Daniel W. Chan

The use of prostate specific antigen, clinical stage and Gleason score to predict pathological stage in men with localized prostate cancer.

Clinical stage, Gleason score and serum prostate specific antigen (PSA) levels are used separately to predict pathological stage in patients with localized prostate cancer. Because the degree of tumor differentiation has a profound influence on the expression of serum PSA, serum PSA levels alone do not reflect tumor burden accurately. To overcome this obstacle we tested these 3 variables alone and in combinations as predictors of final pathological stage in 703 men with clinically localized prostate cancer at our institution. All patients were assigned a clinical stage by 1 urologist. The Gleason score was determined from preoperative needle biopsy and serum PSA levels were measured on an ambulatory basis. Final pathological stage was determined to be either organ confined, established capsular penetration, seminal vesicle involvement or lymph node involvement. Logistic regression analysis with the likelihood ratio chi-square test determined that serum PSA, Gleason score and clinical stage all predicted final pathological stage well. The results were improved with combinations of the 3 variables (serum PSA, Gleason score and clinical stage) and the combination provided the best separation. From these analyses probability plots and nomograms have been constructed to assist urologists in the preoperative prediction of final pathological stage for patients with clinically localized prostate cancer.

Three biomarkers identified from serum proteomic analysis for the detection of early stage ovarian cancer

Early detection remains the most promising approach to improve long-term survival of patients with ovarian cancer. In a five-center case-control study, serum proteomic expressions were analyzed on 153 patients with invasive epithelial ovarian cancer, 42 with other ovarian cancers, 166 with benign pelvic masses, and 142 healthy women. Data from patients with early stage ovarian cancer and healthy women at two centers were analyzed independently and the results cross-validated to discover potential biomarkers. The results were validated using the samples from two of the remaining centers. After protein identification, biomarkers for which an immunoassay was available were tested on samples from the fifth center, which included 41 healthy women, 41 patients with ovarian cancer, and 20 each with breast, colon, and prostate cancers. Three biomarkers were identified as follows: (a) apolipoprotein A1 (down-regulated in cancer); (b) a truncated form of transthyretin (down-regulated); and (c) a cleavage fragment of inter-α-trypsin inhibitor heavy chain H4 (up-regulated). In independent validation to detect early stage invasive epithelial ovarian cancer from healthy controls, the sensitivity of a multivariate model combining the three biomarkers and CA125 [74% (95% CI, 52–90%)] was higher than that of CA125 alone [65% (95% CI, 43–84%)] at a matched specificity of 97% (95% CI, 89–100%). When compared at a fixed sensitivity of 83% (95% CI, 61–95%), the specificity of the model [94% (95% CI, 85–98%)] was significantly better than that of CA125 alone [52% (95% CI, 39–65%)]. These biomarkers demonstrated the potential to improve the detection of early stage ovarian cancer.

Prostate specific antigen in the staging of localized prostate cancer: influence of tumor differentiation, tumor volume and benign hyperplasia.

To evaluate the usefulness of serum prostate specific antigen in the preoperative staging of prostate cancer we examined tumor volume and differentiation, as well as benign prostatic hyperplasia volume to determine their influence on serum antigen levels. Serum prostate specific antigen was measured in 350 men with clinically localized prostate cancer and preoperatively in 72 men with documented benign prostatic hyperplasia. Although the mean antigen levels increased with advancing pathological stage, the usefulness of prostate specific antigen to predict pathological stage for an individual patient was limited: 1 of 102 men (0.9%) with prostate specific antigen levels of less than 2.8 ng./ml. had positive lymph nodes and 5 of 5 men with levels of greater than 100 ng./ml. had either seminal vesicle or lymph node involvement. However, for the majority of men (greater than 70%) with prostate specific antigen values between these 2 extremes the antigen levels did not accurately predict pathological stage. Because serum prostate specific antigen levels correlated with morphometrically determined tumor volume (r equals 0.535, p less than 0.01) they should, in fact, be predictive of pathological stage. However, most men with prostate cancer also have varying degrees of benign prostatic hyperplasia tissue in the gland producing prostate specific antigen. We have found that serum prostate specific antigen does not correlate with the volume of benign hyperplasia within the gland (r equals 0.21, p greater than 0.05). In addition, immunohistochemical studies have suggested that the lack of correlation between pathological stage and serum prostate specific antigen might be explained by a decrease in the production of antigen with increasing histological grade. Our findings of a negative correlation (r equals -0.37, p less than 0.01) between serum prostate specific antigen levels and Gleason score adjusted for tumor volume confirmed this suggestion. Consequently, serum prostate specific antigen levels do not reflect tumor burden and pathological stage accurately in individual patients for 2 reasons: 1) the unpredictable contribution from the benign prostatic hyperplasia component of the gland and 2) the decreasing production of prostate specific antigen by higher grade lesions as tumor volume increases.

Prostate Specific Antigen in the Preoperative and Postoperative Evaluation of Localized Prostatic Cancer Treated with Radical Prostatectomy

The usefulness of prostate specific antigen to predict final pathological stage was studied in 178 consecutive patients. Prostate specific antigen was determined preoperatively in all patients by a monoclonal immunoradiometric assay. All pathological specimens were examined for capsular penetration, seminal vesicle involvement and lymph node involvement. Prostate specific antigen correlated directly with capsular penetration (p less than 0.002), seminal vesicle involvement (p less than 0.02) and lymph node involvement (p less than 0.05). However the diagnostic accuracy of an elevated serum antigen level on an individual basis was only 55 per cent for capsular penetration and 50 per cent for seminal vesicle involvement and lymph node involvement. With a log-linear regression model, the half-life of prostate specific antigen was calculated to be 3.15 +/- 0.09 days. From the equation PSA (t) equals PSA (2) e[-0.2197(t-2)], prostate specific antigen can be used to detect residual cancer on day t in the immediate postoperative period. With respect to long-term followup, 127 patients have been monitored for longer than 2 months postoperatively with prostate specific antigen (mean followup 2 years, range 2 months to 8.6 years). Of the 101 patients who had favorable pathological findings at operation (organ-confined cancer or capsular penetration only) 92 (91 per cent) had a followup antigen concentration in the female range (0.0 to 0.2 ng. per ml.), whereas only 5 of 26 men (19 per cent) with either seminal vesicle involvement or lymph node involvement had an antigen value that was less than 0.2 ng. per ml. All patients with a documented clinical recurrence (8 of 127, 6 per cent) had an elevated followup serum prostate specific antigen concentration. These findings suggest that preoperative levels of prostate specific antigen are not sufficiently reliable to predict final pathological stage on an individual basis in patients with early prostatic cancer, and that the antigen is a sensitive tumor marker for the detection of residual disease after radical prostatectomy and subsequent recurrence of tumor on long-term followup.

Immunosensors--principles and applications to clinical chemistry.

INTRODUCTION Immunosensors are affinity ligand-based biosensor solid-state devices in which the immunochemical reaction is coupled to a transducer. The fundamental basis of all immunosensors is the specificity of the molecular recognition of antigens by antibodies to form a stable complex. This is similar to the immunoassay methodology. Immunosensors can be categorized based on the detection principle applied. The main developments are electrochemical, optical, and microgravimetric immunosensors. In contrast to immunoassay, modern transducer technology enables the label-free detection and quantification of the immune complex. METHODS The analysis of trace substances in environmental science, pharmaceutical and food industries is a challenge since many of these applications demand a continuous monitoring mode. The use of immunosensors in these applications is most appropriate. Similarly, a series of clinical problems may be solved by continuous monitoring of certain analytes. CONCLUSIONS Clinical chemists should take advantage of immunosensors in clinical diagnostics. There are many recent developments in the immunosensor field which have potential impacts. The future role of this technique in intralaboratory, as well as bedside testing, will become even more important as the clinical laboratory is faced with increasing pressure to contain costs.

Proteogenomic characterization of human colon and rectal cancer

Extensive genomic characterization of human cancers presents the problem of inference from genomic abnormalities to cancer phenotypes. To address this problem, we analysed proteomes of colon and rectal tumours characterized previously by The Cancer Genome Atlas (TCGA) and perform integrated proteogenomic analyses. Somatic variants displayed reduced protein abundance compared to germline variants. Messenger RNA transcript abundance did not reliably predict protein abundance differences between tumours. Proteomics identified five proteomic subtypes in the TCGA cohort, two of which overlapped with the TCGA ‘microsatellite instability/CpG island methylation phenotype’ transcriptomic subtype, but had distinct mutation, methylation and protein expression patterns associated with different clinical outcomes. Although copy number alterations showed strong cis- and trans-effects on mRNA abundance, relatively few of these extend to the protein level. Thus, proteomics data enabled prioritization of candidate driver genes. The chromosome 20q amplicon was associated with the largest global changes at both mRNA and protein levels; proteomics data highlighted potential 20q candidates, including HNF4A (hepatocyte nuclear factor 4, alpha), TOMM34 (translocase of outer mitochondrial membrane 34) and SRC (SRC proto-oncogene, non-receptor tyrosine kinase). Integrated proteogenomic analysis provides functional context to interpret genomic abnormalities and affords a new paradigm for understanding cancer biology.

National Academy of Clinical Biochemistry Laboratory Medicine Practice Guidelines for use of tumor markers in testicular, prostate, colorectal, breast, and ovarian cancers

BACKGROUND Updated National Academy of Clinical Biochemistry (NACB) Laboratory Medicine Practice Guidelines for the use of tumor markers in the clinic have been developed. METHODS Published reports relevant to use of tumor markers for 5 cancer sites--testicular, prostate, colorectal, breast, and ovarian--were critically reviewed. RESULTS For testicular cancer, alpha-fetoprotein, human chorionic gonadotropin, and lactate dehydrogenase are recommended for diagnosis/case finding, staging, prognosis determination, recurrence detection, and therapy monitoring. alpha-Fetoprotein is also recommended for differential diagnosis of nonseminomatous and seminomatous germ cell tumors. Prostate-specific antigen (PSA) is not recommended for prostate cancer screening, but may be used for detecting disease recurrence and monitoring therapy. Free PSA measurement data are useful for distinguishing malignant from benign prostatic disease when total PSA is <10 microg/L. In colorectal cancer, carcinoembryonic antigen is recommended (with some caveats) for prognosis determination, postoperative surveillance, and therapy monitoring in advanced disease. Fecal occult blood testing may be used for screening asymptomatic adults 50 years or older. For breast cancer, estrogen and progesterone receptors are mandatory for predicting response to hormone therapy, human epidermal growth factor receptor-2 measurement is mandatory for predicting response to trastuzumab, and urokinase plasminogen activator/plasminogen activator inhibitor 1 may be used for determining prognosis in lymph node-negative patients. CA15-3/BR27-29 or carcinoembryonic antigen may be used for therapy monitoring in advanced disease. CA125 is recommended (with transvaginal ultrasound) for early detection of ovarian cancer in women at high risk for this disease. CA125 is also recommended for differential diagnosis of suspicious pelvic masses in postmenopausal women, as well as for detection of recurrence, monitoring of therapy, and determination of prognosis in women with ovarian cancer. CONCLUSIONS Implementation of these recommendations should encourage optimal use of tumor markers.

Cardiac Troponin I Predicts Short-Term Mortality in Vascular Surgery Patients

Background—Cardiac troponin I (cTnI) is a highly sensitive and specific marker for myocardial injury that predicts outcomes in patients with acute coronary syndromes. Cardiovascular complications are the leading cause of morbidity and mortality in patients who have undergone vascular surgery. However, postoperative surveillance with cardiac enzymes is not routinely performed in these patients. We evaluated the association between postoperative cTnI levels and 6-month mortality and perioperative myocardial infarction (MI) after vascular surgery. Methods and Results—Two hundred twenty-nine patients having aortic or infrainguinal vascular surgery or lower extremity amputation were included in this study. Blood samples were analyzed for cTnI immediately after surgery and the mornings of postoperative days 1, 2, and 3. An elevated cTnI was defined as serum concentrations >1.5 ng/mL in any of the 4 samples. Twenty-eight patients (12%) had postoperative cTnI >1.5ng/mL, which was associated with a 6-fold increased risk of 6-month mortality (adjusted OR, 5.9; 95% CI, 1.6 to 22.4) and a 27-fold increased risk of MI (OR, 27.1; 95% CI, 5.2 to 142.7). Furthermore, we observed a dose-response relation between cTnI concentration and mortality. Patients with cTnI >3.0 ng/mL had a significantly greater risk of death compared with patients with levels ≤0.35 ng/mL (OR, 4.9; 95% CI, 1.3 to 19.0). Conclusions—Routine postoperative surveillance for cTnI is useful for identifying patients who have undergone vascular surgery who have an increased risk for short-term mortality and perioperative MI. Further research is needed to determine whether intervention in these patients can improve outcome.

Nonpalpable stage t1c prostate cancer : Prediction of insignificant disease using free/total prostate specific antigen levels and needle biopsy findings

PURPOSE Approximately 25% of radical prostatectomies performed for stage T1c disease show potentially insignificant prostate cancer. We previously reported the use of serum prostate specific antigen (PSA) density and needle biopsy findings to predict potentially insignificant cancer. We now evaluate whether using free/total serum PSA levels along with needle biopsy findings can better predict tumor significance. MATERIALS AND METHODS We studied 163 radical prostatectomy specimens of stage T1c prostate cancer in which free/total serum PSA levels were determined. Free/total serum PSA levels were measured with Tandem-MP PSA assays. Insignificant prostate cancers were organ confined with tumor volumes less than 0.5 cc and Gleason score less than 7. Advanced tumors were either Gleason score 7 or greater, established extraprostatic extension with positive margins, or positive seminal vesicles or lymph nodes. Other cases were considered as moderate tumor. Moderate and advanced tumors were considered significant. RESULTS Of the tumors 30.7% were insignificant, 49.7% moderate and 19.6% advanced. The best model to predict preoperatively insignificant tumor was a free/total PSA of 0.15 or greater and favorable needle biopsy findings (less than 3 cores involved, none of the cores with greater than 50% tumor involvement and Gleason score less than 7). Using this model of the 18 tumors predicted to be insignificant 17 were insignificant for a positive predictive value of 94.4%. Of the 145 cases that were predicted to be significant 112 were correctly predicted for a negative predictive value of 77.2%. There was only 1 tumor predicted to be insignificant which was classified as moderate. No tumor predicted to be insignificant was advanced. CONCLUSIONS In conjunction with needle biopsy findings, free/total PSA levels accurately predict insignificant tumor in stage T1c disease.

Serum diagnosis of pancreatic adenocarcinoma using surface-enhanced laser desorption and ionization mass spectrometry.

Purpose: Each year in the United States, ∼ 30,000 people die from pancreatic cancer. Fewer than 5% of patients survive >5 years after diagnosis, because most patients present with advanced disease. Early diagnosis may improve the prognosis of patients with pancreatic cancer. Experimental Design: In an attempt to improve on current approaches to the serological diagnosis of pancreatic cancer, we analyzed serum samples from patients with and without pancreatic cancer using surface-enhanced laser desorption and ionization (SELDI) protein chip mass spectrometry. Using a case-control study design, serum samples from 60 patients with resectable pancreatic adenocarcinoma were compared with samples from 60 age- and sex-matched patients with nonmalignant pancreatic diseases, as well as 60 age- and sex-matched healthy controls. To increase the number of proteins potentially identifiable, serum was fractionated using anion exchange and profiled on two ProteinChip surfaces (metal affinity capture and weak cation exchange). Results: We determined a minimum set of protein peaks able to discriminate between patient groups and used the unified maximum separability algorithm to compare the performance of the individual marker panels alone or in conjunction with CA19–9. Among the peaks identified by SELDI profiling that had the ability to distinguish between patient groups, the 2 most discriminating protein peaks could differentiate patients with pancreatic cancer from healthy controls with a sensitivity of 78% and specificity of 97%. These 2 markers performed significantly better than the current standard serum marker, CA19–9 (P < 0.05). The diagnostic accuracy of the 2 markers was improved by using them in combination with CA 19-9. Similarly, a combination of 3 SELDI markers and CA19–9 was superior to CA19–9 alone in distinguishing individuals with pancreatic cancer from the combined pancreatic disease controls and healthy subject groups (P = 0.078). SELDI markers were also better than CA19–9 in distinguishing patients with pancreatic cancer from those with pancreatitis. Conclusion: SELDI profiling of serum can be used to accurately differentiate patients with pancreatic cancer from those with other pancreatic diseases and from healthy controls.