Risk assessment among prostate cancer patients receiving primary androgen deprivation therapy

Abstract

Purpose: Prostate cancer epidemiology has been marked overall by a downward risk migration over time. However, in some populations, both in the United States and abroad, many men are still diagnosed with high-risk and/or advanced disease. Primary androgen deprivation therapy (PADT) is frequently offered to these patients, and disease risk prediction is not well-established in this context. We compared risk features between large disease registries from the United States and Japan, and aimed to build and validate a risk prediction model applicable to PADT patients.

Methods: Data were analyzed from 13,740 men in the United States community-based Cancer of the Prostate Strategic Urologic Research Endeavor (CaPSURE) registry and 19,265 men in the Japan Study Group of Prostate Cancer (J-CaP) database, a national Japanese registry of men receiving androgen deprivation therapy. Risk distribution was compared between the two datasets using three well-described multivariable instruments. A novel instrument (Japan Cancer of the Prostate Risk Assessment [J-CAPRA]) was designed and validated to be specifically applicable to PADT patients, and more relevant to high-risk patients than existing instruments.

Results: J-CaP patients are more likely than CaPSURE patients to be diagnosed with high-risk features; 43% of J-CaP versus 5% of CaPSURE patients had locally advanced or metastatic disease that could not be stratified with the standard risk assessment tools. J-CAPRA--scored 0 to 12 based on Gleason score, prostate-specific antigen level, and clinical stage--predicts progression-free survival among PADT patients in J-CaP with a c-index of 0.71, and cancer-specific survival among PADT patients in CaPSURE with a c-index of 0.84.

Conclusion: The novel J-CAPRA is the first risk instrument developed and validated for patients undergoing PADT. It is applicable to those with both localized and advanced disease, and performs well in diverse populations.

Conflict of interest statement

Authors' disclosures of potential conflicts of interest and author contributions are found at the end of this article.

Figures

Fig 1.

Association of risk and age. Distribution of D'Amico risk groups (modified for 1997 TNM staging) by patient age group is presented for all Cancer of the Prostate Strategic Urologic Research Endeavor (CaPSURE) patients, CaPSURE patients receiving primary androgen deprivation therapy (CaPSURE PADT), and J-CaP patients. Advanced denotes patients with clinical stage higher than T3aN0M0, for whom the D'Amico risk classification does not apply.

Fig 2.

Progression-free survival in J-CaP by J-CAPRA score. Kaplan-Meier survival curves are presented for clinical progression-free survival among (A) J-CaP patients stratified by individual Japan Cancer of the Prostate Risk Assessment (J-CAPRA) scores, and by scores (B) grouped to yield low, intermediate, and high risk strata.

Fig A1.

Cancer-specific survival in the Cancer of the Prostate Strategic Urologic Research Endeavor (CaPSURE) and by Japan Cancer of the Prostate Risk Assessment (J-CAPRA) score. Kaplan-Meier curves are presented for cancer-specific survival among (A) CaPSURE patients stratified by individual J-CAPRA scores, and (B) by scores grouped to yield low, intermediate, and high risk strata.