Funding for this research was provided by:
the Natural Science Foundation of Guangdong, China (2015A030313010)
Text and Data Mining valid from 2018-05-11
Received: 9 February 2018
Accepted: 24 April 2018
First Online: 11 May 2018
Ethics approval and consent to participate
: As the data used was from SEER dataset (public), Ethics approval and consent to participate could be checked in SEER.
: All authors declare that they have no competing interests.
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