This study is significant as it provides an insight into the imaging patterns and features esophageal cancer in Ethiopia.
The result of this study demonstrates that endoscopy, chest CT scan, BS imaging, and AUS scanning are commonly used diagnostic tools in patients with esophageal cancer in Ethiopia. 97% of the patients in this study underwent endoscopy, 96% underwent chest CT scan, 62.2% underwent BS imaging, and 93% underwent AUS scanning. These findings are consistent with the results of previous studies which have shown that endoscopy, chest CT scan and BS commonly used diagnostic tools for esophageal cancer (19). However, there are some differences from the typical recommendations, which advise a work-up based on the stage of the disease, as well as the implementation of various other modalities. The Society of Thoracic Surgeons Guidelines on the Diagnosis and Staging of patients with esophageal cancer recommends CT of the chest and abdomen for both early stage and locoregional esophageal cancer. Additionally, PET scan is also recommended for both stages of cancer. EUS is also recommended in the absence of metastatic disease (20). Despite its high utilization in the present study, AUS was not reported as a routine imaging modality for staging of esophageal cancer.
The esophagus extends from the cricopharyngeus muscle to the GEJ and is divided into four parts: the cervical esophagus (18 cm from the incisors), the upper thoracic (24 cm from the incisors), the middle thoracic (32 cm from the incisors), and the lower thoracic (40 cm from the incisors) (21, 22). Siewert and his colleagues have developed a classification system for cancer involving the GEJ based on the location of the tumor (23). Type I adenocarcinoma is located from > 1 cm up to 5 cm above the junction (Z line), Type II within 1 cm cephalad to 2 cm caudad to the junction, and Type III > 2 cm below the junction. Only Type I/II tumors are included in the most recent American Joint Committee on Cancer (AJCC) staging system for esophageal cancer (23). CT scan and endoscopy can be used to evaluate the primary tumor location of esophageal tumor. Endoscopy can determine the distance of the tumor from the incisors, identify any additional lesions, and check for Barrett esophagus. In this study, chest CT and endoscopy were used to assess the site of the lesion in nearly every case. The results of the study showed that 42.6% of cases had lower thoracic, 23% had middle-third thoracic, 7.8% had upper thoracic esophageal cancer, 6.5% had cervical part esophageal cancer, and 8.7% had GEJ cancer on chest CT scan. Endoscopy findings were similar, with 33.5% in the lower thoracic, 16.5% in the middle third, 5.2% in the upper thoracic, 12.2% in the cervical part, and 9.6% at the GEJ. This finding was in contrast to previous reports, which showed approximately 60% of SCC located in the middle third of the esophagus, 30% in the distal third, and 10% in the proximal third of the intrathoracic esophagus (24). However, our case revealed a different distribution pattern; despite the majority of patients having SCC (80.4%), the majority of tumors were located at a lower thoracic level according to the findings on CT scans (42.6%) and endoscopy (33.5%). This difference may be attributable to risk factors linked to the illness or an unidentified factor that necessitates further exploration. The discrepancy between chest CT and endoscopy can be due to a variety of factors, including the accuracy of imaging techniques, the size and shape of the lesion, and the presence of inflammation or other conditions. CT scans are generally more accurate in detecting larger lesions, while endoscopy is more accurate for smaller lesions.
Esophageal cancer is one of the most aggressive cancers, as it can spreads rapidly to nearby organs and tissues. CT scans are an invaluable cross-sectional imaging tool to detect mediastinal invasion with an accuracy ranging from 59 to 82% (19, 25, 26). Dynamic CT may slightly enhance the accuracy of N staging overall (15). Tumor infiltration of adjacent mediastinal structures, such as the aorta or tracheobronchial tree, classifies the tumor as a T4 lesion and is typically inoperable (19). The results of present study showed that esophageal cancer primarily invades the aorta, trachea or bronchus, atrium, diaphragm, pulmonary vessels, pericardium, liver or peripancreatic structures, pleura, thyroid lobe, and lung.
An autopsy report revealed that 74.5% of esophageal cancer cases had lymph node metastases, while 50% of cases had visceral metastases (27). Previous studies have indicated a distinct pattern of lymph node involvement in esophageal cancer(28, 29). Upper mediastinal nodes are the primary site of metastasis for tumors in the upper esophagus, whereas paracardial nodes have the highest incidence for lower esophageal tumors (28, 29). Additionally, supraclavicular nodes have a high rate of metastasis for both upper and mid-esophageal tumors, and upper mediastinal nodes are almost as likely as lower mediastinal nodes for lower esophageal tumors (28, 29). Squamous cell carcinoma of the esophagus can metastasize to the internal jugular, supraclavicular, paratracheal, hilar, subcarinal, paraesophageal, paraaortic, pericardial, left gastric, and celiac lymph node chains (19, 26). If the celiac lymph nodes are affected, the disease is deemed distant metastasis (M1). For esophageal adenocarcinoma, however, celiac adenopathy is considered a regional nodal metastasis (N1) (19, 26). In our study, the most common lymph nodes involved during presentation were celiac, paraoesophageal, lower mediastinal, paratracheal, subcarinal, superior mediastinal and hilar lymph nodes. This is in line with prior reports mentioned earlier (26, 28, 29).
Esophageal cancers metastasis can occur at any site in the body, with the lymph nodes, the lungs, and liver as the favored sites of metastases (19). Other common metastatic sites reported include adrenals, diaphragm, bronchus, pleura, stomach, bone, kidneys, trachea, pericardium, the heart, pancreas and the vocal cords (30, 31). Esophageal cancer can also spread to the spleen, the brain, and the bones, and some unexpected sites as well (31). CT scans are frequently utilized to identify metastases of esophageal cancer in faraway areas, especially in the lungs and liver. Nevertheless, locating peritoneal deposits, which often accompanies adenocarcinoma, can be difficult. EUS and AUS are also employed to determine metastasis in the mediastinum or abdominal organs. To assess the spread of the tumor within the chest and abdominal organs, CT scans and AUS were commonly used in the present study. Accordingly, one hundred nineteen patients had distant metastases to the liver (19.1%), lung (14.8%), celiac lymph nodes (10.4%), peritoneum (3%), supraclavicular lymph node (1.7%), vertebrae/bone (2.2%), or brain (0.4%). The patterns of metastasis reported in our study are largely similar to those reported previously (30, 31).
Esophageal cancer can present with various endoscopic features, such as abnormal mucosal appearance, mucosal thickening, ulcerations, and stricture formation. Abnormal mucosal appearance can vary from red and friable to atrophic with nodular, exophytic, or ulcerated lesions. Mucosal thickening is usually caused by infiltration of the underlying submucosal structures and can lead to strictures. Ulcerations may be single or multiple and can occur anywhere in the esophagus. Lastly, strictures are a common endoscopic feature of esophageal cancer, which can cause narrowing or blockage of the esophagus. In our study, mass was the most common finding reported on endoscopic evaluation was a mass (79.1%), followed by an ulcer (30.0%), obstruction (39.1%), esophagitis (0.9%), and Barrett's Esophagus (0.4%). Of the 182 endoscopic masses, 62.6% were exophytic, 3.3% were flat, 0.5% were excavated, and 33.5% were not classified in the report.
These days, chest CT scans and endoscopies have largely replaced barium swallows. However, the results of this study showed that barium swallows are still a highly utilized for diagnosing esophageal cancer in our setup. Of those 230 participants, 143 patients underwent barium swallow scanning. 39 (17%) patients had strictures, 22 (9.6%) had masses, and 5 (2.2%) had obstructions. This is in consistent with previous findings and recommendations (32). Previous research has indicated that barium studies can be used to assess the shape and size of esophageal cancer before and after treatment (19). Early-stage esophageal cancers often appear as plaque-like lesions, small polyps, or wall irregularities on a barium swallow (18). Superficial spreading carcinomas may also manifest as poorly defined nodules or merging growths, and may show irregular mucosal contours, exophytic growths, ulceration, or obstruction (18). Advanced esophageal cancers can present as four types: infiltrative, ulcerative, polypoidal, and varicoid (10, 32). Infiltrative lesions are the most common, appearing as narrowing of the lumen with irregular mucosa, nodules and ulceration (18). Ulcerative lesions are giant ulcers surrounded by a tumor rind, polypoid lesions are intraluminal masses with or without ulceration, and varicoid type appears as thickened longitudinal defects caused by submucosal infiltration (18). The results also suggest that barium swallow can be considered as an initial diagnostic test for esophageal cancer, but it may not always be sufficient to diagnose esophageal cancer. In this study, 94 (40.3%) patients had no findings on barium swallow. This indicates that other diagnostic tests are necessary to diagnose esophageal cancer in some cases. Additionally, reporting must follow a protocol to address all required points in order not to miss any findings since it could be due to technical issues.
Endoscopic sonography has proved to be a highly useful and accurate imaging tool for assessing esophageal cancer. It offers detailed images of the esophagus and surrounding structures, making it possible to measure the depth of tumor penetration with great accuracy. Reports indicate that it is even more accurate than CT, with accuracy rates ranging from 85–90% (26, 33). PET scans utilizing 2-F-18 fluoro-2-deoxy-d-glucose (18F-FDG) are becoming a popular way to stage esophageal cancer patients. PET scans have the advantage of total body coverage, allowing it to detect metastatic disease in distant nodes, liver, lung, bone, adrenal and others at initial evaluation (19). Reported accuracy for nodal staging is between 48 and 90% (34, 35). Surprisingly, none of the patients in our study were able to benefit from endoscopic ultrasonography and 18F-FDG PET technology due to limitations in the setup.
Strength
This study was conducted at the only referral hospital in Ethiopia that offers radiotherapy treatment, providing a good representation of the country.
Limitation
CT scan is recommended for both chest and abdomen scanning as a pretreatment imaging and response assessment, instead of AUS. However, in our case, CT scan was done only for the chest. Almost all of the scanning for abdominal metastasis was performed by AUS. Additionally, none of the cases underwent EUS and PET scan imaging, despite its high accuracy in staging, due to limitations in the setup.