31st December 2024

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.