Breast Cancer Treatment: Surgery, Chemo, Radiation, and Targeted Therapy
Written by North Editorial Staff | Clinically reviewed by Laura Morrissey, RN, BSN | Last reviewed: March 2026
Key Takeaways
Breast cancer treatment is highly individualized — your plan depends on tumor stage, hormone receptor status (ER/PR), HER2 status, genomic features, and your overall health and preferences.
Most patients receive a combination of treatments, often surgery plus systemic therapy (chemotherapy, hormone therapy, and/or targeted therapy), with or without radiation.
Lumpectomy followed by radiation offers equivalent survival to mastectomy for eligible patients — the 20-year NSABP B-06 data confirmed this.
Targeted therapies have dramatically improved outcomes for HER2-positive and hormone receptor–positive breast cancers; newer antibody-drug conjugates like T-DXd (Enhertu) are now active even in HER2-low disease.
Clinical trials have driven every major advance in breast cancer treatment — from immunotherapy for triple-negative breast cancer to CDK4/6 inhibitors — and remain a legitimate option worth discussing with your care team at every stage.
How Breast Cancer Treatment Is Decided
Breast cancer treatment is tailored to each patient based on tumor stage, hormone receptor status (ER/PR), HER2 status, genomic features, age, overall health, and personal preference. Most patients receive a combination of treatments — surgery plus systemic therapy, often with radiation. No single treatment plan fits all.
After your diagnosis, a multidisciplinary tumor board (a team that typically includes a surgical oncologist, medical oncologist, radiation oncologist, radiologist, and pathologist) reviews your case together to develop a coordinated treatment plan. This collaborative approach is now standard practice at major cancer centers and has been shown to improve decision-making consistency.
Several factors directly shape which treatments you will receive and in what sequence:
Tumor stage. Stage defines how far the cancer has spread — from Stage I (small, localized tumors) through Stage IV (metastatic disease). Stage guides how aggressive your treatment needs to be.
Hormone receptor status. Tumors that express estrogen receptors (ER) and/or progesterone receptors (PR) — called hormone receptor–positive (HR+) cancers — respond to endocrine (hormone-blocking) therapy. About 70–80% of breast cancers are HR+.
HER2 status. Human epidermal growth factor receptor 2 (HER2) amplification occurs in roughly 15–20% of breast cancers. HER2-positive cancers grow more aggressively but respond dramatically to HER2-targeted therapies. HER2-low (weakly expressing, not amplified) cancers now have their own treatment category after DESTINY-Breast06 data.
Tumor biology and genomic testing. For early-stage, HR+/HER2-negative cancers, genomic assays like Oncotype DX (21-gene recurrence score) and MammaPrint (70-gene assay) estimate the risk of distant recurrence and help determine whether chemotherapy adds meaningful benefit beyond hormone therapy alone. Updated NCCN guidelines (Version 5.2025) now recognize MammaPrint as a tool for identifying HR+/HER2-negative patients who benefit from anthracycline-based chemotherapy.
Treatment sequencing: neoadjuvant vs. adjuvant. Treatment given before surgery is called neoadjuvant (or pre-operative) therapy. Treatment given after surgery is called adjuvant. Neoadjuvant chemotherapy can shrink a tumor before surgery, sometimes making a lumpectomy possible where mastectomy would otherwise have been required, and it allows your oncology team to assess in real time how well your cancer is responding.
Surgery: Lumpectomy vs. Mastectomy
Surgery is typically the first or central step in treating early-stage breast cancer. The two primary options — lumpectomy and mastectomy — differ in how much breast tissue is removed, but for eligible patients, they offer equivalent long-term survival.
Lumpectomy (Breast-Conserving Surgery)
Lumpectomy removes the tumor along with a margin of surrounding healthy tissue while preserving the rest of the breast. It is appropriate for most patients with Stage I–II breast cancer and many with Stage III disease, provided the tumor-to-breast size ratio is favorable and the surgical margin can be cleared.
For the vast majority of patients who have a lumpectomy, radiation therapy to the remaining breast tissue follows. This combination is what makes local control equivalent to mastectomy. The landmark NSABP B-06 randomized trial, with 20-year follow-up published in the New England Journal of Medicine, confirmed that lumpectomy plus breast irradiation achieves the same overall survival as total mastectomy (hazard ratio for death 0.97; P=0.74). When you are eligible, lumpectomy preserves your breast with no compromise to survival.
In selected older postmenopausal women with small, ER-positive, low-grade tumors, radiation may sometimes be omitted, your surgeon and radiation oncologist can advise whether this applies to your situation.
Mastectomy
Mastectomy is total surgical removal of the breast. There are several types:
Simple (total) mastectomy — removes all breast tissue but leaves the chest muscles and most lymph nodes intact
Modified radical mastectomy — removes the breast and the axillary (underarm) lymph nodes
Skin-sparing mastectomy — removes breast tissue while preserving the skin envelope for reconstruction
Nipple-sparing mastectomy — preserves both skin and the nipple-areola complex, where oncologically appropriate
Mastectomy may be preferred or recommended when a tumor is large relative to breast size, when multiple tumors exist in the same breast, after prior radiation to the chest, when surgical margins cannot be cleared with lumpectomy, or when a patient carries a BRCA1 or BRCA2 genetic mutation (which significantly elevates the risk of a second primary breast cancer). Some patients choose bilateral (double) mastectomy for risk reduction — this is a personal decision best made in discussion with your surgical oncologist and a genetic counselor.
Sentinel Lymph Node Biopsy and Axillary Dissection
To determine whether cancer has spread to the lymph nodes, your surgeon will first perform a sentinel lymph node biopsy. A radioactive tracer or dye is injected near the tumor; it travels to the first lymph node(s) that drain from the breast, known as the sentinel nodes. If the sentinel nodes are cancer-free, full removal of the underarm lymph nodes (axillary lymph node dissection) is avoided, significantly reducing the risk of lymphedema and other complications.
Full axillary lymph node dissection is generally reserved for patients with three or more positive sentinel nodes or pre-operative evidence of nodal spread. Updated NCCN guidelines (2025) also allow sentinel lymph node biopsy omission in selected postmenopausal patients over 50 with early-stage, low-grade HR+/HER2-negative tumors who commit to whole-breast radiation and endocrine therapy — ask your surgeon whether you may qualify.
Breast Reconstruction
If you have a mastectomy, breast reconstruction is available and can be performed immediately at the time of mastectomy (immediate reconstruction) or at a later date (delayed reconstruction). Two broad approaches exist:
Implant-based reconstruction — tissue expanders followed by silicone or saline implants
Autologous (flap) reconstruction — uses your own tissue, such as the TRAM or DIEP flap from the abdomen, to recreate the breast mound
Reconstruction does not affect cancer recurrence. Under the Women’s Health and Cancer Rights Act (WHCRA), health insurance plans that cover mastectomy are required to cover reconstruction as well. Discussing reconstruction options with a plastic surgeon before surgery gives you the widest range of choices.
Radiation Therapy
Radiation therapy uses high-energy beams to destroy any remaining cancer cells after surgery. It is a critical part of breast cancer treatment for most patients who have a lumpectomy and for selected patients after mastectomy.
When Radiation Is Used
Radiation is given in nearly all cases after lumpectomy — the combination is what makes breast-conserving surgery as effective as mastectomy. After mastectomy, radiation is typically recommended when four or more lymph nodes were positive, when the tumor was large (generally 5 cm or larger), when surgical margins were positive or close, or in locally advanced disease. Radiation is also used palliatively for metastatic breast cancer spread to bone or other sites.
Types of Radiation
Whole-breast irradiation (WBI) targets the entire remaining breast tissue and is the traditional standard. Modern hypofractionated schedules deliver larger doses over a shorter number of sessions (typically 3–4 weeks instead of 5–6), with comparable outcomes and now broadly recommended by ASCO and NCCN guidelines.
Accelerated partial breast irradiation (APBI) delivers radiation to the tumor bed only, over an even shorter course, and is an option for selected lower-risk patients (generally older women with small, node-negative, ER-positive tumors).
Intraoperative radiation therapy (IORT) delivers a single radiation dose directly to the tumor cavity during surgery. It remains a specialized technique used at select centers.
For patients with left-sided breast cancer, modern techniques including deep inspiration breath hold (DIBH) minimize the dose to the heart, substantially reducing the risk of long-term cardiac effects.
Side Effects
Common side effects of radiation include fatigue and skin changes such as redness, tenderness, or peeling in the treated area — most resolve within weeks of completing treatment. Less common effects include radiation pneumonitis (inflammation of the lung, usually mild and self-limiting) and a modest increase in lymphedema risk when combined with axillary surgery. Long-term cardiac effects have been dramatically reduced with modern heart-sparing techniques.
Chemotherapy
Chemotherapy uses drugs that kill or slow the growth of rapidly dividing cancer cells. It remains a cornerstone of treatment for several breast cancer subtypes and stages.
When Chemotherapy Is Used
Chemotherapy is recommended for most patients with HER2-positive or triple-negative breast cancer regardless of stage, for Stage III disease, and for higher-risk Stage II disease. For HR+/HER2-negative cancers, genomic testing (such as Oncotype DX) guides the decision. Patients with a high recurrence score benefit meaningfully from chemotherapy in addition to hormone therapy, while those with a low score generally do not.
Chemotherapy can be given before surgery (neoadjuvant) or after surgery (adjuvant). The neoadjuvant approach is increasingly common, particularly for HER2-positive and triple-negative breast cancer, because it allows real-time assessment of treatment response and may enable less extensive surgery.
Common Chemotherapy Regimens
Several regimens are used depending on your subtype, stage, and overall health:
AC-T (doxorubicin/cyclophosphamide followed by paclitaxel or docetaxel) — one of the most widely used regimens for higher-risk breast cancer
ddAC-T (dose-dense AC-T, given every 2 weeks rather than every 3) — has shown improved survival in some studies and is preferred for many higher-risk patients
TC (docetaxel/cyclophosphamide) — an option for lower-risk patients where anthracyclines can be avoided
Carboplatin is added to standard regimens for triple-negative breast cancer and patients with germline BRCA1/2 mutations, where it provides additional benefit
For HER2-positive breast cancer, chemotherapy is always combined with HER2-targeted agents — the two work together synergistically
Neoadjuvant Chemotherapy and Pathologic Complete Response
One of the most meaningful outcomes of neoadjuvant chemotherapy is achieving a pathologic complete response (pCR) — meaning no residual invasive cancer is found in the breast or lymph nodes at the time of surgery. Achieving a pCR is strongly associated with better long-term outcomes, especially for HER2-positive and triple-negative breast cancer. Importantly, if residual cancer remains after neoadjuvant chemotherapy, additional (“escalated”) post-surgical therapy can be given. These decisions are guided by how much cancer remained at the time of surgery.
Side Effects
Modern supportive care has dramatically improved the tolerability of chemotherapy. Nausea is now well-managed with antiemetics for most patients. Other common side effects include:
Fatigue — the most universally reported side effect
Hair loss — common with certain agents; scalp cooling caps (cold caps) can reduce hair loss for some patients
Neuropathy — numbness or tingling in the hands and feet, particularly with taxane drugs (paclitaxel, docetaxel)
Increased infection risk — due to lowered white blood cell counts; growth factors like filgrastim are used to reduce this risk
Early menopause and fertility effects — especially important to discuss before starting if you want to preserve fertility; egg or embryo banking before chemotherapy is an option
Cardiac effects — anthracyclines like doxorubicin carry a small risk of cardiomyopathy, particularly at higher cumulative doses; your team will monitor your heart function
Hormone Therapy (Endocrine Therapy)
For ER- and/or PR-positive breast cancer (roughly 70–80% of all diagnoses) hormone therapy, also called endocrine therapy, is the most important systemic treatment. It works by blocking estrogen’s ability to stimulate cancer cell growth. Hormone therapy is typically given after surgery and chemotherapy (if indicated) and continues for 5–10 years.
Tamoxifen
Tamoxifen is a selective estrogen receptor modulator (SERM) that blocks estrogen from binding to receptors in breast cancer cells. It is the standard endocrine therapy for premenopausal women and is also used in some postmenopausal women. According to the Early Breast Cancer Trialists’ Collaborative Group (EBCTCG), 5 years of tamoxifen reduces the annual breast cancer recurrence rate by approximately 40% and breast cancer mortality by approximately 30% compared with no endocrine therapy.
Side effects of tamoxifen include hot flashes, vaginal dryness, a small increased risk of endometrial cancer, and an elevated risk of blood clots. These risks are generally outweighed by the substantial reduction in recurrence.
Aromatase Inhibitors (AIs)
Aromatase inhibitors — anastrozole (Arimidex), letrozole (Femara), and exemestane (Aromasin) — work by blocking the enzyme aromatase, which converts androgens to estrogen in postmenopausal women. AIs are the preferred endocrine therapy for postmenopausal women and are superior to tamoxifen in reducing recurrence in this group.
Common side effects include joint and muscle pain (arthralgia), bone density loss (your doctor will monitor this and may prescribe a bisphosphonate or denosumab to protect your bones), hot flashes, and vaginal dryness.
Ovarian Suppression
For premenopausal women at higher risk of recurrence, adding ovarian function suppression (OFS) — achieved with GnRH agonists such as goserelin (Zoladex) or leuprolide (Lupron) — to endocrine therapy provides additional benefit. The landmark SOFT and TEXT trials demonstrated that premenopausal women at sufficient risk benefit from OFS combined with exemestane (an AI) or tamoxifen, with the OFS-plus-exemestane combination offering the greatest reduction in recurrence. Updated NCCN guidelines (2025) now recommend 5 years of OFS as optimal for eligible patients.
CDK4/6 Inhibitors
CDK4/6 inhibitors represent one of the most significant advances in the treatment of hormone receptor–positive breast cancer in recent years. These drugs — palbociclib (Ibrance), ribociclib (Kisqali), and abemaciclib (Verzenio) — block proteins called cyclin-dependent kinases 4 and 6 that drive cell division. Combined with an aromatase inhibitor or fulvestrant, they are a standard first-line treatment for HR+/HER2-negative metastatic breast cancer.
Critically, abemaciclib is now also approved as adjuvant therapy for high-risk early-stage HR+/HER2-negative breast cancer. The monarchE phase 3 trial enrolled 5,637 patients and, after a median follow-up of 6.3 years, showed that adding 2 years of abemaciclib to standard endocrine therapy reduced the risk of invasive disease recurrence by 27%. At 7 years, invasive disease-free survival rates were 77.4% (abemaciclib) versus 70.9% (endocrine therapy alone). Updated overall survival data presented at ESMO 2025 showed a 15.8% reduction in the risk of death — the first CDK4/6 inhibitor to demonstrate an overall survival benefit in early breast cancer.
Targeted Therapy for HER2-Positive Breast Cancer
HER2-positive breast cancer — defined by amplification of the HER2 gene, occurring in approximately 15–20% of breast cancers — used to carry a particularly poor prognosis. HER2-targeted therapies have transformed that picture entirely, turning it into one of the more treatable subtypes.
Trastuzumab (Herceptin)
Trastuzumab is a monoclonal antibody that binds directly to the HER2 receptor, blocking signaling and triggering immune destruction of cancer cells. It has been the cornerstone of HER2-targeted therapy for more than two decades. In early-stage HER2-positive breast cancer, adding trastuzumab to chemotherapy reduces recurrence risk and improves survival significantly. It is given intravenously or subcutaneously for one year in the adjuvant setting and continued in the metastatic setting.
Pertuzumab (Perjeta)
Pertuzumab is a second monoclonal antibody that binds to a different site on the HER2 receptor, complementing trastuzumab’s mechanism. The CLEOPATRA phase 3 trial showed that adding pertuzumab to trastuzumab plus docetaxel in HER2-positive metastatic breast cancer extended median overall survival to 57.1 months compared with 40.8 months with trastuzumab plus docetaxel alone — a difference of more than 16 months. The combination of pertuzumab plus trastuzumab plus chemotherapy is now standard in high-risk early-stage and metastatic HER2-positive disease.
T-DM1 (Kadcyla)
T-DM1 (trastuzumab emtansine) is an antibody-drug conjugate (ADC) that combines trastuzumab with a cytotoxic chemotherapy agent, delivering the chemo directly to HER2-positive cells. It is the standard of care for patients with HER2-positive early breast cancer who have residual invasive disease after neoadjuvant chemotherapy plus trastuzumab, a situation where additional treatment is needed.
The KATHERINE phase 3 trial demonstrated that adjuvant T-DM1 reduced the risk of recurrence by 50% compared with trastuzumab alone in patients with residual disease (3-year invasive disease-free survival: 88.3% vs. 77.0%). Long-term follow-up at 8.4 years showed an absolute invasive disease-free survival benefit of 13.7% and a 34% improvement in overall survival compared with trastuzumab. T-DM1 is given intravenously every 3 weeks for 14 cycles.
T-DXd (Enhertu)
T-DXd (trastuzumab deruxtecan, marketed as Enhertu) is a next-generation ADC with a broader payload capacity and what is called a “bystander effect” — the released chemotherapy agent can also kill neighboring cancer cells that may not express HER2. The DESTINY-Breast06 phase 3 trial published in the New England Journal of Medicine (2024) established T-DXd as a major advance in HR-positive, HER2-low metastatic breast cancer — a category defined as IHC 1+ or 2+/ISH-negative, which encompasses a large proportion of patients previously considered HER2-negative.
In DESTINY-Breast06, T-DXd nearly doubled median progression-free survival compared with chemotherapy in HER2-low patients (13.2 vs. 8.1 months; HR 0.62; P<0.001). T-DXd is now FDA-approved for HR+/HER2-low and HR+/HER2-ultralow metastatic breast cancer after one or more prior lines of endocrine therapy. In HER2-positive disease, T-DXd is also used in the metastatic setting after prior HER2-directed therapy.
Tucatinib (Tukysa)
Tucatinib is a small-molecule tyrosine kinase inhibitor (TKI) that targets the HER2 receptor. The HER2CLIMB trial showed that adding tucatinib to trastuzumab and capecitabine in previously treated HER2-positive metastatic breast cancer — including patients with active brain metastases — reduced the risk of CNS progression or death by 68%, with a median CNS progression-free survival of 9.9 months compared with 4.2 months for the control arm. Overall survival was 21.6 months with tucatinib versus 12.5 months without. Because brain metastases occur frequently in HER2-positive breast cancer, tucatinib’s CNS efficacy is a particularly meaningful advantage.
Other HER2-Targeted Agents
Lapatinib (Tykerb) and neratinib (Nerlynx) are older small-molecule TKIs that remain options in certain later-line metastatic settings. Neratinib is also approved for extended adjuvant therapy in early-stage HER2-positive breast cancer after completing trastuzumab.
Treatment for Triple-Negative Breast Cancer (TNBC)
Triple-negative breast cancer (TNBC) is defined by the absence of estrogen receptors, progesterone receptors, and HER2 amplification. It accounts for approximately 15% of all breast cancers and has historically been the hardest subtype to treat because it cannot be targeted by hormone therapy or HER2-directed agents. That landscape has changed substantially in recent years.
Chemotherapy remains the backbone of TNBC treatment. Platinum-based drugs such as carboplatin are particularly active in patients with germline BRCA1/2 mutations, who make up a significant proportion of TNBC cases.
Immunotherapy with pembrolizumab (Keytruda) has become standard for early-stage, high-risk TNBC. The KEYNOTE-522 phase 3 trial showed that adding pembrolizumab to neoadjuvant chemotherapy and continuing it as adjuvant therapy for up to nine cycles after surgery significantly improved both pathologic complete response rates and survival. Updated overall survival results published in the New England Journal of Medicine (2024), after a median follow-up of 75.1 months, showed 5-year overall survival of 86.6% with pembrolizumab versus 81.7% with placebo (P=0.002). KEYNOTE-522 established the pembrolizumab-plus-chemotherapy regimen as the standard of care for Stage II–III TNBC — the first immunotherapy approval in early breast cancer.
PARP inhibitors — olaparib (Lynparza) and talazoparib (Talzenna) are approved for patients with germline BRCA1/2 mutations and metastatic TNBC (and HER2-negative disease more broadly). PARP inhibitors exploit a specific DNA repair vulnerability in BRCA-mutated tumors.
Sacituzumab govitecan (Trodelvy) is an antibody-drug conjugate targeting Trop-2, a protein highly expressed in TNBC cells. It is approved for metastatic TNBC after at least two prior therapies and has demonstrated meaningful improvements in progression-free and overall survival in heavily pretreated patients.
TNBC has an active and rapidly evolving clinical trial landscape. If you are diagnosed with this subtype, asking your oncologist about available trials is especially important.
Clinical Trials in Breast Cancer Treatment
Every major treatment advance described in this article came from a clinical trial. From the NSABP B-06 trial that established lumpectomy as equivalent to mastectomy, to CLEOPATRA and KATHERINE that redefined HER2-positive treatment, to KEYNOTE-522 that brought immunotherapy into early TNBC, to monarchE and DESTINY-Breast06 that continue to expand options for HR+ and HER2-low patients breast cancer trials are constantly working to advance treatment options.
Clinical trials are not a last resort. For many patients, a clinical trial offers access to the most current, evidence-based therapy available and sometimes before it receives broad approval. Trials exist for all subtypes and stages of breast cancer, including early-stage, locally advanced, and metastatic disease, as well as for prevention and supportive care.
When you are weighing treatment options — at initial diagnosis, after a recurrence, or after progression on standard therapy — asking your oncologist “Is there a clinical trial I should consider?” is always a reasonable question. Eligibility criteria vary by trial, but your oncology team can help identify options that fit your situation.
Frequently Asked Questions
What is the most common treatment for breast cancer?
Most people with breast cancer receive a combination of treatments rather than a single therapy. Surgery — either lumpectomy or mastectomy — is the most universal first step for early-stage disease. Depending on tumor biology, surgery is followed by some combination of radiation, chemotherapy, hormone therapy, or targeted therapy. For ER/PR-positive cancers, endocrine therapy for 5–10 years is nearly always part of the plan.
Do all breast cancer patients need chemotherapy?
No. Whether you need chemotherapy depends on your tumor’s subtype and stage. Patients with HER2-positive or triple-negative breast cancer almost always receive chemotherapy. For HR+/HER2-negative cancers, genomic tests like Oncotype DX can identify patients whose cancer is unlikely to respond meaningfully to chemotherapy — those patients may be able to skip it and rely on hormone therapy alone. This is a decision your oncologist will make with you based on your complete pathology and test results.
What is the difference between lumpectomy and mastectomy?
A lumpectomy removes the tumor and a surrounding margin of healthy tissue, preserving the rest of the breast. A mastectomy removes the entire breast. For eligible patients, both approaches offer equivalent overall survival — a finding confirmed by 20 years of follow-up in the NSABP B-06 trial. The choice depends on tumor size, location, number of tumors, personal preference, and other clinical factors. Most patients who have a lumpectomy also receive radiation; patients who have a mastectomy may or may not, depending on their risk factors.
How long does breast cancer treatment take?
Treatment duration varies widely by subtype and stage. Surgery itself takes hours, with weeks of recovery. If you receive chemotherapy, treatment typically runs 12–24 weeks depending on the regimen. Radiation therapy (after lumpectomy) usually spans 3–6 weeks, though modern hypofractionated schedules can be as short as 3 weeks. Hormone therapy for HR+ cancers continues for 5–10 years. HER2-targeted therapy (trastuzumab) is given for one year in the adjuvant setting. For most early-stage patients, the active treatment phase — surgery plus chemotherapy and/or radiation — concludes within 6–12 months, after which ongoing maintenance therapy (endocrine therapy) continues.
What is the treatment for HER2-positive breast cancer?
HER2-positive breast cancer is treated with a combination of chemotherapy and HER2-targeted agents. Standard care for early-stage disease typically involves neoadjuvant or adjuvant chemotherapy combined with trastuzumab and pertuzumab (for high-risk cases). If residual disease remains after neoadjuvant therapy, T-DM1 (Kadcyla) replaces trastuzumab for the remainder of the adjuvant course — cutting the risk of recurrence by approximately 50% versus trastuzumab alone (KATHERINE trial). For metastatic HER2-positive disease, treatment is sequenced through multiple HER2-targeted agents including trastuzumab, pertuzumab, T-DM1, T-DXd (Enhertu), and tucatinib (Tukysa), along with chemotherapy partners. The prognosis for HER2-positive breast cancer has improved dramatically over the past two decades thanks to targeted therapy.
Clinical trials have driven every major advance in breast cancer treatment — and new options are actively being studied for all subtypes. Ready to explore trials that may be right for you? Start your search with North’s trial finder.
References
Fisher, B., et al. (2002). Twenty-Year Follow-up of a Randomized Trial Comparing Total Mastectomy, Lumpectomy, and Lumpectomy plus Irradiation for the Treatment of Invasive Breast Cancer. New England Journal of Medicine. https://www.nejm.org/doi/full/10.1056/NEJMoa022152
Cortés, J., et al. (2020). Pertuzumab, trastuzumab, and docetaxel for HER2-positive metastatic breast cancer (CLEOPATRA): end-of-study results from a double-blind, randomised, placebo-controlled, phase 3 study. The Lancet Oncology. https://www.thelancet.com/journals/lanonc/article/PIIS1470-2045(19)30863-0/abstract
von Minckwitz, G., et al. (2019). Trastuzumab Emtansine for Residual Invasive HER2-Positive Breast Cancer (KATHERINE). New England Journal of Medicine. https://www.nejm.org/doi/full/10.1056/NEJMoa1814017
Schmid, P., et al. (2024). Overall Survival with Pembrolizumab in Early-Stage Triple-Negative Breast Cancer (KEYNOTE-522). New England Journal of Medicine. https://www.nejm.org/doi/full/10.1056/NEJMoa2409932
Johnston, S.R.D., et al. (2025). Overall survival with abemaciclib in early breast cancer (monarchE). Annals of Oncology. https://www.annalsofoncology.org/article/S0923-7534(25)04948-8/fulltext
Curigliano, G., et al. (2024). Trastuzumab Deruxtecan after Endocrine Therapy in Metastatic Breast Cancer (DESTINY-Breast06). New England Journal of Medicine. https://www.nejm.org/doi/abs/10.1056/NEJMoa2407086
Murthy, R.K., et al. (2020). Tucatinib, Trastuzumab, and Capecitabine for HER2-Positive Metastatic Breast Cancer (HER2CLIMB). New England Journal of Medicine. https://www.nejm.org/doi/full/10.1056/NEJMoa1914609
National Comprehensive Cancer Network. (2025). NCCN Clinical Practice Guidelines in Oncology: Breast Cancer, Version 5.2025. https://www.nccn.org/guidelines/guidelines-detail?id=1419