Overview of the topic.

This comment is found in a German report covering what were probably the first documented cases of second primary cancer (SPC) [1]. In the intervening 120 years, the research focus on this important area of oncology and epidemiology has been established and gradually intensified. Recently, investigation of prevention options has begun to dominate the agenda. It is well known that cancer survivors are at risk for recurrence of the primary cancer. The chance of getting a so-called SPC is also increased. Simply put, a SPC is a new primary cancer developing in a person with a history of cancer. Interest in SPCs has paralleled the extraordinary improvement in curing primary cancers, which in turn has increased both the longevity and the absolute number of survivors. The concomitant reduction in mortality rates attached to (in particular) cardiovascular disease has augmented the general increase in longevity. Accordingly, the cumulative incidence of SPC has grown, essentially driven by patients surviving long enough for other cancers to develop. It is accurate to say that the SPC story has expanded as a by-product of increasing health awareness, early diagnosis of primary cancers and therapeutic success. The outcome of these forces is that SPCs are now more common; indeed, as a class they are estimated to be the sixth most common form of malignancy in the world [2]. Consequently, research on such cancers has intensified. The last comprehensive textbook on the area covered data up to about 1997 [3]. It appears that the volume of publishing since that point has already matched the academic output in all the previous decades combined. There are 3 imperatives that have prompted the continuing wave of research and analysis. First, there is a need to completely understand the epidemiology of SPC. This