Improved survival of patients with primary distant metastatic breast cancer in the period of 1995-2008. A nationwide population-based study in the Netherlands.

In this study, changes in prognosis for more than 8,000 patients with primary distant metastatic breast cancer were analyzed, using nation-wide data of the Netherlands Cancer Registry. Besides the roll of systemic treatment, the effect of surgery of the primary tumor was evaluated. Between 1995 and 2008, 160,595 new patients were diagnosed with invasive breast cancer. Of these patients, 8,031 (5.0%) had distant metastases at diagnosis. Patients were divided into three periods, based on the year of diagnosis of their disease. The median survival was 1.42 years for patients diagnosed in the period 1995-1999, 1.61 years in the period 2000-2004 and 1.95 years in the period 2005-2008. The improvement of the median survival was most pronounced for patients younger than 50 years. Patients receiving systemic treatment, loco-regional radiotherapy or breast surgery had a significantly lower risk of death compared to patients not receiving these treatments. An improvement of 6 months is observed in the median survival of patients with primary distant metastatic breast cancer between 1995 and 2008. The increased efficacy of chemotherapy and the introduction of targeted treatments are the most likely explanations for this improvement, which was most marked for younger patients.