Combination Therapy Improves Survival For Certain Prostate Cancer Patients

Several studies have documented increased survival when androgen (male sex hormone) suppression therapy (AST) is combined with external beam radiation therapy (RT) compared with RT alone in the treatment of unfavorable localized and locally advanced prostate cancer. However, comorbid (co-existing) illnesses may increase the negative effects of specific anti-cancer treatments such as AST, altering the survival benefit observed when AST is added to RT.

Anthony V. D'Amico, M.D., Ph.D., of Brigham and Women's Hospital and Dana Farber Cancer Institute, Boston, and colleagues performed an analysis of overall survival of 206 men with localized but unfavorable--risk prostate cancer in subgroups defined by their level of comorbidity at the time of their randomization to AST and RT vs. RT alone. During a median follow-up of 7.6 years, 74 deaths occurred.

Estimates of overall survival were significantly higher for men who were randomized to RT and AST compared with RT. The cumulative incidence estimates of prostate cancer--specific mortality significantly favored the RT and AST group, with an increased risk of prostate cancer--specific mortality (14 vs. 4 deaths) that translated into an increased risk of all-cause mortality (44 vs. 30 deaths) in men randomized to RT compared with RT and AST.

A significant interaction was noted between comorbidity score and treatment. For the 157 men with no or minimal comorbidity scores, treatment with RT and AST compared with RT was associated with a significantly higher survival (31 vs. 11 deaths). Among the 49 men with moderate or severe comorbidity, those randomized to RT alone vs. RT and AST did not have an increased risk of all-cause mortality (13 vs. 19 deaths).

"The clinical significance of this finding is that pre-existing comorbid illness may increase the negative effects of specific anti-cancer treatments such as AST," the authors write.

"In conclusion, the addition of 6 months of AST to RT resulted in increased overall survival in men with localized but unfavorable--risk prostate cancer. This result may pertain only to men without moderate or severe comorbidity, but this requires further assessment in a clinical trial specifically designed to assess this interaction."

Journal reference: JAMA. 2008;299[3]:289-295.