Over a century ago, the systematic evaluation of medical treatment outcomes was first described by Ernest Codman. At that time a too progressive thought, while the value of measuring the quality of... Show moreOver a century ago, the systematic evaluation of medical treatment outcomes was first described by Ernest Codman. At that time a too progressive thought, while the value of measuring the quality of care is seen nowadays.The NABON Breast Cancer Audit (NBCA) provides insight into the various care processes that are part of the complex multidisciplinary treatment of patients diagnosed with breast cancer. Results of the NBCA show a good and still improving quality of care for patients diagnosed with breast cancer. In addition, this thesis provides insight into a sub-area where variation between hospitals is found; the performance of an immediate breast reconstruction in patients undergoing mastectomy. Many factors influence this hospital variation, such as patient and tumour factors, hospital factors and differences in indications for immediate breast reconstruction between surgeons and plastic surgeons. Physicians should inform patients about the various breast cancer treatment options. Informing a patient about immediate breast reconstruction results in a 14 times higher chance of actually undergoing a breast reconstruction after mastectomy.These factors should to be evaluated and improved as quality of life is higher for patients with immediate breast reconstruction than with mastectomy alone. By continuously measuring, providing feedback and acting on the data found at both a national level and in the consultation room, Ernest Codman's heritage will certainly be realized. Show less