Relative survival of patients with prostate cancer as a first or subsequent tumor--a Nordic collaborative study

To present a new model for estimating relative survival of patients with two primary cancers, to study whether survival from cancer is similar between a first and subsequent tumor, and to provide an illustration of prognoses for patients with cancer as a subsequent tumor.

Data on Danish, Finnish, and Norwegian patients with a first and subsequent prostate cancer, after a first primary colorectal cancer, were analyzed with a new model.

Survival from first and subsequent prostate cancer was similar within each country. Survival from subsequent prostate cancer was not affected by the time interval between the first colorectal and subsequent prostate cancer.

The survival from subsequent cancer should be adjusted for the underlying first primary cancer. The overall relative survival of patients with two primary cancers will be worse than those with a respective single cancer only. However, with a proper adjustment the subsequent cancer itself is not more fatal than a similar cancer as the only tumor of the patient.