Percentage of free prostate-specific antigen in sera predicts aggressiveness of prostate cancer a decade before diagnosis.

OBJECTIVES: To evaluate serial measurements of free and total prostate-specific antigen (PSA) as a predictor of prostate cancer aggressiveness. METHODS: Twenty men diagnosed with adenocarcinoma of the prostate in the pre-PSA era had serum PSA measurements made on multiple stored frozen sera samples available for up to 18 years prior to diagnosis. Subjects were categorized as having aggressive cancer (n = 12) based on the presence of clinical Stage T3, or nodal or bone metastases (N+, M+), or pathologic positive-margin disease, or a Gleason score of 7 or greater; nonaggressive cancer (n = 8) was identified by the absence of these criteria. RESULTS: There was no statistically significant difference in free PSA levels among men with aggressive and nonaggressive prostate cancers from 0 to 15 years before diagnosis. Total PSA levels were significantly different between the groups by 5 years before diagnosis (P = 0.04). At a time when total PSA levels were not different between groups (10 years before diagnosis), there was a statistically significant difference in the percentage of free PSA between aggressive and nonaggressive cancers (P = 0.008). Among 14 men who had sera available for analysis at 10 years before diagnosis, all 8 men with aggressive cancers had a percent free PSA of 0.14 or less; this compares with only 2 of 6 men (33%) with nonaggressive cancer. CONCLUSIONS: These data suggest that the percentage of free PSA in sera is predictive of tumor behavior at a time when total PSA levels provide no information on tumor aggressiveness. Evaluation of the percentage of free serum PSA may be helpful in making the decision between expectant management and treatment for those men who are diagnosed with early prostate cancers by PSA testing.

Longitudinal analysis of serial measurements of free and total PSA among men with and without prostatic cancer.

OBJECTIVES: Evaluation of free and total serum prostate specific antigen (PSA) levels before diagnosis of prostate cancer. METHODS: Free and total PSA levels were measured on frozen sera samples of 26 men with no history of prostate disease (controls), 29 men with a histologic diagnosis of benign prostatic hyperplasia (BPH) made at simple prostatectomy (BPH cases), and 23 men with a histologic diagnosis of prostatic cancer (cancer cases). Longitudinal regression analysis was used to evaluate PSA levels as a function of years before diagnosis of prostate disease. RESULTS: On average, mean total serum PSA was statistically significantly greater for subjects with cancer (5.0 ng/mL +/- 0.9) versus BPH (2.8 ng/mL +/- 0.3) and control subjects (0.8 ng/mL +/- 0.1) by 4 years before diagnosis, whereas free PSA levels were similar among groups at 4 years before diagnosis. The ratio of free to total serum PSA continuously decreased among cancer cases over the decade before cancer diagnosis. At a time when mean total and free PSA levels were similar among groups (8 years before diagnosis), the ratio of free to total PSA was statistically significantly lower for cancer cases (0.13 +/- 0.01) compared with BPH (0.17 +/- 0.01) and control cases (0.21 +/- 0.02). Use of a free to total PSA ratio of < or = 0.12 when total PSA was between 4.0 and 10.0 ng/mL resulted in the highest sensitivity (76%) and specificity (94%) for diagnosis among subjects with and without cancer. Lowering the reflex range to 2.5 ng/mL increased false positive tests more than it increased sensitivity. CONCLUSIONS: The ratio of free to total PSA is the earliest serum marker predicting a subsequent diagnosis of prostate cancer. Measurement of the free to total serum PSA ratio would appear to reduce false positive results among men without prostate cancer.

Multicenter comparison of the diagnostic performance of free prostate-specific antigen.

OBJECTIVES: This study examined the multicenter clinical performance of noncomplexed (free) prostate-specific antigen (PSA) in men presenting with total PSA values between 2.5 to 20 ng/mL. METHODS: Prebiopsy serum samples were obtained from 1,081 consecutively accrued, histologically diagnosed men between the ages of 40 and 75 years with total PSA values falling between 2.5 and 20 ng/mL. Total PSA was determined by either the Tosoh AIA-1200 or Hybritech method. Free PSA values were determined using the Dianon PSA II immunoradiometric method. Free PSA was expressed as a percentage of total PSA. Immunochemistry was performed at each accrual site. RESULTS: Among men diagnosed with prostate cancer (CaP), only 4% (21/520) had proportions of free to total PSA values > 25%. Conversely, among men with benign prostatic disease, only 2% (13/561) had proportions of free to total PSA values < 7%. These results confirm those of previous research. Differences among sites were found in age and prostate volume. CONCLUSIONS: These data confirm that free PSA values < 7% are highly suspicious for CaP whereas free PSA values > 25% suggest absence of malignancy. The data also suggest that age and/or prostate volume influences the serum level of free PSA but does not affect the diagnostic cutoff points of 7% and 25%. Future analysis is needed to confirm that younger men with small prostates are at higher risk for CaP.

The role of free/total prostate-specific antigen ratio in the prediction of final pathologic stage for men with clinically localized prostate cancer.

OBJECTIVES: The combined use of total prostate-specific antigen (PSA), clinical stage, and Gleason score accurately predicts final pathologic stage for men with clinically localized prostate cancer. Recently, the free/ total PSA ratio has been proposed as an adjunct for early detection of prostate cancer. We examined the association between free/total PSA and pathologic stage. METHODS: In a prospective study, 301 consecutive men with clinically localized prostate cancer (average age 58.8 years, range 45-72) underwent a staging pelvic lymphadenectomy and radical prostatectomy. Total PSA and free PSA were measured from preoperative sera. Pathologic stage was determined as organ-confined (OC, n = 169), capsular penetration (CP+, n = 108), seminal vesicle involvement (SV+, n = 13) and lymph node involvement (LN+, n = 11). RESULTS: Overall, 292/301 (97%) of the free/total PSA values were < 25%, and thus suspicious for prostate cancer. Combination of total PSA, Gleason score, and clinical stage predicted well OC (P = 0.00001) and LN+ (P = 0.023); whereas, replacing total PSA with free/total PSA ratio did not improve the prediction of OC (P = 0.0007) nor LN+ (P = 0.03). CONCLUSIONS: The free/total PSA ratio cutoff point of 25% had high sensitivity for prostate cancer among a group of men with clinically localized disease. The free/total PSA ratio did not significantly improve the prediction of pathologic stage provided by total PSA when used alone or in combination with Gleason score and clinical stage. These preliminary data demonstrate that free/total PSA levels provide no additional information for pathologic stage prediction when combined with Gleason score and clinical stage in men with clinically localized prostate cancer.

Reverse transcriptase-polymerase chain reaction for prostate-specific antigen may be a prognostic indicator in breast cancer.

Among women with node-negative breast cancer and small tumours, it is important to identify those with tumours that will recur, so that they may receive adjuvant therapy, while sparing those with tumours that will not recur the hazards of adjuvant treatment. A reverse transcriptase-polymerase chain reaction (RT-PCR) for prostate-specific antigen (PSA) may be used to identify circulating metastatic cells in patients with prostate cancer. Approximately 30% of breast cancer cells also produce PSA. Therefore, we tested the PSA RT-PCR assay on blood specimens from women with breast cancer. We evaluated 78 women at Mount Sinai Medical Center with histologically confirmed breast cancer. Venous blood (5 cm3) from the women was collected in ethylene diaminetetraacetic acid (EDTA)-treated collection tubes and approximately 400 ng of RNA from each sample was subjected to an RT-PCR. We were able to detect the amplified PSA fragment in 18 of 78 women with breast cancer; 7 of the 18 women with the PSA fragment had localised, small, node-negative tumours, both oestrogen receptor (ER) positive and ER negative. We could not detect the amplified PSA fragment in 20 normal women and 22 normal men. We conclude that PSA RT-PCR may be a useful method for determining the presence of circulating metastatic cells in some women with node-negative breast cancer, and therefore the potential for these women to develop recurrent disease and thus benefit from adjuvant therapy.

Using proportions of free to total prostate-specific antigen, age, and total prostate-specific antigen to predict the probability of prostate cancer.

OBJECTIVES: This study was undertaken to define the probability of prostate cancer as a function of the proportion of free to total prostate-specific antigen (FTPSA), total PSA, and age for those patients with total PSA levels between 2.5 and 20.0 ng/mL. METHODS: Prebiopsy serums were obtained from 428 untreated patients (165 malignant, 263 benign) who had undergone sextant six-core biopsy. Each patient had no prior history of prostate cancer and a prebiopsy total PSA value between 2.5 and 20.0 ng/mL. Total PSA levels were determined using the PA immunoassay performed on the TOSOH AIA-1200 automated immunoassay instrument. Free PSA levels were determined using a monoclonal-polyclonal antibody sandwich radioimmunoassay. RESULTS: In men with total PSA values between 2.5 and 20.0 ng/mL, the FTPSA significantly differentiated between patients with benign and malignant histologic states. Log linear modeling indicated distinct differences in the risk for cancer as a function of FTPSA, total PSA, and age. The highest probability for cancer was observed in men greater than 70 years of age who had a FTPSA less than 7% and total PSA more than 10.0 ng/mL. Conversely, the lowest probability for cancer was observed in patients less than 60 years of age who had a FTPSA more than 25% and a total PSA less than 4 ng/mL. CONCLUSIONS: The probability that prostate cancer will be found on biopsy has a marked gradient that is associated with age, total PSA, and FTPSA. The extreme ends of FTPSA of less than 7% and more than 25% are diagnostic for prostate cancer and benign prostatic disease, respectively.

Breast cancer and family history: levels of lipid-associated sialic acid in plasma and absent family history of breast cancer in women who have breast tumors.

BACKGROUND: Breast cancer has a strong genetic component, and at least two breast cancer genes exist. But these genes probably play little role in most breast cancers. Other factors, such as environmental estrogens and diet, may cause the genetic changes involved in the genesis of sporadic breast cancer. A method of observing genetic changes indirectly might be to measure tumor markers known to be associated with breast cancer. METHODS: We measured, by biochemical extraction and partition, lipid-associated sialic acid in plasma (LASA-P), a circulating tumor marker, in a group of 239 women with benign or malignant breast tumors. RESULTS: The concentration of LASA-P was elevated in women with both benign and malignant tumors and no family history of breast cancer (p = 0.046, one-way ANOVA). Because LASA-P levels rise with age and number of pregnancies, we analyzed our data using multiple linear regression. Benign versus malignant character of the tumor, family history of breast cancer, number of pregnancies, and age were the independent variables. Family history of breast cancer had a significant effect on LASA-P levels (p = 0.0146) independent of the effects of age (p = 0.011), number of pregnancies (0.012), and whether the tumor was benign or malignant (p = 0.31). CONCLUSIONS: We hypothesize that elevated LASA-P in women with breast tumors and no family history of breast cancer is a result of the genetic changes occurring in nonfamilial breast cancer. These genetic changes, possibly related to environmental estrogens or other environmental factors, are distinct from the changes due to mutations of BRCA1 or other familial breast cancer genes. Moreover, the elevation of LASA-P suggests that the surface membranes of breast cancer may differ in composition. Further study may lead to exact characterization of the genetic and cell membrane changes associated with familial and nonfamilial breast tumors, and perhaps to better methods of breast cancer prevention and treatment.

Measurement of the proportion of free to total prostate-specific antigen improves diagnostic performance of prostate-specific antigen in the diagnostic gray zone of total prostate-specific antigen.

OBJECTIVES: This study examined the clinical significance of non-complexed (free) prostate-specific antigen (PSA) in the differential diagnosis of prostate cancer with an emphasis on patients with total PSA values between 4.0 and 10.0 ng/mL (the diagnostic gray zone). METHODS: Serum samples were obtained from three specimen banks. Patient samples consisted of 55 untreated histologically confirmed primary cancer, 62 men with untreated benign prostatic disease histologically confirmed by 6 negative sextant biopsies, and 64 asymptomatic healthy male controls with normal digital rectal examinations and PSA values less than 4.0 ng/mL. All patients were between the ages of 50 and 75 years. Total PSA levels were determined using the PA immunoassay performed on the TOSOH AIA-1200 automated immunoassay instrument. Free PSA levels were determined using a monoclonal-polyclonal antibody sandwich radioimmunoassay. The proportion of free to total PSA was calculated by dividing the patient's free PSA value by the total PSA value. RESULTS: When all subjects were included, both total PSA and the proportion of free to total PSA significantly differentiated between patients with prostate cancer and patients with benign histologic conditions (P < 0.0001). However, in men with total PSA values between 4.0 and 10.0 ng/mL, the proportion of free to total PSA significantly differentiated between patients with benign and malignant histologic conditions (P = 0.0004), whereas the total PSA did not (P = 0.13). Among this subgroup of patients, the analysis of sensitivity and specificity showed that the proportion of free to total PSA had a clearly higher specificity compared with that of the total PSA at the same level of sensitivity. CONCLUSIONS: Measurement of the free PSA level in a patient's serum and calculation of the proportion of free to total PSA enhances the ability to distinguish benign histologic conditions from cancer while retaining high sensitivity for detecting cancer in men who present with total PSA levels between 4.0 and 10.0 ng/mL. A large-scale population-based study is currently in progress to confirm this preliminary finding.

Measurement of ferritin-bearing peripheral mononuclear blood cells in cancer patients by radioimmunoassay.

A radioimmunoassay has been developed to measure ferritin bound to the surface of isolated human peripheral blood mononuclear white blood cells (PBMs) in order to investigate the possible relationship of this phenomenon to breast and other forms of cancer. The assay measures the specific binding (%SP) of affinity-purified 125I-labeled rabbit anti-Hodgkin's spleen ferritin antibody to isolated patient PBMs. A preliminary prospective, preclinical trial on 300 patients was run which included: (a) normals, benign breast disease, and medical/surgical patients as non-cancer controls; (b) postoperative primary cancer and advanced cancer in clinical remission as post cancer controls; and (c) both early preoperative breast cancer patients and cancer patients with localized recurrences or active disseminated disease as test groups. The mean %SP for the non-cancer control groups was in the range of 4.3 to 5.1 (n = 187), which was identical to that for inactive cancer or postoperative cancer, which was no evidence of recurrence. Using a %SP normal cutoff level of 6.5, which resulted in a false-positive rate of approximately 10% for both non-cancer and post-cancer control groups, only 27% of early preoperative cancers (n = 22) gave elevated %SP values. These results suggest that measurement of ferritin-PBM is inappropriate for early disease diagnosis. In contrast, 91% of patients with advanced active breast cancer and 73% of those patients with other types of advanced cancers, including tumors of ovarian, lung, colon or esophageal origin, showed elevated %SP values more than double those of post-cancer controls. The mean %SP value in active advanced cancer was 10.8 for breast (n = 12) and 10.6 for all other solid tumors investigated (n = 34). Paired patient comparisons of ferritin-PBM and plasma carcinoembryonic antigen in breast cancer showed elevations in 91% of the patients for ferritin-PBM and 67% for carcinoembryonic antigen. Overall, these results suggest that patients with advanced cancer display elevated levels of ferritin on the surface of their PBMs and that this measurement may be a useful adjunct in monitoring and evaluating the clinical status of cancer patients.

Hysteresis heating for the treatment of tumours.

A method is described whereby, utilising a biocompatible magnetic glass-ceramic material, effective hysteresis heating in living tissue was accomplished. Initial experiments on mice showed that a significant heating effect can be obtained in the ceramic-impregnated regions. An analysis is also given for the projected safe operating field-frequency regime of the hysteresis therapy.

Characteristics of a specific radioimmunoassay for measurement of ferritin on the surface of peripheral mononuclear white blood cells in cancer patients.

Using 125I-labeled rabbit anti-Hodgkin's spleen ferritin antibody (RHF), a simple radioimmunoassay has been developed for quantitation of ferritin on the surface of peripheral blood mononuclear white blood cells (PBM). This method makes use of a % specific binding determination (%SP) by measuring the amount of 125I-labeled RHF bound to 1 X 10(6) PBM in the presence and absence of soluble ferritin. To standardize this procedure, artificial ferritin positive control cells were prepared by covalently coupling ferritin to cultured acute lymphoblastic leukemia cells. These cells were tested on a daily basis in parallel with patient PBM's to ensure inter and intra-assay precision and remained stable for over two years. Characteristics of 125I-labeled RHF binding to control and patient PBM's were evaluated to determine the specificity of interaction and optimum binding parameters. %SP was linear in the range of 1 X 10(5) - 1 X 10(6) PBM's and was progressively inhibited by graded concentrations of soluble ferritin. F(ab')2 preparations of RHF were equally as effective as intact RHF in blocking 125I-labeled RHF binding confirming that 125I-labeled RHF was not binding non-specifically to PBM Fc receptors. Additional experiments describing kinetics and methods of standardization of new lots of 125I-labeled RHF are also described.

Glass-ceramic-mediated, magnetic-field-induced localized hyperthermia: response of a murine mammary carcinoma.

Hyperthermia has been found to be a useful modality for cancer therapy. In this report, a biocompatible, ferrimagnetic glass-ceramic capable of inducing localized hyperthermia by hysteresis heating upon exposure to an alternating magnetic field is presented. When the glass-ceramic was placed in the region of a subcutaneously transplanted, weakly antigenic breast carcinoma and subjected to the magnetic field, sufficient temperature rise was obtained to cause significant (approximately 50%) tumor regrowth delay and a 12% permanent control. The data demonstrate that glass-ceramic-mediated hysteresis heating may be a useful therapeutic approach in the treatment of cancer which offers the advantage of producing a highly localized and predictable tumor volume hyperthermia.

Separation of bovine spermatozoa by density on water insoluble Newtonian gels and their use for insemination.

Bovine spermatozoa were separated into different density subpopulations utilizing water insoluble hydrocarbon and silicone gels of defined specific gravity. Sperm density profiles were generated for 13 bulls. The separations were found to be repeatable and characteristic of the bull examined. Considerable density variation among animals was demonstrated. Analysis of the separated spermatozoa, before and after freezing, demonstrated that good motility and acrosomal integrity of spermatozoa were maintained. When the least dense fraction of spermatozoa was used for insemination, conception rates were similar to those obtained routinely by artificial insemination with unfractionated spermatozoa. Therefore, this system may be useful in separating spermatozoa of various densities and for removing extraneous matter from semen. However, the sex ratio, among 51 60-day-old fetuses recovered from heifers inseminated with the lowest density fraction of spermatozoa, was 26 males:25 females.

Immunogenicity of random polymers of l-glutamic acid, l-alanine and l-tyrosine in inbred hamsters.

The random terpolymer GAT has been found to be immunogenic in hamsters whereas the random copolymers GA or GT were found to be nonimmunogenic. Although no immune responses to GA or GT could be elicited, the anti-GAT antibody response contained populations inhibited specifically by GA, GT and poly-G. These data suggest that in hamsters, recognition of GAT occurs via determinants which are not present in GA or GT.

Genetic control of the immune response in rats to the known sequential polypeptide (Tyr-Glu-Ala-Gly)n. I. Antibody responses.

In inbred rats, the antibody response to the known sequential polypeptide (Tyr-Glu-Ala-Gly)n (T-G-A-Gly)n is under the control of two independently assorting loci; (co) dominant, Ag-B-linked Ir-(T-G-A-Gly) I, controlling qualitative responsivenss, and a non-Ag-B-linked modifier locus termed Ir-(T-G-A-Gly) II, controlling the level of antibody produced. The antibody response to (T-G-A-Gly)n was solely IgG and the level of antibody produced was dependent upon Ir-(T-G-A-Gly) II for phenotypic response type.