Breast
De-escalation dominates: boost omission (Dutch cohort, IMPORT HIGH), hypofractionation (DBCG HYPO), and 15yr APBI maturity, set against EORTC IM-MS where nodal RT's breast-cancer-mortality gain is erased by late cardiac/lung death.
OLIGOMA (ARO-2021-09) NCT04495309
ForOligometastatic breast (≤5 mets), mostly ER+/HER2-neg, first-line systemic
TL;DRmPFS 35.8 vs 20.4 mo, HR 0.48 (0.25-0.91), p=0.021, adding ablative RT to all mets in oligometastatic breast.
The subtle co-primary is QoL: EORTC QLQ-C30 was non-inferior at 12 wks, so ablative RT to all mets bought the PFS gain without degrading short-term QoL, the read that de-risks offering MDT. Population skewed bone-met-dominant, ER+/HER2-neg, first-line, so it transfers best to favorable oligomet targets. Dose and fractionation not reported in source.
- Adds breast-specific RCT support to MDT signals (e.g. SABR-COMET); confirmatory trials ongoing (TAORMINA, STEREO-SEIN, LARA, others)
| Arm | Median PFS | HR (95% CI) | p |
|---|---|---|---|
| Systemic + ablative RT | 35.8 mo (24.1-NR) | 0.48 (0.25-0.91) | 0.021 |
| Systemic therapy | 20.4 mo (12.4-28.4) | ref | ref |
+2 more figures
| Group | Mean QLQ-C30 (95% CI) | Δ vs control (ANCOVA) |
|---|---|---|
| Experimental | 72.2 (67.2-77.2) | -2.1 (-9.2-5.1) |
| Control | 74.3 (69.3-79.3) | ref |
8 details 5 trials watching
- 🔍 Phase 2 RCT: metastatic breast (any line), ≤5 mets; randomised systemic therapy ± ablative RT to ALL mets
- 🔍 Ablative RT delivered to every metastatic lesion; palliative RT to symptomatic mets allowed, but pts needing it to all mets excluded
- 🔍 Population: mostly ER/PR+ HER2-neg, first-line; >80% had 1-3 mets, ~2/3 of lesions bone (favorable ablation targets)
CONSORT flow
- 📊 First RCT to show a PFS benefit from MDT in oligometastatic breast cancer (investigators' claim)
- 📊 Second co-primary, QoL (EORTC QLQ-C30) at 12 wks, met non-inferiority; MDT did not impair short-term QoL
- ⚠️ Recruitment stopped early: <20% of initial planned N, <40% of amended target; final N=87 (43 vs 44)
- ⚠️ Underpowered: the PFS CI is wide and the upper bound approaches 1.0, so the estimate is fragile despite significance
- ⚠️ RT dose, fractionation, and technique not reported in source; transferability to practice can't be judged
- Which oligometastatic breast subgroups benefit most from MDT n=340 · primary completion 2026-11 · phase 3 MDT stratified by subtype: luminal/HER2/TNnot yet Adding Surgery and Radiation to the Usual Treatment for HER2-Positive Breast Cancer That Had Already Spread at Diagnosis Phase 3n=562 · primary completion 2032-05 · phase 3 SBRT+LRT in HER2+ oligomet subgroup
- OS benefit from MDT beyond the PFS signal n=150 · primary completion 2025-08 · phase 3 RCT, systemic vs +SABR, de novo OMBC
- Optimal RT dose and fractionation for ablative MDT in breast recruiting OligoCare TwiCs (Trials Within Cohorts) Trial Comparing Acute Toxicity in Single-fraction vs Multiple-fraction SBRT for Metastasis-directed Treatment (SPRINT) Phase NAn=302 · primary completion 2029-02 · single- vs multi-fraction SBRT for MDTactive Trial of Superiority of Stereotactic Body Radiation Therapy in Patients With Breast Cancer Phase 3n=154 · primary completion 2033-10 · defines optimal SBRT total dose by met site
📚 Sources · 🐦 3 tweets
📌 Metastases-directed treatment in Patients with Oligometastatic Breast Cancer: Results from the OLIGOMA-trial (ARO-2021-09, NCT04495309) @DavidKrugMD 👏🏻 #ESTRO26 @ESTRO_RT @OncoAlert #OncoAlertAF pic.twitter.com/YDMef0fXRm
— Elisabetta Bonzano MD, PhD (@to_be_elizabeth) May 17, 2026
❗️ The OLIGOMA trial results just dropped at #ESTRO26 and they are massive. A 15-month improvement in median PFS for OMD breast cancer (HR = 0.48). This adds to the growing mountain of evidence that MDT (Metastasis-Directed Therapy) works. Lets’s go 🧵 1/n pic.twitter.com/5uiEVSYtdH
— NonsparseOncologist (@5_utr) May 17, 2026
Here are some details!
— Jeff Ryckman (@jryckman3) May 17, 2026
On OLIGOMA, nearly 3/4 were first line endocrine or chemotherapy. #ESTRO26 #OncTwitter@CJTsaiMDPhD pic.twitter.com/r3kJzNNsyK
APBI-IMRT Florence NCT02104895
ForEarly breast cancer, pT<25mm, margins ≥5mm, age >40, post-lumpectomy
TL;DR15yr IBTR 7.7% vs 4.2% (APBI vs WBI), HR 1.57 (0.82-3.04) p=0.17; excess from new primaries not true relapse, OS equivalent.
The reassuring RT read: true local relapse was near-identical (2.1 vs 1.6%), so the higher IBTR is new ipsilateral primaries elsewhere in the breast, not tumor-bed failure. 30Gy/5fx IMRT-APBI holds local control at 15yr, supporting partial-breast as the default offer for pT<25mm, margin-negative, >40yr pts.
- Extends Florence IMRT-APBI (Livi EJC 2015, Meattini JCO 2020) to 15yr; complements EBRT-APBI RCTs IMPORT-LOW, RAPID, NSABP B-39
| 15yr IBTR | APBI N (%) | WBI N (%) | p |
|---|---|---|---|
| Total IBTR | 20 (7.7) | 11 (4.2) | 0.14 |
| Local relapse | 5 (2.1) | 4 (1.6) | 0.75 |
| New ipsilateral primary | 15 (5.9) | 7 (2.7) | 0.09 |
+2 more figures
| 15yr endpoint | APBI N (%) | WBI N (%) | p |
|---|---|---|---|
| Locoregional recurrence | 20 (7.2) | 13 (5.0) | 0.28 |
| Contralateral breast | 10 (3.8) | 13 (5.0) | 0.67 |
| Distant metastasis | 7 (2.7) | 12 (4.6) | 0.35 |
| All-cause deaths | 56 (21.5) | 51 (19.6) | 0.66 |
| Breast cancer deaths | 6 (2.3) | 8 (3.1) | 0.79 |
6 details 4 trials watching
- 🔍 Phase III equivalence trial, N=520, 1:1 randomized 2005-2013, post-BCS, pT<25mm, margins ≥5mm, age >40
- 🔍 APBI 30Gy/5fx IMRT vs WBI 50Gy/25fx + 10Gy/5fx tumor-bed boost
CONSORT flow
- 📊 IBTR excess is new ipsilateral primaries, not tumor-bed relapse; true local relapse essentially equal between arms
- ⚠️ Absolute IBTR gap is larger at 15yr than at 5 or 10yr; de-escalation risk only fully visible with mature f/u
- ⚠️ Powered for 5yr IBTR equivalence (Δ5%, 80% power); the 15yr between-arm comparison is descriptive, not a powered test
- ⚠️ Highly selected low-risk pts; result doesn't transfer to younger (<40), larger, or margin-positive disease
- Whether the new-primary IBTR excess keeps widening beyond 15yr
- APBI safety in younger (<40yr) or higher-risk pts excluded here active Partial Breast Irradiation (PBI) Using 40 Gy for Select Patients With Early Invasive or Noninvasive Breast Cancer Phase 2n=110 · primary completion 2026-09 · IMRT/3DCRT APBI, enrolls age ≥18 (no age floor)
- IMRT-APBI vs brachytherapy or IORT partial-breast techniques head-to-head n=75 · primary completion 2021-02 · Pd-103 interstitial brachytherapy PBI vs alt RTn=1200 · primary completion 2023-07 · Xoft eBx IORT vs WBI non-inferiority RCTn=100 · primary completion 2029-02 · single-fraction IOeRT partial-breast technique
📚 Sources · 🐦 1 tweet
📌 Fifteen-year outcomes of the randomised APBI-IMRT Florence phase Ill trial of partial versus whole-breast irradiation in early breast cancer ✨
— Elisabetta Bonzano MD, PhD (@to_be_elizabeth) May 17, 2026
Excellent presentation led by @CarlottaB 👏🏻#ESTRO26 @Icro_Meattini @ESTRO_RT @OncoAlert #OncoAlertAF pic.twitter.com/1j4bIA2nyC
IMPORT HIGH
ForEarly breast cancer (pT1-3 pN0-3a M0) post-BCS needing tumour bed boost
TL;DR10yr IBTR 3.7% with 48Gy/15F SIB (3wk) vs 3.5% sequential 40+16Gy boost; 53Gy escalation worse (5.5%), reaffirming 48Gy SIB as SOC.
The deliverable change is the boost: 48Gy/15F SIB in 3 weeks holds non-inferior to a separate 40+16Gy sequential boost at 10yr, so the extra 8-fraction boost phase is droppable. Escalating to 53Gy raised relapse with no OS or late-toxicity gain, so don't dose-escalate beyond 48Gy SIB.
- Boost value in higher-risk pts established by EORTC 22881-10882; IMPORT HIGH addresses delivery (hypofractionated SIB vs sequential), not whether to boost
| Arm | 10yr IBTR (95% CI) |
|---|---|
| 40Gy/15F + 16Gy/8F (seq) | 3.5% (2.4, 5.0) |
| 48Gy/15F SIB | 3.7% (2.6, 5.3) |
| 53Gy/15F SIB | 5.5% (4.1, 7.3) |
+1 more figure
7 details 2 trials watching
- 🔍 Phase 3 RCT, 1:1:1, N=2617, 76 UK hospitals (2009-2015); pT1-3 pN0-3a M0 post-BCS, all needing tumour bed boost
- 🔍 SIB (48 & 53Gy arms) dose-paints the boost within the 15-fraction/3-week course; control adds a separate 16Gy/8F boost (40Gy/15F + 16Gy/8F)
CONSORT flow
- 📊 Prior 5yr IBTR by arm (Lancet 2023; all arms low)
Arm 5yr IBTR (95% CI) 40Gy/15F + 16Gy/8F (seq) 1.9% (1.2, 3.1) 48Gy/15F SIB 2.0% (1.2, 3.2) 53Gy/15F SIB 3.2% (2.2, 4.7) - 📊 53Gy escalation arm showed numerically higher relapse with no OS or toxicity gain; further boost escalation not advantageous
- 📊 10yr OS: no difference vs sequential boost (absolute % difference)
- 48Gy/15F SIB: -0.5 (-3.0, 2.8)
- 53Gy/15F SIB: 1.5 (-1.4, 5.1)
- 📊 Moderate/marked late AEs at 10yr (similar across all 3 arms)
- Breast distortion/shrinkage <18%
- Induration <10%
- Telangiectasia <2%
- Breast oedema <2%
- 📊 Both 40+16Gy and 48Gy arms stayed below the 5% relapse estimate assumed for the control in the original 5yr powering
- Generalizability of hypofractionated SIB boost to nodal or partial-breast RT active Hypofractionated Loco-regional Adjuvant Radiation Therapy of Breast Cancer Combined With a Simultaneous Integrated Boost Phase NAn=2963 · primary completion 2021-07 · hypofx loco-regional RT + SIB boost, node+ ptsrecruiting Single-fraction APBI for Early-stage Breast Cancer With Favorable Histological Subtypes (Breast-1F) Phase NAn=311 · primary completion 2029-06 · single-fraction APBI with SIB to tumor bed
- Cosmetic/PRO durability beyond 5yr (photos and PROs collected only to 5 years)
📚 Sources · 🐦 1 tweet
Day THREE of #ESTRO26 Coverage by OncoAlert 🚨
— OncoAlert (@OncoAlert) May 17, 2026
Ten-year results of the IMPORT HIGH trial (ISRCTN47437448): Dose escalated simultaneous integrated boost radiotherapy in early breast cancer Presented by Charlotte Coles 🇬🇧 #RadOnc ☢️
Ten-year IMPORT HIGH trial data show that a… pic.twitter.com/7RqVy2SrQm
EORTC IM-MS Trial (22922/10925)
ForStage I-III breast cancer, central/medial tumor or node-positive
TL;DROS identical at 20yr (61.0% vs 61.8%, HR 1.00, p=0.967): IM-MS RT's breast-cancer-mortality gain (HR 0.82) erased by excess cardiac/lung death (HR 1.26).
The flat 20-yr OS reflects a tradeoff, not RT failure: IM-MS RT cut breast-cancer mortality (HR 0.82), but excess non-breast-cancer death (HR 1.26, cardiac/lung) erased it. Trial-era heart dose ran 4-9x DBCG IMN2's; modern cardiac-sparing is what makes IM-MS coverage worth it. pN0 pts gained nothing.
- Earlier EORTC report showed DFS/DMFS/BCM gains; at 20yr only the BCM reduction endures (HR 0.82, unchanged)
- vs DBCG IMN2 (Nielsen 2024): modern IM-RT mean heart dose 4-9x lower (MHD 1.2 Gy right, 2.3 Gy left)
- DBCG IMN2: modern IM-RT cut distant mets + BCM and improved OS in node-positive pts at 15yr
| Endpoint | IM-MS RT | No IM-MS RT | HR (95% CI) | p |
|---|---|---|---|---|
| OS, 20y ITT | 61.0% | 61.8% | 1.00 (0.90-1.10) | 0.967 |
+3 more figures
| Endpoint | IM-MS RT | No IM-MS RT | HR (95% CI) | p |
|---|---|---|---|---|
| BCM, 15y | 18.6% | 22.4% | 0.82 (0.72-0.95) | 0.006 |
| Non-BCM, 15y | 20.4% | 15.8% | 1.26 (1.09-1.46) | 0.002 |
| RT-related effect | IM-MS RT | No IM-MS RT |
|---|---|---|
| Lung fibrosis | 6.3% | 3.2% |
| Cardiac fibrosis | 2.7% | 1.7% |
| Cardiac disease | 15.2% | 11.7% |
| Endpoint | IM-MS RT | No IM-MS RT | HR (95% CI) | p |
|---|---|---|---|---|
| DFS, 20y ITT | 48.2% | 49.0% | 0.97 (0.89-1.06) | 0.515 |
| DMFS, 20y ITT | 58.9% | 59.8% | 0.97 (0.88-1.08) | 0.578 |
5 details 5 trials watching
- 🔍 Phase 3 RCT, N=2002/arm: IM-MS nodal RT (internal mammary + medial supraclavicular) vs none, stage I-III breast, 20-yr update
- 📊 pN0 subgroup (20yr): no benefit from IM-MS RT
- ⚠️ 20yr OS wash = excess non-BCM (cardiac/lung) death offsetting a persistent BCM benefit, not lost tumor control
- ⚠️ Net benefit is technique-dependent: modern cardiac-sparing RT may preserve the BCM gain without the late mortality penalty
- ⚠️ pN0 pts derive no benefit → supports omitting IM-MS RT in node-negative disease
- Whether modern cardiac-sparing technique preserves the BCM benefit without excess non-BCM mortality recruiting Robustness Evaluation of Deep Inspiration Breath-Hold (DIBH) Plans in Internal Mammary Irradiationn=25 · primary completion 2026-12 · DIBH heart-sparing dosimetry for IM irradiation
- Whether IM-MS nodal coverage should be omitted given no 20-year survival gain active Standard or Comprehensive Radiation Therapy in Treating Patients With Early-Stage Breast Cancer Previously Treated With Chemotherapy and Surgery Phase NAn=1636 · primary completion 2023-09 · comprehensive nodal vs whole-breast-only RTrecruiting RecurIndex Guided Avoidance of Regional Nodal Irradiation for Node Positive Breast Cancer Phase NAn=540 · primary completion 2029-08 · genomic-guided RNI avoidance in low-risk N1not yet A Study of Postoperative Regional Nodal Radiotherapy in Intermediate-risk Breast Cancer Phase 3n=3142 · primary completion 2032-12 · phase 3 randomizes RNI vs no-RNI omissionrecruiting Level I-II Axillary Irradiation in Breast Cancer With Sentinel-Node Macro-metastases Phase NAn=1608 · primary completion 2032-12 · reduced nodal field: I-II axilla vs whole regional
📚 Sources · 🐦 2 tweets
📌 Internal Mammary and Medial Supraclavicular irradiation in stage I-III breast cancer: 20 years results of the randomised EORTC trial 22922/10925, including in pNo patients
— Elisabetta Bonzano MD, PhD (@to_be_elizabeth) May 17, 2026
Special Joint Presentation Led by Prof. Philip Poortmans and Orit Kaidar-Person ✨ at #ESTRO26 @ESTRO_RT… pic.twitter.com/KIoJtdhEzp
20-year outcomes of @EORTC internal mammary #radiotherapy trial.
— Shankar Siva (@_ShankarSiva) May 17, 2026
➡️internal mammary improved control
➡️ survival counterbalanced by late adverse events #radiotherapy #bcsm
Great to see the long term data at #ESTRO26, and discussing Charlotte Cole suggests with modern RT, long… pic.twitter.com/yPtlfrLcri
DBCG HYPO
ForNode-negative early breast cancer or DCIS, adjuvant whole-breast RT
TL;DR10-yr grade 2-3 induration 19.5% (40Gy/15fx) vs 24.7% (50Gy/25fx), HR 0.76; recurrence and OS non-inferior.
The 10-yr induration HR 0.76 (0.62-0.92) means 40Gy/15fx is superior for late fibrosis, not merely non-inferior, with locoregional control and OS unchanged. The 12.8-yr median f/u closes the long-term-toxicity gap that kept some clinicians on 50Gy/25fx for node-negative whole-breast RT.
- vs START-B (10-yr): same 40/15 vs 50/25 question; DBCG HYPO replicates non-inferior control with reduced late fibrosis
| Endpoint (10y) | 50 Gy/25 fx | 40 Gy/15 fx | HR (95% CI) | p |
|---|---|---|---|---|
| Grade 2-3 induration | 24.7% | 19.5% | 0.76 (0.62-0.92) | 0.005 |
| Overall survival | 92.1% | 93.0% | 0.81 (0.63-1.04) | 0.10 |
5 details 5 trials watching
- 🔍 Phase III non-inferiority RCT (1:1), Denmark/Norway/Germany 2009-2014, N=1,882, node-negative breast cancer or DCIS
- 🔍 1° EP: 3-yr grade ≥2 breast induration; reported here are the prespecified 10-yr toxicity, recurrence, and survival analyses
CONSORT flow
- 📊 No significant difference in locoregional recurrence, distant failure, or breast cancer mortality between arms
- ⚠️ 1° EP is a fibrosis/cosmesis surrogate, not an oncologic endpoint; trial powered for non-inferiority
- ⚠️ Node-negative/DCIS, whole-breast only; doesn't address hypofractionation with regional nodal irradiation
- Hypofractionation safety with regional nodal irradiation active Hypofractionated Radiation Therapy for Patients With Breast Cancer Receiving Regional Nodal Irradiation Phase NAn=388 · primary completion 2024-01 · hypo vs conventional RNI, 1° endpoint lymphedemaactive Breast Fractionation Study - Standard Versus Investigational Fractionation Trial - Nodal Radiation Phase NAn=132 · primary completion 2024-07 · hypo vs conventional incl nodes, morbidity endpointrecruiting Conventionally Fractionated vs. Hypofractionated Comprehensive Nodal Irradiation for Breast Cancer Using Pencil Beam Scanning Proton Therapy Phase 3n=276 · primary completion 2038-02 · phase 3 hypofx vs conventional nodal RT
- Ultra-hypofractionation (5fx) long-term induration vs 15fx n=2100 · primary completion 2029-03 · 1wk 5fx vs 3wk RT, iso-toxic non-inferiorityrecruiting 5 fr Ultrahypofractionated WBI and SIB for Breast Cancer With Unfavorable Characteristics Phase NAn=458 · primary completion 2029-06 · 26Gy/5fx vs 40.05Gy/15fx non-inferiority
📚 Sources · 🐦 1 tweet
Day TWO of #ESTRO26 Coverage by OncoAlert 🚨
— OncoAlert (@OncoAlert) May 17, 2026
10-year Follow-Up of the DBCG HYPO Trial: Breast Induration, Recurrence and Survival After Hypofractionated Whole Breast Irradiation Presented by Hanna Forsberg 🇩🇰 @BOffersen #RadOnc ☢️ #BreastCancer
The DBCG HYPO trial reports… pic.twitter.com/4qf9R3HZwT
DBCG RT Natural
ForLow-risk early breast, ≥60yr, pT1N0 ER+ HER2-normal grade 1-2, post-lumpectomy
TL;DRInvasive LR 1.5% with PBI (40Gy/15fr) vs 9.8% omitting it in low-risk ≥60yr breast; RT+ET gave 0 recurrences.
Either modality alone stayed under the 4% threshold (-RT+ET 3.7%, +RT-ET 3.0%), but RT is the adherence-proof one: the -ET group pools 'ET not indicated' with sub-4.5y dropouts, so omission's recurrence cost partly reflects lost endocrine therapy. With 5-fraction PBI, treating low-risk elderly is easier to justify than omitting.
- Contests the RT-omission trend (PRIME II, LUMINA): those accepted omitting RT in low-risk elderly on ET; here omission carried clear LR cost
- vs EUROPA: in elderly low-risk, RT showed better QoL than endocrine therapy (curator framing), strengthening the case to treat over omit
| Arm | Events/Total | CIF % (95% CI) |
|---|---|---|
| +RT (PBI) | 2/236 | 1.5 (0.3-5.1%) |
| -RT randomised | 19/272 | 9.8 (5.9-14.9%) |
| S-RT self-selected | 18/278 | 8.2 (4.5-13.3%) |
+1 more figure
| Subgroup | Events/Total | CIF % |
|---|---|---|
| +RT +ET | 0/105 | 0.0 |
| +RT -ET | 2/132 | 3.0 |
| -RT +ET | 7/213 | 3.7 |
| -RT -ET | 32/352 | 12.2 |
6 details 3 trials watching
- 🔍 ≥60yr, pT1N0, ER≥10%, HER2-normal, grade 1-2, unifocal non-lobular, post-lumpectomy, margin ≥2mm
- 🔍 Randomised PBI 40Gy/15fr vs no PBI; stratified by institution + ET use; plus a self-selecting no-PBI cohort
- 📊 1° EP 5-yr invasive LR; prespecified expected 2%, max acceptable 4%, omission arm blew past it
- 📊 39 of 41 local recurrences were in pts who had no PBI; all 41 invasive, 36 isolated
- ⚠️ ET not randomised: -ET pooled 'ET not indicated (low-risk)' with pts on ET <4.5y, so RT×ET cells aren't a clean factorial
- ⚠️ Median FU 4yr for a 5-yr 1° EP; reported early on planned stopping rules, absolute LR may climb with maturity
- Whether RT can be safely omitted in pts with good documented ET adherence n=1167 · primary completion 2027-09 · RT vs observation on planned endocrine therapyn=926 · primary completion 2033-09 · no-RT vs PBI in ≥60yr ER+ node-neg
- Optimal PBI fractionation (15fr vs 5fr) in this low-risk population n=72 · primary completion 2026-12 · 1wk (5fr) vs 3wk (15fr) WBI, T1-2N0
- Whether absolute LR rates rise with longer follow-up
📚 Sources · 🐦 2 tweets
Another trial showing even for lR optimal local control with RT and ET and suboptimal adherence to ET. In era of 5 fraction decision making is easier # Estro2026 pic.twitter.com/nkvYl3iuTn
— Sushil (@Sushilberiwal) May 17, 2026
Danish #breastcancer partial breast #radiotherapy “natural” trial.
— Shankar Siva (@_ShankarSiva) May 17, 2026
➡️ No postoperative treatment had highest risk of recurrence
➡️either tamoxifen or #radonc reduced recurrence
➡️combined tamoxifen + RT had no recurrences
In context of EUROPA trial, RT has best QoL vs endocrine… pic.twitter.com/bDVmbDKRNb
HypoG-01
ForBreast cancer, adjuvant locoregional RT including regional nodal irradiation
TL;DRLRR rare (20/118 first events) and mostly in-volume (67%); failure patterns comparable between 40Gy/15fx and 50Gy/25fx, validating ESTRO nodal contouring.
The actionable read is target-volume validation: 20/30 isolated-LRR sites (67%) fell within the CTV and 19/30 were nodal (mainly axillary I-II), so ESTRO-guided contouring is covering where these cancers recur. Failure patterns held across both fractionation arms, supporting 40Gy/15fx with nodal coverage without re-drawing volumes.
- Patterns of failure not obviously different between 3-wk and 5-wk arms → moderate hypofractionation does not shift the failure pattern
6 details 4 trials watching
- 🔍 Pre-planned secondary (patterns-of-failure + dosimetric) analysis, ITT, of HypoG-01 phase III: 40 Gy/15 fx (3wk) vs 50 Gy/25 fx (5wk), all + tumour-bed boost; N=1,260, median f/u 4.8y
- 📊 LRR was the lowest-frequency first event: 20/118; distant recurrence and second malignancy dominated
- 📐 iLRR sites mostly in-volume: 20/30 within CTV (67%) → ESTRO-guided contouring covered where recurrences arose
- 📐 iLRR nodal sites: 19/30, mainly levels I & II (axillary)
- ⚠️ Descriptive analysis; only ~20 LRR events split across two arms — underpowered to detect a between-arm difference, so 'no difference' is not equivalence
- ⚠️ Competing risks dominate: distant recurrence and second malignancy were the main first events; locoregional control is not the limiting factor in this population
- Long-term LRR and second-malignancy rates beyond 4.8y follow-up not yet Ultra-Hypofractionated vs Moderate Hypofractionated Radiotherapy for Regional Lymph Nodes in High Risk Breast Cancer Phase NAn=1950 · primary completion 2034-03 · ultra- vs moderate-hypofx RNI, recurrence endpointrecruiting Conventionally Fractionated vs. Hypofractionated Comprehensive Nodal Irradiation for Breast Cancer Using Pencil Beam Scanning Proton Therapy Phase 3n=276 · primary completion 2038-02 · phase 3 conventional vs hypofx nodal RT, 2038 f/u
- Whether nodal CTV can be tailored given level I-II failure predominance recruiting The T-REX Trial: Tailored Regional External Beam Radiotherapy in Clinically Node-negative Breast Cancer Patients With 1-2 Sentinel Node Macrometastases. Phase NAn=1350 · primary completion 2028-12 · tailored regional RT, omit in 1-2 SN macrometsrecruiting Level I-II Axillary Irradiation in Breast Cancer With Sentinel-Node Macro-metastases Phase NAn=1608 · primary completion 2032-12 · phase 3 level I-II axillary RT vs entire nodal RT
📚 Sources · 🐦 1 tweet
Day TWO of #ESTRO26 Coverage by OncoAlert 🚨
— OncoAlert (@OncoAlert) May 16, 2026
Patterns of locoregional and distant recurrence and dosimetric analysis in the HypoG-01 phase III trial Presented by Louis Munschi 🇫🇷 #RadOnc ☢️
In the HypoG-01 phase III trial (1260 patients, median follow-up 4.8 years), 118… pic.twitter.com/ogARInu0fB
Dutch Breast Boost Indication Study
ForEarly breast cancer, breast-conserving surgery + whole-breast RT
TL;DR10y IBTR 1.2% with or without boost in 0-2 risk-factor pts → tumour-bed boost omittable in the modern systemic-therapy era.
The omission decision turns on absolute IBTR, not the boost-vs-no-boost contrast (confounded by indication: boost arms run higher because higher-risk pts got it). At 0-2 risk factors 10y IBTR is 1.2% either way, so the tumour-bed boost is omittable; ≥3 factors stays open.
- Boost cuts IBTR ~50% in EORTC 22881/10882 (Bartelink, Lancet Oncol 2015), the basis for the current boost indication
| Risk factors | N (no boost / boost) | 5y IBTR (no boost / boost) | 10y IBTR (no boost / boost) |
|---|---|---|---|
| 0-2 | 15,085 / 13,845 | 0.6% / 0.7% | 1.2% / 1.2% |
| ≥3 | 149 / 733 | 1.3% / 2.9% | 2.7% / 3.3% |
| Uncertain | 592 / 944 | 0.8% / 3.3% | 1.4% / 3.6% |
7 details 1 trial watching
- 🔍 Retrospective Dutch national cohort, breast-conserving treatment 2012-2016, boost vs no boost
- 🔍 1° outcome: ipsilateral breast tumour recurrence (IBTR), found via pathology-report algorithm
- 🔍 Five IBTR risk factors counted
- Age ≤40 years
- Grade 3 tumour
- Triple-negative tumour
- Guideline-indicated systemic therapy not adequately given
- No pCR after neoadjuvant chemo in TNBC/HER2+
- 📐 Assisi omission thresholds: 10y IBTR <3% (boost pts) or <6% (no-boost pts)
- 📊 Thresholds exceeded only in the ≥3-risk-factor boost arm at 10y (3.3%); all other subgroups well under
- ⚠️ Boost non-randomized → confounding by indication (higher-risk pts were selected for boost)
- ⚠️ ≥3-risk-factor no-boost arm tiny (N=149) → unstable 10y estimate
- Does a tumour-bed boost help pts with ≥3 risk factors?
- Which subgroups still benefit from a tumour-bed boost? recruiting Ultra-hypofractioNated Adjuvant Radiotherapy ± sImultaneous Integrated Boost for Low-risk Breast Cancer Patients Phase 2n=65 · primary completion 2025-10 · phase 2 ± SIB boost in low-risk pts
📚 Sources · 🐦 1 tweet
Day TWO of #ESTRO26 Coverage by OncoAlert 🚨
— OncoAlert (@OncoAlert) May 16, 2026
Is a boost to the tumour bed still indicated after breast-conserving surgery and whole-breast radiotherapy in the era of modern systemic therapy? Presented by Femke Froklage 🇳🇱 #RadOnc ☢️
We aimed to identify a subgroup of breast… pic.twitter.com/RqK5r9XPqW
RAPCHEM
ForcN+ breast cancer, post-neoadjuvant chemotherapy
TL;DR10yr locoregional recurrence <3% de-escalating RT by nodal response after neoadjuvant chemo; full RT omission still unvalidated.
The RT read is de-escalation, not omission: response-adapted locoregional RT held 10yr recurrence <3%, durable enough to tailor RT volume and intensity to nodal response after NAC. The author draws a hard line at full RT omission, which still awaits NSABP B-51. Per-group LRR and RT volumes not in source.
- De-escalation ≠ omission: full RT omission still under validation per author (prospective trials + NSABP B-51)
5 details 4 trials watching
- 🔍 RT intensity tailored to nodal response after neoadjuvant chemo (de-escalated, not omitted)
- 🔍 RT dose, fractionation, and target volume (involved-field vs elective nodal) not reported in source
- 📊 10yr locoregional recurrence <3% with response-adapted RT de-escalation
- ⚠️ No randomized comparator vs standard full locoregional RT reported in source
- ⚠️ Single conference tweet; per-risk-group LRR, N, and follow-up dates not in source
- Can RT be fully omitted, not just de-escalated, after nodal response? n=12 · primary completion 2027-07 · full RT omission, HER2+ pCR, lumpectomy alonerecruiting Multicenter Trial for Eliminating Breast Cancer Surgery or Radiotherapy in Exceptional Responders to Neoadjuvant Systemic Therapy Phase NAn=120 · primary completion 2028-01 · eliminates RT in exceptional NST respondersrecruiting DESCARTES: De-ESCAlation of RadioTherapy in Patients With Pathologic Complete rESponse to Neoadjuvant Systemic Therapy Phase NAn=595 · primary completion 2032-05 · RT omission after pCR to neoadjuvant systemic txrecruiting Omission of Local Therapies in Women Patients With HER2-positive or Triple-negative Breast Cancer Phase 2n=152 · primary completion 2035-07 · omits RT post-BCS in HER2+/TNBC NST responders
- Per-risk-group LRR and RT target volumes behind the pooled <3%
📚 Sources · 🐦 1 tweet
A 10 años de RAPCHEM son muy buenos y tranquilizadores: desescalar RT locorregional según respuesta nodal tras neoadyuvante da tasas de recurrencia <3%. Sin embargo, la omisión completa de RT sigue en proceso de validación (estudios prospectivos + B-51). #RadOnc#ESTRO26 https://t.co/dlpH8joIGA
— Amadeo Wals (@AmadeoWals) May 17, 2026
