Written by epgonline.org - Last updated 29 May 2018
Breast cancer is the second most commonly diagnosed cancer worldwide, behind only lung cancers; this is even more remarkable when its relative rarity in males is noted (males account for less than 1% of all breast cancers). The most recent figures from the WHO are for 2012, when approximately 1.68 million new cases were diagnosed. This equates to 43.1 cases per 100,000 women, regardless of age, every year. The peak diagnosis is in women between 60 and 65 years old, and the majority of all cases occur after the age of 50. There has been an increase in global incidence over the last 20 years, attributed to changes in reproductive risk, increase in screening programmes, and the proliferation of hormone replacement therapy (HRT) for menopause symptoms. In western countries, this rise has plateaued somewhat since the withdrawal of routine HRT.
The disease process is highly heterogeneous, both histologically and clinically. Traditionally, subtypes were based around the cell line from which the cancer was derived, while more recent classifications have instead focussed on receptors expressed or molecular subtypes. Oestrogen is often a driving factor in the pathogenesis of breast cancer, and the oestrogen pathway has become a major therapeutic target.
Symptomatically the most common presenting complaint is a breast lump, yet other symptoms, including skin changes, nipple changes (including inversion or discharge), pain and axillary masses may prompt a patient to seek advice.
A triple assessment is usually the standard model, comprising clinical examination, imaging (typically ultrasound or mammogram) and a tissue sample (either fine needle aspiration, or core biopsy). Screening has led to a consistent 20% reduction in breast cancer mortality following its introduction; the first European country to initiate a programme was Austria in 1974, and screening has since been implemented much more widely.
Historically, effective treatment for breast cancer was exclusively surgical; it is believed the first recorded mastectomies were carried out in the 6th century CE, while the late 1800s brought radical mastectomies – remaining a mainstay of treatment for much of the next century. In more recent years, breast-conserving surgery and a range of other treatments such radio-, immuno- and chemotherapy, as well as hormonal suppression, have revolutionised treatment and functional outcomes for patients.