Breast cancer

The most common cancer in women — and one where identifying the subtype precisely genuinely changes both treatment and outlook.

The figures at a glance

the most frequently diagnosed cancer in women in Greece

Globocan / IARC · 2022

50–69

ages invited for mammography screening

EU Council Recommendation · 2022

What it is

Breast cancer begins in the cells of the milk ducts or the lobules. It is not one disease: behind the same name sit biologically distinct subtypes that behave differently and are treated differently.

This is precisely why two women with “the same” breast cancer may receive entirely different treatment — and why identifying the subtype accurately is worth the time it takes.

Histological types

Invasive carcinoma of no special type (NST, formerly “ductal”) — the most common type, around 75–80% of cases.
Invasive lobular carcinoma — around 10–15%, with a diffuse growth pattern that can make it harder to see on imaging.
Special types (tubular, mucinous, cribriform and others) — around 5%; several of these have a particularly favourable course.
In situ lesions (DCIS, LCIS) — pre-invasive forms, meaning cells that have not yet moved beyond the duct or lobule.

The four subtypes

Classification is based on hormone receptor (ER/PR) and HER2 expression, and it is what determines the treatment backbone:

Luminal A-like — HR+ / HER2− with low Ki-67, around 40% of cases. Endocrine therapy is the backbone, and the outlook is the most favourable of the four.
Luminal B-like — HR+ / HER2− with high Ki-67, or HR+ / HER2+, around 20%. Endocrine therapy, with chemotherapy where needed.
HER2-positive — around 15–20%. The arrival of anti-HER2 therapies transformed this subtype from the most difficult into one of the most treatable.
Triple-negative (TNBC) — ER− / PR− / HER2−, around 10–15%. Chemotherapy is the backbone, with immunotherapy added in recent years.

Around 15–20% of triple-negative tumours and 10–15% of high-risk HR+/HER2− tumours are associated with germline BRCA1/BRCA2 variants — which opens specific treatment options and also concerns the family.

Symptoms and diagnosis

The most common finding is a painless palpable lump, but other signs also warrant assessment:

A change in the shape or size of the breast.
Nipple retraction or discharge, especially if bloodstained.
Skin change — redness, thickening, an “orange peel” appearance.
Palpable lymph nodes in the armpit.

Investigation combines clinical examination, mammography and ultrasound, and is confirmed by biopsy. MRI is used in selected cases.

Screening

International guidelines converge on mammography as the core test, with small differences in ages and intervals:

The USPSTF recommends mammography every two years for women aged 40–74.
The American Cancer Society offers annual screening from 40–44, annual from 45–54, and a move to biennial from 55.
The American College of Physicians suggests biennial mammography for ages 50–74, with shared decision-making outside that range.

For women at increased risk — BRCA carriers, a lifetime risk of 20% or more, or previous chest radiation — screening starts earlier and combines annual mammography with annual breast MRI. This is set individually.

Treatment by stage

Management combines local treatment (surgery and, where needed, radiotherapy) with systemic therapy, tailored to subtype and stage.

Stage 0 (DCIS) — lumpectomy with radiotherapy, or mastectomy, with endocrine therapy when the tumour is ER positive.
Stages I–III — surgery with axillary staging, plus systemic therapy before or after. In HER2-positive and triple-negative tumours, treatment usually comes before surgery so that the response can be observed — information that guides what follows.
Stage IV — treatable disease, where the aim is long-term control and preserved quality of life. The available treatments have expanded considerably and many women live well with the disease for extended periods.

Systemic treatment by subtype

HR+ / HER2− — endocrine therapy is the backbone. In selected higher-risk cases CDK4/6 inhibitors or chemotherapy are added; gene-expression prognostic tests help avoid chemotherapy that would not add benefit.
HER2-positive — chemotherapy combined with anti-HER2 therapy. Where residual disease remains after pre-operative treatment, effective second-line options now exist.
Triple-negative — chemotherapy, with immunotherapy added in stages II–III and specific targeted options for germline BRCA carriers.

Drug names and doses are deliberately not listed here: the choice depends on subtype, stage, other conditions and your own preferences, and is made together with your doctor.

How this is approached at the practice

Every case is discussed in a multidisciplinary team meeting (MDT) — surgeon, radiation oncologist, pathologist, radiologist and, where needed, psycho-oncologist and dietitian. The treatment decision is not made by one doctor alone.

Before any treatment is proposed, the tumour undergoes full molecular and immunohistochemical characterisation, so the choice targets your specific biology rather than a generic protocol. Every alternative is presented with its trade-offs, and a second opinion is treated as an ally.

Biomarkers tested

Molecular and immunohistochemical characterisation is done before treatment is chosen, so the decision rests on this particular tumour’s biology.

Frequently asked questions

Does a palpable lump mean cancer?

In the large majority of cases no — most breast lumps are benign. Any new finding does need assessment, though, and should not simply be watched without a diagnosis.

If I carry a BRCA variant, will I necessarily need a mastectomy?

No. The variant changes the risk assessment and opens options — intensive surveillance, risk-reducing medication or preventive surgery. The decision is personal and follows genetic counselling.