After breast-cancer radiotherapy, the rate of major coronary events rises by 7.4% for every Gray of mean radiation dose to the heart, linearly and without threshold (Darby 2013).
Original statement
ارتفاع متناسب لأمراض القلب الإقفارية بـ7.4% لكل غراي من إشعاع الصدر
not verbatim – paraphrase. Translation by the project; the Arabic wording is authoritative.
Translation
After breast-cancer radiotherapy, the rate of major coronary events rises by 7.4% for every Gray of mean radiation dose to the heart, linearly and without threshold (Darby 2013).
Origin
- Source status
- Archive editors
- Attribution
- Archive editors (rule page summary/narrative)
- Origin
- https://eltayebat.com/rule/chemo-radiation/
- Attribution uncertainty
- Written by archive operators; not attributed to Elawady.
- Claimed mechanism
Radiation damage to coronary arteries
- Claimed health effect
Ischaemic heart disease
- Population concerned
Women irradiated for breast cancer
- Geographic restriction by Elawady
none found
Scientific assessment
Mostly true – Correct at its core, but with limitations or minor inaccuracies.
Certainty of evidence: moderate – Further research may still affect the assessment.
1. What was claimed?
7.4% per Gray increase in ischaemic heart disease after breast irradiation; 'the heaviest blow'.
2. What is demonstrably correct?
Darby et al. found +7.4% per Gy mean heart dose (95% CI 2.9-14.5), starting within 5 years and lasting into the third decade (A-CHM-04).
3. What is wrong or exaggerated?
The unit is mean dose to the heart, not 'per Gray of chest irradiation'. A relative 7.4%/Gy on a low baseline risk translates into small absolute risks with modern doses: estimated radiation-related cardiac mortality about 0.3% in non-smokers and about 1% in smokers (I-CHM-06). The same radiotherapy halves recurrence and reduces breast-cancer death (I-CHM-02).
4. What remains unclear?
Risk at very low modern heart doses with heart-sparing techniques.
5. Which studies support it?
A-CHM-04; I-CHM-06 (cardiac mortality RR 1.30; 0.04 excess RR per Gy).
6. Which studies contradict it?
I-CHM-02 (benefit); I-CHM-06 (absolute risk small for non-smokers).
7. What applies to Germany and Europe?
European centres use heart-sparing techniques; risk communication in absolute terms recommended.
8. What is known about Egypt?
Not studied; doses depend on equipment and techniques available.
9. What practical conclusion is appropriate?
Keep heart dose low and control cardiac risk factors (especially smoking); the benefit of indicated radiotherapy usually exceeds the cardiac risk.
Assessment details
- Rationale for certainty of evidence
The figure is reported correctly from a well-conducted population-based case-control study; consistent with randomised-trial meta-analysis (I-CHM-06). Downgraded because the archive presents a relative per-Gy increase without absolute risk, and the Arabic summary refers to 'chest irradiation' instead of mean heart dose.
- Source quality
Correctly cited landmark study.
- Regional transferability
High.
- Individual exceptions
Women with cardiac risk factors have larger absolute increases.
- Regional scope of the claim
- general (biological/medical)
- Last reviewed
- 26 October 2026 provisional
Scientific evidence in detail
Scientifically well supported – The claim agrees with consistent, high-quality evidence.
Research question: After breast-cancer radiotherapy, does the rate of major coronary events increase linearly by about 7.4% per Gy of mean heart dose without a threshold, and what does this mean in absolute terms?
Research question in detail (PECO)
- Population
- Women treated with radiotherapy for breast cancer
- Intervention or exposure
- Mean heart dose (Gy)
- Comparison
- Lower dose
- Geographic scope
- universal biology
- Outcomes
- Major coronary events
- Cardiac mortality
Study results as reported by the authors. Our assessment follows below.
What speaks for the claim?
Radiation dose to the heart during breast-cancer radiotherapy raises later heart-attack risk
Darby SC et al.. N Engl J Med 2013 · PMID 23484825 · DOI 10.1056/NEJMoa1209825 Case-control studyabstract checkedPopulation-based case-control study: coronary events rose linearly with mean heart dose.
- Actual result
- 7.4% per Gy (2.9-14.5), no threshold, from within 5 years into the third decade
- Methodological quality
- high (large population-based design, individual dosimetry)
- Relevance
- direct
- Limitations
- Relative measure; older techniques
Heart dose and heart attacks after breast radiotherapy: a check of Darby
van den Bogaard VA et al.. J Clin Oncol 2017 · PMID 28095159 · DOI 10.1200/JCO.2016.69.8480 Cohort studyabstract checkednewly addedIndependent Dutch cohort with 3D CT dosimetry replicated the dose-response.
- Actual result
- 16.5% per Gy (0.6-35.0); median heart dose 2.37 Gy
- Methodological quality
- moderate (cohort, few events)
- Relevance
- direct
- Limitations
- Imprecise slope
What speaks against the claim?
With modern techniques, radiotherapy's heart and lung risks are small for non-smokers
Taylor C et al.. J Clin Oncol 2017 · PMID 28319436 · DOI 10.1200/JCO.2016.72.0722 Meta-analysisabstract checkedModern radiotherapy doses translate into small absolute cardiac mortality risks, larger in smokers.
- Actual result
- Cardiac mortality about 0.3% (non-smokers) and about 1% (long-term smokers)
- Methodological quality
- high (meta-analysis plus dosimetry)
- Relevance
- direct (limits the practical meaning)
- Limitations
- Model-based absolute estimates
Radiotherapy after breast-conserving surgery halves recurrence
EBCTCG. Lancet 2011 · PMID 22019144 · DOI 10.1016/S0140-6736(11)61629-2 Meta-analysisfull text, structured risk-of-bias assessmentRadiotherapy after breast-conserving surgery reduces recurrence and breast cancer death.
- Actual result
- 15-year breast cancer death 21.4% vs 25.2%; all-cause -3.0 points
- Methodological quality
- high (IPD meta-analysis)
- Relevance
- indirect (benefit side)
- Limitations
- Older trials
What does the overall evidence say?
Editorial assessment based on the studies above – not itself a study result.
Which position is better supported?
The 7.4%/Gy figure is reported correctly and has been replicated; it is a relative increase.
Why some studies weigh more
Darby is the pivotal study; van den Bogaard replicates with modern dosimetry; Taylor provides absolute risk.
Is a causal relationship established? Yes, established Dose-response, replication, biological plausibility.
Remaining uncertainty
Shape of the curve at very low doses; substructure doses may be better predictors.
Justified conclusion
Correct as a relative dose-response. With modern mean heart doses of about 1-3 Gy, the relative increase is roughly 7-20%, corresponding to small absolute risks (about 0.3% radiation-related cardiac death in non-smokers).
Does this depend on the country?
- General biological effects
- Universal radiobiology; depends on the technique used (breath-hold, 3D planning).
- Eating habits
- Not relevant.
- Origin of the food
- Not relevant.
- Contaminants
- Not relevant.
- National production conditions
- Not relevant.
- Legal rules
- Not relevant.
- Actual monitoring data
- No monitoring data relevant.
A regional difference that changes the conclusion is not supported by robust data.
Statistical re-check
- Relative vs absolute; CI shape – 7.4%/Gy is an excess relative risk on a linear scale; asymmetric CI (2.9-14.5) is expected for a profile-likelihood interval; not log-symmetric by design recalculated
- Translate slope at typical dose – At 2.37 Gy: +17.5% (Darby slope) to +39% (van den Bogaard slope, imprecise) recalculated
- NNH vs NNT – Radiation-related cardiac death NNH about 333 (non-smokers) vs NNT about 26 to prevent one breast cancer death (I-CHM-02) recalculated
Certainty of the overall evidence (GRADE, simplified)
- Main outcome
- Major coronary events per Gy mean heart dose
- Starting level
- low (observational studies)
- Reasons for upgrading
- dose-response
- Result
- moderate
Simplified assessment by a single reviewer, following the GRADE approach; not a formal GRADE panel. GRADE rates the body of evidence for one outcome, not individual studies.
Clinical guidelines and official statements checked
- ESC: 2022 ESC Guidelines on cardio-oncology (with EHA, ESTRO, IC-OS) (2022) · Original publication
The ESC guideline page states that this first ESC cardio-oncology guideline covers definitions, diagnosis, treatment and prevention of cancer-therapy-related cardiovascular toxicity before, during and after cancer treatment, and that evidence is limited so expert consensus is used where needed. The page lists the Egyptian Society of Cardiology among endorsing national societies. Detailed recommendations (full text, Eur Heart J 2022; PMID 36017568) could not be fetched (HTTP 403) and were not used.
Search strategy
Documented literature searches for this review (search strings in the original database syntax).
| Database | Date | Search | Looking for | Hits | Included |
|---|---|---|---|---|---|
| Europe PMC | 26 October 2026 | (TITLE:"acute coronary events" OR TITLE:"ischemic heart disease" OR TITLE:"coronary") AND TITLE:"breast cancer" AND (TITLE:"radiotherapy" OR TITLE:"radiation") AND (TITLE:"dose" OR TITLE:"validation") AND PUB_YEAR:[2014 TO 2026] | both directions | 25 | |
| Europe PMC | 26 October 2026 | TITLE:"Validation and Modification of a Prediction Model for Acute Cardiac Events in Patients With Breast Cancer Treated With Radiotherapy" | supporting evidence | 1 |
Open questions
Absolute risks with current cardiac-sparing techniques in Egypt (technique availability not reviewed).
How deeply was this checked?
4 linked studies: 1 checked in full text (1 of them with a structured risk-of-bias assessment), 3 on the basis of the abstract, 0 bibliographically only. No formal assessment with two independent reviewers and no independent human expert review has taken place yet.
Last scientific review: 26 October 2026
History of the verdict
- 25 October 2026 · Phase 1 · Initial assessment: Mostly true (moderate)
- 26 October 2026 · Phase 4 (systematic evidence review) · Re-examined with extended evidence; verdict unchanged: Mostly true (moderate)
Replication (I-CHM-122) strengthens the dose-response; the verdict already reflects that the figure is relative and the absolute risk small.
New sources: I-CHM-122
In plain language
Radiation for breast cancer can reach the heart. Each extra unit of radiation dose to the heart increases the later risk of heart attack by a few percent. With modern techniques the heart dose is small, so the extra risk for a non-smoker is about 3 in 1,000. The same radiotherapy halves the chance that breast cancer comes back. Not smoking lowers the heart risk further.
Studies on this claim
Studies supporting the claim (2)
-
Radiation dose to the heart during breast-cancer radiotherapy raises later heart-attack risk
Darby SC et al.. N Engl J Med 2013 · PMID 23484825 · DOI 10.1056/NEJMoa1209825Case-control studycited by the Tayebat archiveabstract checked★ key studyEach extra Gray of average heart dose increased the rate of major coronary events by about 7%.
Source of the 7.4%/Gy figure
Does the study support the specific claim? Yes · Methodological quality: high · Certainty of evidence: see overall assessment of the claim
Original publication · Scientific details
Study explained simply
- What did the researchers want to find out?
Measure heart risk by radiation dose.
- How was the study done?
Case-control with dose reconstruction.
- How many people, animals or samples were studied?
2,168 women.
- What was actually found?
+7.4% per Gy, linear.
- How large was the observed effect?
ERR 7.4%/Gy (2.9-14.5).
- What do the results mean in everyday life?
Keep heart dose as low as possible; control cardiac risk factors.
- What are the study's limitations?
Historical doses; relative measure.
- What does it say about Elawady's specific claim?
Confirms the archive number.
- Do the results apply to Germany and Europe?
High.
- What can explicitly not be concluded from this study?
That radiotherapy does net harm.
-
Heart dose and heart attacks after breast radiotherapy: a check of Darby
van den Bogaard VA et al.. J Clin Oncol 2017 · PMID 28095159 · DOI 10.1200/JCO.2016.69.8480Cohort studyindependent cross-checkabstract checkedRisk of acute heart events rose by about 16.5% per Gy of heart dose; the typical heart dose was low (2.4 Gy).
Independent replication of a linear dose-response for coronary events after breast radiotherapy.
Does the study support the specific claim? Yes · Methodological quality: moderate · Certainty of evidence: see overall assessment of the claim
Original publication · Scientific details
Study explained simply
- What did the researchers want to find out?
Check the Darby dose-response
- How was the study done?
Cohort with 3D dose data
- How many people, animals or samples were studied?
910 Dutch women
- What was actually found?
Dose-response confirmed
- How large was the observed effect?
16.5%/Gy (0.6-35.0)
- What do the results mean in everyday life?
Lower heart dose means lower risk; modern doses are low
- What are the study's limitations?
Few events
- What does it say about Elawady's specific claim?
Supports the 7.4%/Gy claim as relative risk
- Do the results apply to Germany and Europe?
High
- What can explicitly not be concluded from this study?
Does not give absolute lifetime risk
No study in this group is marked as key.
Studies contradicting or limiting the claim (2)
-
With modern techniques, radiotherapy's heart and lung risks are small for non-smokers
Taylor C et al.. J Clin Oncol 2017 · PMID 28319436 · DOI 10.1200/JCO.2016.72.0722Meta-analysisindependent cross-checkabstract checked★ key studyAbout 0.3% risk of radiation-related heart death or lung cancer in non-smokers, higher in smokers.
Absolute risk small with modern doses
Does the study support the specific claim? Partly · Methodological quality: high · Certainty of evidence: see overall assessment of the claim
Original publication · Scientific details
Study explained simply
- What did the researchers want to find out?
Estimate absolute RT risks.
- How was the study done?
Dose review + IPD meta-analysis.
- How many people, animals or samples were studied?
40,781 women.
- What was actually found?
Small absolute risks; smoking key.
- How large was the observed effect?
Cardiac mortality RR 1.30.
- What do the results mean in everyday life?
Stop smoking before/after radiotherapy.
- What are the study's limitations?
Smoking modelled.
- What does it say about Elawady's specific claim?
Puts Darby in perspective.
- Do the results apply to Germany and Europe?
High.
- What can explicitly not be concluded from this study?
Individual dose-specific risk.
-
Radiotherapy after breast-conserving surgery halves recurrence
EBCTCG. Lancet 2011 · PMID 22019144 · DOI 10.1016/S0140-6736(11)61629-2Meta-analysisindependent cross-checkfull text, structured risk-of-bias assessment★ key studyRecurrence within 10 years fell from 35% to 19%, and breast-cancer deaths within 15 years from 25% to 21%.
Benefit context for the heart risk
Does the study support the specific claim? No · Methodological quality: high · Certainty of evidence: see overall assessment of the claim
Original publication · Scientific details
Study explained simply
- What did the researchers want to find out?
Measure radiotherapy benefit.
- How was the study done?
IPD meta-analysis.
- How many people, animals or samples were studied?
10,801 women.
- What was actually found?
Recurrence halved; breast-cancer deaths about one-sixth lower; deaths from any cause at 15 years 3.0 percentage points lower.
- How large was the observed effect?
-15.7% recurrence; -3.8% death.
- What do the results mean in everyday life?
Radiotherapy markedly lowers the chance the cancer returns.
- What are the study's limitations?
Older techniques; risk groups derived from the same data; in low-risk node-negative women the gain in survival was small and uncertain.
- What does it say about Elawady's specific claim?
Benefit side.
- Do the results apply to Germany and Europe?
High.
- What can explicitly not be concluded from this study?
Individual benefit size without risk factors.
No study in this group is marked as key.
Studies with mixed or unclear results (0)
No studies in this group.
Regional context
Germany / EU
European centres use heart-sparing techniques; risk communication in absolute terms recommended.
Egypt
Not studied; doses depend on equipment and techniques available.
What applies in my country?
General scientific assessment
Mostly true The 7.4%/Gy figure is correct but relative; with modern doses the absolute risk is small and usually outweighed by the benefit.
This statement concerns biological or medical relationships. The scientific assessment above applies regardless of the country; country-specific food data do not change it.
References
- Risk of ischemic heart disease in women after radiotherapy for breast cancer.. Darby SC et al.. N Engl J Med 2013 · PMID 23484825 · DOI 10.1056/NEJMoa1209825
- Validation and Modification of a Prediction Model for Acute Cardiac Events in Patients With Breast Cancer Treated With Radiotherapy Based on Three-Dimensional Dose Distributions to Cardiac Substructures.. van den Bogaard VA et al.. J Clin Oncol 2017 · PMID 28095159 · DOI 10.1200/JCO.2016.69.8480
- Estimating the Risks of Breast Cancer Radiotherapy: Evidence From Modern Radiation Doses to the Lungs and Heart and From Previous Randomized Trials.. Taylor C et al.. J Clin Oncol 2017 · PMID 28319436 · DOI 10.1200/JCO.2016.72.0722
- Effect of radiotherapy after breast-conserving surgery on 10-year recurrence and 15-year breast cancer death: meta-analysis of individual patient data for 10,801 women in 17 randomised trials.. EBCTCG. Lancet 2011 · PMID 22019144 · DOI 10.1016/S0140-6736(11)61629-2