Early breast cancer

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

Early invasive breast cancer is classified anatomically and biologically. TNM defines primary size, regional nodes and absence of metastasis, while histological grade estimates differentiation and proliferation. ER-positive luminal cancers often have a prolonged recurrence trajectory and respond to endocrine therapy. HER2 amplification predicts benefit from HER2 blockade. Triple-negative cancer has neither target and generally depends on chemotherapy and, in selected settings, immunotherapy. Treatment cannot be chosen from stage or receptor status alone.

Surgery may follow diagnosis directly or follow neoadjuvant systemic treatment. Breast conservation removes the cancer with an acceptable cosmetic result and is normally completed by radiotherapy; mastectomy is appropriate for extensive disease, inability to obtain margins, contraindication to radiation or informed preference. Reconstruction can be immediate or delayed. Axillary ultrasound samples suspicious nodes before treatment, while clinically node-negative disease is usually staged by sentinel nodes rather than full clearance.

Adjuvant treatment addresses micrometastatic and local risk. Endocrine therapy is foundational for ER-positive disease. Chemotherapy is guided by subtype, grade, burden, age, health and sometimes a validated expression assay. HER2-positive disease receives trastuzumab-based treatment, and residual disease after neoadjuvant therapy may change the postoperative agent. Radiotherapy targets breast or chest wall and selected nodal regions. Bone-modifying treatment is considered in relevant postmenopausal risk groups.

Quality of cure matters. Surgical choice affects sensation, symmetry and reconstruction; axillary treatment affects arm function and lymphoedema; endocrine treatment affects menopause, sexual function, bone and thrombosis; chemotherapy affects fertility, nerves and cognition; HER2 therapy and anthracycline affect myocardium. Shared decisions use absolute benefit, competing risk and patient values, with specialist nurses, genetics, fertility, rehabilitation and psychological care integrated early.

Key points

Early breast cancer is operable invasive disease without distant metastasis; curative planning integrates tumour size, nodes, grade, subtype, comorbidity and patient priorities.
Core pathology should report invasive type and grade and test oestrogen receptor and HER2; progesterone receptor and proliferation or genomic tests add selected prognostic or predictive information.
Do not perform routine CT, bone scan or PET-CT for every asymptomatic small node-negative cancer; stage systemically when symptoms, examination, laboratory results or higher anatomical burden makes metastasis plausible.
Breast-conserving surgery with clear margins followed by appropriate radiotherapy gives survival comparable to mastectomy for suitable tumours; the operations differ in local anatomy, not inherent cancer seriousness.
Sentinel lymph-node biopsy is the preferred surgical axillary staging method for clinically and ultrasound node-negative invasive cancer, reducing lymphoedema compared with routine clearance.
Use neoadjuvant systemic treatment when tumour shrinkage may enable breast conservation, when nodal response guides surgery or when response will direct later HER2-positive or triple-negative therapy.
ER-positive disease needs adjuvant endocrine treatment chosen by menopausal status and recurrence risk; adherence over years is clinically important.
HER2-positive disease usually receives HER2-directed therapy with chemotherapy according to stage and response, with baseline and serial left-ventricular assessment.
Chemotherapy benefit is greatest with high-risk biology; validated tumour-profiling assays can support selected ER-positive, HER2-negative decisions but do not replace clinicopathological judgment.
Radiotherapy is standard after breast conservation and is selected after mastectomy according to tumour, margin and nodal risk; hypofractionated schedules are commonly preferred.
Offer fertility, contraception, bone, menopausal, cardiovascular, employment and psychosocial planning before treatment creates irreversible effects.
Follow-up combines treatment-toxicity review, planned mammography and rapid investigation of new symptoms rather than routine whole-body scans in asymptomatic survivors.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Hormonal and reproductive exposure

Increasing age, early menarche, later menopause, nulliparity, later first birth, alcohol, obesity after menopause and some exogenous hormones increase cumulative proliferative exposure.

Inherited susceptibility

Pathogenic BRCA1, BRCA2, PALB2, TP53, PTEN and other variants explain a minority of cancers but strongly influence bilateral risk, treatment and family management.

Previous radiation and proliferative disease

Young-age thoracic radiotherapy and high-risk breast lesions such as atypical hyperplasia or lobular neoplasia increase future invasive-cancer probability.

Sporadic genomic evolution

Most cases arise through acquired alterations affecting DNA repair, cell-cycle, hormone-receptor and growth-factor signalling without an identifiable germline syndrome.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
In situ cells breach basement membrane
Malignant epithelial clones progress from a ductal or lobular compartment into stroma, gaining access to lymphatics, blood vessels and surrounding tissue.
2
Receptor biology drives growth
Oestrogen-receptor signalling sustains many luminal cancers, HER2 amplification activates proliferative pathways, and triple-negative tumours lack both therapeutic targets and are biologically heterogeneous.
3
Regional spread follows lymphatics
Tumour cells move through axillary and internal mammary drainage, making nodal burden prognostic while sentinel mapping can stage the basin with less morbidity.
4
Micrometastases determine systemic relapse
Occult disseminated cells may remain after complete breast surgery; endocrine, chemotherapy, HER2-directed and bone-modifying treatments reduce recurrence according to biological risk.
5
Treatment response reveals sensitivity
Neoadjuvant therapy shrinks tumour and nodes and provides pathological-response information, particularly useful in HER2-positive and triple-negative subtypes.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Localised primary

A biopsy-proven invasive mass confined to breast with or without mobile regional nodes and no metastatic features is potentially curable early disease.

ER-positive phenotype

Hormone-receptor expression predicts endocrine sensitivity, though grade, size, nodes and genomic risk determine how much additional chemotherapy may help.

HER2-positive phenotype

HER2 overexpression or amplification identifies an aggressive growth pathway and substantial benefit from HER2-directed treatment when cardiac safety permits.

Triple-negative phenotype

Absent ER and HER2 defines a group with earlier average relapse risk, stronger chemotherapy dependence and an important hereditary BRCA association.

Regional nodal disease

Abnormal axillary or supraclavicular nodes change anatomical stage and radiation and systemic planning but do not automatically make disease incurable.

Possible occult metastasisRed flag

Persistent bone pain, neurological change, respiratory symptoms, hepatomegaly or abnormal liver and calcium results requires systemic staging before a purely local plan.

Red flags requiring action

A rapidly expanding postoperative breast or axillary swelling, hypotension, severe pain or drain output suggests haemorrhage requiring urgent surgical review.
Fever or systemic deterioration during cytotoxic treatment is neutropenic sepsis until assessed and must not wait for the neutrophil result.
New dyspnoea, pleuritic pain, syncope or unilateral leg swelling during cancer treatment raises venous thromboembolism.
New orthopnoea, oedema or reduced exercise tolerance during anthracycline or HER2 therapy requires prompt cardiac evaluation.
Persistent focal bone pain, neurological symptoms, jaundice or unexplained respiratory change after early cancer treatment may represent recurrence and requires investigation between routine visits.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
Core histology with ER and HER2First step
Why
Confirm invasion, histological type and grade and identify the principal predictive treatment targets.
Interpretation and limitations
Report ER quantitatively and HER2 by validated immunohistochemistry with in-situ hybridisation for equivocal results; repeat or review discordant or inadequate tissue.
02
First-line breast and axillary imagingFirst line
Why
Define multifocality, extent and contralateral disease and identify nodes requiring preoperative sampling.
Interpretation and limitations
Use diagnostic mammography and targeted ultrasound; biopsy suspicious nodes, and reserve MRI for lobular, occult, discordant or selected extent questions.
03
Clinical and pathological TNM staging
Why
Separate localised operable, locally advanced and metastatic disease and estimate recurrence risk.
Interpretation and limitations
Record pretreatment clinical stage and postoperative pathological stage; after neoadjuvant therapy use yp staging and residual burden rather than substituting the post-treatment size for baseline extent.
04
Selective systemic staging
Why
Detect distant disease when symptoms, nodes, large or aggressive primary or abnormal tests raise pre-test probability.
Interpretation and limitations
Use CT and bone or PET-directed imaging according to the clinical question; routine staging of asymptomatic low-risk stage I disease causes false positives without proven benefit.
05
Validated tumour-profiling assay
Why
Refine chemotherapy benefit in selected ER-positive, HER2-negative early cancer when the decision remains uncertain.
Interpretation and limitations
Use only within the current NICE population and combine with age, menopausal status, nodes, grade and comorbidity; the score is not a universal chemotherapy rule.
06
Treatment-fitness baseline
Why
Identify organ, reproductive and functional risks before systemic, radiation or surgical therapy.
Interpretation and limitations
Include FBC, renal and liver function, pregnancy status when relevant, ECG or echocardiography for cardiotoxic treatment, bone density for selected endocrine plans and fertility discussion before gonadotoxic therapy.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Ductal carcinoma in situ

Malignant ductal cells remain confined by the basement membrane, often presenting through calcification and requiring different nodal and systemic treatment decisions.

Benign proliferative lesion

Radial scar, sclerosing adenosis, papilloma, fibroadenoma and atypia can mimic carcinoma on imaging and need pathology–radiology concordance.

Phyllodes or sarcoma

Stromal tumours can grow rapidly and require clear surgical margins, while nodal spread and receptor-directed treatment are unlike conventional epithelial breast cancer.

Lymphoma or metastasis

Lymphoid malignancy and melanoma, ovarian, renal or other metastases can involve breast or nodes; morphology and immunohistochemistry prevent inappropriate breast-specific surgery.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01Operable diseaseChoose breast and axillary surgeryFirst stepBiopsy confirms invasive cancer that is suitable for primary surgery.

1Map tumour extent, breast-to-tumour ratio, genetics, radiotherapy feasibility, reconstruction and preference and compare breast conservation with mastectomy using equivalent-survival information where appropriate.
2Stage a clinically and ultrasound node-negative axilla with sentinel-node biopsy and plan targeted or more extensive axillary treatment only when nodal findings justify the additional morbidity.
3Review final tumour size, type, grade, margins, lymphovascular invasion, nodes and biomarkers at the MDT and arrange re-excision, radiation and systemic treatment from the complete risk profile.

02NeoadjuvantTreat biology before surgery when response mattersTumour or nodal downstaging or response-adapted postoperative treatment offers a clear advantage.

1Place a marker in the breast tumour and sampled positive node before therapy and document baseline clinical and imaging stage.
2Give subtype-appropriate systemic treatment, monitoring clinical response and investigating progression promptly rather than waiting for the final cycle.
3Perform planned breast and axillary surgery after recovery, report pathological response and use residual disease, baseline stage and subtype to select postoperative systemic and radiotherapy treatment.

03Adjuvant systemicMatch medicines to absolute recurrence riskDefinitiveDefinitive pathology or neoadjuvant response is available after curative surgery.

1Offer endocrine treatment for ER-positive disease and HER2-directed treatment for eligible HER2-positive disease, defining duration and organ monitoring before the first dose.
2Estimate chemotherapy benefit using anatomy, grade, subtype, health and a validated genomic assay only when applicable, explaining absolute benefit and acute and late toxicity.
3Consider adjuvant bisphosphonate, ovarian suppression and residual-disease strategies in the appropriate populations and provide a written sequence across chemotherapy, radiotherapy and endocrine therapy.

04SurvivorshipDetect recurrence without over-imagingCurative local and systemic treatment has been completed or long-term endocrine therapy continues.

1Provide a treatment summary, mammography schedule, endocrine and bone plan, genetic actions and rapid-access route for new breast, bone, neurological, respiratory or abdominal symptoms.
2Review adherence, menopause, sexual health, fertility, cardiovascular risk, fatigue, cognition, arm and shoulder function and lymphoedema, treating modifiable toxicity rather than accepting it as inevitable.
3Avoid routine tumour markers or whole-body imaging in an asymptomatic low-risk survivor, but investigate clinically meaningful new symptoms promptly and anatomically.

Key medicines and prescribing safety4 treatments · regimens, roles and cautions

Blocks oestrogen-receptor signalling and reduces recurrence and contralateral breast cancer in hormone-sensitive disease, including many premenopausal patients.

Tamoxifen for ER-positive disease

Give tamoxifen 20 mg orally once daily for the planned endocrine duration, commonly at least 5 years, with extension or switch determined by menopausal status, recurrence risk, tolerance and current guidance.

Review venous thromboembolism, abnormal uterine bleeding, pregnancy avoidance, cataract and interacting strong CYP2D6 inhibitors; stop or perioperatively interrupt only through an individual thrombosis and cancer plan.

Suppresses peripheral oestrogen synthesis and is a preferred endocrine option for many postmenopausal ER-positive cancers.

Anastrozole after menopause

Give anastrozole 1 mg orally once daily within a postmenopausal adjuvant sequence, with total endocrine duration and any tamoxifen switch chosen from recurrence and toxicity review.

Confirm menopausal status, assess baseline and interval bone density when indicated and manage arthralgia, vaginal symptoms, lipids and fracture risk; it is ineffective alone with functioning ovaries.

Targets HER2 and markedly reduces recurrence when combined with appropriate chemotherapy in eligible HER2-positive early breast cancer.

Trastuzumab for HER2-positive disease

A standard intravenous schedule gives 8 mg/kg loading followed by 6 mg/kg every 3 weeks, usually to complete 1 year across neoadjuvant and adjuvant treatment; licensed subcutaneous dosing may be used by protocol.

Measure left-ventricular function before and during treatment, review prior anthracycline exposure and withhold for protocol-defined decline or symptomatic heart failure; manage infusion reactions and pregnancy risk.

Reduces skeletal recurrence and improves breast-cancer outcomes in selected postmenopausal patients while supporting bone health.

Zoledronic acid for selected adjuvant use

A common adjuvant breast protocol gives zoledronic acid 4 mg intravenously every 6 months for 3 years in an eligible postmenopausal patient; use the exact current local schedule and renal adjustment.

Check creatinine, calcium and vitamin D, complete dental assessment and avoid during major dental healing where possible; counsel about acute-phase symptoms, hypocalcaemia, renal injury and osteonecrosis of the jaw.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Local and regional recurrence

Residual resistant cells can recur in breast, chest wall or nodes, with risk shaped by margins, biology, nodal burden and completion of local therapy.

Distant metastatic relapse

Bone, liver, lung and brain recurrence may occur years later, especially when biological risk is high or effective systemic treatment is not completed.

Surgical and lymphatic morbidity

Haematoma, infection, seroma, altered sensation, shoulder dysfunction and lymphoedema can follow breast and axillary procedures during recovery.

Systemic and radiation toxicity

Myelosuppression, neuropathy, premature menopause, thrombosis, cardiomyopathy, pneumonitis, skin change and second malignancy vary with treatment exposure.

Psychosexual and functional harm

Body-image change, fertility loss, fatigue, fear of recurrence and work or relationship disruption can persist despite cure and require active rehabilitation.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

Review surgical wounds, seroma, infection, breast or flap perfusion, shoulder range, sensation and early lymphatic symptoms after breast and axillary procedures.
During chemotherapy, monitor blood counts, organ function, neuropathy, infection, thrombosis, fertility and cumulative cardiac exposure according to the regimen.
During trastuzumab-based treatment, repeat left-ventricular assessment at protocol intervals and investigate dyspnoea, oedema or palpitations without waiting for the next routine scan.
During endocrine treatment, review adherence, menstrual or menopausal status, thrombosis or uterine symptoms with tamoxifen and bone, joint and sexual effects with aromatase inhibition.
Arrange surveillance mammography at the recommended interval and use immediate diagnostic imaging for new focal symptoms rather than waiting for surveillance.
Track return to work, fatigue, cognition, mood, sexual health, body image, fertility and caring roles as measurable outcomes of curative treatment.
Maintain a rapid-access recurrence pathway and investigate site-specific symptoms with targeted imaging; do not substitute routine tumour markers for clinical review.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

Mastectomy is not automatically stronger

For a suitable localised tumour, conservation plus radiotherapy and mastectomy provide comparable survival; choice concerns anatomy, local control, radiation, reconstruction and preference.

Baseline stage remains important

A complete pathological response after neoadjuvant therapy is favourable, but pretreatment tumour and nodal extent still influences radiation and recurrence decisions.

A genomic score answers one question

Expression assays estimate chemotherapy benefit in defined ER-positive, HER2-negative populations; they do not determine surgery, radiotherapy or endocrine need.

ER positivity is not one risk group

A small low-grade node-negative tumour and a large high-grade node-positive tumour may both be ER positive but need very different additional treatment.

Node staging should minimise harm

Sentinel biopsy obtains staging information in a negative axilla with much less lymphatic disruption than routine clearance, while positive-node strategies remain burden specific.

Adherence changes outcome

Years of endocrine adverse effects can erode use silently; proactive symptom management and reasonable switching preserve more benefit than simply repeating the prescription.

11Common pitfallsFrequent interpretation and management errors.

01
Treating all early breast cancers identically because they share an anatomical stage.
02
Ordering routine PET-CT or bone scan for every asymptomatic small node-negative tumour.
03
Assuming mastectomy gives better survival than eligible breast conservation with radiotherapy.
04
Performing full axillary clearance for a clinically negative axilla without sentinel or burden-based assessment.
05
Starting neoadjuvant treatment without marking the breast lesion and proven positive node.
06
Interpreting a genomic assay outside its validated subtype and nodal population.
07
Continuing trastuzumab despite clinically important cardiac deterioration without protocol review.
08
Prescribing endocrine treatment for years without reviewing adherence, bone, thrombosis, sexual and menopausal toxicity.
09
Using routine scans as reassurance while failing to investigate a new focal symptom.