Breast Cancer Diagnosis: Mammogram, Biopsy, IHC and Staging Tests Explained

Diagnosis & treatment

Finding a suspicious breast lump naturally creates anxiety.

The next question is usually:

“What tests will I need now?”

According to Dr. Deenadayalan T, Consultant Medical Oncologist, breast cancer evaluation generally happens in two broad stages:

1. Diagnostic investigations

These determine whether the breast abnormality is cancer and identify its biological characteristics.

2. Staging investigations

Once cancer is confirmed, selected tests determine how extensive the disease is and whether it has spread elsewhere.

Understanding this sequence can make the diagnostic process much less frightening.

From suspicious lump to treatment plan
01Clinical examination
02Imaging + BI-RADS
03Core needle biopsy
04ER / PR / HER2 testing
05Staging, when indicated
06Personalised treatment plan

Surgery first or treatment first depends on subtype and stage.

Step 1: Clinical Breast Examination

Evaluation begins with a detailed medical history and clinical examination.

The doctor examines:

  • The breast lump
  • Size and location
  • Skin changes
  • Nipple abnormalities
  • The opposite breast
  • Lymph nodes in the armpit and nearby areas

The patient’s age, family history and other symptoms also influence which tests are performed next.

Step 2: Diagnostic Breast Imaging

A suspicious breast lump usually requires imaging.

The most commonly used tests are:

  • Diagnostic mammography
  • Breast ultrasound

However, the first imaging test may vary according to the woman’s age.

Women 40 Years and Older

Diagnostic mammography is commonly used as the initial imaging investigation, often combined with targeted ultrasound.

Women Aged 30–39

Depending on the clinical situation, either targeted breast ultrasound or diagnostic mammography may be used.

Women Younger Than 30

Breast ultrasound is usually the preferred initial imaging test.

Therefore, a mammogram is extremely important—but it is not automatically the first test for every woman with a breast lump.

What Is a BI-RADS Score?

Breast imaging reports commonly use a standardized system called:

BI-RADS — Breast Imaging Reporting and Data System

BI-RADS helps radiologists communicate how suspicious an imaging abnormality appears and what should happen next.

A simplified interpretation is:

BI-RADS 1Negative
BI-RADS 2Benign finding
BI-RADS 3Probably benign — short-term imaging follow-up may be advised
BI-RADS 4Suspicious abnormality — biopsy should be considered
BI-RADS 5Highly suggestive of malignancy — tissue diagnosis and appropriate action are required
BI-RADS 6Cancer already confirmed by biopsy

The critical point is:

A mammogram cannot definitively diagnose breast cancer.

Imaging tells doctors how suspicious a lesion is.

A tissue sample is required to confirm whether it is actually cancer.

Step 3: Breast Biopsy — The Test That Confirms Cancer

If imaging shows a suspicious lesion, particularly BI-RADS 4 or 5, a biopsy is generally required.

A core needle biopsy is commonly used.

During the procedure:

  • The suspicious area is identified
  • A specialized needle is inserted
  • Small cores of tissue are removed
  • The tissue is sent to a pathology laboratory

Ultrasound, mammography or MRI may sometimes be used to guide the biopsy needle accurately.

Why Is a Core Needle Biopsy So Important?

The biopsy tells doctors:

  • Whether cancer is present
  • Whether it is invasive or non-invasive
  • The histological type of cancer
  • The tumor grade
  • Other microscopic characteristics

This information is essential before planning cancer treatment.

Imaging raises suspicion. Biopsy establishes the diagnosis.

Step 4: IHC Testing — Understanding the Biology of the Cancer

Confirming breast cancer is only the beginning.

Doctors also need to understand what type of breast cancer it is biologically.

This is where Immunohistochemistry (IHC) becomes extremely important.

The biopsy tissue is commonly tested for three major biomarkers:

Estrogen Receptor — ER

Progesterone Receptor — PR

HER2

These biomarkers help doctors understand what is driving the cancer and which treatments are most likely to work.

ER and PR Positive Breast Cancer

Some breast cancers grow in response to hormones such as estrogen or progesterone.

If the tumor expresses these receptors, it may respond to hormonal or endocrine therapy.

Examples of endocrine treatment can include medicines that:

  • Block estrogen receptors
  • Reduce estrogen production
  • Suppress ovarian hormone production in selected patients

The exact treatment depends on the patient’s age, menopausal status, cancer stage and other factors.

HER2-Positive Breast Cancer

Some breast cancers produce excessive amounts of a protein called:

HER2

HER2-positive cancers can often be treated with medicines specifically designed to target this protein.

This is one of the great successes of modern precision oncology.

What Is Triple-Negative Breast Cancer?

If a breast cancer is:

  • ER negative
  • PR negative
  • HER2 negative

it is called:

Triple-Negative Breast Cancer (TNBC)

Treatment often relies more heavily on chemotherapy, and immunotherapy may be appropriate for selected patients depending on the stage, clinical setting and additional biomarker information.

Why Biomarker Testing Changes Treatment

Two women can have breast cancers of exactly the same size but require very different treatments.

One may have:

Hormone receptor-positive cancer

Another may have:

HER2-positive cancer

Another may have:

Triple-negative breast cancer

That is why modern breast cancer treatment is not based on tumor size alone.

Doctors consider:

  • Tumor stage
  • ER status
  • PR status
  • HER2 status
  • Tumor grade
  • Lymph-node involvement
  • Menopausal status
  • Patient fitness
  • Other molecular information when appropriate

This allows treatment to be personalized.

Step 5: Staging the Breast Cancer

Once cancer is confirmed, doctors determine its stage.

Breast cancer staging considers:

T — Tumor

Size and local extent of the primary tumor

N — Nodes

Whether nearby lymph nodes are involved

M — Metastasis

Whether the cancer has spread to distant organs

Biological features such as ER, PR, HER2 and tumor grade also contribute to modern breast cancer staging and prognosis.

Does Every Breast Cancer Patient Need a PET Scan?

No.

This is an important misconception.

A full-body PET/CT scan is not routinely required for every newly diagnosed breast cancer patient.

For patients with early-stage breast cancer and a low likelihood of distant spread, extensive staging with PET, CT or bone scans may provide little benefit and can create unnecessary:

  • Radiation exposure
  • Cost
  • Anxiety
  • False-positive findings
  • Additional procedures

The staging investigation should match the patient’s actual clinical risk.

What Tests Are Used in Early Breast Cancer?

If examination and imaging suggest an early breast cancer with no concerning symptoms or evidence of extensive lymph-node involvement, doctors may use limited investigations rather than automatically ordering a PET scan.

Depending on the individual case, evaluation may include:

  • Appropriate breast imaging
  • Axillary ultrasound when needed
  • Routine blood investigations
  • Additional imaging only when clinically indicated

The exact staging approach varies according to the clinical stage and treatment plan.

When Are More Extensive Staging Scans Considered?

More extensive imaging may be appropriate when there is concern for locally advanced or metastatic disease.

Examples include:

  • Large or locally advanced tumors
  • Significant lymph-node involvement
  • Skin or chest-wall involvement
  • Ulcerated tumors
  • Symptoms suggesting distant spread
  • Abnormal laboratory or clinical findings

Imaging options may include:

  • CT scans
  • Bone scan
  • PET/CT
  • Other organ-specific investigations

The decision is based on the entire clinical picture—not one tumor-size cut-off alone.

What Can a PET/CT Scan Show?

PET/CT combines metabolic imaging with anatomical imaging.

In selected patients, it can help identify possible cancer involvement in areas such as:

  • Lymph nodes
  • Bones
  • Lungs
  • Liver
  • Other distant sites

However, PET/CT complements biopsy and clinical staging.

It does not replace tissue diagnosis.

Step 6: Deciding Whether Treatment Starts Before or After Surgery

Once doctors know:

  • The stage
  • Tumor biology
  • ER/PR/HER2 status
  • Lymph-node status
  • Patient’s overall fitness

they can decide the correct sequence of treatment.

There are two common pathways.

Upfront Surgery

Some patients with operable early-stage breast cancer may undergo surgery first.

Depending on the tumor and patient, surgery may involve:

  • Breast-conserving surgery
  • Mastectomy
  • Sentinel lymph-node evaluation
  • Other axillary procedures when required

After surgery, the final pathology determines whether additional treatment is necessary.

This may include:

  • Chemotherapy
  • Radiation therapy
  • Hormonal therapy
  • HER2-targeted therapy
  • Other systemic treatments

Neoadjuvant Treatment — Treatment Before Surgery

In other patients, systemic treatment is intentionally given before surgery.

This is called:

Neoadjuvant therapy

It may involve:

  • Chemotherapy
  • HER2-targeted therapy
  • Immunotherapy in appropriate settings
  • Other systemic treatments

Neoadjuvant therapy can:

  • Shrink the tumor
  • Improve operability
  • Increase opportunities for breast conservation in selected patients
  • Show how well the cancer responds to treatment
  • Provide important information for treatment after surgery

Whether neoadjuvant treatment or surgery should come first depends heavily on the cancer subtype and stage.

Step 7: Genetic Testing — Who Needs It?

Genetic evaluation has also become increasingly important in breast cancer care.

Historically, testing was mainly considered when:

  • Breast cancer occurred at a young age
  • There was a strong family history
  • Multiple relatives had breast or ovarian cancer

Today, recommendations are broader.

Current expert guidance recommends offering BRCA1 and BRCA2 germline testing to many newly diagnosed breast cancer patients, particularly those aged 65 or younger, while selected older patients should also be considered depending on their clinical and family history.

What Is Germline Genetic Testing?

Germline testing looks for inherited genetic changes that are present throughout the body and may have been inherited from a parent.

Testing can usually be performed using:

  • A blood sample
  • Sometimes saliva

Depending on the patient’s history and clinical situation, testing may include:

  • BRCA1
  • BRCA2
  • PALB2
  • TP53
  • CHEK2
  • ATM
  • Other clinically relevant genes

A broader multigene panel may be recommended in selected patients.

An HRR-related panel may also be considered in specific clinical contexts, but it should not be presented as the single standard genetic test for every breast cancer patient.

Why Genetic Testing Matters

Finding an inherited pathogenic variant can influence:

The Patient’s Treatment

Certain genetic abnormalities may affect eligibility for particular targeted medicines.

Surgical Planning

Some high-risk patients may consider risk-reducing surgical strategies after detailed counseling.

Future Cancer Screening

Patients may require enhanced screening for other cancers.

Family Members

Close relatives may be offered genetic counseling and appropriate testing.

This makes genetic testing relevant not only to the patient—but potentially to the entire family.

Step 8: Baseline Blood Tests

Before surgery, chemotherapy or other systemic treatment, patients usually undergo routine blood investigations.

These may include:

  • Complete blood count
  • Kidney function
  • Liver function
  • Blood glucose
  • Electrolytes
  • Other tests based on the patient’s medical condition

Additional investigations may be required before specific medicines.

For example, certain treatments may require assessment of heart function before therapy begins.

The Complete Breast Cancer Diagnostic Journey

A simple way to understand the process is:

1. Suspicious Breast Lump

2. Clinical Examination

3. Mammogram and/or Ultrasound

4. BI-RADS Assessment

5. Core Needle Biopsy if Suspicious

6. Pathology + ER / PR / HER2 Testing

7. Clinical Staging and Appropriate Imaging

8. Genetic Testing When Indicated

9. Multidisciplinary Treatment Planning

10. Surgery First OR Neoadjuvant Treatment First

This is how modern breast cancer treatment becomes personalized rather than one-size-fits-all.

Why a Multidisciplinary Team Matters

Breast cancer treatment may involve:

  • Medical oncologists
  • Breast/surgical oncologists
  • Radiation oncologists
  • Radiologists
  • Pathologists
  • Genetic counselors
  • Nuclear medicine specialists
  • Other healthcare professionals

Ideally, complex cases are discussed through a multidisciplinary or tumor board approach.

This ensures that imaging, pathology, stage, biology and the patient’s overall health are considered together before treatment begins.

Breast Cancer Diagnosis and Treatment in Madurai

Dr. Deenadayalan T is a Consultant Medical Oncologist in Madurai with expertise in:

  • Breast cancer evaluation
  • Chemotherapy
  • Targeted therapy
  • Immunotherapy
  • Precision oncology
  • Genetic and molecular-guided cancer treatment
  • Personalized cancer care

If you have discovered a suspicious breast lump, do not delay evaluation out of fear.

Not every breast lump is cancer.

But if cancer is present, obtaining the correct diagnosis, biomarkers and stage is essential for choosing the right treatment.

Frequently Asked Questions

Can a mammogram confirm breast cancer?

No. Mammography can identify suspicious abnormalities, but a biopsy is required to confirm cancer.

What does BI-RADS 4 mean?

BI-RADS 4 means the finding is suspicious and biopsy should generally be considered.

What does BI-RADS 5 mean?

BI-RADS 5 means the imaging abnormality is highly suggestive of malignancy and appropriate tissue diagnosis and treatment planning are required.

Which biopsy is commonly used for a breast lump?

An image-guided core needle biopsy is commonly used because it provides a tissue sample for detailed pathological and biomarker evaluation.

What is an IHC test in breast cancer?

Immunohistochemistry helps evaluate important biomarkers such as estrogen receptor, progesterone receptor and HER2.

Why are ER, PR and HER2 important?

They help classify the breast cancer and determine whether treatments such as hormonal therapy or HER2-targeted therapy may be effective.

Does every breast cancer patient need a PET scan?

No. Extensive staging imaging such as PET/CT is not routinely recommended for low-risk early breast cancer. It is more useful when the clinical stage or symptoms raise concern about distant spread.

Is a PET scan better than a biopsy?

No. PET/CT and biopsy answer different questions. Biopsy confirms the diagnosis and tumor biology; imaging evaluates the extent of disease.

Does everyone with breast cancer need genetic testing?

Genetic testing recommendations have broadened significantly. BRCA1/2 testing should be offered to many newly diagnosed patients, particularly those aged 65 or younger, while testing in older patients depends on additional clinical and family-history factors.

What determines whether chemotherapy is given before surgery?

The decision depends on factors such as tumor size, lymph-node involvement, cancer subtype, HER2 status, hormone receptors, stage, patient fitness and expected benefit from treatment.

Final Takeaway

Breast cancer diagnosis is not based on one scan or one blood test.

It is a step-by-step process.

Doctors need to answer four fundamental questions:

1. Is it cancer?

Biopsy provides the answer.

2. What type of breast cancer is it?

Pathology and biomarkers such as ER, PR and HER2 provide the answer.

3. How far has it spread?

Clinical staging and appropriate imaging provide the answer.

4. What is the best treatment?

Stage + tumor biology + genetics + patient fitness guide the answer.

Modern breast cancer care is therefore not simply about finding a tumor.

It is about understanding that particular tumor well enough to choose the right treatment for that particular patient.