Article History
Received: 18 February 2018
Accepted: 15 May 2018
First Online: 31 May 2018
Compliance with ethical standards
:
: This work followed the guidelines set forth in the Helsinki Declaration of 1975, as revised in 2000, concerning Human and Animal Rights. This article does not contain human or animal subjects performed by any authors. This was a retrospective study approved by the institutional review board of the National Cancer Center Hospital.
: There are no financial or other relations that could lead to a conflict of interest.