Introduction

Recent studies suggested an inverse stage migration towards more aggressive pathological characteristics in high-risk prostate cancer. We evaluated whether patients with metastatic prostate cancer (mPCa) experienced changes in clinical patterns and oncological outcomes in the most recent years.

Methods

Within the Surveillance, Epidemiology and End Results (SEER) database, we identified 12,681 patients diagnosed with mPCa between 2004 and 2013. Only patients with complete clinical data were considered. After stratification according to the year of diagnosis, lowess smoother weighted functions were used to plot the prevalence of each metastatic stage, according to the sixth edition of American Joint Committee on Cancer [AJCC] Cancer Staging Manual (M1a, M1b, M1c), according to local T stage (T1, T2, T3+) and according to biopsy Gleason score (≤6, 7, ≥8). Similarly, overall mortality rates at 2-year were evaluated for patients diagnosed between 2004 and 2011. Temporal trends were quantified using the annual percentage change (APC) with the least squares linear regression.

Results

Overall, 700 (5.7%) M1a, 9,192 (74.8%) M1b and 2,399 (19.5%) M1c patients were identified. The prevalence of M1c stage significantly decreased from 21.7% in 2004 to 15.6% in 2013 (APC: 5.46%: 95% CI: 3.21-7.82; p<0.01). Local T staging significantly changed over the study period. Specifically, an increasing rate has been observed of individuals with local T1 disease, ranging from 22.8% in 2004 to 36.1% in 2013 (APC: 4.72%; 95% CI: 3.41-6.07; p<0.001). The proportion of patients with T2 disease decreased from 48.7% in 2004 to 36.1% in 2013 (APC: -3.09%; 95% CI: 2.25-3.94; p<0.001). No statistically significant variation has been observed for T3+ stage (p=0.1). Similarly, a decrease in the proportion of patients with gleason score of ≤6 or 7 was observed (both p<0.001). This was accompanied by a significant increase in the proportion of patients with gleason score of 8 or higher, which increased from 67.2% in 2004 to 84.4% in 2013 (APC: 2.54%; 95% CI: 2.14-2.94; p<0.001). The 2-year mortality rates after diagnosis decreased from 43.7% in 2004 to 39.0% in 2011 (APC: 1.89%; 95% CI: 1.33-2.45; p<0.001).

Conclusions

The stage migration phenomenon that has been described in surgically-treated PCa holds valid also in the metastatic setting. This results in a higher proportion of high-grade cancer when diagnosed at metastatic stage. However, early detection efforts resulted in a decreasing rate of patients with visceral metastases (stage M1c) and decreasing 2-year mortality rates.

Funding

none