Favorable versus unfavorable intermediate-risk prostate cancer

This study evaluated long-term mortality with intermediate-risk prostate cancer and the significance of favorable versus unfavorable prognostic factors in the selection of the most appropriate therapy.

Men newly diagnosed with prostate cancer are initially stratified into three risk groups based on low, intermediate, or high prognostic risk factors. These factors include the tumor TNM staging system (accounting for clinical tumor size and extent of cancer spread), the Gleason score (a system for evaluating cancer aggressiveness according to the appearance of the tumor cells when examined under a microscope), and prostate-specific antigen (PSA) levels (a protein found at increased levels with prostate cell growth). It is generally agreed upon that low risk prostate cancer patients can be managed with active surveillance, sparing patients unnecessary medical interventions. Intermediate risk prostate cancer, however, often varies in nature and outcomes, and some debate exists as to which intermediate risk patients would most benefit from aggressive cancer treatments. Therefore, intermediate risk prostate cancer is currently further classified as having favorable or unfavorable prognostic factors.

Unfavorable intermediate-risk prostate cancer is defined as the presence of two or more intermediate-risk factors. These factors include a PSA level of 10 to 40 ng/mL, a Gleason score greater than 7, or a high fraction of prostate biopsies showing cancerous cells (referred to as a percentage of positive biopsies greater than 50%, a known indicator of tumor volume within the prostate gland). Favorable intermediate-risk prostate cancer is defined as the presence of no more than one of these risk factors.

This study analyzed long-term prostate cancer-specific mortality among favorable and unfavorable intermediate-risk prostate cancer patients.

The study analyzed results from a previous controlled trial in which 197 intermediate or high risk prostate cancer patients were randomly assigned to receive radiation therapy alone (100 patients), or radiation therapy plus androgen deprivation therapy (97 patients). Among intermediate-risk patients, the number of men with favorable versus unfavorable intermediate-risk cancer was similar.

After an average follow-up of 14.3 years, 127 deaths (64.5%) were recorded, 17% (22 patients) of these were prostate cancer-specific deaths. No prostate cancer-specific deaths were noted among the favorable intermediate-risk patient group.

Overall, 5-year cancer-specific mortality rates were estimated at 0% for favorable intermediate-risk patients, 13.10% for unfavorable intermediate-risk patients and 20.05% for high-risk patients. These results, showing 0% cancer-mortality among favorable patients regardless of therapy group, suggest that while aggressive cancer treatments (such as androgen deprivation therapy) may be crucial in the management of unfavorable intermediate-risk cancer, they may be unnecessary in the case of favorable intermediate-risk prostate cancer.

Despite higher mortality rates, the difference between cancer-mortality risk among unfavorable intermediate-risk patients and high-risk patients was not deemed to be statistically significant. Among both unfavorable intermediate-risk patients and high-risk patients, the risk for prostate cancer-specific mortality was 3-times greater with radiotherapy alone compared to combined radiation and androgen-suppression therapy.

This analysis concluded that while patients with unfavorable intermediate-risk prostate cancer may benefit from long term androgen-suppression therapy, those with favorable intermediate-risk prostate cancer may not require aggressive hormonal therapy.