[Chronic diseases and neoplasms, a view from complex sciences and primary care]

80% of adults older than 65 years have at least one chronic, degenerative or neoplasm disease (CDND). The health care cost is high, and they represent the main causes that affect the quality of life. From the scope of the complexity sciences, the CDND are common problems of health but their study and solutions are complex and difficult. One strategy for preventing and treating them is to identify "the weak corner," the causal factors or the ordering parameter as the relevant point of intervention. The evidence shows that 80% of the CDND could be prevented with primary care actions like immunizations and lifestyle changes.