Bone marrow acid phosphatase in staging of prostatic cancer: how reliable is it?

Bone marrow prostatic specific antigen and prostatic acid phosphatase levels: are they helpful in staging prostatic cancer?

We analyzed serum and bone marrow levels of prostatic specific antigen and prostatic acid phosphatase quantified by double antibody radioimmunoassay in 70 patients. Of the patients 36 had prostatic cancer, including 23 with metastatic disease. There was a significant correlation between the serum and bone marrow levels of prostatic specific antigen and prostatic acid phosphatase independently of the metastases (p less than 0.001). No patient with prostatic cancer and positive bone marrow prostatic specific antigen or prostatic acid phosphatase levels had normal serum levels. Quantification of bone marrow prostatic specific antigen and prostatic acid phosphatase does not provide more information than does serum determination.

Tumor markers: value and limitations in the management of cancer patients

Sixteen tumor markers are reviewed, and measured to the ideal: produced by the tumor cell alone absent in health and in benign disease present in all patients with a given malignancy level in the blood representative of tumor mass detectable in occult disease. The only marker that approaches the ideal is human chorionic gonadotropin (HCG) in gestational trophoblastic tumors. In this malignancy, the HCG level suggests the diagnosis and stage, confirms response to therapy, and predicts relapse. The three most widely used and intensely studied tumor markers are carcinoembryonic antigen (CEA), alphafetoprotein (AFP), and HCG. CEA cannot be used in screening for cancer, but in carcinoma of the colon its elevation preoperatively increases the likelihood of advanced disease and postoperative recurrence. Postoperatively, elevated titers are often but not invariably associated with recurrent disease. AFP and HCG are useful in the management of nonseminomatous germ cell testicular tumors. Like CEA, they cannot be used for screening. They are more likely to be increased with advancing stage, and after therapy rising levels almost always mean recurrent disease. Some markers are valuable in specific circumstances, such as calcitonin in screening for familial medullary carcinoma of the thyroid. In multiple myeloma, immunoglobulins are useful in determining the tumor mass and response to therapy. In neuroblastoma, catecholamine metabolites are useful primarily in making the diagnosis. In some malignancies, the absence of effective therapy lowers the value of the marker, as for AFP in hepatoma. The remaining markers are too unreliable or too little studied to be useful in the management of an individual patient with cancer. The purpose of this paper is to provide the clinician with an understanding of the limitations of the present tumor markers that will lead to wiser use of the tests, and to provide standards to which future tumor markers should be measured.

The detection and evaluation of human tumor metastases

Many biochemical indices are purported to have clinical utility in the detection and management of neoplasia. Experience gained during the past decade tends to indicate their having a more important role in the detection and monitoring of metastases than of the primary lesion. From this present review of some of the commoner human tumours, it is concluded that such marker substances are important adjuncts in the management of germ cell and certain endocrine and endocrine-related tumours. The carcinoembryonic antigen (CEA) provides a marker for many gastrointestinal cancers, but there are no presently available substances with clinical usefulness for either breast or lung neoplasms. Alternative approaches to the detection of metastases are also presented. The particular use of antibody probes at an immunohistochemical level has been claimed to be able to detect micrometastastic disease in bone marrow or tumour-related monoclonal antibody probes may have application to other cancers in the future.

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.

Immunofluorescent identification of antibodies specific for prostatic acid phosphatase

Antisera demonstrated by precipitation and passive haemagglutination to possess antibodies specific for prostatic tissue-specific acid phosphatase have been employed to localize this isoenzyme in the prostate by indirect immunofluorescence. Antisera specific for prostatic acid phosphatase may permit the immunohistological localization of this enzyme, thereby serving as a biological marker for metastatic prostatic cancer, where histological and/or clinical staging of the primary tumour remain uncertain.

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.

Immunological detection of metastases from prostatic adenocarcinoma

In six patients with known prostatic adenocarcinoma, extraprostatic (metastatic) tumor was suspected on radiographic or radionucleotide studies. When cytological examination of tissue obtained by needle aspiration or biopsy was nondiagnostic, radial gel immunodiffusion was used to identify the presence of prostatic acid phosphatase in the tissue. Four specimens demonstrated prostate-specific acid phosphatase activity, permitting the diagnosis of metastatic prostatic adenocarcinoma. The technique is simple and highly specific.

Prostatic adenocarcinoma: considerations in management

Prostatic adenocarcinoma is the third most common cause of cancer death in men. Although cure of early disease is possible, distant metastases are present at diagnosis in about 50% of patients. Management will improve as understanding of the variables affecting prognosis increases.

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.

Immunohistological approaches to human prostatic epithelial cells

Specific anti-acid phosphatase antisera were prepared by the use of purified prostatic acid phosphatase (PAP) from prostatic tissue and lysosomal acid phosphatase (L-AcP) from diploid fibroblast (WI-38) as antigen. Since the antigenic difference between the PAP and L-AcP was established, distribution of these enzymes among various tissues and tissue culture cells was investigated by the indirect immunofluorescence method and the unlabeled antibody method [14]. The L-AcP has been detected as granules localized in a perinuclear portion of all of the epithelial cells, fibroblasts, and peripheral blood cells except erythrocytes. Presence of the PAP was limited to the prostatic epithelial cells. It is also noted that the biosynthesis of the PAP is strikingly diminished in the long-term culture of prostatic epithelial cells. However, because of the antigenic difference between the PAP and L-AcP, and because of the high concentration of PAP in the cytoplasm of prostatic epithelial cells, it is feasible to apply the anti-PAP immunofluorescence method to the identification of metastatic prostatic carcinoma cells in the biopsy materials.

Clinical significance of serum and bone marrow acid phosphatase

Currently available immunochemical assays for the determination of serum prostatic acid phosphatase have improved the reliability of this biological marker in carcinoma of the prostate. Although the value of such methods for screening the general population is questionable, a certain percentage of elevated serum levels is observed in patients with localized disease. The significance of such findings is unclear at the present time. Recent evidence suggests that in elevated bone marrow acid phosphatase, using these methods is of predictive value in the future development of metastatic disease.

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.

Reliability of bone marrow acid phosphatase as a parameter of metastatic prostatic cancer

The reliability of bone marrow acid phosphatase determination by a spectrophotometric assay and 2 immunochemical methods was evaluated in 40 patients: 20 men with known prostatic carcinoma and 20 men of comparable age without clinical evidence of prostatic cancer. The large percentage of falsely positive results obtained by the colorimetric assay invalidates this method as the sole parameter of metastatic prostatic carcinoma.