Paula C. Southwick

Comparison of Digital Rectal Examination and Serum Prostate Specific Antigen in the Early Detection of Prostate Cancer: Results of a Multicenter Clinical Trial of 6,630 Men

&NA; To compare the efficacy of digital rectal examination and serum prostate specific antigen (PSA) in the early detection of prostate cancer, we conducted a prospective clinical trial at 6 university centers of 6,630 male volunteers 50 years old or older who underwent PSA determination (Hybritech Tandom‐E or Tandem‐R assays) and digital rectal examination. Quadrant biopsies were performed if the PSA level was greater than 4 &mgr;g./l. or digital rectal examination was suspicious, even if transrectal ultrasonography revealed no areas suspicious for cancer. The results showed that 15% of the men had a PSA level of greater than 4 &mgr;g./l., 15% had a suspicious digital rectal examination and 26% had suspicious findings on either or both tests. Of 1,167 biopsies performed cancer was detected in 264. PSA detected significantly more tumors (82%, 216 of 264 cancers) than digital rectal examination (55%, 146 of 264, p = 0.001). The cancer detection rate was 3.2% for digital rectal examination, 4.6% for PSA and 5.8% for the 2 methods combined. Positive predictive value was 32% for PSA and 21% for digital rectal examination. Of 160 patients who underwent radical prostatectomy and pathological staging 114 (71%) had organ confined cancer: PSA detected 85 (75%) and digital rectal examination detected 64 (56%, p = 0.003). Use of the 2 methods in combination increased detection of organ confined disease by 78% (50 of 64 cases) over digital rectal examination alone. If the performance of a biopsy would have required suspicious transrectal ultrasonography findings, nearly 40% of the tumors would have been missed. We conclude that the use of PSA in conjunction with digital rectal examination enhances early prostate cancer detection. Prostatic biopsy should be considered if either the PSA level is greater than 4 &mgr;g./l. or digital rectal examination is suspicious for cancer, even in the absence of abnormal transrectal ultrasonography findings.

Comparison of percent free PSA, PSA density, and age-specific PSA cutoffs for prostate cancer detection and staging.

OBJECTIVES Various methods have been proposed to increase the specificity of prostate-specific antigen (PSA), including age-specific PSA reference ranges, PSA density (PSAD), and percent free PSA (%fPSA). In this multicenter study, we compared these methods for their utility in cancer detection and their ability to predict pathologic stage after radical prostatectomy in patients with clinically localized, Stage T1c cancer. METHODS Seven hundred seventy-three men (379 with prostate cancer, 394 with benign prostatic disease), 50 to 75 years old, from seven medical centers were enrolled in this prospective blinded study. All subjects had a palpably benign prostate, PSA 4.0 to 10.0 ng/mL, and a histologically confirmed diagnosis. Hybritechs Tandem PSA and free PSA assays were used. RESULTS %fPSA and age-specific PSA cutoffs enhanced PSA specificity for cancer detection, but %fPSA maintained significantly higher sensitivities. Age-specific PSA cutoffs missed 20% to 60% of cancers in men older than 60 years of age. %fPSA and PSAD performed equally well for detection (95% sensitivity) if cutoffs of 25% fPSA or 0.078 PSAD were used. The commonly used PSAD cutoff of 0.15 detected only 59% of cancers. %fPSA and PSAD also produced similar results for prediction of the post-radical prostatectomy pathologic stage. Patients with cancer with higher %fPSA values (greater than 15%) or lower PSAD values (0.15 or less) tended to have less aggressive disease. CONCLUSIONS The results of this study demonstrated that cancer detection (sensitivity) is significantly higher with %fPSA than with age-specific PSA reference ranges. %fPSA and PSAD provide comparable results, suggesting that %fPSA may be used in place of PSAD for biopsy decisions and in algorithms for prediction of less aggressive tumors since the determination of %fPSA does not require ultrasound.

Selection of optimal prostate specific antigen cutoffs for early detection of prostate cancer: receiver operating characteristic curves.

A prospective clinical trial of prostate cancer screening was conducted at 6 university centers including 6,630 men 50 years old or older who underwent a serum prostate specific antigen (PSA) determination and digital rectal examination. Biopsies were performed if the PSA level was greater than 4.0 ng./ml. (Hybritech Tandem assay) or digital rectal examination was suspicious for cancer. We evaluated the effect on biopsy rate and cancer detection if the cutoff value was shifted from 4.0 to age-specific reference ranges recommended in the literature. In men 50 to 59 years old with normal digital rectal examination findings a decrease from 4.0 to 3.5 ng./ml. would have resulted in a 45% increase in the number of biopsies (39 of 87) and a projected 15% increase in cancer detection. An increase from 4.0 to 4.5 ng./ml. in men 60 to 69 years old would result in 15% fewer biopsies (35 of 238) and would miss 8% of the organ confined tumors (2 of 25). Increasing the cutoff to 6.5 ng./ml. in men 70 years old or older would result in 44% fewer biopsies (70 of 159) and would miss 47% of the organ confined cancers (7 of 15). The number of biopsies performed for each cancer detected with a PSA level of greater than 4.0 ng./ml. remains constant across age groupings, which suggests that the cutoff of 4.0 ng./ml. does not need to be altered in the older men, since it is apparently unaffected by the simultaneously increasing prevalence of benign prostatic hyperplasia and cancer with age. We conclude that a serum PSA concentration of 4.0 ng./ml. should be used as a general guideline for biopsy in all age groups.

Analysis of percent free prostate-specific antigen (PSA) for prostate cancer detection: Influence of total psa, prostate volume, and age

OBJECTIVES To determine whether the use of the free-to-total PSA ratio (percent free PSA) could increase the specificity of PSA testing for prostate cancer detection in men with serum PSA concentrations between 4.0 and 10.0 ng/mL, and to assess the influence of total PSA, prostate volume, and age on percent free PSA. METHODS Sera were obtained from 217 men with histologically confirmed diagnoses (139 prostate cancer, 78 benign). Free and total PSA concentrations were determined using Hybritech Tandem assays. RESULTS Use of percent free PSA increased PSA specificity: 29% of negative biopsies would be spared while retaining 95% sensitivity. Percent free PSA increased with increasing age and prostate volume. Percent free PSA decreased as total PSA increased. A significant relation exists between percent free PSA and the probability of a positive biopsy; in this cohort, a patient with a low percent free PSA (< or = 10%) had a higher probability of cancer (63 +/- 9%) than a patient with a high percent free PSA (> or = 26%) (probability 2 +/- 3%). CONCLUSIONS Percent free PSA may be used as an aid in distinguishing prostate cancer from benign disease in men with a total PSA between 4.0 and 10.0 ng/mL. Large prospective multicenter trials are required to develop consistent recommendations and determine the appropriate cutpoints and risk probabilities, controlling for total PSA, prostate volume, age, and biopsy history.

Comparison of Prostate Specific Antigen Concentration Versus Prostate Specific Antigen Density in the Early Detection of Prostate Cancer: Receiver Operating Characteristic Curves

We present the results of a prospective multicenter clinical trial of nearly 5,000 men in which prostate specific antigen (PSA) density was compared to the serum PSA concentration alone for early detection of prostate cancer. All men were evaluated with PSA and digital rectal examination. If PSA was elevated (greater than 4 ng./ml., Hybritech Tandem assay) or digital rectal examination was suspicious, transrectal ultrasound guided biopsies were recommended. Prostate volume was estimated by transrectal ultrasound measurements using a prolate ellipse volume calculation and PSA density was calculated by dividing serum PSA concentration by gland volume. Using a PSA density cutoff of 0.15 as recommended in the literature enhanced specificity but at the cost of missing half of the tumors. Of the organ confined neoplasms 47% were detected by a PSA of greater than 4.0 ng./ml. but they were missed by a PSA density of more than 0.15. PSA density may not be predictive for cancer because accurate estimation of transrectal ultrasound volume is difficult (r = 0.61 for estimated transrectal ultrasound volume versus pathological prostate weight). However, a relationship does exist among transrectal ultrasound volume, PSA and positive predictive value for cancer. PSA concentrations of less than 4.0 ng./ml. did not indicate a need for biopsy (positive predictive value 12 to 17%) unless the digital rectal examination findings were suspicious for cancer. A high percentage of patients with a PSA of more than 10 ng./ml. had cancer (30 to 75%), regardless of gland size. Patients with intermediate PSA concentrations (4.1 to 9.9 ng./ml.) and a gland size of 50 cc or less had a 35 to 51% positive predictive value, while those with intermediate PSA concentrations and a large gland (more than 50 cc) had a 15% positive predictive value. We conclude that in men with a PSA level of 4.1 to 9.9 ng./ml., and normal digital rectal examination and transrectal ultrasound findings, the use of a PSA density cutoff of more than 0.15 for biopsy results in half of the tumors being missed. Thus, we recommend that men in this group undergo biopsy based upon serum PSA concentration rather than PSA density.

Interpretation of free prostate specific antigen clinical research studies for the detection of prostate cancer

PURPOSE We reviewed the use of percent free prostate specific antigen (PSA) to enhance specificity of PSA testing and aid in the discrimination of benign and malignant prostate disease. We present proposed percent free PSA cut points and probability factors, and discuss factors that are believed to affect study outcomes and conclusions. MATERIALS AND METHODS We reviewed the literature with respect to PSA and free PSA with particular emphasis on clinical use of percent free PSA and factors that may affect study outcomes. RESULTS Percent free PSA may increase the specificity of PSA testing without sacrificing the cancer detection rate. Differences in study designs and subject populations may account for the confusion in the current literature. Specific factors that may influence study outcomes include sample size, PSA range, age, race, digital rectal examination findings, prostate size, tumor size and pathology, as well as treatment history, sample collection and storage conditions, and the particular assays used to determine free and total PSA values. CONCLUSIONS The use of percent free PSA to enhance the specificity of prostate cancer screening is thought to provide useful information to aid in the differentiation of benign and malignant prostate diseases. There is evidence to suggest a benefit cost advantage to a tailored biopsy approach based on percent free PSA. However, statistically valid multisite clinical trials that take into account influencing factors are needed to set assay specific cut points and probability determinations.

EFFECT OF PATIENT AGE ON EARLY DETECTION OF PROSTATE CANCER WITH SERUM PROSTATE-SPECIFIC ANTIGEN AND DIGITAL RECTAL EXAMINATION *

This study was designed to determine the effects of age by decade on the efficacy of digital rectal examination (DRE) and serum prostate-specific antigen (PSA) for early detection of prostate cancer in men aged fifty and over. A prospective multicenter clinical trial was conducted at six university centers. All 6,630 male volunteers underwent a serum PSA (Hybritech, Tandem) determination and DRE. Quadrant biopsies of the prostate were performed if PSA was > 4 ng/mL or DRE suspicious. A total of 1,167 biopsies were performed, and 264 cancers were detected. The cancer detection rate increased from 3 percent in men aged fifty to fifty-nine to 14 percent in men eighty years or older (p < 0.0001). PSA detected significantly more of the total cancers than DRE at all age ranges (p < 0.05). The positive predictive values (PPV) for PSA were 32 percent (50-59 years), 30 percent (60-69 years), 34 percent (70-79 years), and 38 percent (80+ years). The corresponding PPVs for DRE were 17 percent, 21 percent, 25 percent, and 38 percent. Eighteen percent of the cancers were detected solely by DRE, whereas 45 percent of cancers were detected solely by PSA. Thus, the use of both tests in combination provided the highest rate of detection in all age groups. One hundred-sixty patients underwent radical prostatectomy and pathologic staging. Cancer was organ-confined in 74 percent (25/34) of men aged fifty to fifty-nine, 76 percent (65/86) of men aged sixty to sixty-nine, and 60 percent (24/40) of men aged seventy or over (chi 2, < 70 vs. > or = 70, p < 0.05). Early detection programs yield a lower, yet still substantial, cancer detection rate in younger men, and there is a greater likelihood for detection of organ-confined disease in this age range. Younger men have the longest projected life expectancy and, therefore, the most to gain from early prostate cancer detection.

Accuracy of Digital Rectal Examination and Transrectal Ultrasonography in Localizing Prostate Cancer

Not all prostate cancers are sonographically hypoechoic or palpable on digital rectal examination, and suspicious areas on transrectal prostatic ultrasonography or digital rectal examination often are not cancer. We present quadrant biopsy results from a multicenter prostate cancer screening study in which men were evaluated with prostate specific antigen (PSA) and digital rectal examination. If the PSA level was elevated (greater than 4.0 ng./ml., Hybritech Tandem assay) or digital rectal examination was suspicious quadrant biopsies were performed. Biopsy specimens were labeled separately, and histological findings were correlated by quadrant with the findings on ultrasonography and digital rectal examination. Of the 6,630 subjects enrolled into the study 16% were biopsied. Of 1,002 quadrants that were suspicious on digital rectal examination 110 (11%) had cancer, while 308 of 418 quadrants containing cancer (74%) were not suspicious on digital rectal examination. Of 855 quadrants that were sonographically suspicious 153 (18%) had cancer, while 282 of 435 quadrants containing cancer (65%) were not sonographically suspicious. Of 225 patients with cancer 137 (61%) would have been missed if only the exact site of the palpable induration had been biopsied. Of 251 patients with cancer 131 (52%) would have been missed if only the exact site of the hypoechoic lesion had been biopsied. We conclude that digital rectal examination and transrectal ultrasonography have limited accuracy in identifying and localizing prostate cancer. Our study emphasizes the importance of obtaining systematic biopsies if the PSA level is elevated, even in the absence of digital rectal examination or ultrasound anomalies.

Improved differential diagnosis of anemia of chronic disease and iron deficiency anemia: a prospective multicenter evaluation of soluble transferrin receptor and the sTfR/log ferritin index.

Anemia of chronic disease (ACD) and iron deficiency anemia (IDA) are the most prevalent forms of anemia and often occur concurrently. Standard tests of iron status used in differential diagnosis are affected by inflammation, hindering clinical interpretation. In contrast, soluble transferrin receptor (sTfR) indicates iron deficiency and is unaffected by inflammation. Objectives of this prospective multicenter clinical trial were to evaluate and compare the diagnostic accuracy of sTfR and the sTfR/log ferritin index (sTfR Index) for differential diagnosis using the automated Access® sTfR assay (Beckman Coulter) and sTfR Index. We consecutively enrolled 145 anemic patients with common disorders associated with IDA and ACD. Subjects with IDA or ACD + IDA had significantly higher sTfR and sTfR Index values than subjects with ACD (P < 0.0001). ROC curves produced the following cutoffs for sTfR: 21 nmol/L (or 1.55 mg/L), and the sTfR Index: 14 (using nmol/L) (or 1.03 using mg/L). The sTfR Index was superior to sTfR (AUC 0.87 vs. 0.74, P < 0.0001). Use of all three parameters in combination more than doubled the detection of IDA, from 41% (ferritin alone) to 92% (ferritin, sTfR, sTfR Index). Use of sTfR and the sTfR Index improves detection of IDA, particularly in situations where routine markers provide equivocal results. Findings demonstrate a significant advantage in the simultaneous determination of ferritin, sTfR and sTfR Index. Obtaining a ferritin level alone may delay diagnosis of combined IDA and ACD. Am. J. Hematol., 2011.

Assessment of Amyloid β Protein in Cerebrospinal Fluid as an Aid in the Diagnosis of Alzheimer's Disease

Abstract: The principal constituent of amyloid plaques found in the brains of individuals with Alzheimers disease (AD) is a 39–42‐amino‐acid protein, amyloid β protein (Aβ). This study examined whether the measurement of Aβ levels in CSF has diagnostic value. There were 108 subjects enrolled in this prospective study: AD (n = 39), non‐AD controls (dementing diseases/syndromes; n = 20), and other (n = 49). CSF was obtained by lumbar puncture, and Aβ concentrations were determined using a dual monoclonal antibody immunoradiometric sandwich assay. The mean Aβ value for the AD group (15.9 ± 6.8 ng/ml) was not significantly different from that for the non‐AD control group (13.0 ± 7.1 ng/ml; p = 0.07), and substantial overlap in results were observed. Aβ values did not correlate with age (r = −0.05, p = 0.59), severity of cognitive impairment (r = 0.22, p = 0.21), or duration of AD symptoms (r = 0.14, p = 0.45). These findings are in conflict with other reports in the literature; discrepant results could be due to the instability of Aβ in CSF. Aβ immunoreactivity decays rapidly under certain conditions, particularly multiple freeze/thaw cycles. Use of a stabilizing sample treatment buffer at the time of lumbar puncture allows storage of CSF without loss of Aβ reactivity. In conclusion, the total CSF Aβ level is not a useful marker for current diagnosis of AD.