The Value of Early PET/CT in Patients With Metastasising Cancer of Unknown Primary

Background:

Every year, 800-1000 patients in Denmark are classified with a diagnosis of metastasising cancer of unknown primary (CUP). This corresponds to approximately 3 % percent of all new cancer cases on a national scale. The number is probably higher, since this is a heterogeneous group of patients that is not registered consistently. The prognosis is poor; the average survival is only approximately one year.

CUP is characterized by the finding of a metastasis the starting point of which (the primary tumour) is unknown. Typically, one finds an enlarged lymph node in the neck, a swelling in the throat or in the stomach, a filling in the skin or a tumour detected somewhere in the body during an X-Ray examination, an endoscopy or the like. In spite of a search applying multiple techniques, the primary tumour remains unknown in 70-80% of the patients.

A great number of patients experience a long and discontinuous examination sequence marked by various contacts with doctors, many examinations dispersed over many days and locations, as well as a lot of time wasted, because there exists no single option or institution that takes care of the patient and handles diagnostic procedures and treatment efficiently.

Treatment is often initiated too late, typically as a combination of several chemotherapeutics in order to cover different types of cancer simultaneously, but modern chemotherapeutical regimes have not increased the survival rate. The bad prognosis is undoubtedly due to the fact that the patients are diagnosed in an advanced phase. Alternatively, the primary tumour is not detected at all. This, in part, is due to the absence of any single agency in possession of the competence and responsibility to implement the work-up without delay, and maybe because one does not offer examination by the modality (PET/CT) which is most likely to detect the presence of cancer, its starting point and dispersion in an early stage.