Assessing Prognosis and Survival in Metastatic Prostate Cancer

Assessing Prognosis and Survival in Metastatic Prostate Cancer

(By Jeni Crockett-Holme & Jackie Johnson)

Hormone therapy, also known as androgen deprivation therapy (ADT), has long been the standard of care for metastatic prostate cancer; however, there is still no cure. Survival is affected by both patient characteristics and new therapies being added to standard treatment. Understanding of these factors may help doctors with making better treatment decisions for their patients.

The study
Researchers analyzed 917 European men with newly diagnosed metastatic prostate cancer [1]. All were about to start with ADT treatment. The patient group represents the control arm of the STAMPEDE clinical trial – a trial that compares the addition of different therapies with ADT in patients (experimental group) to patients with ADT treatment alone (control group).
Metastases (cancer that has spread) were grouped by location in bone, in soft tissue, or in both, and involvement of the lymph nodes was noted. Other prognostic factors included age, Gleason score, tumor stage, PSA level, and well-being as measured by World Health Organization (WHO) performance status [2,3]. The authors measured overall survival (OS), which is the time until death from any cause, and failure-free survival (FFS), which is the time until an increase in PSA level, tumor growth, or death from prostate cancer specifically.

Results
Overall survival (OS) of these patients was 3.5 years (median: 42 months) compared to 30-36 months in older studies. At 2 years from study enrollment, 72% of the patients were living.

Survival outcomes were worse for patients with metastases in bone, with or without soft-tissue metastases. Men with a worse WHO performance status, higher Gleason score, and age younger than 60 years also tended to have shorter overall survival (OS). In addition, higher primary tumor stage and higher PSA level before starting initial ADT treatment with ADT, indicated worse failure-free survival (FFS).

What do the results tell us?
The results show that although many patients lived with metastatic disease for 3.5 years or longer, initial treatment was successful for only 1 year. Over time many patients became castrate-resistant. This means that the cancer was able to grow and continue to spread despite using ADT [3] – and additional treatments were needed to maintain survival and reduce related illness.

Practical implications
Since 2002, a variety of therapies have become available to actively treat men who are castrate-resistant. The improvement in overall survival would seem to reflect the benefit of this strategy for these patients.
In conclusion, survival outcomes for patients with metastatic prostate cancer have improved over time but are still limited. Men with metastases in bone, worse WHO performance status, higher Gleason score, and younger age tended to have shorter overall and failure-free survival. Subsequent therapies are available and should be accessed by appropriate patients.

[1] James ND, Spears MR, Clarke NW, et al. Survival with newly diagnosed metastatic prostate cancer in the “docetaxel era”: data from 917 patients in the control arm of the STAMPEDE trial (MRC PR08, CRUK/06/019). Eur Urol 2015;67:1028–38.
[2] Cancer Research UK. The stages of prostate cancer. http://www.cancerresearchuk.org/about-cancer/type/prostate-cancer/treatment/the-stages-of-prostate-cancer. Accessed October 12, 2015.
[3] EAU patient information: glossary of terms. http://patients.uroweb.org/glossary/. Accessed October 12, 2015.

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