TABLE 1.

Study characteristics included studies

Authors	Treatment groups	Time points, T	Objective tests, N	Criteria cognitive impairment	Criteria cognitive decline	Risk of bias individual studies	Conclusion
Collins et al. (2009) 32	CT (N = 53)	T0: before CT	19	N/A	Standardized regression‐based scores of −2 or less on at least two tests. 75	Low	From T0 to T1, 34% of CT patients and 13% of no‐CT patients declined. From T0‐T3, 11% of CT patients and 10% of no‐CT patients declined.
	No‐CT (N = 40)	T1: after CT
		T2: 12 months FU
Collins et al. (2013) 3	CT (N = 60)	T0: before CT	17	Scores lower than 2 SD on at least two tests.	N/A	Low	At T0, 12% of CT patients scored impaired, and at T1, 37%.
	HC (N = 60)	T1–T6: after each CT cycle
Collins et al. (2014) 45	CT (N = 56)	T0: before CT	17	N/A	Standardized regression‐based scores of −2 or less on at least two tests. 75	Low	48% of the CT patients declined. From T0‐T3, 22% declined.
	HC (N = 56)	T1–T6: after each CT cycle
		T7: 12 months FU
Debess et al. (2010) 46	CT (N = 75)	T0: before CT	4	N/A	Significant changes (between 5th and 95th percentile in controls) on at least two tests. 76	Low	From T0 to T1, 4% of CT patients and 15% of no‐CT patients declined.
	No‐CT (N = 26)	T1: after CT
	No‐T (N = 19)
	HC (N = 208) a
Hermelink et al. (2007) 37	CT (N = 101)	T0: before CT	7	Scores in the lower 5% range on two or more tests.	Reliable change index, with a probability error of 10%. 77	Medium	At T0, 31% of CT‐patients scored impaired. From T0‐T1, 27% declined.
		T1: after CT
Hermelink et al. (2017) 43	CT (N = 91)	T0: before CT	8	Scores below 1.5 SD on five or more tests or lower than 2 SD on at least four tests.	N/A	Low	At T1, 6% of CT patients and 3% of no‐CT patients scored impaired. At T2, 18% of CT patients and 18% of no‐CT patients scored impaired.
	No‐CT (N = 66)	T1: after CT
	HC (N = 60)	T2: 6 months FU
Hurria et al. (2006) 38	CT (N = 31)	T0: before CT	10	Scores lower than 2 SD on at least two tests.	A decrease of one or more SD on at least two tests in at least two domains.	Low	At T0, 11% of CT‐patients scored impaired and at T2, 29%. From T0‐T1, 39% declined and 11% improved.
		T1: 6 months FU
Jansen et al. (2011) 27	CT (N = 71)	T0: before CT	7	Scores below 1.5 SD on at least two tests or lower than 2 SD on at least one test.	Indicated on each cognitive domain by using hierarchical linear modelling. 78	Low	At T0, 23% of CT patients scored impaired, at T1, 52%, and at T2, 20%. From T0‐T1, 29% declined and from T0 to T2, 3% declined.
		T1: mid‐CT
		T2: after CT
		T3: 6 months FU
Jenkins et al. (2006) 47	CT (N = 85)	T0: before CT	8	N/A	Reliable change index on at least two measurements. 77	Low	From T0 to T1, 20% of CT patients and 26% of no‐CT patients declined. From T0–T3, 18% of CT‐patients and 14% of no‐CT patients declined.
	No‐CT (N = 43)	T1: after CT
	HC (N = 49)	T2: 12 months FU
Kesler et al. (2017) 39	CT (N = 31)	T0: before CT	4	Scores below 1.5 SD on at least two tests or lower than 2 SD on at least one test.	N/A	Medium	At T0, 32% of the CT patients scored impaired and at T3, 55%.
		T1: after CT
		T2: 12 months FU
Mehlsen et al. (2009) 48	CT (N = 34)	T0: before CT	13	N/A	Reliable change index on at least three measurements. 77	Medium	From T0 to T1, 28% of the CT patients declined.
	Cardio (N = 12)	T1: after CT
	HC (N = 12)
Menning et al. (2016) 44	CT (N = 31)	T0: before CT	11	Multivariate normative comparison with a probability error of 5%.	N/A	Low	At T2, 16% of systemic patients (CT and/or ET) and 4% of non‐systemic patients scored impaired.
	No‐CT (N = 24)	T1: 6 months FU
	HC (N = 33)
Ruzich et al. (2007) 40	CT (N = 35)	T0: before CT	15	Scores below 1 SD on at least two tests.	N/A	Low	At T0, 51% of CT patients scored impaired, at T1, 31%, and at T2, 30%.
		T1: mid‐CT
		T2: after CT
		T3: 6 months FU
Schagen et al. (2006) 36	CT (N = 67)	T0: before CT	10	Scores below 2 SD on at least three tests.	Reliable change index on at least four measurements. 77	Low	At T0, 16% of systemic patients (CT and/or ET) and 30% of non‐systemic patients scored impaired. At T2, 15% and 23% scored impaired, respectively. From T0 to T2, 18% of systemic patients and 18% of nonsystemic patients declined.
	No‐CT (N = 57)	T1: 6 months FU
	HC (N = 60)
Schrauwen et al. 2020 49	CT (N = 69)	T0: before CT	5	N/A	Standardized difference score exceededing ‐2.5 SD on at least one test.	Low	From T0 to T1, 24% of CT patients, 15% of no‐CT patients declined, and 7% of healthy controls declined.
	No‐CT (N = 41)	T1: after CT
	HC (N = 56)
Vearncombe et al. (2009) 79	CT (N = 136)	T0: before CT	10	N/A	Reliable change index on at least two measurements. 77	Low	From T0 to T1, 17% of CT patients declined.
		T1: after CT
Wefel et al. (2010) 26	CT (N = 42)	T0: before CT	6	Scores below 2 SD on at least one test.	Reliable change index. 77	Low	At T0, 21% of CT patients scored impaired. From T0 to T2, 65% declined and from T0 to T3, 61% declined.
		T1: mid‐CT
		T2: after CT
		T3: 12 months FU

Note: The “CT‐group” consists of patients indicated for chemotherapy and if necessary, radiotherapy and/or endocrine therapy. The “no‐CT group” consists of patients indicated for radiotherapy and/or endocrine therapy.

Abbreviations: CT, chemotherapy; FU, follow‐up; HC, healthy control group; N, sample size; NA, not assessed; no‐CT, endocrine therapy and/or radiation therapy.

^aThe authors did not report the prevalence of cognitive decline or cognitive improvement for the healthy controls.