A Swedish retrospective study of a nationwide cohort of patients with localized prostate cancer aged 70 years or younger reported that 10-year prostate cancer-specific mortality was 2.4% among men diagnosed with clinically local stage T1a, T1b, or T1c, with a serum PSA of less than 10 ng/mL, and with a Gleason score of 2 to 6, referred to as low-risk cases, of which there were 2,686. This subgroup analysis was derived from a cohort study of 6,849 men diagnosed between January 1, 1997 and December 31, 2002, aged 70 years or younger, who had local stage T1 to T2 with no signs of lymph node metastases or bone metastases, and a PSA serum level of less than 20 ng/mL, as was abstracted from the Swedish Cancer Registry, which captured 98% of solid tumors among men aged 75 years or younger. Cohort treatment options were surveillance (n = 2,021) or curative intent by radical prostatectomy (n = 3,399) or radiation therapy (n = 1,429), which were to be determined at the discretion of treating physicians. Surveillance or expectancy treatment was either active surveillance with curative treatment if progression occurred or watchful waiting—a strategy for administering hormonal treatment upon symptomatic progression. Using all-cause mortality as the benchmark, the study calculated cumulative incidence mortality for the three treatment groups of the entire cohort and the low-risk subgroup. Surveillance was more common among men with high comorbidity and among men with low-risk tumors. The 10-year cumulative risk of death from prostate cancer for the entire 6,849 person cohort was 3.6% in the surveillance group and 2.7% in the curative-intent group compared with the low-risk surveillance group (2.4%) and the low-risk curative-intent group (0.7%). Biases inherent in treatment assignment could not be accounted for adequately in the analysis, which prevented conclusions about the relative effectiveness of alternative treatments. However, a 10-year prostate cancer-specific mortality of 2.4% among patients with low-risk prostate cancer in the surveillance group suggested that surveillance may be a suitable treatment for many patients with low-risk disease compared with the 19.2% 10-year risk of death from competing causes observed in the surveillance group and 10.2% in the curative-intent group of the total 6,849 person cohort.
Digital Rectal Exam
Although DRE has been used for many years, careful evaluation of this modality has yet to take place. Several observational studies have examined process measures such as sensitivity and case-survival data, but without appropriate controls and with no adjustment for lead-time and length biases.[7,8]
In 1984, one study reported on 811 unselected patients aged 50 to 80 years who underwent rectal examination and follow-up. Thirty-eight of 43 patients with a palpable abnormality in the prostate agreed to undergo biopsy. The positive predictive value (PPV) of a palpable nodule, i.e., prostate cancer on biopsy, was 29% (11 of 38). Further evaluation revealed that 45% of the cases were stage B, 36% were stage C, and 18% were stage D. More results from the same investigators revealed a 25% positive predictive value, with 68% of the detected tumors clinically localized but only approximately 30% pathologically localized after radical prostatectomy. Some investigators reported a high proportion of clinically localized disease when prostate cancer is detected by routine rectal examination, while others reported that even with annual rectal examination, only 20% of cases are localized at diagnosis. It has been reported that 25% of men presenting with metastatic disease had a normal prostate examination. Another case-control study examining screening with both DRE and PSA found a reduction in prostate cancer mortality that was not statistically significant (OR, 0.7; 95% CI, 0.46–1.1). Most men in this study were screened with DRE rather than PSA. All four of these case-control studies are consistent with a reduction of 20% to 30% in prostate cancer mortality. Potential biases inherent in this study design, however, limit the ability to draw conclusions on the basis of this evidence alone.