Breast
Two reads on regional nodal RT arriving together: a 20-yr randomised toxicity ledger and a genomic-era observational LRR floor.
SWOG S1007
ForHR+/ERBB2- breast, 1-3 positive nodes, Oncotype RS ≤25
TL;DR5yr LRR 0.85% with RNI vs 0.55% without after BCS+RT in RS≤25 N1 disease; IDFS unchanged by RNI.
The number that moves the RNI decision is 0.55% 5yr LRR after BCS+RT without RNI, and equally low LRR in the endocrine-alone arm. Chemotherapy omission on a low RS does not by itself justify adding supraclavicular coverage. Target-volume detail beyond supraclavicular is not reported in source.
In HR+/ERBB2- N1 disease with RS ≤25 treated with BCS and whole-breast RT, this argues low RS alone does not compel nodal irradiation; it does not speak to RS >25, higher nodal burden, or ERBB2+ disease.
The actionable number is 0.55% 5yr LRR after BCS+RT without RNI in RS ≤25 N1 disease, against 0.85% with RNI. That floor leaves little absolute room for regional coverage, and IDFS did not move (premenopausal HR 1.03, postmenopausal HR 0.85). This informs the elective supraclavicular decision.
LRR stayed similarly low in the endocrine-therapy-alone group, so omitting chemotherapy on a low Recurrence Score did not raise locoregional risk. The conclusion is explicit: chemo omission is not an independent indication for RNI, which removes a reason to hedge a de-escalation decision.
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Secondary analysis of the randomized SWOG S1007 trial (endocrine therapy alone vs chemotherapy then endocrine therapy). Radiotherapy data were prospectively collected across diverse practice settings, but RNI receipt itself was not randomized. Data analyzed June 2022 to April 2023.
Hormone receptor-positive, ERBB2-negative breast cancer with 1 to 3 involved nodes and Oncotype DX 21-gene Recurrence Score ≤25. 4871 female patients had radiotherapy forms; median age 57 (range 18-87).
RNI defined as targeting at least the supraclavicular region. 3947 (81.0%) reported radiotherapy receipt; of 3852 with complete target information, 2274 (59.0%) received RNI. Dose, fractionation, and internal mammary coverage are not reported in source.
Cumulative incidence of locoregional recurrence by locoregional treatment received, plus association between invasive disease-free survival and locoregional therapy, adjusted for menopausal status, treatment group, recurrence score, tumor size, nodes involved, and axillary surgery.
Median follow-up 6.1 years. See the LRR and IDFS tables above; IDFS did not differ by RNI receipt in either menopausal stratum.
| Locoregional treatment | 5yr LRR |
|---|---|
| BCS + RT with RNI | 0.85% |
| BCS + RT without RNI | 0.55% |
| Mastectomy + PMRT | 0.11% |
| Mastectomy, no RT | 1.7% |
| Group | HR (95% CI) | P |
|---|---|---|
| Premenopausal | 1.03 (0.74-1.43) | .87 |
| Postmenopausal | 0.85 (0.68-1.07) | .16 |
MA.20 and EORTC 22922 established the regional irradiation question in node-positive disease, both without an overall survival gain, in cohorts assembled before genomic risk stratification. This analysis reads that question in the population those trials could not define, biologically favorable N1, and finds an LRR floor low enough that a relative benefit has little absolute room to operate.
Radiotherapy information was recorded only in the first year after randomization, forcing a 1-year landmark that excludes the earliest events. Target detail stops at supraclavicular coverage, so internal mammary treatment cannot be separated, and the low absolute event count leaves the IDFS confidence intervals wide enough to accommodate a small effect in either direction.
The finding that matters is the floor, not the comparison: with 5yr LRR at or below 1.7% in every locoregional strategy examined, the population has too few events for regional irradiation to demonstrate meaningful absolute benefit. The explicit conclusion is that omission of chemotherapy is not an independent indication for RNI, which addresses a specific compensatory reflex rather than the general RNI question.
Prospectively collected RT data in a large trial cohort, but RNI receipt was not randomized; observational comparison, so an unmeasured-confounding read is unavoidable.
- Does any favorable N1 subgroup (3 nodes, RS near 25) still warrant RNI?
- Internal mammary coverage contribution, unseparable in this dataset
- Longer follow-up for late locoregional events in HR+ disease
📚 Sources · 📄 1 paper
Abstract
EORTC 22922/10925
ForStage I-III breast, central/medial tumor or involved axilla, post-ALND
61.0% vs 61.8% at 20yr
HR 1.00, p=.967; primary endpoint not met
TL;DR20yr OS 61.0% vs 61.8% (HR 1.00, p=.967): IM-MS nodal RT cut breast cancer mortality but added non-cancer deaths.
The breast cancer mortality gain (22.4% vs 18.6%, HR 0.82) is real and was fully offset by non-breast-cancer deaths (15.8% vs 20.4%, HR 1.26) that only emerged after 15 years. Cardiac disease ran 15.2% vs 11.7%. In a 1996-2004 planning era, that trade gates IM-MS coverage on achievable heart dose, not on nodal risk alone.
In a woman with a medial or central stage I-III tumor being considered for IM chain coverage, this supports treating the cardiac dose constraint as co-equal with nodal risk; it does not speak to modern DIBH or proton delivery, where the competing-mortality arm may not hold.
Breast cancer mortality fell (HR 0.82) and non-cancer death rose (HR 1.26), netting OS HR 1.00, with cardiac disease 15.2% vs 11.7% and lung fibrosis 6.3% vs 3.2%. Planning ran in the 2D era, so the decision this moves is achievable heart dose, not whether to cover the IM chain.
Systemic therapy was per institutional preference across 1996-2004 accrual, so the disease-specific gain (HR 0.82) sits on a backbone that predates current regimens. For a med onc the read is competing mortality: the excess non-cancer deaths after 15 years reframes how long-term cardiac surveillance should run in irradiated survivors.
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Prospective multicenter randomized phase 3 trial, accrual 1996-2004, 4004 pts, with an RT quality-assurance program built in. The last analysis was planned at 20 years on the assumption that any survival effect of IM-MS-RT would be delayed. Median follow-up 22.2 years.
Women ≤75 yrs, unilateral histologically confirmed breast adenocarcinoma, stage I-III. Gate was tumor location or nodal status: centrally or medially located primary irrespective of axillary involvement, or any quadrant with axillary involvement. Median age 54.
Randomization was to internal mammary and medial supraclavicular (levels 3-4) nodal irradiation or not, layered on standard breast or chest wall treatment. Dose and fractionation are not given in the source excerpt. Planning ran in the two-dimensional and early-conformal era, when IM coverage at least doubled heart dose.
Primary: overall survival. Secondary: disease-free survival, distant metastases-free survival, breast cancer mortality, any breast recurrence.
Lung fibrosis 6.3% vs 3.2%, cardiac fibrosis 2.7% vs 1.7%, cardiac disease 15.2% vs 11.7% with IM-MS-RT. Severe (grade 3-4) events were uncommon and near-equal: cardiac 1.9% vs 1.7%, lung 0.3% vs 0.0%, so the excess sits in lower-grade, chronic morbidity rather than catastrophic events.
MA.20 and DBCG-IMN both read regional nodal RT positively at roughly ten-year horizons, and DBCG-IMN reported an OS gain. This trial covers the same anatomic question at twice that follow-up and shows the disease-specific gain surviving while the survival gain does not, which is the read those trials were too short to produce.
Systemic therapy was left to physician and institutional preference across an eight-year accrual, so the systemic backbone is heterogeneous and predates current regimens. The competing-mortality signal is a cause-of-death attribution over two decades in a population whose baseline cardiovascular risk rises independently, and the source does not report a cardiac-specific mortality breakdown separating RT-attributable from age-attributable death.
The two effects are both real and point opposite ways: HR 0.82 on breast cancer mortality, HR 1.26 on other deaths, netting HR 1.00 on OS. That arithmetic is the finding, and it argues the relevant question is not whether IM-MS coverage works but whether its cost can be engineered down.
| Endpoint | Control | IM-MS-RT | Effect size |
|---|---|---|---|
| Overall survival | 61.8% | 61.0% | HR 1.00, p=.967 |
| Disease-free survival | 49.0% | 48.2% | HR 0.97 (0.89-1.06), p=.5148 |
| Distant metastasis-free survival | 59.8% | 58.9% | HR 0.97 (0.88-1.08), p=.578 |
| Breast cancer mortality | 22.4% | 18.6% | HR 0.82 (0.72-0.95), p=.006 |
| Death not from breast cancer/unknown | 15.8% | 20.4% | HR 1.26, p=.002 |
Randomised, prespecified 20yr primary analysis, adequate power, endpoint reported honestly. Divergence from the 10yr-era read of nodal RT is internally valid, not a design artifact.
- Does modern heart-sparing delivery erase the excess non-cancer mortality?
- Which subgroups have enough breast cancer risk to justify the trade?
- Cardiac surveillance interval for irradiated long-term survivors