Once prostate cancer metastasizes, a person’s chances of survival diminish. But in an extensive analysis, Duke University Medical Center researchers found that the location of the cancer’s spread has a large impact on survival — a finding that could guide future treatment approaches.

“Smaller studies had given doctors and patients indications that the site of metastasis in prostate cancer affects survival, but prevalence rates in organ sites were small, so it was difficult to provide good guidance,” Susan Halabi, professor of biostatistics at Duke and lead study author, said in a press release.

The study, titled “Meta-Analysis Evaluating the Impact of Site of Metastasis on Overall Survival in Men With Castration-Resistant Prostate Cancer” and published online in the Journal of Clinical Oncology, is the largest of its kind. The research team analyzed previously published data from of 8,736 patients treated at cancer centers worldwide as part of nine large Phase 3 clinical trials of metastatic prostate cancer.

All men had received standard chemotherapy with the drug docetaxel, excluding the possibility that the survival times were influenced by different treatments. For the analysis, researchers divided metastases into four groups: lung, liver, lymph nodes only, and bone with or without lymph nodes.

While lymph metastases affected only 6.4 percent of study patients, they were associated with the longest survival, a median time of 32 months. In contrast, men with liver metastases, 8.6 percent of those studied, had the shortest survival time at around 14 months.

Patients with cancer spreading to the lungs did a little better, with a median survival time of 19 months, while the largest group — bone metastases, affecting 73 percent of patients — survived for about 21 months.

“With the large numbers we analyzed in our study, we were able to compare all of these different sites and provide information that could be helpful in conveying prognosis to patients,” Dr. Halabi said. “This information could also be used to help guide treatment approaches using either hormonal therapy or chemotherapy … [and] clinical decision-making for men with advanced prostate cancer.”

She added, “[t]hey also suggest that prognostic subgroups should be considered for investigational therapies that are tested in clinical trials.”