Early HER2-positive breast cancer: the decisions you may face
5 treatment settings, 5 with more than one named option. Each section lays out the options the standard of care names, what each is for, the trials behind them with their recorded results, the side effects and cautions on record, and questions to ask. Built from the cancer page's standard-of-care rows; nothing here is advice for your case.
Stage I, small node-negative tumours
Surgery first, then twelve weeks of paclitaxel with a year of trastuzumab (APT).
A microtubule poison discovered in the Pacific yew tree, among the most used chemotherapies in breast, lung, and ovarian cancer.
The first targeted antibody for a solid tumour (1998), which turned HER2-positive breast cancer from the worst subtype into one of the most treatable.
- Small (≤3 cm), node-negative HER2+ breast cancer: 12 weeks paclitaxel + 1 year trastuzumab
Show survival figures (1)
Averages across everyone diagnosed, often years ago. Your stage, subtype, age, fitness and the treatment you receive matter more than the average, and the numbers are improving quickly.
- 7-year DFS 93%; 10-year RFI 96.3%.
No side-effect rates or interaction flags are recorded for these options yet. The side-effect lookup and interaction checker cover the products that have them.
- Between Paclitaxel / nab-paclitaxel and Trastuzumab, which do you recommend for me, and what about my case would make you choose differently?Why: Guidelines list several reasonable options; the choice turns on details of your tumour, your health and your priorities.
- What is each option trying to achieve: cure, long control, or relief of symptoms, and over what time?Why: The aim shapes how much side effect and disruption is worth accepting.
- How closely do I match the people in APT (adjuvant paclitaxel-trastuzumab), and does that change what the results mean for me?Why: Trial populations are selected; age, fitness, prior treatment and biomarkers all affect how far results carry.
- What happens if I delay, or decline this step for now? Is the decision reversible?Why: Some decisions can wait for a second opinion or a trial slot; others cannot. Knowing which is part of the choice.
- For my situation (stage i, small node-negative tumours), which of the standard options do you recommend and why?Why: Guideline options include: Surgery first, then twelve weeks of paclitaxel with a year of trastuzumab (APT).
- Am I a candidate for Paclitaxel / nab-paclitaxel, 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 APT (adjuvant paclitaxel-trastuzumab) apply to someone like me?Why: Trial populations differ from individual patients; ask how closely you match.
Add these to your appointment list, or take the full question set for this cancer.
Stage II to III, before surgery
Carboplatin, a taxane, trastuzumab and pertuzumab for six cycles without an anthracycline (TRAIN-2), or trastuzumab deruxtecan followed by taxane, trastuzumab and pertuzumab (DESTINY-Breast11).
Carboplatin is a platinum chemotherapy that crosslinks DNA; it is part of the standard pre-surgery regimen for triple-negative breast cancer.
The first chemotherapy to extend life in prostate cancer (2004), now part of triplet therapy at first metastatic diagnosis.
A microtubule poison discovered in the Pacific yew tree, among the most used chemotherapies in breast, lung, and ovarian cancer.
The first targeted antibody for a solid tumour (1998), which turned HER2-positive breast cancer from the worst subtype into one of the most treatable.
A second HER2 antibody that binds a different spot from trastuzumab, blocking HER2 from pairing with HER3; together they extended survival by 16 months in CLEOPATRA.
Trastuzumab deruxtecan (Enhertu) is the most successful ADC ever. It redefined HER2 by working in tumours with only tiny amounts of the protein, and in 2026 moved into early-stage breast cancer.
- Stage II to III HER2-positive breast cancer: neoadjuvant carboplatin and paclitaxel with trastuzumab and pertuzumab, with or without three cycles of anthracycline first
Show survival figures (1)
Averages across everyone diagnosed, often years ago. Your stage, subtype, age, fitness and the treatment you receive matter more than the average, and the numbers are improving quickly.
- Pathological complete response 67% without anthracycline vs 68% with; 3-year event-free survival 93.5% vs 92.7%.
Pathological complete response (breast and axilla) (%): Carboplatin-paclitaxel + trastuzumab + pertuzumab 67 (n=219) vs FEC then carboplatin-paclitaxel + trastuzumab + pertuzumab 68 (n=219) · source - Tests Trastuzumab deruxtecanNeoadjuvant high-risk HER2+ early breast cancer: T-DXd followed by THP vs ddAC-THP
pCR 67.3% vs 56.3%.
Pathologic complete response (ypT0/Tis ypN0) (%): T-DXd → THP 67.3 (n=321) vs ddAC → THP 56.3 (n=320) · source
- Dose by Calvert formula using GFR (see the calculators).
- Do not give if bilirubin above ULN, or AST/ALT above 1.5 x ULN with alkaline phosphatase above 2.5 x ULN (treatment-related deaths).
| Side effect | Any grade | Grade 3+ |
|---|---|---|
| Neutropenia · DESTINY-Breast03/04; all-grade rates ≥20% per label | - | 18% |
| Nausea · DESTINY-Breast03/04; all-grade rates ≥20% per label | - | 7% |
| Anaemia · DESTINY-Breast03/04; all-grade rates ≥20% per label | - | 7% |
| Fatigue · DESTINY-Breast03/04; all-grade rates ≥20% per label | - | 6% |
- Interstitial lung disease in 10-15%: hold for any respiratory symptom and image; permanently discontinue for grade 2 or above. Moderately emetogenic: three-drug prophylaxis.
Rates from the label or pivotal trial as recorded on the product page; each grade 3+ figure links to its source.
- Between Carboplatin, Docetaxel, Paclitaxel / nab-paclitaxel and the other options, which do you recommend for me, and what about my case would make you choose differently?Why: Guidelines list several reasonable options; the choice turns on details of your tumour, your health and your priorities.
- What is each option trying to achieve: cure, long control, or relief of symptoms, and over what time?Why: The aim shapes how much side effect and disruption is worth accepting.
- How closely do I match the people in TRAIN-2 and DESTINY-Breast11, and does that change what the results mean for me?Why: Trial populations are selected; age, fitness, prior treatment and biomarkers all affect how far results carry.
- Which side effects of Trastuzumab deruxtecan are most likely for me, which are reversible, and which would make us stop?Why: The recorded rates below come from labels and trials; your own risk depends on dose, other medicines and your health.
- What happens if I delay, or decline this step for now? Is the decision reversible?Why: Some decisions can wait for a second opinion or a trial slot; others cannot. Knowing which is part of the choice.
- For my situation (stage ii to iii, before surgery), which of the standard options do you recommend and why?Why: Guideline options include: Carboplatin, a taxane, trastuzumab and pertuzumab for six cycles without an anthracycline (TRAIN-2), or trastuzumab deruxtecan followed by taxane, trastuzumab and pertuzumab (DESTINY-Breast11).
- Am I a candidate for Carboplatin, Docetaxel, Paclitaxel / nab-paclitaxel 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 TRAIN-2 and DESTINY-Breast11 apply to someone like me?Why: Trial populations differ from individual patients; ask how closely you match.
Add these to your appointment list, or take the full question set for this cancer.
Pathological complete response at surgery
Trastuzumab, with pertuzumab in node-positive disease, to complete one year (APHINITY, HERA); endocrine therapy if hormone receptor-positive.
The first targeted antibody for a solid tumour (1998), which turned HER2-positive breast cancer from the worst subtype into one of the most treatable.
A second HER2 antibody that binds a different spot from trastuzumab, blocking HER2 from pairing with HER3; together they extended survival by 16 months in CLEOPATRA.
- Tests Trastuzumab, PertuzumabAdjuvant HER2+ early breast cancer: pertuzumab + trastuzumab + chemotherapy vs placebo + trastuzumab + chemotherapy
Show survival figures (1)
Averages across everyone diagnosed, often years ago. Your stage, subtype, age, fitness and the treatment you receive matter more than the average, and the numbers are improving quickly.
- 8-year iDFS HR 0.78; node-positive absolute +4.9%.
8-year invasive disease-free survival (%): Pertuzumab arm 88.4 (n=2400) vs Placebo arm 85.8 (n=2405) · HR 0.78 · source - Tests TrastuzumabAdjuvant HER2+ early breast cancer: one year of trastuzumab with or after chemotherapy vs chemotherapy alone
Show survival figures (1)
Averages across everyone diagnosed, often years ago. Your stage, subtype, age, fitness and the treatment you receive matter more than the average, and the numbers are improving quickly.
- B-31/N9831 10-year OS 84% vs 75.2%, HR 0.63.
No side-effect rates or interaction flags are recorded for these options yet. The side-effect lookup and interaction checker cover the products that have them.
- Between Trastuzumab and Pertuzumab, which do you recommend for me, and what about my case would make you choose differently?Why: Guidelines list several reasonable options; the choice turns on details of your tumour, your health and your priorities.
- What is each option trying to achieve: cure, long control, or relief of symptoms, and over what time?Why: The aim shapes how much side effect and disruption is worth accepting.
- How closely do I match the people in APHINITY and HERA, NSABP B-31 & NCCTG N9831 (adjuvant trastuzumab), and does that change what the results mean for me?Why: Trial populations are selected; age, fitness, prior treatment and biomarkers all affect how far results carry.
- What happens if I delay, or decline this step for now? Is the decision reversible?Why: Some decisions can wait for a second opinion or a trial slot; others cannot. Knowing which is part of the choice.
- For my situation (pathological complete response at surgery), which of the standard options do you recommend and why?Why: Guideline options include: Trastuzumab, with pertuzumab in node-positive disease, to complete one year (APHINITY, HERA); endocrine therapy if hormone receptor-positive.
- 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.
Add these to your appointment list, or take the full question set for this cancer.
Residual invasive disease at surgery
Trastuzumab deruxtecan (DESTINY-Breast05) or trastuzumab emtansine for fourteen cycles (KATHERINE).
Trastuzumab deruxtecan (Enhertu) is the most successful ADC ever. It redefined HER2 by working in tumours with only tiny amounts of the protein, and in 2026 moved into early-stage breast cancer.
Trastuzumab emtansine (Kadcyla, T-DM1) was the first ADC for a solid tumour (2013). It is still standard after surgery for HER2+ breast cancer patients whose tumour did not fully respond to pre-surgery treatment.
- High-risk HER2+ early breast cancer with residual invasive disease after neoadjuvant therapy: T-DXd vs T-DM1
Show survival figures (1)
Averages across everyone diagnosed, often years ago. Your stage, subtype, age, fitness and the treatment you receive matter more than the average, and the numbers are improving quickly.
- 3-year iDFS 92.4% vs 83.7%, HR 0.47.
- Tests Trastuzumab emtansineHER2+ early breast cancer with residual invasive disease after neoadjuvant therapy: T-DM1 vs trastuzumab for 14 cycles
iDFS HR 0.50; OS HR 0.66.
3-year invasive disease-free survival (%): T-DM1 88.3 (n=743) vs Trastuzumab 77 (n=743) · HR 0.5 · source
| Side effect | Any grade | Grade 3+ |
|---|---|---|
| Neutropenia · DESTINY-Breast03/04; all-grade rates ≥20% per label | - | 18% |
| Nausea · DESTINY-Breast03/04; all-grade rates ≥20% per label | - | 7% |
| Anaemia · DESTINY-Breast03/04; all-grade rates ≥20% per label | - | 7% |
| Fatigue · DESTINY-Breast03/04; all-grade rates ≥20% per label | - | 6% |
- Interstitial lung disease in 10-15%: hold for any respiratory symptom and image; permanently discontinue for grade 2 or above. Moderately emetogenic: three-drug prophylaxis.
Rates from the label or pivotal trial as recorded on the product page; each grade 3+ figure links to its source.
| Side effect | Any grade | Grade 3+ |
|---|---|---|
| Thrombocytopenia · KATHERINE (adjuvant) | 29% | 6% |
| Fatigue · KATHERINE (adjuvant) | 50% | - |
| Nausea · KATHERINE (adjuvant) | 42% | - |
| Transaminases increased · KATHERINE (adjuvant) | 32% | - |
Rates from the label or pivotal trial as recorded on the product page; each grade 3+ figure links to its source.
- Between Trastuzumab deruxtecan and Trastuzumab emtansine, which do you recommend for me, and what about my case would make you choose differently?Why: Guidelines list several reasonable options; the choice turns on details of your tumour, your health and your priorities.
- What is each option trying to achieve: cure, long control, or relief of symptoms, and over what time?Why: The aim shapes how much side effect and disruption is worth accepting.
- How closely do I match the people in DESTINY-Breast05 and KATHERINE, and does that change what the results mean for me?Why: Trial populations are selected; age, fitness, prior treatment and biomarkers all affect how far results carry.
- Which side effects of Trastuzumab deruxtecan or Trastuzumab emtansine are most likely for me, which are reversible, and which would make us stop?Why: The recorded rates below come from labels and trials; your own risk depends on dose, other medicines and your health.
- What happens if I delay, or decline this step for now? Is the decision reversible?Why: Some decisions can wait for a second opinion or a trial slot; others cannot. Knowing which is part of the choice.
- For my situation (residual invasive disease at surgery), which of the standard options do you recommend and why?Why: Guideline options include: Trastuzumab deruxtecan (DESTINY-Breast05) or trastuzumab emtansine for fourteen cycles (KATHERINE).
- Am I a candidate for 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-Breast05 and KATHERINE apply to someone like me?Why: Trial populations differ from individual patients; ask how closely you match.
Add these to your appointment list, or take the full question set for this cancer.
Local therapy and the heart
Breast conservation or mastectomy with sentinel node biopsy, radiotherapy by stage, and echocardiography every three months during trastuzumab.
Removing just the first lymph node a tumour drains to, instead of all of them, to check for spread.
- Avoids lymphoedema from full dissection
Fewer, larger daily doses instead of the classic five to seven weeks of small ones. Large trials in breast and prostate cancer showed the same control with the same or fewer late effects and far less time in hospital.
- One to three weeks instead of five to seven
- Same cancer control in randomised trials
- Frees machine capacity
No trial record is attached to this row yet. The trials tab lists what is recruiting and the landmark trials for this cancer.
- False negatives in ~5-10%
- Long-term follow-up still accruing for the shortest schedules
- Not suitable where large volumes of normal tissue are treated
- Requires precise setup
- Between Sentinel lymph node biopsy and Hypofractionated radiotherapy, which do you recommend for me, and what about my case would make you choose differently?Why: Guidelines list several reasonable options; the choice turns on details of your tumour, your health and your priorities.
- What is each option trying to achieve: cure, long control, or relief of symptoms, and over what time?Why: The aim shapes how much side effect and disruption is worth accepting.
- What happens if I delay, or decline this step for now? Is the decision reversible?Why: Some decisions can wait for a second opinion or a trial slot; others cannot. Knowing which is part of the choice.
- For my situation (local therapy and the heart), which of the standard options do you recommend and why?Why: Guideline options include: Breast conservation or mastectomy with sentinel node biopsy, radiotherapy by stage, and echocardiography every three months during trastuzumab.
Add these to your appointment list, or take the full question set for this cancer.