Living with itHER2-positive breast cancer

Back to the HER2-positive breast cancer hub →43 questions · 6 red cards

The decisions you may face, the aids that walk through them, the warnings on record, the first sixty days and the questions to ask.

Living with it

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The first 60 days →Appointment prep sheet →Side effects →Help with costs →

Decisions you may face

11 with more than one option · full decision page →

One section per setting: the options named, what each is for, the trials behind them, the recorded trade-offs and the questions to ask.

Early stage3 Metastatic2 Stage I (≤2-3 cm, node-negative)3 Stage II-III, neoadjuvant2 Post-neoadjuvant, pathologic complete response2 Post-neoadjuvant, residual invasive disease3 Adjuvant (upfront surgery), node-positive2 Metastatic, first line4 Metastatic, second line2 Metastatic, later lines7 Brain metastases3 Cardiac monitoring and survivorship

Red cards

From the labels and guidelines behind the standard of care. Your team's thresholds win.

Emergency services now
Skin reaction
Blisters, peeling, or sores in the mouth or eyes with a rash. Enfortumab vedotin carries a boxed warning for Stevens-Johnson syndrome and toxic epidermal necrolysis, mostly in the first cycle.
Disitamab vedotin Trastuzumab deruxtecan Trastuzumab emtansine Trastuzumab rezetecan source
Emergency services now
Fainting or palpitations
Fainting, near-fainting, or an irregular or racing heartbeat; several kinase inhibitors prolong the QT interval and the labels require ECG and electrolyte monitoring.
Lapatinib Neratinib Tucatinib source
Emergency services now
Bleeding or bruising
Bleeding that will not stop, black or bloody stools, or unexplained bruising when platelets are expected to be low.
Paclitaxel / nab-paclitaxel source
Emergency services now
Fainting or palpitations (ribociclib)
Fainting, dizziness or an irregular heartbeat; QT prolongation is a labelled warning and ECGs are checked in the first cycles.
Palbociclib source
Call the 24-hour line now
Interstitial lung disease or pneumonitis
Any new or worsening cough, breathlessness or fever. The label says to interrupt treatment for any suspected ILD and to permanently discontinue for grade 2 or higher.
Trastuzumab deruxtecan source
Check before combining
Lapatinib with Tucatinib: major interaction
CYP3A4: Tucatinib (strong inhibitor) raises Lapatinib exposure (sensitive substrate).. Avoid; if unavoidable, reduce to 500 mg daily.
Lapatinib Tucatinib source

See all on the product pages:Disitamab vedotin Lapatinib Neratinib Paclitaxel / nab-paclitaxel Palbociclib Trastuzumab deruxtecan Trastuzumab emtansine Trastuzumab rezetecan Tucatinib·Printable cards in the navigator

Treatment journeys

What the next twelve months look like, phase by phase, with the decision points.

Stage II-III (operable)

Questions to ask

Bring to your appointment

Questions to ask your oncologist about HER2-positive breast cancer

Generated from this cancer's standard of care, biomarkers, and pipeline · 43 questions

Newly diagnosed

What is my exact diagnosis, stage, and grade, and which tests established them?
Why: Everything else follows from an accurate stage and subtype.
Which biomarkers have been tested on my tumour (for example HER2 IHC 3+ or ISH-amplified, HR status, pCR after neoadjuvant therapy, HER2 IHC 3+ or IHC 2+ with ISH amplification; HER2 heterogeneity, HR status), and what were the results?
Why: These results decide eligibility for targeted therapy, immunotherapy, and trials.
Which subtype is my cancer, and does that change the recommended treatment?
Why: Recognised subtypes for this cancer include HER2-enriched, HR+/HER2+, HR-/HER2+.
Is germline (inherited) genetic testing recommended for me or my family?
Why: Inherited variants can change treatment and matter for relatives.

Early stage

For my situation (early stage), which of the standard options do you recommend and why?
Why: Guideline options include: Neoadjuvant THP or T-DXd → surgery → trastuzumab/pertuzumab (pCR) or T-DXd/T-DM1 (residual).
Am I a candidate for Trastuzumab, Trastuzumab deruxtecan, Trastuzumab emtansine, and what side effects should I expect?
Why: Knowing the expected toxicities helps you plan work, family, and supportive care.
How do the results of DESTINY-Breast11 apply to someone like me?
Why: Trial populations differ from individual patients; ask how closely you match.

Metastatic

For my situation (metastatic), which of the standard options do you recommend and why?
Why: Guideline options include: T-DXd + pertuzumab first line (DESTINY-Breast09); tucatinib + trastuzumab + capecitabine for brain metastases; palbociclib maintenance if HR+.
Am I a candidate for Tucatinib, Palbociclib, and what side effects should I expect?
Why: Knowing the expected toxicities helps you plan work, family, and supportive care.
How do the results of DESTINY-Breast09 apply to someone like me?
Why: Trial populations differ from individual patients; ask how closely you match.

Stage I (≤2-3 cm, node-negative)

For my situation (stage i (≤2-3 cm, node-negative)), which of the standard options do you recommend and why?
Why: Guideline options include: Surgery then weekly paclitaxel × 12 + trastuzumab × 1 year (APT); T-DM1 × 17 cycles is an alternative (ATEMPT). Endocrine therapy if HR+.
Am I a candidate for Paclitaxel / nab-paclitaxel, Trastuzumab, Trastuzumab emtansine, and what side effects should I expect?
Why: Knowing the expected toxicities helps you plan work, family, and supportive care.
How do the results of APT (adjuvant paclitaxel-trastuzumab) apply to someone like me?
Why: Trial populations differ from individual patients; ask how closely you match.

Stage II-III, neoadjuvant

For my situation (stage ii-iii, neoadjuvant), which of the standard options do you recommend and why?
Why: Guideline options include: TCHP (docetaxel, carboplatin, trastuzumab, pertuzumab) or anthracycline-taxane + HP; from 2026, T-DXd × 4 → THP (DESTINY-Breast11, pCR 67%). PET-adapted chemotherapy omission (PHERGain) in trials.
Am I a candidate for Trastuzumab deruxtecan, Pertuzumab, and what side effects should I expect?
Why: Knowing the expected toxicities helps you plan work, family, and supportive care.
How do the results of DESTINY-Breast11 and PHERGain apply to someone like me?
Why: Trial populations differ from individual patients; ask how closely you match.

Post-neoadjuvant, pathologic complete response

For my situation (post-neoadjuvant, pathologic complete response), which of the standard options do you recommend and why?
Why: Guideline options include: Complete 1 year of trastuzumab (± pertuzumab if node-positive at diagnosis); endocrine therapy if HR+; radiation per stage.
Am I a candidate for Trastuzumab, Pertuzumab, and what side effects should I expect?
Why: Knowing the expected toxicities helps you plan work, family, and supportive care.
How do the results of APHINITY and HERA, NSABP B-31 & NCCTG N9831 (adjuvant trastuzumab) apply to someone like me?
Why: Trial populations differ from individual patients; ask how closely you match.

Post-neoadjuvant, residual invasive disease

For my situation (post-neoadjuvant, residual invasive disease), which of the standard options do you recommend and why?
Why: Guideline options include: T-DXd (DESTINY-Breast05, iDFS HR 0.47 vs T-DM1; approved 2026) replacing T-DM1 (KATHERINE); consider extended adjuvant neratinib for HR+ high-risk.
Am I a candidate for Trastuzumab deruxtecan, Trastuzumab emtansine, Neratinib, and what side effects should I expect?
Why: Knowing the expected toxicities helps you plan work, family, and supportive care.
How do the results of DESTINY-Breast05 and KATHERINE apply to someone like me?
Why: Trial populations differ from individual patients; ask how closely you match.

Adjuvant (upfront surgery), node-positive

For my situation (adjuvant (upfront surgery), node-positive), which of the standard options do you recommend and why?
Why: Guideline options include: Chemotherapy + trastuzumab + pertuzumab for 1 year (APHINITY); trastuzumab alone for lower risk; 6 months acceptable where resources are limited (PERSEPHONE).
Am I a candidate for Pertuzumab, Trastuzumab, and what side effects should I expect?
Why: Knowing the expected toxicities helps you plan work, family, and supportive care.
How do the results of APHINITY and PERSEPHONE apply to someone like me?
Why: Trial populations differ from individual patients; ask how closely you match.

Metastatic, first line

For my situation (metastatic, first line), which of the standard options do you recommend and why?
Why: Guideline options include: T-DXd + pertuzumab (DESTINY-Breast09, PFS 40.7 months; approved 2025) or taxane + trastuzumab + pertuzumab (CLEOPATRA) followed by maintenance: HP ± tucatinib (HER2CLIMB-05) and, if HR+, endocrine therapy + palbociclib (PATINA, approved 2026).
Am I a candidate for Trastuzumab deruxtecan, Pertuzumab, Tucatinib or related drugs, and what side effects should I expect?
Why: Knowing the expected toxicities helps you plan work, family, and supportive care.
How do the results of DESTINY-Breast09 and CLEOPATRA apply to someone like me?
Why: Trial populations differ from individual patients; ask how closely you match.

Metastatic, second line

For my situation (metastatic, second line), which of the standard options do you recommend and why?
Why: Guideline options include: T-DXd if not used first line (DESTINY-Breast03, PFS HR 0.33 vs T-DM1); tucatinib + trastuzumab + capecitabine, especially with brain metastases (HER2CLIMB).
Am I a candidate for Trastuzumab deruxtecan, Tucatinib, and what side effects should I expect?
Why: Knowing the expected toxicities helps you plan work, family, and supportive care.
How do the results of DESTINY-Breast03 and HER2CLIMB apply to someone like me?
Why: Trial populations differ from individual patients; ask how closely you match.

Metastatic, later lines

For my situation (metastatic, later lines), which of the standard options do you recommend and why?
Why: Guideline options include: T-DM1; neratinib or lapatinib + capecitabine; margetuximab + chemotherapy; trastuzumab + chemotherapy (continued HER2 blockade); zanidatamab and Chinese ADCs (trastuzumab rezetecan, disitamab vedotin) where available; trials.
Am I a candidate for Trastuzumab emtansine, Neratinib, Lapatinib or related drugs, and what side effects should I expect?
Why: Knowing the expected toxicities helps you plan work, family, and supportive care.

Brain metastases

For my situation (brain metastases), which of the standard options do you recommend and why?
Why: Guideline options include: Systemic: tucatinib triplet or T-DXd (DESTINY-Breast12, intracranial ORR 72%); local: stereotactic radiosurgery or surgery for symptomatic or large lesions; whole-brain RT reserved.
Am I a candidate for Tucatinib, Trastuzumab deruxtecan, and what side effects should I expect?
Why: Knowing the expected toxicities helps you plan work, family, and supportive care.
How do the results of HER2CLIMB and DESTINY-Breast12 apply to someone like me?
Why: Trial populations differ from individual patients; ask how closely you match.

Cardiac monitoring and survivorship

For my situation (cardiac monitoring and survivorship), which of the standard options do you recommend and why?
Why: Guideline options include: LVEF every 3 months during anti-HER2 therapy; hold and cardioprotect for declines; anthracycline-free regimens preferred; long-term surveillance for late recurrence in HR+/HER2+.
How do the results of PERSEPHONE apply to someone like me?
Why: Trial populations differ from individual patients; ask how closely you match.

Any stage

Are there clinical trials I could join, for example of HER2 PET, Zanidatamab, Disitamab vedotin, TQB2102?
Why: Trials are how the next standard of care is set; asking early keeps options open.
Would a second opinion at a high-volume centre change anything, and can you help arrange it?
Why: Rare or high-stakes decisions benefit from a centre that treats many similar patients.
What supportive care (symptom control, nutrition, exercise, mental health, financial help) is available from the start?
Why: Supportive care improves quality of life and helps patients complete treatment.
I read that “Brain metastases in ~50% of metastatic patients”. How does that affect my plan?
Why: Open problems are where trials and second opinions matter most.
I read that “Which patients can skip chemotherapy entirely”. How does that affect my plan?
Why: Open problems are where trials and second opinions matter most.

Newly diagnosed? Read the first 60 days with HER2-positive breast cancer, then print the one-page appointment sheet with room for the answers.

Print this page for your appointment (your browser's print command). These prompts are for discussion; your clinical team knows your case.

Model panel1 model

Machine commentary by named AI models on a date, not clinical review. Claims are tied to the record's own sources; check them before relying on anything here.

FableAnthropic · v5.12026-09-17low confidence

The record's core narrative is sound and consistent with its cited overview: HER2 amplification as an adverse marker, trastuzumab in 1998, adjuvant dual blockade, response-adapted post-neoadjuvant therapy and de-escalation for small node-negative tumours. Its weaknesses are sourcing and internal consistency. Much of the standard of care now rests on 2025 and 2026 approvals (DESTINY-Breast09, DESTINY-Breast05, DESTINY-Breast11, PATINA) and on figures such as PFS 40.7 months, iDFS HR 0.47, pCR 67% and 400,000 cases a year that none of the three listed sources can be shown to contain, and the record itself admits the NCCN guideline is 'pending update' for T-DXd in one setting while claiming category 1 for it in another. ESMO-MCBS grades are attached to an NCCN URL. The history, biomarkers and state-of-the-art lists contain duplicated entries, the 'Stage I' setting label mixes stage I and IIA tumours, and the inclusion of HER2-mutant, non-amplified disease as a subtype contradicts the record's own IHC 3+/ISH-amplified definition.

Right 2Disputed 1Unclear 4Show verdicts

Right
HER2-positive breast cancer (15-20% of cases; HER2 IHC 3+ or ISH-amplified) was the most aggressive subtype until trastuzumab (1998) made it one of the most treatable.
The definition, prevalence range and the 1998 trastuzumab turning point are consistent with the encyclopaedic overview the record cites. Two internal points weaken presentation: the history section carries the Slamon 1987, trastuzumab 1998, T-DM1 2013, DESTINY-Breast03 2021 and 2026 entries twice each, and the Slamon note quotes 25-30% amplification while the headline says 15-20%, a gap the record does not explain (older assays versus current ASCO/CAP criteria).
Wikipedia
Right
Stage I (≤2-3 cm, node-negative): surgery then weekly paclitaxel × 12 + trastuzumab × 1 year (APT); T-DM1 × 17 cycles is an alternative (ATEMPT).
De-escalated paclitaxel-trastuzumab for small node-negative HER2-positive tumours is the approach the cited NCCN guideline covers, and the NCCN 2A label is plausible. The setting label is loose: a node-negative tumour of 2-3 cm is stage IIA, not stage I, so '≤2-3 cm' and 'Stage I' do not describe the same group.
Guideline (Stage I (≤2-3 cm, node-negative))
Unclear
T-DXd (DESTINY-Breast05, iDFS HR 0.47 vs T-DM1; approved 2026) replacing T-DM1 (KATHERINE)
The record's own guideline field for this setting reads 'NCCN 1 (T-DM1); T-DXd pending update', so the cited guideline does not yet back T-DXd here. The Stage II-III neoadjuvant entry claims NCCN category 1 for 'T-DXd × 4 → THP' without the same caveat, which is internally inconsistent. Neither listed source can be shown to cover the 2026 approvals.
Guideline (Stage I (≤2-3 cm, node-negative))
Unclear
esmoMcbs: A (KATHERINE); A (HERA); C (NeoSphere, APHINITY)
ESMO-MCBS grades are attached to a guideline object whose only URL is the NCCN early-stage article. NCCN does not issue ESMO-MCBS scores, and no ESMO source is listed, so the grades (here and the '4' scores in the metastatic settings) cannot be checked against the record's sources.
NCCN Guidelines: Breast Cancer (Early stage)
Disputed
HER2-mutant (activating mutations without amplification; T-DXd tumour-agnostic, HER2 TKIs; more common in lobular and HER2-low)
The record defines HER2-positive disease as IHC 3+ or ISH-amplified, and this subtype is described as lacking amplification and being commoner in HER2-low tumours. By the record's own definition it is not a subtype of HER2-positive breast cancer; it belongs in a HER2-mutant or HER2-low record.
Wikipedia
Unclear
T-DXd + pertuzumab first line (DESTINY-Breast09, PFS 40.7 months; approved 2025) ... palbociclib maintenance (PATINA, approved 2026)
The record's metastatic standard of care rests on approvals dated 2025 and 2026 and on a PFS figure and NCCN 'category 1, preferred' status that none of the three listed sources is shown to contain. Linked OnCo records repeat the same claims but are not independent sources. Primary regulatory or trial references should be attached.
Guideline (Stage I (≤2-3 cm, node-negative))
Unclear
Brain metastases, which develop in up to half of patients, are now treatable systemically with tucatinib (HER2CLIMB) and T-DXd (DESTINY-Breast12).
The 'up to half' figure is stated consistently in the summary and open problems and matches the linked term record, but none of the listed sources is shown to give this incidence, nor the DESTINY-Breast12 intracranial response rate of 72% quoted in the brain metastases setting. The tucatinib triplet's role in brain metastases is well established and plausibly in the NCCN guideline cited.
Wikipedia

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ProvenanceLast edited 2026-09-18 · Jude Gomila · Link cancer subtypes to their siblings and name parents i… · diff · file · history

Wikipedia

HER2-positive breast cancer

Sources & links

Wikipedia