Table 1.

Characteristics of included studies

Reference	Study type	Country	Study period	Sample size (n)			Follow-up time (months)
				Total	ART	SRT	ART	SRT
Briganti 2012	match-controlled	Italy	1991–2007	780	390	390	Median (IQR):71.9 (39–103)	Median (IQR):41 (10–60)
Buscariollo 2017	retrospective cohort	United States	1992–2013	401	171	230	Median (IQR):89 (55–158)	Median (IQR):96 (63–130)
Fossati 2016	retrospective cohort	Italy	1996–2009	510	243	267	Median (IQR):94 (53–126)	Median (IQR):92 (70–136)
Hwang 2018	retrospective cohort	United States	1987–2013	732	366	366	Median (IQR):65.8 (40–107)	Median (IQR):73.3 (44.9–106.6)
Borghetti 2017	retrospective cohort	Italy	1999–2012	258	127	131	Overall median:50.7	–
Hervas 2017	retrospective cohort	Spain	1991–2011	702	223	479	Overall median (range):34 (3–141)	–
Mishra 2015	retrospective cohort	United States	1990–2009	186	74	112	Overall median (range):103 (30–247)	–
Hsu 2015	retrospective cohort	United States	1995–2009	305	76	229	Overall median (range):74 (7–256)	–
Tilki 2016	retrospective cohort	Germany	2005–2013	718	213	505	Overall median (IQR):33.8 (17.1–49.0)	–
Detti 2012	retrospective cohort	Italy	1995–2010	307	203	104	Mean ± SD:3.3 ± 2.3	Mean ± SD:4.5 ± 2.5
Ost 2011	match-controlled	Belgium	1999–2009	178	89	89	Median (range):36 (3–120)	Median (range):36 (3–120)
Trabulsi 2008	matched-Control	United States	1987–2002	192	96	96	Median (range):97 (30–207)	Median (range):94 (26–190)
Tsien 2003	retrospective cohort	United States	1986–1997	95	38	57	Median (range):10.1 (4.8–14.5)	Median (range):8.8 (2.0–17.0)
Taylor 2003	retrospective cohort	United States	1988–1998	146	75	71	Median:68	Median:39

ART: adjuvant radiotherapy; SRT: salvage radiotherapy; IQR: interquartile range; SD: standard deviation