Primary invasive breast cancer

Overview 
Theory 
Diagnosis 
Management 
Follow up 
Resources 

Last reviewed: 26 Jun 2025

Last updated: 01 May 2025

Breast cancer is a malignancy that is often strongly influenced by age, family history, genetic factors, hormonal exposure, and lifestyle factors.

The majority of patients are asymptomatic and present with abnormal calcifications and/or architectural distortion, or asymmetric density, on a routine screening mammogram.

Clinical breast exam may demonstrate a firm breast mass, which may be associated with axillary lymphadenopathy, skin changes, and nipple discharge.

Treatment requires a multidisciplinary approach, involving medical oncologists, breast surgeons, and radiation oncologists.

Complications of therapy are specific to each modality of treatment, and careful monitoring and preventive therapy for adverse events (e.g., antiemetic pre-medications in the prevention of chemotherapy-induced nausea) are essential.

Definition

Primary invasive breast cancer is a malignancy originating in the ducts or lobules. The term "invasive" indicates that the malignancy has penetrated past the basement membrane of the duct or lobule of the breast and has spread to the surrounding tissues, but has not spread to other organs.

The American Joint Committee on Cancer TNM (tumor, node, metastasis) staging system classifies invasive breast cancer into the following stages based on the extent of disease: IA, IB, IIA, IIB, IIIA, IIIB, and IIIC.[1]

Stages IA, IB, and IIA are generally considered early-stage breast cancer. Stages IIIA, IIIB, and IIIC are generally considered locally advanced breast cancer.

Staging can also be defined by the pathologic node status (pN0 - pN3), which is dependent on the number of axillary nodes with metastases.

History and exam

Key diagnostic factors

breast mass
nipple discharge
axillary lymphadenopathy

Full details

Other diagnostic factors

skin thickening or discoloration
retraction, inversion, or scaling of the nipple

Full details

Risk factors

increasing age
female sex
ethnic origin
positive family history
genetic mutations
endogenous estrogen exposure
exogenous estrogen/progestin exposure
alcohol consumption
radiation exposure
atypical breast disease
increased breast density
mild, moderate, or marked background parenchymal enhancement (BPE) on breast MRI
reduced physical activity
poor diet
high socioeconomic status
smoking
obesity
high dibutyl-phthalate exposure

Full details

Diagnostic tests

1st tests to order

mammogram

Full details

Tests to consider

breast ultrasound
breast MRI
biopsy
hormone receptor testing
HER2 testing
gene expression assays
computed tomography
bone scan
genetic testing
CBC
LFTs
alkaline phosphatase

Full details

Treatment algorithm

ACUTE

early-stage breast cancer (stages I to IIB [T2 N1 M0])

locally advanced breast cancer (stages IIB [T3 N0 M0] to III)

ONGOING

disease recurrence

Contributors

Authors

Kandace P. McGuire, MD

Professor of Surgery

Virginia Commonwealth University

Richmond

Disclosures

KPM declares that she has no competing interests.

Acknowledgements

Dr Kandace McGuire would like to gratefully acknowledge Dr Krystal Cascetta, Professor Amy Tiersten, Dr Hope S. Rugo, Dr Amal Melhem-Bertrandt, Dr Gabriel N. Hortobagyi, and Dr Phuong Khanh H. Morrow, the previous contributors to this topic.

Disclosures

KC, AMB, GNH, and PKHM declare that they have no competing interests. AT is on the advisory board for Immunomedics, AstraZeneca, Novartis, Eisai, and Healthline; receives research funding from Pfizer, Novartis, Genentech, Lilly, and AstraZeneca; and does expert testimony work. HSR receives research funding through the University of California from Novartis, Pfizer, Genentech, Macrogenics, Plexxikon, Merck, Nektar, and GSK; has been reimbursed for travel by Novartis, Genentech, and Nektar; and has received speaker honorarium from Genomic Health.

Peer reviewers

Katherine H.R. Tkaczuk, MD, FACP

Professor of Medicine

University of Maryland School of Medicine

Baltimore

Disclosures

KHRT declares that she has no competing interests.

Susan Tannenbaum, MD

Associate Professor, Medicine

Chief, Division of Hematology/Oncology

Medical Director, Neag Comprehensive Cancer Center

University of Connecticut

Farmington

Disclosures

ST declares that she has no competing interests.

Emily Hsu, MD

Fellow

Division of Hematology/Oncology

University of Connecticut

Farmington

Disclosures

EH declares that she has no competing interests.

Anees Chagpar, MD

Assistant Professor

University of Louisville

Louisville

Disclosures

AC declares that she has no competing interests.

Gurhan Celik, MD

General Surgeon

General Surgery Department

Istanbul Training and Research Hospital

Istanbul

Turkey

Disclosures

GC is an author of a number of references cited in this topic.

Edward R. Sauter, MD, PhD

Medical Officer

Breast and Gynecologic Cancer Working Group

Division of Cancer Prevention

National Cancer Institute

Bethesda

Disclosures

ERS declares that he has no competing interests.

References

Our in-house evidence and editorial teams collaborate with international expert contributors and peer reviewers to ensure that we provide access to the most clinically relevant information possible.

Key articles

National Comprehensive Cancer Network. NCCN clinical practice guidelines in oncology: breast cancer screening and diagnosis [internet publication].Full text

National Comprehensive Cancer Network. NCCN clinical practice guidelines in oncology: breast cancer [internet publication].Full text

Loibl S, André F, Bachelot T, et al. Early breast cancer: ESMO clinical practice guideline for diagnosis, treatment and follow-up. Ann Oncol. 2024 Feb;35(2):159-82.Full text Abstract

Denduluri N, Somerfield MR, Eisen A, et al. Selection of optimal adjuvant chemotherapy regimens for human epidermal growth factor receptor 2 (HER2)-negative and adjuvant targeted therapy for HER2-positive breast cancers: an American Society of Clinical Oncology guideline adaptation of the Cancer Care Ontario clinical practice guideline. J Clin Oncol. 2016 Jul 10;34(20):2416-27.Full text Abstract

Lyman GH, Somerfield MR, Bosserman LD, et al. Sentinel lymph node biopsy for patients with early-stage breast cancer: American Society of Clinical Oncology clinical practice guideline update. J Clin Oncol. 2017 Feb 10;35(5):561-64.Full text Abstract

Reference articles

A full list of sources referenced in this topic is available to users with access to all of BMJ Best Practice.

Differentials
- Fibrocystic changes
- Fibroadenoma
- Mastitis
More Differentials
Guidelines
- NCCN clinical practice guidelines in oncology: breast cancer risk reduction
- Early breast cancer: ESMO clinical practice guideline for diagnosis, treatment and follow-up
More Guidelines
Patient information
Breast cancer, locally advanced: what is it?
Breast cancer: breast-conserving surgery
More Patient information
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Primary invasive breast cancer

Summary

Definition

History and exam

Key diagnostic factors

Other diagnostic factors

Risk factors

Diagnostic tests

1st tests to order

Tests to consider

Treatment algorithm

early-stage breast cancer (stages I to IIB [T2 N1 M0])

locally advanced breast cancer (stages IIB [T3 N0 M0] to III)

disease recurrence

Contributors

Authors

Kandace P. McGuire, MD

Disclosures

Acknowledgements

Disclosures

Peer reviewers

Katherine H.R. Tkaczuk, MD, FACP

Disclosures

Susan Tannenbaum, MD

Disclosures

Emily Hsu, MD

Disclosures

Anees Chagpar, MD

Disclosures

Gurhan Celik, MD

Disclosures

Edward R. Sauter, MD, PhD

Disclosures

References

Key articles

Reference articles

A full list of sources referenced in this topic is available to users with access to all of BMJ Best Practice.

Differentials

Guidelines

Patient information

Log in or subscribe to access all of BMJ Best Practice

Log in or subscribe to access all of BMJ Best Practice

Log in to access all of BMJ Best Practice