Limitations
Due to its observational non-randomized design, the current study is
subject to limitations as described in detail previously (17). Thus,
despite efforts to control for confounding factors by applying
multivariate analysis, we cannot exclude unmeasured factors, which could
have biased the results. Moreover, data regarding 5 years survival rate
is limited in the late period with no long term data since the year
2016. Nevertheless, in spite of these limitations, the study in a
multicenter nationwide survey with large study population and long term
outcomes.