Therapeutic outcome and related predictors of stereotactic body radiotherapy for small liver-confined HCC: a systematic review and meta-analysis of observational studies

Table 1 Assessment of study quality by Newcastle–Ottawa scale

Study	Selection				Comparability		Ascertainment of exposure/outcome			Score
Study	1	2	3	4	5	6	7	8	9	Score
Sun et al. [10]	√	√	√	√	×	√	√	√	√	8
Parikh et al. [11]	√	√	√	√	×	×	√	×	√	6
Jun et al. [22]	√	√	√	√	×	×	√	×	√	6
Jun et al. [17]	√	√	√	√	√	×	√	√	√	8
Jeong et al. [19]	√	√	√	√	×	√	√	√	√	8
Su et al. [23]	√	√	√	√	√	√	√	×	√	8
Takeda et al. [26]	√	√	√	√	×	×	√	√	√	7
Scorsetti et al. [8]	√	√	√	√	√	√	√	×	√	8
Kimura et al. [24]	√	√	√	√	√	√	√	√	√	9
Shiozawa et al. [12]	√	√	√	√	×	×	√	×	√	6
Naoko Sanuki et al. [25]	√	√	√	√	×	×	√	√	√	7
Yoon et al. [9]	√	√	√	√	×	×	√	√	√	7
Jung et al. [18]	√	√	√	√	√	√	√	√	√	9
Kwon et al. [16]	√	√	√	√	√	√	√	√	√	9

For cohort studies: 1, truly representative of exposed cohort; 2, non-exposed cohort drawn from the same community; 3, ascertainment of exposure; 4, outcome of interest not present at start; 5, cohorts comparable on basis of tumor stage (BCLC/UICC), or tumor size, or Child–Pugh class/score according to different research endpoint (tumor stage was used if studies mainly on treatment outcome OS, or tumor size was used if studies mainly on treatment outcome LC, or CP class/score was used if studies only about toxicity); 6, cohorts comparable on other factors (for example, we use liver Dmean for SBRT toxicity, CP class/score for OS, radiation dose for LC); 7, quality of outcome assessment; 8, follow-up long enough for outcome to occur (median/mean FU ≥ 12 months for adverse effect, and ≥ 24 months for treatment outcome OS/LC); and 9, complete accounting for cohort

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