Breast Cancer
Breast cancer is not a single disease. Its course and its treatment change considerably depending on the biological subtype. This page covers diagnosis, staging, subtypes and current treatment options.
- 4 main biological subtypes
- 0 – IV staging range
- 40 – 69 national mammography screening ages in Türkiye
What is breast cancer?
Breast cancer arises when cells in breast tissue multiply without control. It most often begins in the milk ducts or in the milk-producing lobules. In the early stages it usually causes no pain — so the absence of pain never means there is nothing wrong.
Treatment is decided on more than the size of the lump: the biology of the tumour matters just as much. Two patients at the same stage may be treated entirely differently depending on hormone receptor and HER2 status.
Staging
The stage describes how far the disease has spread within the breast and whether it has reached other parts of the body. It is the first thing that shapes the treatment plan.
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Stage 0
In situ disease
Abnormal cells have not moved outside the duct where they formed. The risk of spread is very low and the response to treatment is generally excellent.
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Stage I
Early stage
The tumour is small and there is either no lymph node involvement or only very limited involvement.
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Stage II
Early to intermediate
The tumour is larger and/or there is limited involvement of the lymph nodes in the armpit.
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Stage III
Locally advanced
The tumour has reached the chest wall or the skin, or there is extensive lymph node involvement. Drug treatment usually comes before surgery.
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Stage IV
Metastatic disease
The disease has spread to distant organs such as bone, liver or lung. The aim is to keep it under control for as long as possible while protecting quality of life.
Biological subtypes
The hormone receptor (ER/PR) and HER2 results in your pathology report determine which treatment will work. Subtype can shape treatment even more than stage does.
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HR+ / HER2−
Hormone receptor positive
The most common subtype. The tumour is fuelled by oestrogen and/or progesterone, so endocrine therapy forms the backbone of treatment. CDK4/6 inhibitors are added for suitable patients.
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HER2+
HER2 positive
The HER2 protein is overproduced on the cell surface. Drugs that target HER2 have changed the course of this subtype markedly over the past two decades.
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HER2-low
HER2 low
Tumours traditionally counted as HER2 negative but carrying a small amount of HER2. The development of antibody-drug conjugates has given this group a treatment option of its own.
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TNBC
Triple negative
Hormone receptor and HER2 negative. It is sensitive to chemotherapy; immunotherapy is used in PD-L1 positive patients and PARP inhibitors in those carrying a BRCA mutation.
Why knowing your subtype matters
The ER, PR and HER2 lines in your pathology report are the most important pieces of information shaping your treatment plan. Deciding on treatment before those results are clear is not sound practice.
Two tumours of the same size are treated with entirely different drugs if their biological subtypes differ. That is why it matters to bring your complete pathology report when seeking a second opinion.
Treatment options
Breast cancer treatment usually combines several methods. The order depends on stage and subtype: some patients have surgery first, while others receive drug treatment first to shrink the tumour.
The plan is set by a multidisciplinary board. Medical oncology, surgery, radiation oncology, radiology and pathology decide together — a more reliable method than the opinion of any single doctor.
Frequently Asked Questions
Is every lump in the breast cancer?
No. Most palpable lumps are benign — fibroadenomas and cysts are the most common. But benign and malignant cannot be told apart by touch alone; imaging and, if needed, a biopsy are always required.
There is no breast cancer in my family — am I still at risk?
Yes. Most women diagnosed with breast cancer have no family history. A family history raises the risk, but the absence of one does not remove it, which is why screening recommendations apply to all women.
When should I start having mammograms?
The national screening programme in Türkiye recommends a mammogram every two years for women aged 40 to 69. Women with a family history of breast or ovarian cancer may need to start earlier and with different methods — decide this with your doctor.
Does every patient need chemotherapy?
No. In early-stage hormone receptor positive disease in particular, gene expression tests help identify who will actually benefit from chemotherapy. For some patients endocrine therapy alone is enough.
Can I keep working during treatment?
Many patients do. It depends on the type of treatment, the severity of side effects and the nature of your work. It is worth raising with your doctor while the plan is being made.
Does breast cancer occur in men?
Yes, although it is rare. A lump in the breast or a change in the nipple in a man should always be assessed; because it is rare, diagnosis is often delayed.