The proportion of patients with early stage breast cancer who had sentinel lymph node biopsy increased from approximately 9% in 1998 to more than 70% in 2003.14 Recently, Mittendorf et al published data indicating that in patients with small breast cancers lymph node micro metastases are not of any prognostic value.12 An explanation might be the increasing effectiveness of systemic therapy.In more recent years, (neo )adjuvant systemic treatment for breast cancer has improved considerably and is applied more often. Improvements include the use of trastuzumab, which significantly increases both short term and long term prognosis in HER2 positive breast cancer patients.15 16 Trastuzumab treatment was implemented in the Netherlands between 2005 and 2006.17 18 Moreover pandora necklaces, a switch to more effective chemotherapy regimens has occurred. CMF (cyclophosphamide https://www.pandorajewellrycanada.ca, methotrexate, 5 fluorouracil) was prescribed to 90% of breast cancer patients receiving chemotherapy in 2000 and to almost none in 2005.19 It was gradually replaced by the more effective anthracyclines (4% use in 2000 to 96% in 2005), which in turn were partly replaced by regimens containing taxane.19Data published on the effect of screening and better treatment options on survival were based on cohorts of patients with breast cancer diagnosed in 2004 at the latest, and changes to more recent systemic therapy had not yet occurred.
We assembled secondary prevention cohorts, which included patients who were admitted to a hospital between 1 January 1998 (or one year after the beginning of data availability) and 31 March 2011, who received a coded diagnosis (principal or secondary) for acute myocardial infarction or stroke or a procedure for coronary artery bypass graft or percutaneous coronary intervention during their stay in hospital, who had no record of a diabetes diagnosis during their hospitalisation, and who then received a statin prescription within 90 days after being discharged, having not been prescribed a cholesterol lowering drug in the previous year (World Health Organization Anatomical Therapeutic Class C10, cerivastatin excluded). Patients were required to have a length of stay in hospital for their cohort defining event or procedure of at least three days and no greater than 30 days. Diagnostic codes for myocardial infarction and stroke and procedural codes for coronary artery bypass graft and percutaneous coronary intervention are listed in the data supplement appendix.Patients’ cohort entry dates were defined as the date of the first statin prescription after discharge from hospital.