For nearly 80 percent of men with prostate cancer, doctors diagnose the disease early, in the local or regional stages. Doctors expect most of these men will be cured with radiation or surgery. However, one in five men with prostate cancer is diagnosed with high-risk disease—which has a tendency to spread even though, by all clinical appearances, it is localized. Despite having been treated for prostate cancer, about 30 to 40 percent of men suffer a relapse, meaning their cancer returns. Among these men, fewer than 50 percent are cured. Men with recurrent disease account for most of the 27,000 prostate cancer deaths in the United States each year.
The only therapy that has been adequately tested in clinical studies to treat prostate cancers that might have spread is hormone therapy. It is commonly used in combination with radiation therapy or after surgery (prostatectomy) for men with metastasis to lymph nodes. Hormone therapy is also used to treat cancers that weren’t cured with either radiation or surgery. Hormone therapy lowers serum testosterone, depriving prostate cancer cells of a growth factor critical for their survival.
Seattle Cancer Care Alliance is at the forefront of developing new treatment strategies designed to improve results in men with high-risk prostate cancer. These approaches involve treating both the cancer in the prostate and any cancer that might have spread. A new generation of systemic therapies is showing clinical promise when combined with surgery or radiation therapy.
Risk of Relapse Despite Treatment
Various tools have been developed to assist patients and doctors trying to decide on treatment for prostate cancer by predicting the efficacy of and likelihood of cure with surgery or radiation therapy. The main pretreatment factors that predict the likelihood of cure, as defined by the ability to suppress and maintain low levels of prostate-specific antigen (PSA) without androgen deprivation, are PSA level, clinical stage by digital rectal exam, Gleason score, and extent of disease by biopsy. These factors are a general means of assessing the volume and biologic aggressiveness of prostate cancer and, thus, the likelihood that the cancer will spread beyond the prostate.
Researchers have evaluated how the “PSA doubling time” (how quickly PSA is rising) before treatment affects cure. Some studies have found that an increase in PSA of greater than 2 ng/mL in the year preceding the diagnosis predicted a higher risk of recurrence and a higher likelihood of death despite therapy.
Studies have shown that some patients are at high risk for biochemical progression (further cancer growth), regardless of whether they had surgery or radiation, if they had a pretreatment PSA level greater than 20 ng/mL or advanced cancer (stage T2b or greater) or high-grade disease (Gleason score of 8 to 10). Many men with a PSA level of 10 to 20 ng/mL or stage T2a cancer or intermediate-grade disease (Gleason score of 7) also have an unacceptably high risk of relapse.