Improved systemic treatment for early breast cancer improves cure rates, modifies metastatic pattern and shortens post-metastatic survival: 35-year results from the Munich Cancer Registry.
Systemic therapies (ATHs) in early breast cancer have improved the survival of breast cancer (BC) patients in recent decades. The magnitude of the changes in overall, metastasis-free (MFS) and post-metastatic (PMS) survival and in the metastasis (MET) pattern will be described.We analysed 60,227 patients with a diagnosis of T-N-M0 BC between 1978 and 2013 and 11,983 patients with metastases (MET) in the Munich Cancer Registry. Patients will be divided into four time periods to identify relationships between BC and METs. Survival was estimated using Kaplan-Meier curves, and Cox proportional hazards models were used to explore the impact of the BC subtype and MET status on survival with the time periods as surrogate markers for ATH evolution.During the observation period, 5-year relative survival has improved from 80.3 to 93.6% with an adjusted hazard ratio of 0.54 (P < 0.0001). Successful implementation of ATH has changed the MET pattern. The percentage of liver and CNS METs has more than doubled, the rate of lung METs remains stable, and the rate of bone METs has been reduced by approximately 50%. MFS has been prolonged with a hazard ratio 0.75 (P < 0.0001), but PMS has declined (hazard ratio 1.36; P < 0.0001); however, effects of adjuvant and palliative treatments cannot be separated. These results do not contradict improvements in advanced BC and do not suggest alterations of MET tumour biology by ATH.Over the past three decades, ATHs have dramatically improved patient survival after BC diagnosis-most likely, by eradicating prevalent micro-METs; as a result, the MET pattern has changed. Eradicating only a portion of the first METs results in delaying the onset of subsequent MET, which leads to an apparently paradoxical effect: an extension of the MET-free interval and a reduction in PMS.