Systemic nonhormonal management of advanced prostate cancer and its likely impact on patients' survival and quality of life

Prostate cancer is a hormonal sensitive disease with a response rate ranging from 80 to 90%; however, the majority of patients develop hormone resistance resulting in poor long term survival. Chemotherapy has demonstrated a benefit over steroids in improving the quality of life in the hormone refractory phase. Furthermore, the introduction of docetaxel succeeded in improving the survival of these patients in first-line therapy. Second-line treatment following docetaxel is challenging with no agent classified as standard in this setting. In the last 5 years, several drugs have shown promising results in initial evaluation. However, randomized phase III trials would be needed to answer this question. The majority of patients develop bone metastasis and the use of bisphosphonates has yielded encouraging results. Our understanding of the biology of hormone refractory prostate cancer has improved dramatically over the past few years and has translated into the developments of new therapeutic targets for this disease. Agents affecting several targets, including calcitriol, endotheline-1, bcl-2, and angiogenesis, are being studied currently and have the potential to change the treatment paradigms of this otherwise fatal disease. This review focuses on current and potential treatment options, including cytotoxic agents, bisphosphonates, and targeted agents, for patients with hormone refractory prostate cancer and the impact of these options on survival and quality of life.

Advances in the Treatment of Prostate Cancer

Several recent advances have been made in the management of prostate cancer. Active surveillance is an increasingly attractive and reasonable approach for those with low-volume, low-risk disease. For locally advanced or localized high-risk disease, neoadjuvant and adjuvant therapies are emerging as the standard of care. Innovative uses of traditional hormonal treatments can potentially limit common side effects. Recent data also support the utility of second-line hormonal therapy. For the first time, a survival advantage with the use of chemotherapy has been established. Much work is under way to augment its efficacy with novel agents such as targeted therapeutics and tumor vaccines. Recent scientific breakthroughs suggest additional strategies in treating prostate cancer.

Therapie des hormonrefraktären Prostatakarzinoms

PSA-progression following primary ADT defines an androgen-refractory but still hormone sensitive PCA which might respond to secondary hormonal manipulations. Secondary hormonal manipulations will result in a PSA decline >50% in about 60-80% of the patients with a mean duration of 7-17 months depending on the type of treatment. PSA-progression following secondary endocrine treatment defines hormone-refractory prostate cancer (HRPCA) which might be treated by systemic chemotherapy. Based on the results of 2 prospective, randomized clinical phase-III trials comparing docetaxel and mitoxantrone, docetaxel results in a statistically significant survival benefit of 2.5 months, a significantly higher PSA- and pain response and represents the treatment of choice in the management of HRPCA. Bisphosphonates such as zoledronate represent another cornerstone in the management of PSA-progressive PCA demonstrating a significant benefit with regard to the prevention of skeletal related events. Furthermore, bisphosphonates might be indicated in the treatment of symptomatic bone pain. The current article critically reflects the various therapeutic options in the management of PSA progression following primary androgen deprivation for advanced prostate cancer.

Achieving Treatment Goals for Hormone‐Refractory Prostate Cancer with Chemotherapy

The belief that hormone-refractory prostate cancer (HRPC) is a chemotherapy-resistant disease has been effectively refuted by the results of two recent randomized phase III trials. The TAX327 trial compared weekly docetaxel, every-3-weeks (Q3W) docetaxel, and Q3W mitoxantrone plus prednisone in 1,006 patients with HRPC, and results demonstrated that survival was significantly longer with a docetaxel-based regimen than with mitoxantrone. That trial demonstrated that only Q3W docetaxel was significantly superior to mitoxantrone with respect to overall survival. Quality of life was also superior in the docetaxel groups. In the Southwest Oncology Group (SWOG) 9916 trial, 674 men with progressive HRPC were randomized to 3-week cycles of docetaxel plus estramustine or mitoxantrone plus prednisone. Overall and disease-free survival times were significantly longer in the docetaxel arm. Collectively, the results of these trials demonstrate that survival can be significantly improved with chemotherapy in patients with HRPC to an extent that is comparable with the survival benefits seen in other cancers considered sensitive to chemotherapy such as breast cancer. Among various research tasks in HRPC is the definition of potential surrogate end points for survival, which will facilitate the conduct of pivotal trials. Prostate-specific antigen (PSA) response rate and changes in PSA constructs (i.e., PSA doubling time and PSA velocity) are promising potential surrogate end points for future trials and are being actively evaluated at the present time. Until there is clear demonstration of a surrogate role for these alternative end points, survival remains the appropriate end point for phase III trials in HRPC. There is a need for safe and effective second- and third-line regimens for patients progressing after docetaxel, and these patients should enter clinical trials designed for this population. Mitoxantrone, vinorelbine, the platinum analogue satraplatin, and epothilone are among compounds that require careful testing in this setting. The addition of targeted therapies, such as the endothelin receptor antagonist, atrasentan, and angiogenesis inhibitors, such as thalidomide and bevacizumab, to docetaxel-based therapy is being evaluated. High-dose calcitriol may also be an effective addition to docetaxel. The extensive effort devoted to the evaluation of chemotherapy and other systemic modalities of treatment of HRPC is likely to yield additional clinical benefit for patients, making HRPC a more manageable, less lethal, and less debilitating disease.