Meta-analysisindependent cross-checkabstract checked I-CHM-112 standard review
Self-reported thinking problems after chemotherapy
Association of chemotherapy and subjective cognitive impairment in breast cancer patients: Meta-analysis of longitudinal prospective cohort studies.
Overview
Kim HJ et al.. Eur J Oncol Nurs 2022 · PMID 35255262 · DOI 10.1016/j.ejon.2022.102099
Patients reported more thinking problems mainly in the first month after chemotherapy; the difference was small compared with patients who had no chemotherapy.
Does the study support the specific claim? Partly · Methodological quality: moderate
Plain-language summary
Study explained simply
- What did the researchers want to find out?
Pool long-term studies
- How was the study done?
Meta-analysis
- How many people, animals or samples were studied?
13 studies
- What was actually found?
Mostly short-term effect
- How large was the observed effect?
g -0.19 to -0.85
- What do the results mean in everyday life?
Many people improve after treatment ends
- What are the study's limitations?
Self-report only
- What does it say about Elawady's specific claim?
Limits 'persistent'
- Do the results apply to Germany and Europe?
High
- What can explicitly not be concluded from this study?
Cannot rule out lasting problems in a subgroup
Scientific in-depth review
1. Full reference
- Authors
- Kim HJ et al.
- Journal
- Eur J Oncol Nurs
- Year
- 2022
- Identifier
- PMID 35255262 DOI 10.1016/j.ejon.2022.102099
- Verification
- verified – PubMed efetch 2026-10-26 (PublicationType and CommentsCorrections checked); Crossref 2026-10-26
- Retracted
- no
- Corrections
- none
- Extent checked
- abstract only
- Conflicts of interest and funding
Not stated in abstract.
2. Research question
Is chemotherapy associated with time-dependent subjective cognitive impairment in breast cancer?
3. Study design and population
- Study design
- Meta-analysis – Meta-analysis of longitudinal prospective cohort studies
- Population
Breast cancer patients with and without chemotherapy; healthy controls
- Country
International
- Period
Not stated in abstract
- Sample size
13 studies (9 data sets)
- Inclusion and exclusion criteria
Longitudinal prospective cohorts
4. Methods and endpoints
- Exposure / intervention
Chemotherapy
- Comparator
Non-chemotherapy patients; healthy controls
- Endpoints
Subjective cognitive impairment by time period
- Statistical methods
Hedges g by clinical period
5. Actual results
- Results
Chemotherapy patients had worse subjective cognitive impairment after starting chemotherapy: g -0.19 vs non-chemotherapy patients and -0.50 vs healthy controls; largest effect within 1 month post-chemotherapy (g -0.85).
- Absolute risks
not applicable (standardised mean differences)
- Authors' conclusion
Chemotherapy is associated with subjective cognitive impairment; the impact appears acute rather than chronic.
6. Strengths
- Longitudinal designs only
- Time-period analysis
7. Weaknesses
- Few data sets
- Subjective outcomes only
- Overlap with other meta-analyses
8. Risk of bias
- Orienting tool
- AMSTAR 2
- Type of assessment
- simplified assessment (abstract only)
- Full formal assessment
- no
- Overall risk of bias
- some concerns
- Rationale
Abstract-level; small evidence base.
9. Assessment of the statistical interpretation
g -0.19 means about 42% of treated patients score better than the control mean (U3), i.e. a small effect (stats/C-CHM-04.py).
10. Relevance to the specific claim
Limits the word 'persistent': effects are strongest shortly after treatment and small against non-chemotherapy patients.
11. Independent contrary findings
Janelsins 2018 (I-CHM-111): decline still present at 6 months.
12. Transferability to Germany and Europe
Applicable.
13. Overall methodological judgement
Small-to-moderate, mostly acute effect.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | moderate |
| Risk of bias | some concerns |
| Precision of results | moderate |
| Directness | direct |
| Reproducibility | partly replicated |
| Consistency with the overall evidence | mixed |
| Regional transferability | high |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
Long-term trajectory.
15. Linked fact checks
- Chemotherapy causes persistent cognitive decline ('chemo fog'). – Studies with mixed or unclear results