Breast cancer

• Breast cancer is the most common female malignancy and accounts for approximately 30% of all new cancer cases among women. Women have a one in nine lifetime-risk of developing breast cancer.
  
  
  • the incidence of breast cancer increases with age, doubling every 10 years until menopause, after which the rate of increase slows down
    
  • breast cancer is the most common cancer in the UK, with approximately 54,000 new cases of invasive disease and around 7,000 new cases of pre-invasive (in situ) disease diagnosed annually
    
  • most of the breast cancers occur in women, but just over 300 men in the UK are also diagnosed with invasive breast cancer every year. Most breast cancers are diagnosed at an early stage and are therefore potentially curable with modern treatments
    
    
  • survival rates have improved over recent decades with almost 90% of women diagnosed with breast cancer surviving their disease for 5 or more years after diagnosis. Survival is, however, linked to the stage of the disease at diagnosis; only 15% of women diagnosed with stage IV disease are alive at 5 years
    • breast cancer remains the leading cause of death in women aged 35-49 years, and is second only to lung cancer as the leading cause of cancer death in all women.
      
      
• metastatic breast cancer is an advanced stage of the disease when it has spread to other organs
  • an estimated 5% of patients present with metastatic breast cancer, and approximately 30% of people who present with localised breast cancer will later develop metastatic breast cancer
  • common sites of metastasis include bone, liver, lung and brain.

Risk factors:

• main risk factor for breast cancer is being female; the disease is 100 times less common in men
  
  
• a disease of ageing, with the risk of breast cancer increasing with increasing age
  
  
• some breast cancers are linked to lifestyle factors that include obesity, alcohol intake and use of hormone replacement therapy, whereas other lifestyle factors, including physical activity and breastfeeding, protect against breast cancer
  
  
• about 5% of breast cancers are because of inherited mutations in high-risk genes such as BRCA1/2 and p53.

Taylor et al note:

• since the 1990s, the five year risk of death from breast cancer has decreased from 14.4% to 4.9% overall, with reductions seen in nearly all patient group

Evidence has found women diagnosed since 2000 have about a fifth lower rate of distant recurrence than the 1990s, with most of the improvement explained by a greater proportion of women with lower-risk disease entering trials and improved adjuvant treatment (6).

Reference:

1. Siegel RL, Giaquinto AN, Jemal A. Cancer statistics, 2024. CA Cancer J Clin. 2024 Jan-Feb;74(1):12-49.
2. Breast cancer statistics. Cancer research UK. 2024 online publication.
3. NICE (June 2012). Lapatinib or trastuzumab in combination with an aromatase inhibitor for the first-line treatment of metastatic hormonereceptor- positive breast cancer that overexpresses HER2
4. NICE (June 2023). Early and locally advanced breast cancer: diagnosis and management
5. Taylor C, McGale P, Probert J, Broggio J, Charman J, Darby S C et al. Breast cancer mortality in 500,000 women with early invasive breast cancer in England, 1993-2015: population based observational cohort study BMJ 2023; 381:e074684 doi:10.1136/bmj-2022-074684
6. Early Breast Cancer Trialists' Collaborative Group. Reductions in recurrence in women with early breast cancer entering clinical trials between 1990 and 2009: a pooled analysis of 155 746 women in 151 trials. Lancet October 12th 2024.