# Table 3. Axillary pathologic complete response (ypN0) rates after neoadjuvant chemotherapy, by molecular subtype

Reported per umbrella-review convention as the **range across published meta-analytic and pooled estimates** (no re-pooling). The Samiei 2021 column lists the random-effects meta-analytic point estimates from a pool of 33 studies (n = 57,531 patients); the project-level meta-regression column lists the random-effects DerSimonian-Laird pooled estimate computed in the companion analysis (`predictor_ypN0/nivel2_metaregresion/results.md`, k = 22 studies after exclusions of pembrolizumab arms, breast-pCR-conditional cohorts, and ypN0-selected cohorts). Anchor primary cohorts in italics.

| Molecular subtype | Samiei 2021 (pooled MA) | Range across other SRs | Project meta-regression (DL) | I² | Anchor primary cohorts (illustrative) |
|---|---|---|---|---|---|
| HR-/HER2+ (HER2-enriched) | **60%** | 56-72% | **65.7%** (95% CI 53.1-76.4) | 90.7% | *van Amstel 2024 (RISAS): 72%; Boughey 2013 (Z1071, HER2+): ~50%* |
| HER2+ overall (HR-/HER2+ + HR+/HER2+) | **59%** | 47-67% | **53.3%** (95% CI 41.7-64.7) | 95.8% | *Chen 2021: 47.1%; Mukhtar 2025 (I-SPY2 HER2+ subset): >60%* |
| HR+/HER2+ (luminal-HER2) | **45%** | 35-55% | **49.3%** (95% CI 39.7-59.0) | 86.4% | *van Amstel 2024: 55%; Samiei 2021 stratum: 45%* |
| Triple-negative (TNBC) | **48%** | 38-50% (chemo only); 67-86% (chemo + pembrolizumab) | **48.0%** (95% CI 47.6-48.4) | 0.0% | *Sharma 2021 NeoSTOP: 54% (CbP); Chen 2021: 50.8%; Kuemmel 2026 KEYNOTE-522 pembro: 76.7%; Woodfin 2023: 86%; Perry 2025 MSK chemo-IO: 67%* |
| HR+/HER2- (luminal A/B) | **18%** (Luminal B 35%; Luminal A 13%) | 7-25% | **21.2%** (95% CI 13.8-31.1) | 99.9% | *van Amstel 2024: ~7%; Chen 2021: 23.8%; Boughey 2022 (Mayo, Ki67-stratified): 2.6-35.8%; Vasigh 2024 (NAC arm): 14.9%; Vasigh 2024 (NET arm): 8.9%* |
| Lobular (ILC) | NR | 31-67% (subtype-dependent) | Not pooled (k=1) | — | *Mukhtar 2025 I-SPY2: lobular HR+/HER2- 30.6%; lobular HER2+ 72.7%; lobular TNBC 66.7%* |

## Convergence and divergence

**Convergence (high confidence).** Across all 33 SRs and the companion meta-regression, the ranking is consistent: HR-/HER2+ > HR+/HER2+ ≈ TNBC ≫ HR+/HER2-. The differential of ~40-50 absolute percentage points between the highest- and lowest-responding subtypes is reproduced in every review that stratifies by subtype.

**Divergence (lower confidence).** Absolute pCR within HR+/HER2- ranges five-fold (4-25%) across reviews, reflecting genuine heterogeneity in Ki-67, age, genomic risk distribution, and regimen intensity (Boughey 2022; van Amstel 2024). Absolute pCR within TNBC varies from 38% to 86% depending on whether the regimen included pembrolizumab (Kuemmel 2026; Woodfin 2023; Perry 2025) — highlighting the need to recalibrate baseline expectations in the chemo-IO era.

**Validation against Z1071.** The companion meta-regression model predicts a population-weighted ypN0 of 42.2% in Z1071, observed 41.0% (absolute error 1.2 percentage points). It predicts 74.1%/66.8% in the pembro/placebo arms of KEYNOTE-522, observed 76.7%/69.9% (errors ≤3.1 pp). Cohort-level Brier score 0.0078, supporting good external calibration of the subtype-stratified estimates against landmark trials.
