T1-2N1 mastectomy without PMRT (MSKCC)
ForT1-2N1 breast, mastectomy + ALND, no neoadjuvant chemo
TL;DR10y LRR 7.0% without PMRT vs 4.0% with it (p=0.32) in T1-2N1 after mastectomy; age <40 + LVI reached 28% without PMRT.
The RT read is the no-PMRT stratification: 10y LRR 28% for age <40 with LVI vs 2% for ≥40 without LVI. Supraclavicular nodes carried 27% of LRRs and the axilla only 15.9%, so where PMRT is chosen for the high-risk stratum, the regional field targets where these pts actually failed.
In a woman ≥40 with T1-2N1, no LVI, after mastectomy with completion ALND and no neoadjuvant chemo, this supports omitting PMRT; it does not extend to a positive-sentinel axilla left undissected or to post-NAC pts.
Without PMRT, 10y LRR spans 2% (≥40, no LVI) to 28% (<40, LVI), defining whom to offer RT. Supraclavicular nodes carried 27% of LRRs versus 15.9% axillary involvement, supporting chest wall plus SCV coverage when PMRT is chosen.
The low LRR without PMRT rests on ALND in 94.2% with a median 18 nodes removed; the authors state omission does not apply to positive sentinel nodes without completion ALND. For women <40 with LVI, they suggest axillary RT may replace completion ALND.
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Single-institution retrospective cohort from a prospectively maintained database, mastectomy 1995-2006. PMRT given at physician discretion. Median follow-up 10.8 yr.
T1-2N1 (1-3 positive nodes), N=1087. Excluded T3/T4, neoadjuvant chemotherapy, and isolated tumor cells. Median age 51, median tumor 1.8 cm; 58% had one positive node.
All PMRT pts received chest wall RT; supraclavicular field in 137/163 (84%), axilla 7 (4%), IMN 6 (4%). Dose and fractionation not reported in source.
Systemic therapy in 98%; chemo 88%, mostly anthracycline and/or taxane. All ER+ pts received hormone therapy; trastuzumab in 51/123 HER2-amplified.
Without PMRT, age <40 (HR 4.15) and LVI (HR 3.47) independently predicted LRR. Chest wall (51%) and supraclavicular nodes (27%) dominated failure sites.
| Endpoint | PMRT (n=163) | No PMRT (n=924) | p |
|---|---|---|---|
| LRR | 4.0% | 7.0% | 0.32 |
| RFS | 75% (95% CI 69-82) | 73% (95% CI 69-76) | 0.46 |
| OS | 81% (95% CI 73-86) | 80% (95% CI 77-82) | 0.44 |
| Subgroup | 5-yr LRR | 10-yr LRR |
|---|---|---|
| <40, LVI | 15% | 28% |
| <40, no LVI | 6% | 11% |
| ≥40, LVI | 6% | 8% |
| ≥40, no LVI | 1% | 2% |
The EBCTCG 1-3 node subset showed 20.3% 10-yr LRR without PMRT, versus 7.0% here, a gap the authors attribute to modern systemic therapy and thorough ALND (median 18 nodes). EORTC 22922 included lumpectomy and stage I-III pts, limiting direct comparison.
Dose and target-volume data absent, so the 4.0% PMRT LRR cannot be tied to a technique. Pathology not re-reviewed, and HER2-directed therapy was incomplete in the cohort. The 10-yr LRR 28% subgroup CI as printed (11.0-22.1) excludes its own estimate.
The useful product is a risk filter for omission, not a PMRT efficacy estimate. It shows age and LVI separating a 2% from a 28% 10-yr LRR in unirradiated pts, which is the decision a T1-2N1 consult turns on.
Retrospective, non-randomized; PMRT selected for higher-risk pts, so null LRR/RFS/OS difference cannot estimate PMRT effect. Risk-stratification value lies in the no-PMRT cohort only.
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- Should intermediate-risk T1-2N1 pts (one of age <40 or LVI) receive PMRT? n=1106 · primary completion 2026-12 · phase 3 PMRT vs no PMRT in pN1, 7y DFS non-inferiority
- Does modern HER2-directed therapy lower LRR further without PMRT?
📚 Sources · 📄 1 paper
The longer read
This paper is best read as a natural history of selectively unirradiated T1-2N1 disease, not as a test of PMRT. The headline comparison, 10-year LRR 4.0% with PMRT versus 7.0% without and overlapping RFS and OS curves, is the least informative part of the analysis. The 163 irradiated women were chosen precisely because they looked worse: younger, larger tumors, more LVI, more extracapsular extension, more positive nodes. A null unadjusted difference between a high-risk treated group and a low-risk untreated group says only that clinicians at this center triaged sensibly, which the authors themselves acknowledge when they warn against reading Fig 1 as a randomized comparison.
The value lies in the 924 women who did not get PMRT. Their 7.0% 10-year LRR sits far below the 20.3% the EBCTCG reported for the 1-3 node subset, and in line with the 4-10% the authors cite from contemporary series. That gap is the central argument for de-escalation in this population: the absolute LRR benefit PMRT can deliver shrinks as the baseline risk falls, and the EBCTCG mortality benefit was estimated against a baseline that no longer describes most pts. The plausible explanations offered, anthracycline/taxane chemotherapy, aromatase inhibitors, and an ALND removing a median of 18 nodes, are reasonable but untested here, and the cohort was treated before trastuzumab was universal, so a modern HER2+ population would likely sit lower still.
The stratification by age and LVI is where a radiation oncologist should spend attention. A 10-year LRR of 2% in women 40 and older without LVI is a level at which PMRT toxicity, cardiac dose and reconstruction complications plausibly outweigh benefit. A 28% rate in women under 40 with LVI is in the range where historical trials showed a survival gain, and the authors agree it warrants PMRT. The two intermediate cells (11% and 8%) are where the decision remains genuinely open, and this dataset cannot resolve them. Confidence in the extreme cells should also be tempered: the high-risk subgroup started with only 75 women, and the printed confidence interval for the 28% estimate does not contain the point estimate, suggesting a reporting error.
The pattern of failure matters for anyone who does irradiate. Chest wall carried half the recurrences and supraclavicular nodes about a quarter, while the dissected axilla contributed little. This supports chest wall plus supraclavicular coverage when PMRT is chosen, and argues that the axillary field adds little after a thorough dissection. It also cuts the other way for the modern axilla: these outcomes rest on 94% ALND, and the authors explicitly say omission does not transfer to pts with positive sentinel nodes who skip completion dissection. In the post-AMAROS era, where many such pts receive nodal RT in place of ALND, this cohort's low regional recurrence cannot be borrowed to justify omitting both.
For this to mislead, unmeasured selection within the no-PMRT group would need to have kept high-risk features out of it beyond what age and LVI capture, which is plausible given discretionary allocation. Randomized evidence on intermediate-risk PMRT, such as SUPREMO, is the appropriate check on whether these thresholds hold.