Introduction

Breast cancer is the most common cancer in the UK, accounting for almost a sixth (15%) of all cases in females.

Classification

The terminology surrounding breast cancer can sometimes be confusing and has changed over recent years. It is useful to start by considering basic breast anatomy

Image sourced from Wikipedia
Basic breast anatomy

Most breast cancers arise from duct tissue followed by lobular tissue, described as ductal or lobular carcinoma respectively. These can be further subdivided as to whether the cancer hasn't spread beyond the local tissue (described as carcinoma-in-situ) or has spread (described as invasive). Therefore, common breast cancer types include:
  • Invasive ductal carcinoma. This is the most common type of breast cancer. To complicate matters further this has recently been renamed 'No Special Type (NST)'. In contrast, lobular carcinoma and other rarer types of breast cancer are classified as 'Special Type'
  • Invasive lobular carcinoma
  • Ductal carcinoma-in-situ (DCIS)
  • Lobular carcinoma-in-situ (LCIS)

Rarer types of breast cancer are shown in the following list. These are classed as 'Special Type' but as noted previously remember that a relatively common type of breast cancer (lobular) is also Special Type:
  • Medullary breast cancer
  • Mucinous (mucoid or colloid) breast cancer
  • Tubular breast cancer
  • Adenoid cystic carcinoma of the breast
  • Metaplastic breast cancer
  • Lymphoma of the breast
  • Basal type breast cancer
  • Phyllodes or cystosarcoma phyllodes
  • Papillary breast cancer

Other types of breast cancer include the following (although please note they may be associated with the underlying lesions seen above, rather than completely separate subtypes):

Paget's disease of the nipple is an eczematoid change of the nipple associated with an underlying breast malignancy and it is present in 1-2% of patients with breast cancer. In half of these patients, it is associated with an underlying mass lesion and 90% of such patients will have an invasive carcinoma. 30% of patients without a mass lesion will still be found to have an underlying carcinoma. The remainder will have carcinoma in situ.

Inflammatory breast cancer where cancerous cells block the lymph drainage resulting in an inflamed appearance of the breast. This accounts for around 1 in 10,000 cases of breast cancer.

Epidemiology

  • Incidence: 95.00 cases per 100,000 person-years
  • Peak incidence: 60-70 years
  • Sex ratio: more common in females 100:1
Condition Relative
incidence
Breast abscess1.32
Breast cancer1
Fat necrosis of the breast0.04
<1 1-5 6+ 16+ 30+ 40+ 50+ 60+ 70+ 80+

Aetiology

Predisposing factors
  • BRCA1, BRCA2 genes - 40% lifetime risk of breast/ovarian cancer
  • 1st degree relative premenopausal relative with breast cancer (e.g. mother)
  • Nulliparity, 1st pregnancy > 30 yrs (twice risk of women having 1st child < 25 yrs)
  • Early menarche, late menopause
  • Combined hormone replacement therapy (relative risk increase * 1.023/year of use), combined oral contraceptive use
  • Past breast cancer
  • Not breastfeeding
  • Ionising radiation
  • P53 gene mutations
  • Obesity
  • Previous surgery for benign disease (?more follow-up, scar hides lump)

Clinical features


Many patients will have abnormalities detected on mammography during routine screening.

Referral criteria

NICE cancer referral guidelines for breast cancer suggest the following:


Refer people using a suspected cancer pathway referral (for an appointment within 2 weeks) for breast cancer if they are:
  • aged 30 and over and have an unexplained breast lump with or without pain or
  • aged 50 and over with any of the following symptoms in one nipple only:
    • discharge
    • retraction
    • other changes of concern.

Consider a suspected cancer pathway referral (for an appointment within 2 weeks) for breast cancer in people:
  • with skin changes that suggest breast cancer or
  • aged 30 and over with an unexplained lump in the axilla.

Consider non-urgent referral in people aged under 30 with an unexplained breast lump with or without pain.

Management

The management of breast cancer depends on the staging, tumour type and patient background. It may involve any of the following:
  • Surgery
  • Radiotherapy
  • Hormone therapy
  • Biological therapy
  • Chemotherapy

Surgery

The vast majority of patients who have breast cancer diagnosed will be offered surgery. An exception may be a very frail, elderly lady with metastatic disease who may be better managed with hormonal therapy.

Depending on the characteristics of the tumour women either have a wide-local excision or a mastectomy. Around two-thirds of tumours can be removed with a wide-local excision. The table below lists some of the factors determining which operation is offered:

MastectomyWide Local Excision
Multifocal tumourSolitary lesion
Central tumourPeripheral tumour
Large lesion in small breastSmall lesion in large breast
DCIS > 4cmDCIS < 4cm

Women should be offered breast reconstruction to achieve a cosmetically suitable result regardless of the type of operation they have. For women who've had a mastectomy this may be done at the initial operation or at a later date.

Radiotherapy

Whole breast radiotherapy is recommended after a woman has had a wide-local excision as this may reduce the risk of recurrence by around two-thirds. For women who've had a mastectomy radiotherapy is offered for T3-T4 tumours and for those with four or more positive axillary nodes

Hormonal therapy

Adjuvant hormonal therapy is offered if tumours are positive for hormone receptors. For many years this was done using tamoxifen for 5 years after diagnosis. Tamoxifen is still used in pre- and peri-menopausal women. In post-menopausal women, aromatase inhibitors such as anastrozole are used for this purpose*. This is important as aromatisation accounts for the majority of oestrogen production in post-menopausal women and therefore anastrozole is used for ER +ve breast cancer in this group.

Important side-effects of tamoxifen include an increased risk of endometrial cancer, venous thromboembolism and menopausal symptoms.

Biological therapy

The most common type of biological therapy used for breast cancer is trastuzumab (Herceptin). It is only useful in the 20-25% of tumours that are HER2 positive.

Trastuzumab cannot be used in patients with a history of heart disorders.

Chemotherapy

Cytotoxic therapy may be used to either downstage a primary lesion or after surgery depending on the stage of the tumour, for example if there is axillary node disease.

Screening and prevention

The NHS Breast Screening Programme is being expanded to include women aged 47-73 years from the previous parameter of 50-70 years. Women are offered a mammogram every 3 years. After the age of 70 years women may still have mammograms but are 'encouraged to make their own appointments'.

The effectiveness of breast screening is regularly debated although it is currently thought that the NHS Breast Screening Programme may save around 1,400 lives per year.

Familial breast cancer

NICE published guidelines on the management of familial breast cancer in 2013, giving guidelines on who needs referral.

If the person concerned only has one first-degree or second-degree relative diagnosed with breast cancer they do NOT need to be referred unless any of the following are present in the family history:
  • Age of diagnosis < 40 years
  • Bilateral breast cancer
  • Male breast cancer
  • Ovarian cancer
  • Jewish ancestry
  • Sarcoma in a relative younger than age 45 years
  • Glioma or childhood adrenal cortical carcinomas
  • Complicated patterns of multiple cancers at a young age
  • Paternal history of breast cancer (two or more relatives on the father's side of the family)

Women who are at an increased risk of breast cancer due to their family history may be offered screening from a younger age. The following patients should be referred to the breast clinic for further assessment:
  • One first-degree female relative diagnosed with breast cancer at younger than age 40 years, or
  • One first-degree male relative diagnosed with breast cancer at any age, or
  • One first-degree relative with bilateral breast cancer where the first primary was diagnosed at younger than age 50 years, or
  • Two first-degree relatives, or one first-degree and one second-degree relative, diagnosed with breast cancer at any age, or
  • One first-degree or second-degree relative diagnosed with breast cancer at any age and one first-degree or second-degree relative diagnosed with ovarian cancer at any age (one of these should be a first-degree relative), or
  • Three first-degree or second-degree relatives diagnosed with breast cancer at any age