Prostate
cancer may be divided, based on its clinical presentation into localized or
advanced disease. For men with clinical T1-T2 prostate cancer, curative therapy
or observation are options. For men with advanced disease (T3 or above),
hormonal therapy and other palliative treatments are the primary approaches for
consideration. Men who have a less than 10 year life expectancy with localized
disease, as well as men with less than 5 year life expectancy and asymptomatic
advanced disease, expectant management is the optimal initial treatment.
Management of localized prostate cancer is a controversial issue, in part
because the natural history of localized prostate cancer has been only
segmentally elucidated. At present, prostate cancer is the most common cancer
diagnosed in men in the United States and the second most common cause of
cancer death. The ratio of death rate to incidence suggests that between 20 and
50 percent of men with a clinical diagnosis of prostate cancer will die of the
disease. In considering the management of localized prostate cancer, it is
important to remember that men with latent, incidental microscopic tumors can
only rarely have these cancers detected using today's screening tests of PSA
and transrectal ultrasound-guided biopsies (Gardner et al., 1998). Preliminary
studies that have evaluated a program of observation or watchful waiting rather
than screening with a PSA-based approach suggest that the death rate from
prostate cancer will decrease with screening. In addition, the small decrease
in prostate cancer death rates associated with the increased screening by PSA
(with a five- to seven-year lag period) suggests that earlier screening,
detection and treatment of men with prostate cancer may have resulted in saving
lives. However, little evidence is available at this point with well-performed
randomized studies to confirm that treatment of localized prostate cancer will
actually decrease death rates from this disease. In distinction, there is
widespread acceptance that breast cancer is an important cause of death in
women (Walsh, 1994).
Studies on the natural history of localized prostate cancer have
suffered from selection biases, but they allow us some insight into what would
occur if patients were not treated with curative intention for localized
disease. Almost all of these studies indicate that men with metastatic disease
had unrecognized advanced disease at least ten years prior to diagnosis. This
is supported by the studies of Carter et al. (1992) where serum PSA levels were
followed serially in a number of patients in the Baltimore Longitudinal Study
of Aging. Therefore, patients who are candidates for curative local therapy
should have a 10-year life expectancy.
