Breast cancer is the most common cancer in women

Breast cancer is the most common cancer in women, both worldwide and in Europe, where there are an estimated 320,000 new cases every year. It is also the most common cause of death from cancer in women in all but three of the EU-27 countries. It is very rare in men.

Incidence and mortality vary twofold across the EU

Breast cancer incidence and mortality were on the increase for decades until the 1980s, when mass screening began to be introduced. After that, the incidence rates continued to rise, boosted by early detection, but some slow-down has recently been observed in a few countries. Mortality rates are now falling or stable in most European countries.

Prognosis is highly dependent on stage at diagnosis

Treatment is very effective for cancers diagnosed at an early stage. The 5-year survival rate among cases detected when the tumour is less than 2 cm in size and only a few lymph nodes are involved can be as high as 85%. Prognosis and survival are less favourable the greater the size of the tumour and the deeper the involvement of other tissues.

On average 5-year relative survival of European breast cancer patients diagnosed in 1995-1999 was 79.5% and ranged from 69.3% in the Czech Republic to 84.3% in Sweden.

Causes and risk factors are poorly understood

Breast cancer has a complex aetiology which is still poorly understood. Full-term pregnancies reduce the risk of breast cancer as well as an early age at first delivery. Breastfeeding entails an additional benefit for women who have given birth one or more times. Regular alcohol consumption and excess body weight after menopause increase the risk of breast cancer, as does the use of exogenous hormones to alleviate menopausal symptoms.

Two genes have been identified that predispose to breast cancer. Carriers of mutations in the BRCA1 and BRCA2 genes have a 10-fold increased risk of developing breast cancer in their life-span. However, since this is a rare genetic condition, only a small proportion of all cases are related to it.

Mortality rates can be greatly reduced by early diagnosis combined with good treatment

Limiting the consumption of alcohol, maintaining a normal body weight (BMI ≤ 25), breastfeeding babies and refraining from taking exogenous hormones are all good practices that reduce one’s probability of developing breast cancer. Nevertheless such measures offer no guarantee for avoiding the disease.

Screening by mammography in women above 50 years of age, combined with optimal treatment substantially improves prognosis and can reduce mortality at the population level.