Table 4.

Modified Newcastle-Ottawa Score and Jadad scale.

Cohort Studies	Selection				Comparability			Outcome			Modified Newcastle-Ottawa Score (Risk of Bias)
Author	Representativeness of cohort	Selection of non-exposed cohort	Ascertainment of exposure	Outcome of interest not present at onset	Control of confounding factors (extraction)	Control of confounding factors (field of radiation, timing, extraction protocol)		Assessment of outcome	Length of follow-up	Lost to follow-up
Morrish et al., 1981 [19]	x	x	x	x	x			x	x	x	8
Beumer et al., 1983 [15]	x		x	x		x		x	x	x	7
Epstein et al., 1987 [21]	x	x	x	x	x	x		x			7
Maxymiw et al., 1991 [12]	x		x	x	x			x	x	x	7
Lambert et al., 1997 [22]	x		x	x	x			x	x		6
David et al., 2001 [23]	x		x	x	x	x		x	x	x	8
Ben-David et al., 2007 [14]	x	x	x	x	x			x	x	x	8
Al-Bazie et al., 2016 [11]	x		x	x	x	x		x	x	x	8
RCT Studies	Randomization				Blinding			Description of Withdrawal and Dropouts			Jadad Scale
Author	1 point if randomization is mentioned	1 point if the method of randomization is appropriate		Deduct 1 point if the method of randomization is inappropriate	1 point if blinding is mentioned	1 point if the method of blinding is appropriate	Deduct 1 point if the method of blinding is inappropriate	1 point if withdrawal and dropouts are described
Marx et al., 1985 [20]	x