Radioimmunochemical measurement of bone marrow prostatic acid phosphatase

Acid phosphatase in prostatic tissue homogenates from patients with benign prostatic hyperplasia and prostatic carcinoma

Acid phosphatase activity biochemically in the primary tumor of 20 patients with prostatic carcinoma, was studied in an attempt to understand the basis for a correlation or lack of correlation between serum and/or bone marrow acid phosphatase levels and the presence and/or clinical behavior of prostatic carcinoma. The enzyme activity was similarly measured in 19 patients with benign prostatic hyperplasia as controls. On the average, enzyme activities were lower (P less than 0.002) in the tissues from patients with carcinoma. There was no correlation of enzyme activity in tumor with the age of the patient, stage of disease, degree of differentiation of the tumor, or serum acid phosphatase activity.

Radioimmunoassayable prostate-specific acid phosphatase in peripheral and bone marrow sera compared in diagnosis of prostatic cancer patients

Measurements of human prostate-specific acid phosphatase by radioimmunoassay in peripheral and bone marrow sera were compared. We studied 20 patients with benign prostatic hyperplasia, 27 with untreated prostatic cancer without bone metastases and 11 with metastases, in addition to 7 with cancer treated by hormonal therapy. The prostate-specific acid phosphatase concentrations in peripheral and bone marrow serum samples were equal and did not exceed the upper limit of our health-associated reference interval, 2.8 microgram. per 1. (mean plus 2 standard deviations) in patients with prostatic hyperplasia. Of 27 prostatic cancer patients without bone metastases the concentration of prostate-specific acid phosphatase was elevated in the peripheral sera of 20 and in the bone marrow sera of 21, and 21 had an extracapsular tumor (stage T3 to T4). Prostate-specific acid phosphatase concentrations were elevated in peripheral and bone marrow serum specimens of all 11 patients with metastases and bone marrow cytology studies were positive in 2. There was no difference in prostate-specific acid phosphatase concentrations in peripheral and bone marrow serum specimens from prostatic cancer patients undergoing hormonal treatment. We conclude that the use of bone marrow serum for the measurement of radioimmunoassayable prostate-specific acid phosphatase in prostatic cancer patients does not provide any further information in regard to the detection of prostatic cancer compared to the use of peripheral serum specimens. Falsely positive findings in bone marrow specimens were not observed with the method used.

Serum and bone marrow radioimmunoassay of acid phosphatase in prostatic cancer

Use of radioimmunoassay (RIA) for determinations of prostatic acid phosphatase has recently received considerable attention because of reported higher sensitivity and specificity than previous enzymatic assays. We have compared the sensitivity and specificity of a commercially available RIA to a highly specific enzymatic assay (thymolphthalein monophosphate) using 37 patients with prostatic cancer and 34 patients with surgically proved benign prostatic hyperplasia. Seventeen of the cancer patients and all 34 of the BPH patients were studied prospectively. We further evaluated specificity by performing the RIA on 25 specimens of bone marrow from patients with nonprostatic disease. Our results indicate the radioimmunoassay is not, at this time, an adequate screening tool, and we question its accuracy in staging patients anymore reliably than by enzymatic assay.

Bone marrow acid phosphatase by radioimmunoassay: 3 years of experience

Clinical followup of 112 patients staged by the immunochemical determination of prostatic acid phosphatase from bone marrow aspirates is presented. This represents a 94 per cent (112 of 118) retrieval rate of a group studied more than 2 years previously. Of the 11 patients judged to be at high risk 4 (36 per cent) have suffered bony metastases, whereas only 3 of 86 patients (3 per cent) with normal bone marrow acid phosphatase by radioimmunoassay have done so. An additional 184 patients with carcinoma and 77 controls have been studied. Although radioimmunoassay greatly improves specificity in bone marrow aspirates a few falsely positive results can occur. This finding may be secondary to cross reaction from leukocyte acid phosphatase and/or interference from lipid.

Bone marrow acid phosphatase in prostate cancer: an assessment by immunoassay and biochemical methods

Comparisons of the bone marrow and serum acid phosphatase values obtained by counter-immunelectrophoresis and the Roy biochemical test were made in 72 patients with and in 13 patients without prostatic cancer. The counter-immunoelectophoresis test, when positive at more than 1 international unit per liter, showed only 4.4 per cent falsely positive results. The Roy biochemical test, which used sodium thymolphthalein monophosphate as the substrate, had 65 per cent falsely positive bone marrow acid phosphatase levels. Conflicting reports regarding the value of bone marrow acid phosphatase determinations in patients with prostatic cancer result from the use of non-specific substrates in biochemical methods for measurement and from the trauma incidental to bone marrow aspiration, which releases many non-prostatic acid phosphatase enzymes. The use of immunoassay such as counter-immunoelectrophoresis minimizes this source of error.

Overview of past and current philosophy of prostatic cancer

Carcinoma of the prostate is the second most common cancer in men, yet no significant change in overall survival has occurred since the original description of the results of castration by Huggins and Hodges. Many important questions about the disease remain unanswered. The cause of prostatic cancer is unknown, and few specific environmental or viral agents have been linked with the tumor. Increased recognition of the importance of frequent digitial rectal examination has resulted in more tumors being diagnosed in early stages. Developments in sonography suggest that it may be useful in detecting the presence of prostatic cancer and whether extraprostatic extension has occurred. Recent inprovements in the sensitivity of prostatic acid phosphatase assays have been made, but their use as a screening tool remains limited. In patients with clinical stage B lesions that are microscopically confined to the prostate, treatment by radical prostatectomy appears to confer greatest survival. The exact role of radiotherapy remains to be defined. However, when the tumor extends beyond the prostate and is localized to the pelvis, external beam ro interstitial radiation is appropriate. Pelvic lymphadenectomy has significant morbidity, but less invasive methods of pelvic nodal evaluation are less accurate. Lymphadenectomy has not been shown to have any therapeutic effect. Whether hormonal therapy improves survival needs further investigation, and efforts must continue to develop means of predicting hormonal responsiveness. Those patients unlikely to respond to hormonal therapy should be treated with early chemotherapy.

Combined serum and bone marrow radioimmunoassays for prostatic acid phosphatase

Combined serum and bone marrow radioimmunoassays for prostatic acid phosphatase provide a unique means for the early diagnosis and more accurate clinical staging of prostatic cancer. The combined screening technique appears to be helpful, particularly in providing a clinical assessment of the presence or absence of early, subclinical lymphatic and bone marrow metastases. Low titer elevations of bone marrow prostatic acid phosphatase by radioimmunoassay have been observed commonly in clinically understaged C prostatic cancer with normal technetium bone scans, indicating the presence of unrecognized stage D disease with bone metastases. The combined screening method also is of distinct clinical value in the early diagnosis of prostatic cancer and in monitoring the effects of specific therapy. In therapeutically responsive patients marked suppression of serum and bone marrow prostatic acid phosphatase is observed regularly with the radioimmunochemical method under study.

Acid phosphatase: new developments

Acid phosphatase was the first "tumor marker" to be measured in the blood, and over 40 years have passed since an elevation of the serum acid phosphatase level was observed in patients with prostatic carcinoma. However, significant elevations in the level of this enzyme have been observed in other diseases, as well as elevations of other tissue phosphatases. Many improvements in the colorimetric technique have been introduced, but none has been used successfully to detect the tissue origin of this ubiquitous enzyme. The finding that prostatic acid phosphatase is antigenically distinct from acid phosphatase of other tissues opened a new horizon in the measurement of acid phosphatase in prostatic cancer. On the basis of this immunochemical specificity, several immunoassays have been employed for determining the prostatic acid phosphatase level.