Breast Cancer Statistics
Breast cancer is the most common cancer affecting women in the UK and one in nine women will have this disease at some point in their lives (NHS Direct, 2007). Women in the US now have an astonishing one in eight lifetime chance of developing breast cancer (American Cancer Society, 2007). There are over 40,000 new cases in the UK every year, representing a third of all cancers in women. Between 1971 and 2003, the incidence rates of breast cancer have increased by 80 per cent (National Statistics, 2005). In the UK in 2005 there were 12,509 deaths from breast cancer (99 per cent in women, one per cent in men). Breast cancer accounts for 17 per cent of female deaths from cancer in the UK (Cancer Research UK, 2007).
Figure 2.0 shows that while the incidence of breast cancer has risen sharply, mortality from breast cancer has remained fairly constant over the same period thanks largely to improved diagnostic methods and more efficient treatment. For women in the UK, there are similar numbers of deaths from lung and breast cancer. Deaths Figure 2.0 Incidence of, and mortality from, breast cancer in from breast, lung and large bowel cancer together England and Wales between 1971 and 2003. Source: National account for nearly half (45 per cent) of all female Statistics, 2005. deaths from cancer (Cancer Research UK, 2005).
Male breast cancer
Although less prevalent, breast cancer does occur in men too; one in 300 men in the UK will have breast cancer at some point in their lives (NHS Direct, 2007). Furthermore, the incidence of breast cancer among men is increasing. One large-scale study of more than 2,500 American men with the disease showed that between 1973 and 1998 the incidence of breast cancer among men increased by 26 per cent (Giordano et al., 2004). This study found that men tended to have larger tumours which had spread further by the time they sought help. That said, breast cancer remains a rare disease among men. Lung, prostate, bowel, oesophageal and stomach cancer are the five biggest causes of cancer death among men in the UK (Cancer Research UK, 2003).
Breast cancer around the world
Disease incidence rates measure the number of new diagnoses per 100,000 people during a defined time period (usually a given year). Age standardisation, often referred to as 'age-adjustment', is used to eliminate the confounding effects of differences in the age composition of different populations. This allows us to make statistical comparisons of incidence rates between different populations.
The age-adjusted incidence rates for breast cancer per 100,000 women differ markedly from one country to another. For example, Uruguay has a very high rate at 114.9, followed by 92.1 in the US and 87.1 in Israel. Much lower rates are seen in Korea at just 12.7, 20.0 in Mali and 16.1 in Thailand (Ganmaa and Sato, 2005). In response to this discrepancy, an increasing amount of attention is now focusing on the links between diet and breast cancer, particularly the relationship between the consumption of animal-based foods (meat and milk) and breast cancer.
Studying cancer incidence among particular groups of people can provide useful insights into the causes of disease. Researchers from the London School of Hygiene and Tropical Medicine recently reported breast cancer incidence is substantially lower, and survival rates higher, in South Asians living in the UK than other women (Farooq and Coleman, 2005). The authors of this study suggested that differences in diet and lifestyle could explain the different rates observed.
Earlier research published in the British Journal of Cancer also showed that South Asian women living in the UK are less likely to be diagnosed with breast cancer than other women, but found that the risk varied according to their specific ethnic subgroup. This research showed that Muslim women from India and Pakistan are almost twice as likely to develop breast cancer as Gujarati Hindu women. This study examined the diet and found that the Gujarati Hindu women were more likely to be vegetarian and therefore had more fibre in their diet due to their higher intake of fruit and vegetables (McCormack et al., 2004). There are several mechanisms by which the diet might influence breast cancer risk. One possible mechanism is through an effect on hormones: increasing the amount of fibre in the diet may reduce breast cancer risk by altering the levels of female hormones (oestrogens) circulating in the blood (Gerber, 1998).
Oestrogen sensitive cancers
Oestrogen receptor-positive cancer (also called oestrogen-sensitive cancer) is when there are specific proteins on the cancer cell's surface that respond to the hormone oestrogen by causing the cell to grow. Oestrogen receptor-positive cancer makes up around 75 per cent of breast cancers in postmenopausal women and around 50 to 60 per cent in premenopausal women (Breast Cancer Care, 2007). Determining whether a breast cancer tumour is positive for oestrogen receptors can help to guide treatment and determine prognosis.
Current national guidelines recommend that women who have oestrogen receptor-positive breast cancer should usually be offered hormone therapy and women with oestrogen receptor-negative breast cancer should be offered chemotherapy (Cancer Research UK, 2002).