Period Analysis of Prostate Cancer Survival
Authors: George Wilding, Patrick Remington
Journal: Journal of Clinical Oncology (2004)

More than 220,000 men will be diagnosed with prostate cancer this year, representing about one third of all cancers diagnosed among men, and more than any other cancer. Once diagnosed, men and their families often face difficult treatment decisions, ranging from radical prostatectomy and radiation to watchful waiting. Unfortunately, for some men, the disease continues to progress, resistant to all forms of treatment. Many questions remain in our quest to understand better ways to prevent, diagnose, and treat prostate cancer. In the 1990s and early 2000s, we witnessed a marked initial increase in new diagnoses, followed by a plateau in the incidence of the disease, likely attributable to the increasing use of prostate-specific antigen (PSA). After a frightening increase to approximately 40,000 American prostate cancer deaths per year, we have experienced a decline in prostate cancer-related deaths to approximately 28,900 in 2003. Why did this reduction in the death rate occur? What can we do to sustain this rate of improvement in survival? How does a patient improve his chances of surviving his prostate cancer 5 or 10 years from now? And who should be implementing the changes in how we approach this disease? Brenner and Arndt, in this issue of the Journal of Clinical Oncology, do not provide definitive answers to any of these questions. But, they do provide helpful, up-to-date information about the survival experience among men diagnosed with prostate cancer. The bottom line is that most men diagnosed with the disease today can expect to live as long as, or longer than, men their age without the disease. Given the many uncertainties about this disease, this information alone will be helpful for clinicians and their patients when discussing treatment options and when considering what life will be like, living as a prostate cancer survivor. The authors of the study used a novel method to estimate long-term survival experiences of men diagnosed with the disease in an era of rapidly changing patterns of care of this disease. This is not a report on the value of PSA screening. PSA screening started to enter clinical practice in the late 1980s in the United States. By 2000, more than 50% of men aged 65 years or older had undergone a PSA test within the past year. Clearly, the 1990s represented a transition decade, when American men and their physicians were increasingly utilizing PSA screening. This resulted in an increase in diagnoses and in stage migration to more localized cancers, as well as an increase in the number of men undergoing therapy. In such a dynamic setting, standard cohort analyses for 5and 10-year survival estimates would follow men diagnosed more than a decade ago; therefore, any impact of changes in patterns of care introduced recently might not be detected. The study by Brenner and Arndt used period analysis of more recent data; therefore, the impact of current treatment and diagnostic approaches is more likely reflected in the results. What is period analysis? In the context of this study, estimates of 5and 10-year survival were generated using data on the survival experience of patients in the year 2000. To obtain survival estimates with this approach, the entire experience of cohorts of patients diagnosed in the previous 10 consecutive years (1990 to 1999) is used (not just those diagnosed a decade or more ago). The data from these more recent cohorts are then used to estimate 5and 10-year absolute and relative survival rates. In contrast, more traditional cohort analysis would use data solely from men diagnosed in 1995 and 1990 to calculate the 5and 10-year survival estimates. Importantly, this period analysis approach has been shown in other evaluations to provide more timely estimates of long-term survival rates than traditional survival analyses, as period analysis survival estimates for a particular year have closely reflected the survival eventually observed in patients diagnosed in that year. In the Brenner and Arndt study, Surveillance, Epidemiology, and End Results data on 180,605 men diagnosed in the United States between 1990 and 2000 were used to calculate both absolute and relative survival rates of prostate cancer patients compared with the general population. The results presented are very encouraging. Absolute JOURNAL OF CLINICAL ONCOLOGY E D I T O R I A L VOLUME 23 NUMBER 3 JANUARY 2