[Margins in oncology surgery]

The author describes, within the important frequency of the cancer in current population, the fact that the surgery continues being the first step of therapeutic action in most cases. Furthermore, he describes how these surgeries have changed from the former big exeresis with amputations and alterations of the corporal silhouette to more effective conservative surgeries of the organ without producing the harmful effects of the previous ones. These conservative surgeries entail the extirpation of the tumor keeping some margins, which should be understood as the distance between the tumor and the end of the piece found. The procedures which are currently used to achieve some acceptable negative margins in the different parts of the organism and specially in breasts are listed below.