Lori J. Sokoll

Circulating mutant DNA to assess tumor dynamics

The measurement of circulating nucleic acids has transformed the management of chronic viral infections such as HIV. The development of analogous markers for individuals with cancer could similarly enhance the management of their disease. DNA containing somatic mutations is highly tumor specific and thus, in theory, can provide optimum markers. However, the number of circulating mutant gene fragments is small compared to the number of normal circulating DNA fragments, making it difficult to detect and quantify them with the sensitivity required for meaningful clinical use. In this study, we applied a highly sensitive approach to quantify circulating tumor DNA (ctDNA) in 162 plasma samples from 18 subjects undergoing multimodality therapy for colorectal cancer. We found that ctDNA measurements could be used to reliably monitor tumor dynamics in subjects with cancer who were undergoing surgery or chemotherapy. We suggest that this personalized genetic approach could be generally applied to individuals with other types of cancer (pages 914–915).

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.

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.

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.

Human Immunodeficiency Virus Load in Breast Milk, Mastitis, and Mother-to-Child Transmission of Human Immunodeficiency Virus Type 1

Human immunodeficiency virus (HIV) type 1 load in breast milk and mastitis were examined as risk factors for vertical transmission of HIV-1. Six weeks after delivery, HIV-1 load and sodium (an indicator of mastitis) were measured in breast milk from 334 HIV-1-infected women in Malawi. Median breast milk HIV-1 load was 700 copies/mL among women with HIV-1-infected infants versus undetectable (<200 copies/mL) among those with uninfected infants, respectively (P<. 0001). Elevated breast milk sodium levels consistent with mastitis occurred in 16.4% of HIV-1-infected women and were associated with increased vertical transmission of HIV-1 (P<.0001). Median breast milk HIV-1 load was 920 copies/mL among women with versus undetectable among those without elevated breast milk sodium levels, respectively (P<.0001). Mastitis and breast milk HIV-1 load may increase the risk of vertical transmission of HIV-1 through breast-feeding.

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.

One Hundred Consecutive Minimally Invasive Parathyroid Explorations

ObjectiveTo review the outcomes of 100 consecutive minimally invasive parathyroid explorations. Summary Background DataMinimally invasive parathyroidectomy (MIP) has challenged the traditional approach of bilateral neck exploration for patients with primary hyperparathyroidism. Most patients with primary hyperparathyroidism have a single adenoma that when resected results in cure. It therefore appears logical to perform a directed approach to adenoma extirpation. MIP involves high-quality sestamibi images obtained with single photon emission computed tomography to localize enlarged parathyroid glands in three dimensions, limited exploration after surgeon-administered cervical block anesthesia, rapid intraoperative parathyroid hormone assay to confirm the adequacy of resection, and discharge within 1 to 3 hours of surgery. MethodsMIP was offered to 100 selected consecutive patients during an 18-month period beginning in March 1998. ResultsNinety-two cases were accomplished under cervical block anesthesia and 89 of these on an ambulatory basis. The cure rate was 100%, and there were no long-term complications. The mean hospital charge for MIP was less than 40% of that associated with traditional exploration. ConclusionsOutpatient MIP appears to be the procedure of choice for most patients with primary hyperparathyroidism.

A multicenter study of [-2]pro-prostate specific antigen combined with prostate specific antigen and free prostate specific antigen for prostate cancer detection in the 2.0 to 10.0 ng/ml prostate specific antigen range

PURPOSE Prostate specific antigen and free prostate specific antigen have limited specificity to detect clinically significant, curable prostate cancer, leading to unnecessary biopsy, and detection and treatment of some indolent tumors. Specificity to detect clinically significant prostate cancer may be improved by [-2]pro-prostate specific antigen. We evaluated [-2]pro-prostate specific antigen, free prostate specific antigen and prostate specific antigen using the formula, ([-2]pro-prostate specific antigen/free prostate specific antigen × prostate specific antigen(1/2)) to enhance specificity to detect overall and high grade prostate cancer. MATERIALS AND METHODS We enrolled 892 men with no history of prostate cancer, normal rectal examination, prostate specific antigen 2 to 10 ng/ml and 6-core or greater prostate biopsy in a prospective multi-institutional trial. We examined the relationship of serum prostate specific antigen, free-to-total prostate specific antigen and the prostate health index with biopsy results. Primary end points were specificity and AUC using the prostate health index to detect overall and Gleason 7 or greater prostate cancer on biopsy compared with those of free-to-total prostate specific antigen. RESULTS In the 2 to 10 ng/ml prostate specific antigen range at 80% to 95% sensitivity the specificity and AUC (0.703) of the prostate health index exceeded those of prostate specific antigen and free-to-total prostate specific antigen. An increasing prostate health index was associated with a 4.7-fold increased risk of prostate cancer and a 1.61-fold increased risk of Gleason score greater than or equal to 4 + 3 = 7 disease on biopsy. The AUC of the index exceeded that of free-to-total prostate specific antigen (0.724 vs 0.670) to discriminate prostate cancer with Gleason 4 or greater + 3 from lower grade disease or negative biopsy. Prostate health index results were not associated with age and prostate volume. CONCLUSIONS The prostate health index may be useful in prostate cancer screening to decrease unnecessary biopsy in men 50 years old or older with prostate specific antigen 2 to 10 ng/ml and negative digital rectal examination with minimal loss in sensitivity.

Plasma selenium level before diagnosis and the risk of prostate cancer development.

PURPOSE Epidemiological studies and a randomized intervention trial suggest that the risk of prostate cancer may be reduced by selenium intake. We investigated whether plasma selenium level before diagnosis correlated with the risk of later developing prostate cancer. MATERIALS AND METHODS A case control study was performed on men from the Baltimore Longitudinal Study of Aging registry, including 52 with known prostate cancer and 96 age matched controls with no detectable prostatic disease. Plasma selenium was measured at an average time plus or minus standard deviation of 3.83 +/- 1.85 years before the diagnosis of prostate cancer by graphite furnace atomic absorption spectrophotometry. Adjusted odds ratio and 95% confidence interval were computed with logistic regression. RESULTS After correcting for years before diagnosis, body mass index, and smoking and alcohol use history, higher selenium was associated with a lower risk of prostate cancer. Compared with the lowest quartile of selenium (range 8.2 to 10.7 microg./dl.), the odds ratios of the second (10.8 to 11.8), third (11.9 to 13.2) and fourth (13.3 to 18.2) quartiles were 0.15 (95% confidence interval 0.05 to 0.50), 0.21 (0.07 to 0.68) and 0.24 (0.08 to 0.77, respectively, p =0.01). Furthermore, plasma selenium decreased significantly with patient age (p <0.001). CONCLUSIONS Low plasma selenium is associated with a 4 to 5-fold increased risk of prostate cancer. These results support the hypothesis that supplemental selenium may reduce the risk of prostate cancer. Because plasma selenium decreases with patient age, supplementation may be particularly beneficial to older men.

Proteomic Approaches to Tumor Marker Discovery

CONTEXT Current tumor markers for ovarian cancer still lack adequate sensitivity and specificity to be applicable in large populations. High-throughput proteomic profiling and bioinformatics tools allow for the rapid screening of a large number of potential biomarkers in serum, plasma, or other body fluids. OBJECTIVE To determine whether protein profiles of plasma can be used to identify potential biomarkers that improve the detection of ovarian cancer. DESIGN We analyzed plasma samples that had been collected between 1998 and 2001 from patients with sporadic ovarian serous neoplasms before tumor resection at various International Federation of Gynecology and Obstetrics stages (stage I [n = 11], stage II [n = 3], and stage III [n = 29]) and from women without known neoplastic disease (n = 38) using proteomic profiling and bioinformatics. We compared results between the patients with and without cancer and evaluated their discriminatory performance against that of the cancer antigen 125 (CA125) tumor marker. RESULTS We selected 7 biomarkers based on their collective contribution to the separation of the 2 patient groups. Among them, we further purified and subsequently identified 3 biomarkers. Individually, the biomarkers did not perform better than CA125. However, a combination of 4 of the biomarkers significantly improved performance (P < or =.001). The new biomarkers were complementary to CA125. At a fixed specificity of 94%, an index combining 2 of the biomarkers and CA125 achieves a sensitivity of 94% (95% confidence interval, 85%-100.0%) in contrast to a sensitivity of 81% (95% confidence interval, 68%-95%) for CA125 alone. CONCLUSIONS The combined use of bioinformatics tools and proteomic profiling provides an effective approach to screen for potential tumor markers. Comparison of plasma profiles from patients with and without known ovarian cancer uncovered a panel of potential biomarkers for detection of ovarian cancer with discriminatory power complementary to that of CA125. Additional studies are required to further validate these biomarkers.