The baseline presence of visceral disease was a negative prognostic factor in men with castration-resistant prostate cancer (CRPC), and the site of metastasis impacted survival: Overall survival (OS) was worse with liver metastasis than lung metastasis, which, in turn, was worse than bone metastasis with or without lymph node (LN) involvement.
Median OS for men with metastasis in the liver was 13.5 months (95% confidence interval, 12.7-14.4); in the lung, 19.4 months (17.8-20.7); and in the bone, 21.3 months (20.8-21.9). Men with liver vs. lung metastasis had a significantly increased risk of death, with a pooled multivariable hazard ratio of 1.52 (95% CI, 1.35-1.73; P = .0001). Men with lung vs. bone metastasis had a significantly increased risk of death, with a pooled multivariable HR of 1.14 (95% CI, 1.04-1.25; P = .007), investigators reported online in the Journal of Clinical Oncology.
The authors observed little variability in OS across trials for each metastatic site, and suggested that differences observed in median OS from trial to trial could be explained by the relative proportion of metastatic subsets in each trial.
“The heterogeneity of men with (metastatic) CRPC enrolled into trials and the substantially different outcomes among these subgroups highlight the importance of reporting OS by disease location,” wrote Dr. Susan Halabi of Duke University Medical Center and colleagues. They added, “These data suggest that the distribution of patients across the following categories should be routinely reported: LN-only disease, bone with or without LN involvement with no visceral metastases, any lung metastases (but no liver), and any liver metastases.” (J Clin Oncol. 2016 Mar 7. doi: 10.1200/JCO.2015.65.7270 ).
The meta-analysis evaluated nine randomized, controlled, phase III trials published from 2004 to 2015, including 8,736 men with metastatic CRPC who received docetaxel with or without an experimental agent. The median age of patients was 68 years. The median follow-up time was 21.8 months (range, 0-91.2 months), and there were 5,470 deaths.
Most patients had bone metastasis (6,356; 72.8%); visceral disease was observed in 1,815 patients (20.8%); and LN-only disease was present in 565 patients (6.4%). Of those with visceral disease, 791 (9.1%) had lung metastasis and 752 (8.6%) had liver metastasis (173 had both lung and liver metastases and were included in the liver category).
The authors noted as a limitation of the study that abiraterone acetate or enzalutamide, now generally administered before chemotherapy, was not used in most of the studies evaluated.