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Received Sep 25, 2017; Accepted Jan 4, 2018
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1. Introduction
Esophageal carcinoma is a highly aggressive neoplasm and is the eighth most common cancer worldwide [1]. The most patients are diagnosed at a locally advanced stage, with a long-term survival rate of around 10%–60% [2–4]. In 2008, there is an estimate of 482,000 patients newly diagnosed with esophageal carcinoma and 407,000 died of this disease [5]. Identification of prognostic factors of esophageal cancer is of clinical significance since it may be helpful to conduct clinical interventions to improve the prognosis of the high-risk patients. Currently, transthoracic esophagectomy with radical lymphadenectomy followed by postoperative adjuvant chemotherapy or radiotherapy is the standard curative treatment for locally advanced esophageal cancer [6].
Highly malignant tumors usually grow rapidly and metabolize actively and even lead to progressive body consumption and weight loss at diagnosis. This poor physical condition will hinder the treatment process, thereby affecting the survival. Excessive pretreatment weight loss has been shown to have an adverse effect on the survival outcome in many cancers, such as pancreatic cancer [7] and head and neck cancer [8]. Due to the tumor-related dysphagia, vomiting, reduced oral intake, and altered nutrient metabolism associated with systemic inflammation, weight loss is also a common presenting symptom of esophageal cancer [9–11]. On the other hand, both body weight and body mass index (BMI) are important factors for evaluating patient’s nutritional status, tolerance to therapeutic interventions, and other considerations associated with the treatment response [12]. Hence, a number of studies have been conducted to investigate the effects of weight loss and BMI on the prognosis of esophageal cancer patients.
Until now, however, the impact of initial BMI on the survival of esophageal carcinoma patients remains contradictory [13–15]. Duan et al. have demonstrated that high BMI has a distinctly adverse impact on the long-term survival of esophageal squamous cell carcinoma patients after esophagectomy [14]. On the contrary, Miao et al. have reported that a high BMI is not associated with increased overall morbidity following esophagectomy [15]. Likewise, the influence of weight loss on the survival outcome of...