplastic disease of the small bowel, ultrasound can be helpful, but not conclusive, and must be supplemented by axial methods.

CT and MRI, with or without enteroclysis, not only provide adequate detail of the wall but also extraparietal, locoregional, and distant metastases, so that it is possible to obtain at one time a correct staging (Di Mizio et al. 2006). MRI has a higher intrinsic contrast resolution than CT, but the long execution times of the examination and the frequently poor cooperation of patients reduce the performance in clinical practice. CT examination is faster and better tolerated (Engin 2008). In the last 10 years, CT has become the method of choice for the study of the small intestine thanks to the possibility of acquiring thin collimation images and with the help of double contrast, oral and venous, as well as the possibility of post-processing reconstruction of the images in coronal and sagittal planes (Maglinte et al. 2007). CT also plays a role in the follow-up of patients during neoadjuvant, adjuvant, and postoperative therapy identifying early complications and relapse or recurrence of local/distant disease (La Seta et al. 2006).