Funding for this research was provided by:
Natural Science Foundation of Zhejiang Province (LQ17H260001)
Text and Data Mining valid from 2018-11-16
Received: 13 February 2018
Accepted: 25 October 2018
First Online: 16 November 2018
Ethics approval and consent to participate
: The data in this study was obtained from SEER database and National Cancer Institute had given us permission to access data for researching (Reference number: 11114-Nov2016). Given that SEER data is de-identified and ethics approval is waived, this study was exempted from Institutional Research Board review.
: Not applicable.
: The authors declare that we have no competing interests.
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