Breast Cancer Biopsy Types: FNAC, Core and Frozen Section

The main breast cancer biopsy types are fine needle aspiration cytology (FNAC), core needle biopsy, incisional biopsy, excisional biopsy and frozen section. Core biopsy has largely replaced FNAC because it gives a histological diagnosis, a piece of tissue rather than loose cells. Surgical biopsy is the fallback when needle methods fail, and the tissue then goes for receptor testing that decides the treatment sequence.

That is the pathological arm of triple assessment as Dr. Jalaj Baxi, Director Surgical Oncology, Fortis Hospital, Noida, India, set it out for international doctors in a Jivo Masterclass. Biopsy rarely comes first. It follows imaging, and imaging follows the clinical examination. This article works through the radiological and pathological steps in the order a patient meets them, then explains the receptor tests that turn a diagnosis into a plan. The wider pathway, from presentation to treatment, is in the guide to breast cancer diagnosis and management for general practitioners.

The clinical assessment that precedes imaging

Triple assessment starts in the consulting room. The history establishes how the patient noticed the lump, when, and for how long it has been present. The physical examination establishes whether the tumour is palpable or non-palpable. Only once a tumour is identified clinically, or suspected, does radiological evaluation follow. A non-palpable lesion found on imaging follows the same path from that point.

Imaging a breast lump: mammography first

Mammography is the first radiological investigation. The characteristic sign of malignancy is a spiculated density: a mass with irregular, spiky projections radiating into the surrounding tissue. Dr. Baxi noted that there are specific mammographic features which tell the radiologist that a lesion is suspicious of malignancy.

The BI-RADS classification

Mammographic findings are reported using BI-RADS (Breast Imaging Reporting and Data System), which grades findings from category 0 to category 6. Categories 4 and 5 are suspicious of malignancy, and category 6 is a confirmed malignancy. The standard categories are:

For a referring doctor, the practical line falls between 3 and 4. A BI-RADS 4 or 5 report means tissue is needed, whatever the clinical impression. Imaging and BI-RADS in the wider workup of a breast lump are also covered, from a separate masterclass, in breast lump diagnosis with imaging, BI-RADS and biopsy.

Ultrasound: young patients and dense breasts

Ultrasound comes to the rescue, in Dr. Baxi's phrase, when mammography struggles. He uses breast ultrasound when the patient is young, when the breast is dense, or when the mammogram is not conclusive. Dense glandular tissue appears white on a mammogram, as tumours do, which lowers the sensitivity of mammography in younger women. Ultrasound distinguishes solid masses from cysts regardless of density.

Breast MRI: for specific questions

MRI of the breast is the next investigation, used in two situations in Dr. Baxi's practice: a post-operative breast, and a lesion without specific findings on mammography or ultrasound. It is a problem-solving tool rather than a routine first step.

PET-CT: only after the diagnosis is confirmed

A PET-CT scan combines positron emission tomography, which shows metabolically active tissue, with computed tomography. Dr. Baxi orders it only once the diagnosis is confirmed, to see whether and where the disease has spread. It is a staging investigation, not a diagnostic one, and it does not replace a biopsy.

Breast cancer biopsy types compared

Once imaging has identified a suspicious lesion, the pathological assessment begins. Dr. Baxi described five methods, in the order they are usually considered.

FNAC: fine needle aspiration cytology

In FNAC, a fine needle is passed into the tumour, and cells are drawn out by making multiple passes and aspirating. The cells are spread on a slide. The result is a cytological diagnosis: the pathologist sees individual cells, not the architecture of the tissue.

Dr. Baxi noted that FNAC is no longer performed in most centres. A cytological sample cannot reliably distinguish invasive cancer from cancer confined to the ducts, and it gives limited material for receptor testing, which is why core biopsy has become the standard.

Core biopsy: the current standard

A core biopsy, also called a Tru-Cut biopsy, uses a larger needle mounted in a specialised biopsy gun. Under imaging guidance, the needle is placed in the tumour and the gun takes out a piece of the tumour. The result is a histological diagnosis: the pathologist sees the tissue as it sits in the tumour.

The distinction is the core of the choice:

Incisional biopsy

If FNAC and core biopsy both fail to give an answer, the next step is incisional biopsy. This is a surgical biopsy, done under local or general anaesthesia: the surgeon incises the skin, reaches the tumour and cuts out a piece of it for examination.

Excisional biopsy

An excisional biopsy removes the whole tumour surgically and sends it for histology.

Frozen section: a diagnosis in half an hour

Frozen section is a specialised technique available only at larger hospitals, and not everywhere even in India. Tissue from an incisional or excisional biopsy is sent to the laboratory immediately, rapidly frozen and cut, and within half an hour the pathologist reports whether cancer is present. The surgeon receives the answer while the patient is still in the operating theatre.

Receptor testing: ER, PR and HER2 by immunohistochemistry

Once the diagnosis is made, Dr. Baxi's team carries out immunohistochemistry (IHC) on the biopsy tissue. IHC uses special stains that bind to specific proteins, here three receptors:

• Oestrogen receptor (ER).
• Progesterone receptor (PR).
• HER2, a growth-factor receptor on the surface of the cancer cell.

ER and PR together are the hormone receptors. Dr. Baxi calls this step the biological assessment of the tumour: it describes how the cancer behaves rather than how big it is.

The four receptor combinations

The results fall into four combinations:

1. All three receptors positive.
2. Hormone receptors positive, HER2 negative.
3. Hormone receptors negative, HER2 positive.
4. All three negative: triple-negative breast cancer.

Dr. Baxi described triple-negative breast cancer as the worst kind of breast cancer a patient can have. It offers no hormone or HER2 target, so chemotherapy carries the treatment.

How biopsy and receptor results change the plan

The receptor result changes what happens next, and in particular whether surgery or chemotherapy comes first. In Dr. Baxi's approach:

• Triple negative: chemotherapy first, then surgery.
• HER2 positive: neoadjuvant chemotherapy, meaning chemotherapy before surgery, then surgery.
• Hormone receptor positive: surgery first, then chemotherapy.

Receptor status also opens the targeted options: hormonal therapy for ER-positive and PR-positive disease, and HER2-directed targeted therapy for HER2-positive disease. Both are covered in breast cancer chemotherapy and metastatic disease options.

This is why a biopsy that yields tissue matters more than a quick cytology result. A diagnosis of "malignant cells" without receptor status leaves the treating team unable to decide the first step. For a doctor working without a core biopsy gun or an IHC laboratory, the priority is to secure a tissue diagnosis wherever it can be obtained, so that the receptor tests can be run on the same specimen.

Where the workup leads

With the clinical, radiological, pathological and biological assessments complete, the patient can be staged and treated. The surgical decisions that usually follow, breast conservation or mastectomy and sentinel node biopsy or axillary dissection, are set out in breast surgery, the axilla and when radiotherapy follows. Dr. Niti Raizada describes how the same triple assessment applies alongside ovarian and cervical cancer in the diagnostic workup for breast, ovarian and cervical cancer.