Peter S. Bunting

Feasibility study : watchful waiting for localized low to intermediate grade prostate carcinoma with selective delayed intervention based on prostate specific antigen, histological and/or clinical progression

PURPOSE We assessed the feasibility of a watchful waiting protocol with selective delayed intervention using clinical, prostate specific antigen (PSA) or histological progression as treatment indications for clinically localized prostate cancer. MATERIALS AND METHODS In this prospective, single arm cohort study patients with favorable clinical parameters (stage T1b to T2b N0M0, Gleason score 7 or less and PSA 15 ng./ml. or less) are conservatively treated with watchful waiting. When a patient meets disease progression criteria, arbitrarily defined by the 3 parameters of the rate of PSA increase, clinical progression or histological upgrade on repeat prostate biopsy, appropriate treatment is implemented. Patients are followed every 3 months for the first 2 years and every 6 months thereafter. Serum PSA measurement and digital rectal examination are done at each visit and repeat prostate biopsy is performed 18 months after study enrollment. RESULTS Since November 1995, the study has accrued 206 patients with a median followup of 29 months (range 2 to 66). Of these men 137 remain on the surveillance protocol with no disease progression, while 69 were withdrawn from study for various reasons. There was clinical, PSA and histological progression in 16, 15 and 5 cases, respectively. The estimated actuarial probability of remaining on the surveillance protocol was 67% at 2 years and 48% at 4. The probability of remaining progression-free was 81% and 67% at 2 and 4 years, respectively. CONCLUSIONS A policy of watchful waiting with selectively delayed intervention based on predefined criteria of disease progression is feasible. This strategy offers the benefit of an individualized approach based on the demonstrated risk of clinical or biochemical progression with time and, thus, it may decrease the burden of therapy in patients with indolent disease, while providing definitive therapy for those with biologically active disease.

Human kallikrein 6 (zyme/protease M/neurosin): a new serum biomarker of ovarian carcinoma

BACKGROUND There is an urgent need for discovery and validation of new serum biomarkers for ovarian carcinoma. Early diagnosis of ovarian cancer with serologic analysis may improve clinical outcomes through administration of effective treatment. Human kallikrein 6 (hK6, encoded by the KLK6 gene) is a serine protease of the kallikrein gene family. Recently, we were able to develop an immunofluorometric procedure for the quantitative measurement of hK6 in biologic fluids, including serum. METHODS We have used an hK6-specific immunofluorometric assay to quantify hK6 protein in a large number of serum samples from normal individuals, as well as from patients with various malignancies. RESULTS We report for the first time, significant increase of serum hK6 concentration in a large proportion of patients with ovarian carcinoma. The elevations of hK6 appear to be relatively specific for ovarian cancer because other malignancies did not cause any increase in the concentration of this biomarker in serum. Serial hK6 measurements appear to correlate with CA125 levels in patients monitored postsurgery. CONCLUSIONS This is the first report describing significant elevations of hK6 concentration in serum of ovarian cancer patients. These data suggest that hK6 may represent a potential new biomarker for diagnosis and monitoring of ovarian carcinoma.

Human kallikrein 10: a novel tumor marker for ovarian carcinoma?

BACKGROUND Human kallikrein 10 (hK10, encoded by KLK10 gene) is a recently discovered member of the human kallikrein family. hK10 is a secreted serine protease. With the development of a highly sensitive and specific immunoassay for hK10, quantification of hK10 in the circulation is now feasible. Our aim was to investigate whether hK10 concentration in serum changes in various malignancies. METHODS We used a highly specific and sensitive immunofluorometric assay to quantify hK10 protein in 374 serum samples from healthy individuals and patients with various malignancies. RESULTS Serum hK10 concentration was found to be significantly elevated in 56% of the ovarian cancer patients and such an increase was not observed in serum of healthy individuals or in serum of patients with other types of cancer, with the exception of approximately 15% of patients with gastrointestinal cancer. This hK10 elevation does not correlate well with CA 125. We have further demonstrated that hK10 concentration changes during ovarian cancer progression. CONCLUSION This is the first report describing that hK10 serum concentration is significantly elevated in the majority of ovarian cancer patients. Our results indicate that hK10 may be a potential new serological marker for ovarian cancer diagnosis and monitoring.

PSA doubling time of prostate carcinoma managed with watchful observation alone

PURPOSE To study prostate-specific antigen (PSA) doubling time of untreated, favorable grade, prostate carcinoma. METHODS AND MATERIALS A prospective single-arm cohort study has been in progress to assess the feasibility of a watchful observation protocol with selective delayed intervention using clinical, histologic, or PSA progression as treatment indication in untreated, localized, favorable grade prostate adenocarcinoma (T1b-T2bN0 M0, Gleason Score < or = 7, and PSA < or = 15 ng/mL). Patients are conservatively managed with watchful observation alone, as long as they do not meet the arbitrarily defined disease progression criteria. Patients are followed regularly and undergo blood tests including PSA at each visit. PSA doubling time (Td) is estimated from a linear regression of ln(PSA) on time, assuming a simple exponential growth model. RESULTS As of March 2000, 134 patients have been on the study for a minimum of 12 months (median, 24; range, 12-52) and have a median frequency of PSA measurement of 7 times (range, 3-15). Median age is 70 years. Median PSA at enrollment is 6.3 (range, 0.5-14.6). The distribution of Td is as follows: <2 years, 19 patients; 2-5 years, 46; 5-10 years, 25; 10-20 years, 11; 20-50 years, 6; > 50 years, 27. The median Td is 5.1 years. In 44 patients (33%), Td is greater than 10 years. There was no correlation between Td and patient age, clinical T stage, Gleason score, or initial PSA level. CONCLUSION Td of untreated prostate cancer varies widely. In our cohort, 33% have Td > 10 years. Td may be a useful tool to guide treatment intervention for patients managed conservatively with watchful observation alone.

A guide to the interpretation of serum prostate specific antigen levels

OBJECTIVE To review the factors that affect the concentration of prostate specific antigen (PSA) in the serum. RESULTS The discussion includes the structure of PSA; its distribution and metabolism; various analytical aspects of PSA measurements; the effects of clinical manipulations on PSA, including digital rectal examination, transrectal ultrasound, cystoscopy, biopsy and transurethral resection of the prostate; factors affecting PSA levels in health, in benign disease, and in prostate cancer; the effect of various treatments on PSA; and the issue of reference ranges. CONCLUSION Laboratory staff and physicians must take many factors into consideration when interpreting PSA results.

Variability in the pharmacokinetics of cyclophosphamide, methotrexate and 5-fluorouracil in women receiving adjuvant treatment for breast cancer

A total of 23 women with stage II breast cancer receiving adjuvant cyclophosphamide, methotrexate and 5-fluorouracil had detailed pharmacokinetic monitoring performed on the first and third courses of therapy. The area under the concentration time curve (AUC) of each of these three drugs varied by a factor of 3–4 among patients. No systematic change in pharmacokinetics between the first and third courses was seen for cyclophosphamide, methotrexate or 5-fluorouracil, and the mean AUC for each of the three drugs did not change. However, significant intrapatient variability in drug pharmacokinetics was observed for all three drugs such that the AUC, clearance and half-life in an individual on the third course could not be reliably predicted from data generated on the first course. On the basis of these results, cyclophosphamide, methotrexate, and 5-fluorouracil pharmacokinetic data from one treatment would not be useful information from which the doses for subsequent courses could be determined.

Intraindividual variation of PSA, free PSA and complexed PSA in a cohort of patients with prostate cancer managed with watchful observation

OBJECTIVE To determine the intraindividual variation of prostate-specific antigen (PSA) isoforms in prostate cancer patients managed conservatively with watchful observation. METHODS Patients with favorable clinical parameters (stage T1b-T2b N0 M0, Gleason score </= 7, and PSA </= 15) were recruited to participate in a watchful observation program. Specimens were drawn for measurement of total (tPSA), free (fPSA) and complexed (cPSA) prostate-specific antigen isoforms. Total biologic variation and between-day analytical variation were used to calculate intraindividual variation. RESULTS Total variation for each isoform and two ratios were not greatly affected by the time window for measurements in the interval 6 months to 2.7 yr. Analytical variation made only a small contribution to the total biologic variation. Intraindividual variation for a 1-yr time interval for tPSA, fPSA, cPSA and the ratios of fPSA and cPSA to tPSA was, respectively, 21.6, 19.3, 25.4, 20.0 and 13.1%. The amount of change required for a significant difference between two readings (with 95% confidence) was, respectively, 59.8, 53.4, 70.4, 55.3 and 36.2%. CONCLUSIONS There is a significantly higher intraindividual variation of cPSA (25.4%), and a significantly lower intraindividual variation of the ratio cPSA to tPSA (13.1%) compared to the other individual PSA isoforms and to the ratio of fPSA to tPSA. The amount of change required for a significant difference between two concentrations is large for all variables studied, but the lowest is the ratio of cPSA to tPSA (36.2%). These results have significance for diagnosis and monitoring of patients with prostate cancer.

Development and validation of a limited sampling strategy for 5-fluorouracil given by bolus intravenous administration

A wide range of interindividual variability of 5-fluorouracil (5-FU) pharmacokinetics exists after bolus administration. The degree to which this variability in 5-FU exposure impacts upon the response and toxicity of the drug has not been determined. The area under the concentration time curve (AUC) is a commonly used indicator of exposure, but normally requires the collection of 8–10 timed blood samples after i.v. bolus administration. This presents difficulties if large-scale population samplings are required. This study involved the development and testing of a strategy to estimate AUC from a limited number of blood samples in patients with gastrointestinal and breast cancer. The optimal single time point for AUC estimation was 0.17 h (r2 = 0.954). Addition of the 0.75 h time point significantly improved predictability (r2 = 0.983). Addition of a third or fourth time point did not provide further benefit. These models were then tested separately in a group of women who received a higher dose of 5-FU. The two data points model performed significantly better than the single time point model (r2 = 0.70 and 0.85, respectively). The AUC of standard dose 5-FU after bolus administration can be reliably estimated from two timed samples taken 10 and 45 min after injection.

A rapid sensitive method for accurate analysis of individual bile acids in biological fluids by high performance thin layer chromatography and densitometry

1. A rapid new micromethod for quantitative analysis of individual bile acids in duodenal juice by high performance thin-layer chromatography (HPTLC) and densitometry is described and evaluated by comparison with standard TLC and spectrophotometry. 2. Advantages of HPTLC over TLC include more rapid separation, better resolution and more sensitive detection (5 - 10 fold), without the need for prior extraction. Densitometry provides simple, direct and rapid quantitation. 3. The method is accurate and reliable over a range of bile acid concentrations. In the 0.5 mM range, recovery was greater than 89%, and coefficients of variation for within-day analysis were 2 - 12% and for between-day analysis were 6 - 18% for the individual bile acids. Twenty analyses can be performed by one worker in a single day. 4. We conclude that the method offers several advantages over most currently described techniques, is suitable for routine use and is deserving of wider application.

Diagnostic aspects of angiotensin converting enzyme in pulmonary sarcoidosis

Angiotensin converting enzyme (ACE) has been measured in 102 biopsy-proven sarcoid patients, 70 patients diagnosed by clinical and radiological methods and 74 nonsarcoid patients as controls. The distributions of the various groups have been examined, and the effects of stage of disease, disease activity and prednisone treatment have been evaluated. Receiver operating characteristic (ROC) curves have been established for ACE, and the appropriateness of various statistical procedures is discussed. We have not discerned any effect of stage of sarcoidosis or of extent of disease activity on ACE values. The ROC curves suggest an upper limit of normal of about 50 U/L for our assay, and a sensitivity of 63% and specificity of 93%, yielding predictive values of 93% for a positive result and 74% for a negative result, with a likelihood ratio of 3.6. The results are discussed in the context of other work on ACE and in relation to the more invasive procedures of bronchoalveolar lavage and Gallium scan.