Breast Cancer: Risk Factors, Diagnosis and Treatment

Breast cancer occurs when cells in the breast tissue grow and divide abnormally, forming a tumour. It is the most frequently diagnosed cancer in women globally and the second leading cause of cancer death in women after lung cancer. It also occurs in men, though rarely — accounting for less than 1% of all breast cancer cases.

Early detection dramatically improves outcomes. When breast cancer is found while still confined to the breast, the five-year survival rate exceeds 99%.

How Breast Cancer Develops

Most breast cancers begin in the milk ducts (ductal carcinoma) or the milk-producing glands (lobular carcinoma). Over time, abnormal cells can invade surrounding breast tissue and ultimately spread to lymph nodes and distant organs through the lymphatic and blood vessel systems.

In Situ (Non-Invasive) vs Invasive Cancer

• Ductal carcinoma in situ (DCIS) — cancer cells are confined within the milk duct and have not invaded surrounding tissue; highly treatable and often detected on screening mammography
• Invasive ductal carcinoma (IDC) — the most common form (~80% of all breast cancers); cancer has breached the duct wall and entered surrounding breast tissue
• Invasive lobular carcinoma (ILC) — cancer originates in the lobules and spreads to adjacent tissue; often presents with diffuse thickening rather than a discrete lump

Risk Factors

Non-Modifiable Risk Factors

Age — risk increases steadily with age. The majority of breast cancers are diagnosed in women over 50; the median diagnosis age is 63. However, younger women are not protected — about 7% of cases occur under age 40.

Genetic mutations — BRCA1 and BRCA2 gene mutations are present in less than 1% of women but account for 5–10% of all breast cancers. They confer a lifetime risk of approximately 70–80%. Other genes including PALB2, CHEK2, ATM and TP53 also increase risk.

Family history — a first-degree relative (mother, sister or daughter) with breast cancer roughly doubles the risk; two or more first-degree relatives raise it three to four times.

Prior breast cancer — a personal history of breast cancer in one breast raises the risk of cancer in the other breast by approximately 0.4% per year.

Reproductive factors:

• Early menarche (first period before age 12)
• Late menopause (after age 55)
• First full-term pregnancy after age 30
• Never having been pregnant
• These factors increase cumulative lifetime oestrogen exposure

Dense breast tissue — increases both the risk of breast cancer and the difficulty of detecting it on mammography.

Prior radiation to the chest — particularly during adolescence (e.g. for Hodgkin lymphoma).

Modifiable Risk Factors

Factor	Effect on Risk
Alcohol consumption	Risk increases with amount; even 1 drink/day raises risk by ~10%
Obesity (postmenopausal)	Adipose tissue produces oestrogen; raises risk 20–40%
Physical inactivity	Increases risk; regular exercise is protective
Combined HRT (oestrogen + progestogen)	Modest increase in risk during and shortly after use
Smoking	Modest increase, particularly with long-term heavy use

Symptoms

Most early breast cancers cause no symptoms and are detected on routine mammography. When symptoms occur, they include:

• A painless lump or area of thickening in the breast or armpit
• Change in breast size, shape or contour
• Skin changes — dimpling, puckering, redness, or a texture resembling orange peel
• Nipple changes — inversion, discharge (especially blood-stained), or ulceration
• Persistent breast pain (rare as the only symptom of cancer)

A lump that is hard, irregular in shape, and fixed rather than mobile carries a higher probability of malignancy. However, most breast lumps are benign — the majority are cysts, fibroadenomas, or fibrocystic changes.

Any new breast change should be assessed by a clinician promptly.

Diagnosis

Mammography

Mammography (low-dose breast X-ray) is the primary screening tool. It detects cancers typically 2–3 years before they become palpable.

Screening recommendations vary by country. Most guidelines recommend annual or biennial mammography from age 40–50 onwards. Women with BRCA mutations or strong family history begin screening earlier and often include annual MRI.

Limitations: mammography is less sensitive in women with dense breasts; supplemental ultrasound or MRI is sometimes used.

Ultrasound

Useful for characterising a lump found on examination or mammography — distinguishing a fluid-filled cyst from a solid mass. Also guides biopsy.

Breast MRI

More sensitive than mammography; used for high-risk screening, pre-surgical planning, and when mammography results are equivocal.

Biopsy

A tissue sample is essential for definitive diagnosis. Options include:

• Core needle biopsy — a hollow needle removes small cylinders of tissue; performed under local anaesthetic, usually ultrasound-guided; the standard approach
• Fine needle aspiration (FNA) — less tissue obtained; used primarily for cyst drainage or lymph node assessment
• Surgical biopsy (excision) — used when needle biopsy is non-diagnostic or the lesion is too small to target

Receptor and Genetic Testing

The biopsy specimen is tested for:

Marker	Significance
Oestrogen receptor (ER)	Positive in ~75% of cancers; drives hormone therapy eligibility
Progesterone receptor (PR)	Usually co-positive with ER
HER2 overexpression	Present in ~15–20%; drives HER2-targeted therapy
Ki-67	Proliferation marker; helps classify tumour aggressiveness

These markers define four key subtypes with different prognoses and treatment strategies:

• Luminal A (ER+, HER2−, low Ki-67) — most common; best prognosis; hormone therapy alone often sufficient
• Luminal B (ER+, HER2−, high Ki-67 or HER2+) — more aggressive; may require chemotherapy
• HER2-enriched (ER−, HER2+) — targeted HER2 therapy essential
• Triple-negative (ER−, PR−, HER2−) — no targeted therapy currently approved for general use; treated with chemotherapy and immunotherapy (pembrolizumab in PD-L1+ disease); BRCA mutations common

Staging

TNM staging defines spread:

Stage	Description	5-Year Survival
0	DCIS only	~99%
I	Small tumour, no nodal spread	~95–99%
II	Larger tumour or limited nodal involvement	~75–86%
III	Extensive nodal or locally advanced	~50–70%
IV	Distant metastases (bone, liver, lung, brain)	~28%

Sentinel lymph node biopsy is the standard for assessing nodal spread without full axillary clearance — reducing the risk of lymphoedema.

Treatment

Surgery

• Breast-conserving surgery (lumpectomy/wide local excision) — removes the tumour with a clear margin of normal tissue; followed by radiotherapy; equivalent survival to mastectomy for most early-stage cancers
• Mastectomy — removal of the entire breast; preferred for large tumours relative to breast size, multifocal disease, BRCA carriers, or patient preference
• Breast reconstruction — immediate or delayed; using implant or autologous tissue (e.g. TRAM flap, DIEP flap)

Radiotherapy

• Standard after breast-conserving surgery to eliminate residual microscopic disease
• Used after mastectomy in high-risk cases (large tumours, involved margins, extensive node disease)
• Modern techniques: intensity-modulated radiotherapy (IMRT) and proton therapy reduce dose to heart and lung

Hormone (Endocrine) Therapy

For ER-positive cancers:

• Tamoxifen — blocks oestrogen receptors; used for 5–10 years; reduces recurrence by ~40%; suitable for pre- and postmenopausal women
• Aromatase inhibitors (letrozole, anastrozole, exemestane) — reduce oestrogen production; more effective than tamoxifen in postmenopausal women
• CDK4/6 inhibitors (palbociclib, ribociclib, abemaciclib) — combined with aromatase inhibitors in metastatic ER+ disease; dramatically extend progression-free survival

Chemotherapy

Used in:

• High-risk early-stage cancers (large tumours, node-positive, high Ki-67, triple-negative)
• HER2-positive cancers (combined with targeted therapy)
• As neoadjuvant (pre-surgery) treatment to shrink the tumour
• As palliative treatment in metastatic disease

Common regimens: anthracyclines (doxorubicin) ± cyclophosphamide, followed by taxanes (docetaxel, paclitaxel).

HER2-Targeted Therapy

For HER2-positive cancers:

• Trastuzumab (Herceptin) — the first and most established; dramatically improves outcomes in early and metastatic HER2+ disease
• Pertuzumab — combined with trastuzumab and chemotherapy for higher-risk disease
• T-DM1 (ado-trastuzumab emtansine) — antibody-drug conjugate; used after neoadjuvant therapy failure and in metastatic disease
• Tucatinib + trastuzumab — highly effective in HER2+ brain metastases

Immunotherapy

Pembrolizumab (anti-PD-1) is approved combined with chemotherapy for PD-L1-positive metastatic triple-negative breast cancer, and as neoadjuvant/adjuvant therapy in early high-risk TNBC.

PARP Inhibitors

Olaparib and talazoparib for BRCA1/2-mutated HER2-negative breast cancer — approved in both early high-risk and metastatic settings.

Breast Cancer Treatment in China

China's comprehensive cancer centres provide:

• Diagnostic pathway: mammography, ultrasound, MRI, core biopsy with full receptor and HER2 testing, and genetic BRCA testing
• Multidisciplinary tumour board review at the time of diagnosis — breast surgery, medical oncology, radiation oncology, plastic surgery, and psycho-oncology
• Breast-conserving surgery with immediate reconstruction — performed routinely by specialist oncoplastic surgeons
• Access to biosimilar trastuzumab as an alternative to branded agents, with the hospital confirming the price for your regimen
• Comprehensive genomic profiling for patients with metastatic disease, identifying emerging targetable alterations
• English-language care navigation throughout the treatment journey

Contact a ChinaMedicalTour care navigator to arrange a breast cancer assessment, second opinion, or treatment consultation.

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Medical content based on MSD Manuals, authored by Lydia Choi MD (Karmanos Cancer Center), reviewed by Oluwatosin Goje MD MSCR (Cleveland Clinic). Last reviewed October 2023, updated April 2025.

Frequently Asked Questions

How can an international patient have breast imaging and pathology evaluated remotely?

Mammography, breast MRI, ultrasound reports, and core needle biopsy pathology (ER/PR, HER2, Ki-67) can be submitted for review by Chinese multidisciplinary breast cancer specialists prior to travel.

What surgical and reconstructive options are evaluated in Chinese tertiary hospitals?

Specialized breast centers evaluate breast-conserving surgery with oncoplastic reconstruction, sentinel lymph node biopsy, skin-sparing mastectomy with immediate reconstruction, and tailored adjuvant systemic therapies.

How does China Medical Tour support international breast cancer patients during care?

We provide non-clinical coordination including medical translation, hospital appointment scheduling, on-site navigation, and obtaining certified bilingual medical records.