Collision Tumors of the Gastrointestinal Tract: A Systematic Review of the Literature

Abstract

Background/aim: Collision tumors are rare neoplasms which consist of two or more distinct neoplasms that develop adjacent to one another and coexist with no or minimal intermingling between them. Their diagnosis is often incidental and their behavior remains widely unknown. Several theories have been proposed regarding their pathogenesis. The objective of this study was the evaluation of current evidence on collision tumors of the gastrointestinal tract regarding their pathology, biological behavior and treatment approach.

Materials and methods: The PubMed and Cochrane bibliographical databases were searched from January 1997 to July 2018 (last search: July 5th, 2018) for studies reporting on collision tumors of the gastrointestinal tract that also included a therapeutic approach.

Results: Forty-seven studies reporting on collision tumors of the gastrointestinal tract were identified. They reported collectively on 53 cases (43 males, 10 females) with collision tumors of the esophagus, stomach, small intestine and large intestine. The vast majority (96.2%) of tumors consisted of two distinct histological components and only two cases involved a greater number of histological subtypes. Fifty-one patients underwent a surgical or endoscopic tumor resection, accompanied in 22 cases by adjuvant or neoadjuvant therapy. The remaining two patients underwent palliative operations. In total, three patients experienced immediate postoperative complications.

Conclusion: Collision tumors of the gastrointestinal tract, despite their rare nature, constitute a quite interesting field of study. This review offers a thorough insight into the clinicopathological characteristics and biological behavior of these rare tumors.

Keywords: Collision tumors; esophagus; gastrointestinal tract; large intestine; rare tumors; small intestine; stomach; systematic review.