Prospective, randomized, controlled trials and meta-analyses of prospective, randomized, controlled trials.
The randomized, double-blinded, controlled trial is the gold standard of study design. To achieve this ranking, the study allocation must be blinded to the investigator both before and after the randomization and the assignment to intervention group. This design provides protection from allocation bias by the investigator and from bias in the assessment of outcomes by both the...
The incidence of esophageal cancer has risen in recent decades, coinciding with a shift in histologic type and primary tumor location.[2,3] Adenocarcinoma of the esophagus is now more prevalent than squamous cell carcinoma in the United States and western Europe, with most tumors located in the distal esophagus. The cause for the rising incidence and demographic alterations is unknown.
While risk factors for squamous cell carcinoma of the esophagus have been identified (e.g., tobacco, alcohol, diet), the risk factors associated with esophageal adenocarcinoma are less clear. The presence of Barrett esophagus is associated with an increased risk of developing adenocarcinoma of the esophagus, and chronic reflux is considered the predominant cause of Barrett metaplasia. The results of a population-based, case-controlled study from Sweden strongly suggest that symptomatic gastroesophageal reflux is a risk factor for esophageal adenocarcinoma. The frequency, severity, and duration of reflux symptoms were positively correlated with increased risk of esophageal adenocarcinoma.
Esophageal cancer is a treatable disease, but it is rarely curable. The overall 5-year survival rate in patients amenable to definitive treatment ranges from 5% to 30%. The occasional patient with very early disease has a better chance of survival. Patients with severe dysplasia in distal esophageal Barrett mucosa often have in situ or even invasive cancer within the dysplastic area. Following resection, these patients usually have excellent prognoses.
Primary treatment modalities include surgery alone or chemotherapy with radiation therapy. Combined modality therapy (i.e., chemotherapy plus surgery, or chemotherapy and radiation therapy plus surgery) is under clinical evaluation. Effective palliation may be obtained in individual cases with various combinations of surgery, chemotherapy, radiation therapy, stents, photodynamic therapy,[6,7,8] and endoscopic therapy with Nd:YAG laser.
One of the major difficulties in allocating and comparing treatment modalities for patients with esophageal cancer is the lack of precise preoperative staging. Standard noninvasive staging modalities include computed tomography (CT) of the chest and abdomen and endoscopic ultrasound (EUS). The overall tumor depth staging accuracy of EUS is 85% to 90%, as compared with 50% to 80% for CT; the accuracy of regional nodal staging is 70% to 80% for EUS and 50% to 70% for CT.[10,11] EUS-guided fine-needle aspiration (FNA) for lymph node staging is under prospective evaluation; one retrospective series reported a 93% sensitivity and 100% specificity of regional nodal staging with EUS-FNA. Thoracoscopy and laparoscopy have been used in esophageal cancer staging at some surgical centers.[13,14,15] An intergroup trial reported an increase in positive lymph node detection to 56% of 107 evaluable patients using thoracoscopy/laparoscopy, from 41% (using noninvasive staging tests, e.g., CT, magnetic resonance imaging, EUS) with no major complications or deaths. Noninvasive positron emission tomography using the radiolabeled glucose analog 18-F-fluorodeoxy-D-glucose for preoperative staging of esophageal cancer is under clinical evaluation and may be useful in detecting stage IV disease.[17,18,19,20]