Proteins can predict bone tumors and survival in hormone-resistant prostate cancer

The authors aimed to determine whether specific proteins can predict bone tumors and death in patients with hormone-resistant prostate cancer. 

In advanced prostate cancer, tumors can spread out from the initial site of cancer to other parts of the body and bones, making treatment difficult. Hormone therapy (treatment that targets the male sex hormones active in prostate cancer, such as testosterone) is an option used to treat bone tumors; however resistance in patients can occur. 

Hormone-resistant prostate cancer is cancer that has become resistant to hormone therapy. Alkaline phosphatase (AP – a protein) has already been used in hormone-resistant cancer patients to determine overall survival (patients who did not die from prostate cancer following treatment) and has the potential to become a more widely-used predictor for cancer spread and death in patients with this type of prostate cancer. 

The aim of this study was to determine whether AP protein can predict bone tumors and death in prostate cancer patients immune to hormone therapy.

347 patients were used in this study. Patients who experienced rapid increases in AP protein also had shorter prostate specific antigen (PSA – protein elevated in the blood in the presence of prostate cancer) doubling times at diagnosis (time taken for PSA levels to double). A short PSA doublint time was considered less than 10 months for PSA levels to double. Time from hormone treatment until resistance developed was 16.9 months in patients with rapidly increasing levels of AP compared to 21.7 months in patients with slowly increasing levels of AP protein.

Patients who had rapidly increasing levels of AP and shorter PSA doubling times were more likely to experience bone tumors compared to patients with slowly increasing levels of AP. In these patients with short PSA doubling times, 54.8% of patients with rapidly increasing levels of AP and 33.3% of patients with slowly increasing levels of AP developed bone metastasis. 

Patients with rapidly increasing levels of AP were 2.7 times more at risk of developing bone tumors than patients with slowly increasing levels. Patients with rapid PSA doubling times were over 12 times more at risk of developing bone tumors compared to patients with slow PSA doubling times.

Patients with rapidly increasing AP levels experienced significantly shorter overall survival and were over 5 times more at risk of dying compared to patients with slowly increasing AP levels. Patients with rapid PSA doubling times experienced significantly shorter overall survival and were over 4 times more at risk of dying compared to patients with slow PSA doubling times. 

The authors conclude that alkaline phosphatase protein can be used to determine survival and the risk of developing bone tumors in patients with hormone-resistance prostate cancer. 

Generally there was limited data available on alkaline phosphatase protein levels in patients which limited the size of the patient group available for analysis.

If you have concerns regarding your alkaline phosphatase or PSA levels, please consult your doctor.