Randomised controlled trialcited by the Tayebat archiveabstract only checked A-CHM-08 standard review
Tamoxifen raises the small risk of uterine cancer but prevents far more breast-cancer events
Endometrial cancer in tamoxifen-treated breast cancer patients: findings from the National Surgical Adjuvant Breast and Bowel Project (NSABP) B-14.
Overview
Fisher B et al.. J Natl Cancer Inst 1994 · PMID 8133536 · DOI 10.1093/jnci/86.7.527
Uterine cancer about 1.6 vs 0.2 per 1,000 women per year; 38% fewer recurrence-type events.
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?
Assess second cancers under tamoxifen.
- How was the study done?
RCT vs placebo.
- How many people, animals or samples were studied?
2,843 + 1,220.
- What was actually found?
RR 7.5 endometrial cancer; benefit outweighs.
- How large was the observed effect?
1.6 vs 0.2/1000/year.
- What do the results mean in everyday life?
Report abnormal bleeding during tamoxifen; continue therapy.
- What are the study's limitations?
Few events; data-integrity issue.
- What does it say about Elawady's specific claim?
Mixed.
- Do the results apply to Germany and Europe?
High.
- What can explicitly not be concluded from this study?
That tamoxifen is net harmful.
Scientific in-depth review
1. Full reference
- Authors
- Fisher B, Costantino JP, Redmond CK, Fisher ER, Wickerham DL, Cronin WM
- Journal
- J Natl Cancer Inst
- Year
- 1994
- Identifier
- PMID 8133536 DOI 10.1093/jnci/86.7.527
- Verification
- verified – PubMed E-utilities efetch, 2026-10-25
- Retracted
- no
- Corrections
- none
- Extent checked
- abstract only
- Conflicts of interest and funding
not stated in abstract | Grants: NCI NIH HHS
2. Research question
Endometrial and other cancers in tamoxifen-treated breast cancer patients.
3. Study design and population
- Study design
- Randomised controlled trial – Randomised placebo-controlled trial (NSABP B-14) plus registered tamoxifen cohort
- Population
Node-negative ER-positive invasive breast cancer
- Country
USA/Canada (NSABP)
- Period
Average 8 years on study (randomised)
- Sample size
2,843 randomised + 1,220 registered
- Inclusion and exclusion criteria
Node-negative ER+ invasive breast cancer
4. Methods and endpoints
- Exposure / intervention
Tamoxifen 20 mg/d
- Comparator
Placebo
- Endpoints
Endometrial and other cancers; disease-free survival
- Statistical methods
Hazard rates per 1,000 patient-years; relative risks
5. Actual results
- Results
Endometrial cancer annual hazard 1.6/1000 (tamoxifen) vs 0.2/1000 (placebo), RR 7.5; vs SEER or NSABP B-06 rates RR 2.2 and 2.3. Most tumours FIGO stage I, good/moderate grade; 4 deaths from uterine cancer. No increase in liver, GI, urinary or non-uterine genital cancers. 5-year hazard of disease-free-survival events 38% lower with tamoxifen. Abstract discloses that some data came from an investigator who submitted fraudulent data (falsification in 24 of 182 and 8 of 37 records, pre-randomisation characteristics).
- Absolute risks
Endometrial cancer about 1.6 vs 0.2 per 1,000 patient-years
- Authors' conclusion
Endometrial cancer risk increases with tamoxifen, but net benefit greatly outweighs risk; tamoxifen should continue.
6. Strengths
- Randomised placebo comparison
- Long follow-up
7. Weaknesses
- Small number of endometrial events
- Data-integrity issue disclosed in the abstract (fraudulent records from one investigator)
8. Risk of bias
- Orienting tool
- RoB 2
- Type of assessment
- simplified assessment (abstract only)
- Full formal assessment
- no
- Overall risk of bias
- some concerns
- Rationale
Randomised, but disclosed falsification of some baseline records.
9. Assessment of the statistical interpretation
Large relative risk on a low baseline; absolute excess about 1.4 per 1,000 patient-years versus a 38% reduction in DFS events.
10. Relevance to the specific claim
Second cancer from cancer treatment, with net-benefit context.
11. Independent contrary findings
Itself.
12. Transferability to Germany and Europe
High.
13. Overall methodological judgement
Harm real, small in absolute terms; cited without the authors' net-benefit conclusion.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | moderate |
| Risk of bias | some concerns |
| Precision of results | low |
| Directness | direct |
| Reproducibility | replicated |
| Consistency with the overall evidence | consistent |
| Regional transferability | high |
| Adequacy of the interpretation (by the archive) | taken out of context |
14. Open questions
15. Linked fact checks
- Chemotherapy and radiotherapy can cause second cancers (e.g., breast cancer after chest radiation for Hodgkin disease, therapy-related myeloid leukaemia) years after cure. – Studies with mixed or unclear results
- The archive's 19 chemo/radiation studies are presented on the homepage as 'scientific studies confirming what Dr. Diaa proposed'; the harm-only study selection implies that the harms of chemotherapy and radiotherapy outweigh their benefits. – Studies contradicting or limiting the claim
Use by the Tayebat archive
Note: according to the archive, the studies were compiled by the archive operators. Whether Dr. Elawady himself cited this study is not established.
- What the archive says about the study
Listed in the bibliography without interpretation.
- A. What was actually studied?
Second cancers under tamoxifen (endocrine therapy, not chemotherapy or radiotherapy).
- B. What did the authors find?
Higher endometrial cancer risk; large net benefit.
- C. What conclusions do the authors themselves draw?
Net benefit greatly outweighs risk.
- D. What does the archive derive from it?
Implied evidence of treatment-induced cancer.
- E. Is this derivation scientifically justified?
Only partly: harm is documented, but the authors explicitly state the benefit greatly outweighs it; tamoxifen is hormone therapy, not chemo/radiotherapy.
- Adequacy of the interpretation (by the archive)
- taken out of context