title: Factors influencing difficulty of the thoracic procedure in minimally invasive esophagectomy.
abstract: Minimally invasive esophagectomy (MIE) is being increasingly performed worldwide. When performing MIE, we sometimes experienced difficulties due to a narrow upper mediastinum or a middle to lower thoracic esophagus hidden by the projection of the vertebral body. However, there were no reports regarding the influence of anatomical factors on the difficulty of performing MIE. The aim of this study was to evaluate whether anatomical factors could be related to the difficulty of the thoracic procedure in MIE.
  
  
  
  We investigated 87 consecutive patients undergoing MIE for primary esophageal cancer between 2013 and 2015 and created novel indices to assess the upper mediastinal narrowness and vertebral body projection at middle thoracic part on preoperative computed tomography images. We assessed clinicopathological and anatomical factors and determined the factors influencing the thoracic procedural difficulty in MIE. The thoracic procedure duration was selected as the variable representing technical difficulty.
  
  
  
  The mean thoracic procedure duration was 280.2 ± 52.5 min. There were no significant correlations between the indices and patient factors such as age, sex, and body mass index. Meanwhile, there was a significant correlation between the upper mediastinal narrowness and the vertebral body projection (p < 0.01). Of the clinicopathological and anatomical factors, blood loss during the thoracic procedure, thoracic duct resection, and vertebral body projection independently were related to the prolonged thoracic procedure duration in multiple linear regression analysis (p = 0.01, 0.03, and <0.01, respectively). The other factors including upper mediastinal narrowness were not statistically significant.
  
  
  
  This is the first study to reveal the influence of anatomical factors on the difficulty of the thoracic procedure in MIE. The vertebral body projection at middle thoracic part appears to be a useful tool for predicting the thoracic procedural difficulty in MIE preoperatively.
authors.affiliation: Department of Gastroenterological Surgery, Cancer Institute Hospital of the Japanese Foundation for Cancer Research, 3-8-31 Ariake, Koto-ku, Tokyo, 135-8550, Japan.
authors.forename: Akihiko
authors.initials: A
authors.lastname: Okamura
authors.affiliation: Department of Gastroenterological Surgery, Cancer Institute Hospital of the Japanese Foundation for Cancer Research, 3-8-31 Ariake, Koto-ku, Tokyo, 135-8550, Japan. masayuki.watanabe@jfcr.or.jp.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Watanabe
authors.affiliation: Department of Gastroenterological Surgery, Cancer Institute Hospital of the Japanese Foundation for Cancer Research, 3-8-31 Ariake, Koto-ku, Tokyo, 135-8550, Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Mine
authors.affiliation: Department of Gastroenterological Surgery, Cancer Institute Hospital of the Japanese Foundation for Cancer Research, 3-8-31 Ariake, Koto-ku, Tokyo, 135-8550, Japan.
authors.forename: Koujiro
authors.initials: K
authors.lastname: Nishida
authors.affiliation: Department of Gastroenterological Surgery, Cancer Institute Hospital of the Japanese Foundation for Cancer Research, 3-8-31 Ariake, Koto-ku, Tokyo, 135-8550, Japan.
authors.forename: Yu
authors.initials: Y
authors.lastname: Imamura
authors.affiliation: Department of Gastroenterological Surgery, Cancer Institute Hospital of the Japanese Foundation for Cancer Research, 3-8-31 Ariake, Koto-ku, Tokyo, 135-8550, Japan.
authors.forename: Takanori
authors.initials: T
authors.lastname: Kurogochi
authors.affiliation: Department of Surgery, School of Medicine, Keio University, Tokyo, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Kitagawa
authors.affiliation: Department of Gastroenterological Surgery, Cancer Institute Hospital of the Japanese Foundation for Cancer Research, 3-8-31 Ariake, Koto-ku, Tokyo, 135-8550, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Sano
mesh_terms: D016063:Blood Loss, Surgical; D004938:Esophageal Neoplasms / Q000601:surgery*; D016629:Esophagectomy / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008482:Mediastinum / Q000033:anatomy & histology; D008875:Middle Aged; D019060:Minimally Invasive Surgical Procedures / Q000009:adverse effects* / Q000379:methods*; D061646:Operative Time; D013904:Thoracic Vertebrae / Q000033:anatomy & histology
keywords: Anatomical factor; Minimally invasive esophagectomy; Surgical difficulty; Vertebral body