Epidemiology
Breast cancer is the most frequent cancer in women after non-melanotic skin tumours (32% of female cancers) and is the commonest cause of death in women aged 35–54 years in England. It follows an unpredictable course with metastases presenting up to 20 years after initial diagnosis. England has one of the highest age-standardised incidences and mortality from breast cancer in the world, with a lifetime risk of breast cancer of 1 in 9. Earlier detection by screening and improved treatment are improving the 5-year survival.
Aetiology and pathophysiology
Both genetic and hormonal factors play a role in the aetiology of breast cancer. Hereditary predisposition is implicated in around 10% of breast cancer cases, including BRCA1 and BRCA2 hereditary breast cancer, and Li–Fraumeni syndrome. Prolonged exposure to oestrogen is thought to play a role and early menarche, late menopause, late first pregnancy (over 35 years old) and nulliparity are established risk factors.
The combined oral contraceptive pill does not significantly increase the relative risk for breast cancer (see Chapter 3), but hormone replacement therapy (HRT) has been shown to increase the incidence of breast cancer in long-term current users (relative risk 1.66).
Invasive ductal carcinoma with or without ductal carcinoma in situ (DCIS) is the commonest histology, accounting for 70% of cases, while invasive lobular carcinoma accounts for most of the remaining cases. DCIS constitutes 20% of screening-detected breast cancers, is multifocal in one-third of women and has a high risk of becoming invasive (10% at 5 years following excision only). Pure DCIS does not cause lymph node metastases, although these are found in 2% of cases where nodes are examined, owing to undetected invasive cancer. Lobular carcinoma in situ (LCIS) is a predisposing risk factor for developing cancer in either breast (7% at 10 years).
Clinical presentation
Related posts:
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
