Natural history and prognostic factors in localized prostate cancer

Abstract: The natural history of localized prostate cancer is not fully understood. In most patients the tumor will never progress to a lethal disease, while a subset of patients will ultimately die of the disease. Efficient tools to separate indolent from lethal disease is currently lacking which means that many patients will be offered treatment without any benefit, but still be at risk of experiencing treatment related side effects.The aims of these studies were to get more insight into the natural history of untreated localized prostate cancer, to assess the prognostic value of established clinical parameters such as Gleason score, nuclear grade and tumor volume and, moreover, some new prognostic markers Ki-67, AMACR and MUC-1. We also aimed to study time trends in the detection of incidental tumors in Sweden.Patients with localized disease (n=223) and no initial treatment were followed for 21 years. Most patients had a favorable outcome. However, a subset of patients developed lethal disease even beyond 15 years of follow-up and these patients define the group that may benefit most from treatment with curative intent. Patients with poorly differentiated tumors experienced a 9 time higher risk of dying in prostate cancer.The studies on prognostic markers are based on a cohort of patients (n=253) with incidental prostate cancer detected by transurethral resection for presumed benign hyperplasia. All patients were left without initial treatment. Gleason grade, nuclear grade and tumor volume turned all out to be independent prognostic factors. MUC-1, AMACR and Ki-67 also carried prognostic information. However, after adjustment for Gleason grade, nuclear grade and tumor volume only MUC-1 and AMACR remained as statistically significant prognostic factors. When tested for sensitivity and specificity they all failed and, consequently, they seem to be of less value in daily practice for cancelling an individual patient regarding the choice of treatment.Time trends in incidental prostate tumors in Sweden were analyzed in a cohort of patients with prostate tumors detected by transurethral resection (TUR-P). Through linkage of the national registration number (NRN) with several registers, e.g. the Swedish Cancer Registry, the National Inpatient registry and the Cause of Death Registry we identified, during the period 1970 through 2003, in total 23288 patients with incidental prostate cancer, who constituted the study group. As comparison group we choose all patients diagnosed with prostate cancer between 1970-2003 excluding those with incidental cancer, in total 112204 patients. Our result confirms earlier findings that there has been a dramatic change over time in incidence of incidental prostate cancers in Sweden, which parallels the introduction of prostate specific antigen. We also found that the cumulative incidence of prostate cancer death is high in the incidental group, opposing earlier findings that incidental tumours are a non-lethal disease.