Linking the number of metastases to outlook in prostate cancer

This study attempted to examine the contribution of different components of prostate cancer on the outlook of patients diagnosed with metastatic disease despite treatment.

In some cases of prostate cancer, the primary treatment does not cure the disease, and metastases (cancer lesions in other body parts) can be discovered. In other cancer types it has been demonstrated that the number of metastases is an important prognostic factor (indicative of the outlook of the disease), but this has been less clearly studied in prostate cancer.

The authors evaluated the association between the number of metastases and outlook in prostate cancer patients with metastatic disease despite previous treatment.

The medical records of 80 non-castrated patients (testosterone levels >50 ng/dl) were analyzed. All patients were diagnosed with metastases after receiving primary treatment, which did not involve androgen deprivation therapy (intended to reduce the production of male sex hormones such as testosterone, or inhibit their effect on cancer cell growth). The main sites of metastasis were the lymph nodes (48%), bone (39%) and viscera (organs in the chest and abdomen; 1%). Treatment following metastatic diagnosis included active surveillance (close observation of cancer rather than immediate treatment), androgen deprivation therapy or treatment directed at the metastatic tumors.

The analysis shows that the 5-year prostate cancer-specific survival rate (the percentage of patients who have not died of prostate cancer after 5 years) of patients with only 1 metastasis was 90% compared to 32% for patients with 2 or more metastases.

For patients with 1 metastasis whose PSA doubling-time (the time it takes to the blood levels of PSA to double) was more than 3 months, the 5-year prostate cancer-specific survival rate was 100% compared to 88% for patients with PSA doubling-time was shorter than 3 months. For patients with 2 or more metastases whose PSA doubling-time was more than 3 months, the 5 year survival rate was 76%, compared to 8% for a doubling-time shorter than 3 months.

For every month increase in PSA doubling-time there was a 27% decrease in the risk of prostate cancer-specific mortality (death). For every increase in number of metastases there was a 7% increased risk and extensive metastatic spread was associated with 3.6 times the risk of prostate cancer-specific mortality compared to minimal spread.

This study shows that a longer PSA doubling-time and lower number of metastases are associated with an improved prostate cancer-specific survival.

This study is limited by the fact it took place in only 1 hospital, and was based on medical records only (retrospective study).