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31st December 2024

Breast cancer

Overview of breast cancer

Female breast cancer is the most common cancer globally. Male breast cancer is a relatively rare entity.

Risk factors include age (rare under age 30), oestrogen exposure (early menarche, late menopause, nulliparity, older maternal age at first pregnancy, not breastfeeding, use of exogenous oestrogens), previous breast disease (malignant or benign), ionising radiation exposure and obesity. There may be a genetic predisposition, more prevalent in male breast cancer (BRCA2, Klinefelter’s).

Pathology of breast cancer

Histological types of invasive breast cancer include ductal carcinoma (most common), lobular carcinoma, mixed ductal/lobular carcinoma, sarcoma (e.g. angiosarcoma), and lymphoma. Metastases in the breast most commonly arise from a breast primary. ‘In situ’ disease, as in ductal carcinoma in situ (DCIS) and lobular carcinoma in situ (LCIS), refers to a non-invasive tumour confined to the basement membrane which has the potential to become invasive.

Breast cancer metastasis is usually initially by lymphatic invasion of the axillary, supraclavicular and, less often, the internal mammary lymph node chains. Common sites of breast cancer metastasis include bone, brain, liver, lung, lymph nodes and skin.

Presentation of breast cancer

Most cases of breast cancer in the UK are detected by national screening.

The most common symptomatic presentation is with a self-detected breast lump. Other presenting symptoms include breast thickening, skin changes, nipple changes, nipple discharge, and a lump in the axilla. Breast pain is a less common presenting symptom but nevertheless warrants attention, particularly if persistent.

Paget’s disease of the breast classically presents with an eczema-like rash affecting the nipple and areola.

In inflammatory breast cancer, local invasion along lymphatic ducts gives rise to the hallmark peau d’orange appearance of the oedematous, erythematous breast.

Diagnosis of breast cancer

GP referrals for suspected breast cancer are to a specialist breast one-stop clinic at which triple assessment is performed: clinical examination, imaging and biopsy of any suspicious lesion. Imaging consists of bilateral mammograms, usually with the addition of ultrasound (US) of the breasts and axillae, particularly useful in younger patients whose breasts are typically denser. Those presenting with signs of inflammatory breast cancer require a punch biopsy of the skin.

Receptor status is determined on immunohistochemistry (IHC) ± fluorescence in situ hybridisation (FISH) if IHC is equivocal. Breast cancer receptors help determine cancer behaviour and may present targets for treatment:

  • Oestrogen receptor (ER) positive: the majority of breast cancers. Better prognosis.
  • Human epidermal growth factor receptor 2 (HER2) positive: worse prognosis but a target for therapy.
  • Triple negative: a minority of breast cancers. Negative for expression of ER, HER2 and progesterone receptors (PR). Poor prognosis.

Staging investigations are not routinely performed, but CT of the chest, abdomen and pelvis and a bone scan should be obtained if the tumour is larger than 5 cm (T3 disease), if the skin or chest wall is involved (T4, includes all cases of inflammatory breast cancer), if lymph nodes are involved, and/or if the patient presents with features suggestive of metastatic disease. If suspected metastases are identified, a confirmatory biopsy should usually be performed.

Breast cancer staging

Breast cancer may be staged using the TNM classification system or with the number staging system (I-IV). Stages I and II are considered to be early breast cancer, whereas stages III and IV are classed as advanced breast cancer. A simplified summary of the number staging system is as follows:

  • Stage I: tumour <2 cm ± lymph node(s) affected within the ipsilateral breast.
  • Stages I-II: tumour <5 cm ± involvement of up to 3 ipsilateral axillary lymph nodes OR tumour >5 cm with no nodal involvement.
  • Stage III: tumour >5 cm with nodal involvement OR tumour of any size with 4-9 axillary (or internal mammary) lymph nodes  ± local invasion of skin or chest wall.
  • Stage IV: metastatic disease, e.g. to bone, liver, lung or distant lymph nodes.

Genetics referrals in breast cancer

BRCA1 and BRCA2 gene mutations are germline mutations in tumour suppressor genes, which, if inherited, confer a higher lifetime risk of developing breast cancer. BRCA1 also confers a relatively high risk of ovarian cancer, whilst male carriers of BRCA2 and, to a lesser extent, BRCA1 are at an increased risk of male breast cancer and prostate cancer. Ashkenazi Jewish ancestry is a risk factor for BRCA mutation carriage.

Genetic syndromes that predispose to breast cancer include Lynch syndrome (hereditary non-polyposis colorectal cancer, HNPCC), which is most associated with colorectal (and endometrial) cancers, and Li-Fraumeni syndrome (TP53 mutation), which also causes sarcoma, brain cancer and leukaemia.

NICE guidelines outline the criteria for specialist genetics referral, which include the following:

  • Family history of breast cancer at a young age (e.g. 2 first-degree or 1 first-degree and 1 second-degree relative aged <50)
  • Family history of bilateral breast cancer (e.g. at least 1 first-degree relative aged <50)
  • Family history of ovarian cancer in combination with a family history of breast cancer at a young age
  • Family history of male breast cancer in combination with a family history of breast cancer at a young age

Furthermore, genetics referral should also be considered if there is a family history of sarcoma at a young age (<45), strong paternal family history of breast cancer or childhood glioma.

Those identified to be at an increased lifetime risk of breast cancer may be offered annual surveillance ± prophylactic mastectomy ± oophorectomy ± preventative use of hormone therapy.

Breast cancer screening

National screening programme

In the UK, people registered as female and trans men without a prior history of breast cancer are invited for three-yearly mammograms between ages 50-70, after which they may opt in to ongoing screening. In the rest of this section, we will refer to ‘women’ for simplicity, but the information also applies to trans men.

Breast cancer screening in those with previous breast cancer

According to NICE, women who have been successfully treated for breast cancer, with no known genetic risk factor, should have annual mammograms for five years following treatment.

However, women who have been successfully treated for breast cancer but are at high risk for further breast cancer (e.g. a positive family history or a known genetic mutation) should have more frequent screening:

  • Ages 30-49 (or aged 30 to 59 with a TP53 mutation): annual MRI scans
  • Ages 50-69: annual mammograms

Breast cancer screening in those who have risk factors

Women who have not had breast cancer but are at high risk due to a strong family history or known genetic mutation should have regular surveillance. In general, younger women are offered breast MRIs in preference to mammograms as breast tissue is usually denser.

NICE advises the following:

  • TP53 mutation (known, or at high risk of): annual MRI between ages 20-69. Note that TP53 mutation is the only risk factor that makes women eligible for surveillance under age 30.
  • BRCA mutation: annual MRI ± mammogram between ages 30-59, then three-yearly mammograms as part of the national screening programme.
  • High risk for another reason, e.g. family history: annual MRI ± mammogram between ages 40-59, then three-yearly mammograms as part of the national screening programme. May additionally be considered for surveillance between ages 30-39 on a case-by-case basis.

Management of breast cancer

Management of early breast cancer

Patients with early breast cancer (stages I-II) have a disease which can, by definition, be fully excised; they should be offered surgery if fit. This may be either mastectomy or breast-conserving surgery (wide local excision, WLE, or ‘lumpectomy’), depending on factors including size and position of the lesion and overall breast size. Patients simultaneously undergo axillary surgery:

  • For those with established nodal disease at diagnosis, axillary lymph node clearance is recommended. This carries the risk of lymphoedema and shoulder stiffness.
  • Patients who are node negative at diagnosis may undergo sentinel lymph node biopsy, in which the excised sentinel nodes are used to complete pathological staging and determine the need for node clearance.

Surgery for early breast cancer is usually followed by the offer of adjuvant therapy to reduce the risk of recurrence. Adjuvant radiotherapy may be offered to reduce the risk of locoregional recurrence, whilst adjuvant systemic therapies may be offered to reduce the risk of distal recurrence from occult micrometastases.

Adjuvant systemic therapies include chemotherapy, hormonal therapy and targeted therapy:

  • Hormonal therapy is offered to patients with ER-positive breast cancer. Tamoxifen is first line in pre- and peri-menopausal women; aromatase inhibitors such as letrozole are first line in post-menopausal women. Tamoxifen increases the risk of venous thromboembolism and endometrial cancer, whilst arthralgia syndrome (isolated joint pain and swelling) is the most common reason for discontinuation of aromatase inhibitors. This is secondary to reduced oestrogen levels causing reduced bone mineral density.
  • Targeted anti-HER2 therapy is offered to patients with HER2-positive breast cancer and is usually in the form of recombinant monoclonal antibodies trastuzumab (Herceptin) and/or pertuzumab. The main associated adverse effect is of cardiotoxicity and patients are surveyed with regular echocardiograms.
  • Targeted therapy with abemaciclib (a CDK4/6 inhibitor) is authorised for use alongside aromatase inhibitors in cases of hormone receptor-positive, HER2-negative, node-positive early breast cancer where there is estimated to be a high risk of recurrence. Abemaciclib can cause diarrhoea, which can be explosive.

Neoadjuvant systemic therapy (given prior to surgery) aims to reduce tumour size and, therefore, make breast-conserving surgery more feasible, as well as reduce the risk of recurrence. Neoadjuvant therapy is indicated in a number of settings, one example being HER2-positive early breast cancer where there is a high risk of recurrence, in which case neoadjuvant therapy combining taxane-containing chemotherapy with targeted anti-HER2 therapy (pertuzumab plus trastuzumab) is usually offered.

Management of advanced breast cancer

Patients with advanced breast cancer may have locally advanced disease and/or distal metastases, meaning their disease is not, at least initially, completely resectable. In patients with locally advanced disease, achieving local control to prevent tumour fungation is a priority. Patients are usually treated with a combination of radiotherapy and systemic therapies. If there is a good response, surgery may become feasible. Metastatic breast cancer is incurable and any treatment is with palliative intent. A full description of treatment options is beyond the scope of this chapter. However, it is important to appreciate that, as with early breast cancer, decisions are guided by performance status, hormone receptor status and, increasingly, immune-related biomarkers. Several examples follow.

ER-positive, HER2-negative advanced breast cancer: first-line management is usually endocrine therapy, which, as in the adjuvant setting, may be combined with targeted therapy (e.g. letrozole ± a CDK4/6 inhibitor such as abemaciclib). Chemotherapy is usually reserved for hormone-refractory disease further down the line.

PD-L1-positive advanced triple negative breast cancer: patients whose tumours express specific immune-related biomarkers may be offered targeted treatment with immune checkpoint inhibitors. These work to ‘activate’ the immune system against tumour cells by preventing tumour cells from binding to and de-activating T-cells. First-line treatment options for advanced triple-negative breast cancers include:

  • Pembrolizumab (anti-PD-1) + nab-paclitaxel (paclitaxel bound by albumin nanoparticles, also known as Abraxane)
  • Atezolizumab (anti-PD-L1) + nab-paclitaxel

Management of carcinoma in situ

Patients with DCIS are offered resection (usually wide local excision, unless very large), and adjuvant radiotherapy should be considered. LCIS may be observed unless features are non-classical (usually pleomorphic LCIS), in which case patients may be offered resection.

References

Complete Guide to Clinical Genetics ST3 Application and Recruitment (2027)

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Complete Guide to Clinical Radiology ST3 Application and Recruitment (2027)

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Complete Guide to Paediatric Surgery ST3 Application and Recruitment in United Kingdom (2026)

Written by Medibuddy. Last updated: October 2026. If you’re planning

Paediatric Surgery ST3
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