Multiple biochemical tumor markers in seminoma. A double-blind study

Organ Specific Tumor Markers: What's New?

Tumor markers are molecules produced in the body in response to cancer. An ideal tumor marker should have high sensitivity and specificity, should be cheap, and should be easily detected in body fluids. Identification of novel markers is important and it is expected that with the advent of newer technologies, more reliable markers will be discovered. This review discusses the currently available tumor markers for different malignancies.

Neoplasia of the male reproductive tract

Genital neoplasms in the male horse are relatively uncommon. Squamous cell carcinomas and squamous papillomas are the most commonly diagnosed neoplasms of the penis and prepuce. Geldings appear to be overrepresented for these types of neoplasms, and accumulation of smegma may be a contributing factor. Early diagnosis and treatment are essential for salvaging these organs before lesions become excessively large and invasive or are allowed to metastasize. Newer treatment modalities such as 5-fluorouracil appear to be promising alternatives to surgical excision. Although generally considered to be uncommon, testicular tumors may occur more frequently than previously thought and have the potential for devastating effects on stallion fertility. Cryptorchidism appears to play a role in the development of equine testicular tumors, especially teratomas. Seminoma is by far the most common testicular tumor of the mature stallion. Seminomas are rapidly growing tumors with a greater potential to metastasize in the horse than in other domestic species. Leydig cell and Sertoli cell tumors have been reported but are relatively rare in the stallion. Orchiectomy is the standard treatment for most testicular tumors. In certain circumstances, however, such as neoplasia occurring in the only functional testis, local cryotherapy of testicular tumors may prolong the breeding career of an affected stallion.

Enolase isozymes in seminoma

We determined concentrations of alpha and gamma-enolases in normal testis and in seminoma tissues by enzyme immunoassay. Concentrations of alpha-enolase were 4,170 +/- 2,040 ng/mg protein in normal testis (n = 8) and 8,140 +/- 4,480 ng/mg protein in seminoma (n = 8). Concentrations of gamma-enolase in seminoma (460 +/- 571 ng/mg protein) were significantly higher than those of normal testis (59 +/- 15 ng/mg protein). Immunohistochemistry showed positive tumor cells for gamma-enolase in 6 of 8 seminoma cases (75%). Serum gamma-enolase levels were elevated (greater than 6.0 ng/ml) in 9 of 12 patients (75%) with seminoma: 60% of stage I, and 100% of stages II and III. In 10 patients treated by surgical excision and chemotherapy, serum gamma-enolase was significantly reduced after the treatment. These findings indicate that elevated serum gamma-enolase is derived from enhanced gamma-enolase in seminoma tissues, and that serum gamma-enolase could be a useful biomarker for staging and monitoring clinical course in patients with seminoma.

Placental-like alkaline phosphatase in seminoma

Tumor marker identification in testicular cancer has contributed to early detection and monitoring of non-seminomatous disease. A placental alkaline phosphatase-like (PLAP-like) enzyme derived from seminomas has recently been focused upon as a possible marker for this disease. The biochemistry of the PLAP-like enzyme is reviewed, as well as its occurrence in tissue and sera from healthy persons and patients with testicular cancer.

The abnormal occurrence and the differentiation-dependent distribution of N-acetyl and N-glycolyl species of the ganglioside GM2 in human germ cell tumors. A study with specific monoclonal antibodies

Human primary germ cell tumors were analyzed for the presence of the ganglioside GM2 using three specific monoclonal antibodies which can distinguish the molecular species of the sialic acid moiety: the antibody MK1-16 is specific for N-acetyl GM2, MK2-34 is specific for N-glycolyl GM2, and MK1-17 detects both N-acetyl and N-glycolyl GM2. When the occurrence of the GM2 antigen was tested in 107 cases of human germ cell tumors by the immunohistochemical technique using these antibodies, seminoma was characterized as having the highest frequency of N-acetyl GM2 (89.4%, 42 of 47 cases) among germ cell tumors, followed by embryonal carcinoma (40.0%), and teratocarcinoma (26.6%). Compared with this, yolk sac tumors and choriocarcinoma had a much lower positive incidence of the N-acetyl GM2 antigen. On the other hand, the N-glycolyl GM2 antigen was not found at all in 47 cases of seminoma (0%), and the positive incidence was very low in embryonal carcinoma (6.6%), although considerably higher incidences were obtained with choriocarcinoma (25.0%), yolk sac tumor (22.2%), and teratocarcinoma (13.3%). The presence and molecular species of the GM2 antigens in these human germ cell tumors were also ascertained chemically by the thin-layer chromatography (TLC) immunostaining of the ganglioside fractions prepared from primary germ cell tumors. These results indicate that seminoma specifically contains N-acetyl GM2 and no N-glycolyl GM2, suggesting that N-acetyl GM2 could be a good marker for seminoma. On the other hand, non-seminomatous germ cell tumors were characterized by the presence of N-glycolyl GM2, one of the Hanganutziu-Deicher antigens (H-D antigens). Moreover, the positive occurrence of N-glycolyl GM2 correlated very well with the degree of differentiation of non-seminomatous germ cell tumors, i.e., the differentiated tumors such as yolk sac tumors, choriocarcinoma, and teratocarcinoma had a higher positive incidence of N-glycolyl GM2 type H-D antigen but a lower positive incidence of N-acetyl GM2 when compared with embryonal carcinoma, the most undifferentiated tumors among non-seminomatous germ cell tumors.

Clinical biochemistry of neuron specific enolase

The soluble brain protein 14-3-2 first described by Moore and McGregor in 1965 is now known to be a cell specific isoenzyme of the glycolytic enzyme enolase (EC 4.2.1.11), designated neuron specific enolase (NSE). It is not only a marker for all types of neurons, but also for all neuroendocrine or paraneuronal cells. The appearance of NSE is a late event in neural differentiation, thus making NSE a useful index of neural maturation. The demonstration that tumors of the nervous system and of neuroendocrine origin contain NSE has promoted the study of NSE as a possible tumor marker. Immunocytochemistry has been used to identify NSE in cytologic preparations from several types of tumors, offering useful indications for differential diagnosis. NSE levels in serum from tumor patients are not useful in the diagnosis of early stage disease. However, serum NSE levels have been shown to be helpful in the identification of advanced small cell lung cancer, neuroblastoma and several other neoplasms. The main use of serum NSE is the monitoring of chemotherapy and the detection of a relapse in these cases.

High frequency of incomplete human chorionic gonadotropin in patients with testicular seminoma

We measured human chorionic gonadotropin by 2 immunometric assays that require that the entire human chorionic gonadotropin molecule is intact, and by a competitive radioimmunoassay that measures intact human chorionic gonadotropin and its free beta-chain. The sera tested were samples from male cancer patients with elevated human chorionic gonadotropin levels obtained by the radioimmunoassay method. Elevated levels were confirmed in 67 of 92 samples (72 per cent) with the immunometric methods. However, in 25 of 97 patients (28 per cent) elevated human chorionic gonadotropin was found with the radioimmunoassay, whereas the values were in the normal range when measured with the immunometric assays. These discrepancies were found in 22 patients with seminomatous tumors, including 2 extragonadal germ cell tumors, which constitutes 42 per cent of all seminoma patients tested. Of the remaining 3 discrepant patients 2 had lung cancer and 1 had metastases from an unknown primary cancer.

Testicular cancer

Testicular cancer, which predominantly occurs in young men, has become increasingly common; it is presently the most common malignancy in men aged 20-34. Despite a lack of knowledge of aetiology, empirical advances, particularly in the management of patients with advanced disease, have been dramatic. Prior to the development of effective chemotherapy in the 1970s, less than 10% of men with metastatic non-seminomatous germ cell tumours were cured; nowadays approximately 90% of patients are potentially curable. The introduction of effective chemotherapy has led to a reappraisal of surgery and radiotherapy in the management of early stage disease and the introduction of a policy of surveillance in patients without evidence of metastases at the time of removal of the primary tumour. Following chemotherapy, surgery is required in approximately 25% of patients with advanced disease to excise residual masses, which in one-fifth of cases will show evidence of residual malignancy. In a proportion of patients, testicular cancer develops on a background of long-standing infertility, whereas in many men there is temporary oligospermia, despite a previous history of fertility. The majority of patients with prior evidence of spermatogenesis recover this function following chemotherapy and there is no evidence that children fathered by such patients have an increased risk of malformation. Despite physician optimism and excellent prospects for cure, significant psycho-social morbidity is associated with the diagnosis and treatment of testicular cancer. Factors contributing to this are being identified and will lead, hopefully, to the minimisation of such problems by appropriate intervention.

Patterns of seminoma tissue markers and deletions

Seminomas and control tissues were analyzed for several tumor markers. Very high levels of placental alkaline phosphatase (PLAP)-like enzyme levels were found in all 18 seminomas studied. The majority of the seminomas were of phenotype I, thus differing from palcental PLAP. The mean amount of enzyme protein as measured by monoclonal antibodies, was 100 times higher than in non-malignant tissues and 10 times lower than in placental tissue. The specific enzymatic activity in seminomas was about half of that observed in placenta. Similarly, the specific activity of PLAP-like enzymes in sera of patients with seminoma was only about half of that found in pregnancy sera. HCG was strongly elevated in 3 seminomas, but not obviously related to PLAP. Thirteen of the 17 pure seminomas had HCG over 100 IU/g, which was not seen in normal testes. Liver alkaline phosphatase (LAP) and intestinal alkaline phosphatase (IAP) were high in seminomatous tissues, the mean increases being 60-fold and 20-fold, respectively. The highest IAP levels were found in 2 yolk-sac tumors. Ferritin was moderately elevated in seminomas, but high in several control tissues. Carcinoembryonic antigen (CEA) was not elevated and alpha-fetoprotein (AFP) was not detected at all in pure seminomas. A decrease in carbohydrate antigen 50 (CA-50) content was noted in seminomas as compared to normal testes, yolk-sac tumors and choriocarcinomas. Defects in tumor-related enzymes may account for increase of PLAP and decrease of CA-50.

Clinical evaluation of basic fetoprotein in testicular cancer

We attempted to determine the efficacy of basic fetoprotein as a marker in testicular cancer. The levels of serum basic fetoprotein were studied in 58 patients (31 with seminoma and 27 with nonseminoma). Elevated levels were observed in 22 seminoma (71 per cent) and 15 nonseminoma (56 per cent) patients, while the levels of other markers (beta-subunit of human chorionic gonadotropin, alpha-fetoprotein and lactic dehydrogenase) remained normal in 6 seminoma (19 per cent) and 2 nonseminoma (7 per cent) patients. The levels of basic fetoprotein changed in relation to the clinical courses and they elevated again in 3 of 4 patients with recurrence. The concentration of basic fetoprotein in testicular cancer tissue was significantly higher than in the normal testis. Histological localization of basic fetoprotein in testicular cancer tissue was demonstrated immunohistochemically. Thus, basic fetoprotein was considered to be a useful serum marker for testicular cancer.

Serum neuron-specific enolase. A marker for responses to therapy in seminoma

Neuron-specific enolase (NSE) was evaluated as a serum marker in 105 patients with testicular cancer and compared with the established tumor markers alphafetoprotein (AFP) and human chorionic gonadotropin (HCG). Increased serum NSE activity was measured in eight of 11 (73%) patients with metastatic seminoma. Serum NSE concentrations fell to within the normal range following chemotherapy. Localization of NSE in seminoma cells was demonstrated immunohistochemically. Only six of 40 (15%) patients with metastatic nonseminomatous germ cell tumors showed elevated serum NSE levels. AFP and HCG were both positive in 70% of patients in this group, and NSE determination gave no additional information. Serum NSE concentrations were normal in 53 of 54 testicular cancer patients after orchiectomy and there was no evidence of metastatic disease; only one had borderline NSE levels, indicating the specificity of serum NSE determination. NSE is a new marker of seminoma and its measurement may be of clinical value in monitoring chemotherapy in patients with metastatic seminoma.

Biological markers in urologic cancer

Tumor markers (TMs) play an important part in the management of urologic cancer. Alpha-fetoprotein, human chorionic gonadotropin, and occasionally lactic dehydrogenase serological determinations have become indispensable in the management of nonseminomatous germ cell testicular tumor patients, particularly after initial therapy, whereas human chorionic gonadotropin and probably placental alkaline phosphatase are important in seminoma. Prostatic acid phosphatase has long been important for the monitoring of patients with carcinoma of the prostate. The availability of the immunologic assays instead of the enzymatic assays has improved sensitivity somewhat but clinical interpretation has also become more complicated. Prostatic specific antigen is already an important tissue marker for carcinoma of the prostate and promises to be an important serological one, possibly surpassing prostatic acid phosphatase in importance. Analysis of DNA by automated flow cytometry is becoming important in the early detection and follow-up of bladder cancer patients. Studies concerning the tissue analysis of blood group antigens in bladder cancer continue to demonstrate that this approach can provide unique clinical information and interesting biological insights, but its role in routine clinical management remains to be determined. Currently, TMs have little clinical significance in renal cell carcinoma, but the availability of monoclonal antibodies to renal cell carcinoma preferential antigens may change this deficiency soon. In fact, in the near future, monoclonal antibodies will probably reveal many new substances for many urological cancers which can be used for markers serologically, histochemically, and, with their corresponding antibody, for radioimmune imaging and possibly immunotherapy. Now, as then, familiarity with the nuances of the marker and good clinical judgement will be essential.

Methods of early diagnosis in genitourinary cancer

The commonly employed methods for the early detection of urologic cancers remain the traditional techniques of a carefully performed history and physical examination. Newer developments include, among others, prostate-specific antigen and monoclonal antibodies in prostate cancer, flow cytometry in bladder cancer, computerized axial tomography (CAT) scanning in renal cancer, and ultrasound in testicular cancer. These and other new diagnostic techniques, with further testing and wider use, will hopefully permit the earlier diagnosis of genitourinary cancer.

Stage I testicular seminoma: rationale for postorchiectomy radiation therapy

The cases of 163 patients with Stage I seminoma of the testis treated by orchiectomy and adjuvant radiation therapy (XRT) were retrospectively evaluated to document outcome and to determine the prognostic significance of age side or primary, cryptorchidism, prior ipsilateral herniorrhaphy, status of the contralateral testis, history of prior testicular cancer, scrotal incision, postorchiectomy beta- human chorionic gonadotropin (BHCG) level, invasion of the epididymis, spermatic cord involvement, vascular invasion in the primary and mediastinal XRT. Of the prognostic factors evaluated, only spermatic cord involvement proved to be a significantly adverse factor. However, the true significance of cord involvement is unclear because the para-aortic regions were not irradiated in 2 of the patients in whom there was this finding, and in 1 of these there was failure in the retroperitoneum. Spermatic cord involvement was not a prognostically significant finding in patients whose para-aortic region was treated. For all 163 patients who underwent XRT, disease-free survival was 95% at 5, 10, and 15 years. Total survival corrected for intercurrent death was 97% from 5 through 20 years. Seven patients relapsed (4%) and 4 died of seminoma (2%). The XRT technique described is simple to implement and is extremely effective. Of 161 patients whose para-aortic region was irradiated, none developed subdiaphragmatic nodal recurrence. Only 1 patient developed acute leukemia. No patient developed any of the recognized delayed XRT-induced complications involving small bowel, large bowel, bladder, kidney, liver or spinal cord. The virtues and limitations of surveillance in Stage I testicular seminoma are discussed, and it is concluded that routine postorchiectomy XRT is the treatment of choice.

Vinblastine-ifosfamide-cisplatin treatment of bulky seminoma

Eighteen patients with pure seminoma in advanced Stages IIC-IV of disease were treated with VIP combination chemotherapy consisting of vinblastine (6 mg/m2, days 1 and 2), ifosfamide (1.5 g/m2, days 1 to 5), and cisplatin (20 mg/m2, days 1 to 5). Eleven patients had Stage IIC, four had Stage III, three had Stage IV, and two had primary extragonadal seminoma. Primary histologic diagnoses were typical seminoma in 15 patients and anaplastic seminoma in three patients. Human chorionic gonadotropin (HCG) levels were elevated to 350 U/1 in eight patients; alpha-fetoprotein (AFP) levels were always normal. No primary lymphadenectomy was carried out. Seven of 18 patients had prior radiotherapy and were treated because of relapse or progression. There was one early death and one patient has not yet completed therapy. Of 16 evaluable patients, 14 reached complete remission (CR) (88%), which was documented surgically in six cases, whereas in the non-pretreated group, all nine patients reached CR and in the pretreated group, CR could be induced in five of seven patients (71%). The remission duration ranged from 6+ to 41+ months (median, 29+ months). No relapse has occurred. The bone marrow toxicity of VIP was remarkable. Because of leukopenia below 1000/mm3 and/or thrombopenia below 50,000/mm3, dose reduction and interval prolongation were necessary in 10 of 16 patients, especially in all those who were pretreated. Even though it is not superior to other platin-based regimens, VIP chemotherapy is highly effective in bulky seminoma with and without prior radiotherapy.

Phenotypes of placental-type alkaline phosphatase in seminoma sera as defined by monoclonal antibodies

PLAP-like enzymes could be detected in serum of patients with primary testicular tumors, in particular seminomas. The use of a panel of monoclonal antibodies (MAbs) permitted typing into 6 different testicular serum phenotypes, of which one appeared similar to a placental type (II) and 2 have not been previously described. Most tumor sera belonged to type I, as described for seminoma tissues. With a more advanced tumor the mean serum PLAP-like levels increased. After operation, after radiotherapy or with no evidence of disease lower or non-detectable enzyme levels were found. In typing the tissue PLAP-like antigen in serum of the same patient or sera from recurrences of a seminoma in the same patient, the same phenotypes of PLAP-like antigen were usually but not always found. None of the 6 phenotypes appeared to confer a poorer prognosis. We conclude that the expression of PLAP-like antigen is eutopic and is enhanced by testicular malignancy, especially in seminoma cells.

Preliminary observations on the application of carcino-placental alkaline phosphatase to the investigation of patients with seminoma of the testes

Suitable tumour markers for monitoring the treatment of seminoma of the testis have not yet been established in clinical practice. Carcino-placental alkaline phosphatase (CPAP) has been suggested for this purpose but it is difficult to detect and specifically analyse this enzyme. We have devised an immunoenzymatic method of analysis in which cross-reactions with liver type and intestinal alkaline phosphatase are minimal and we have applied this test to seven patients with histologically proven seminoma. CPAP was raised in 4 patients prior to treatment and chorionic gonadotrophin in two of these. Alpha-fetoprotein was normal in all cases. We conclude that the use of CPAP in monitoring treatment of testicular seminoma is worthy of further attention.

Enzymes, isozymes, and enzyme variants in the diagnosis of cancer. A short review

Changes of enzyme activity in tissues, body fluids, and serum as well as changes of isozymes and enzyme variants in patients with malignancy suggest that these parameters may be used in the diagnosis of some types of cancer. A review of available information indicates that: changes of serum enzymes in patients with malignancies relate to the presence of a heavy tumor burden or of metastases, and cannot be utilized for the early diagnosis of malignancies; changes in isozyme patterns and newly developed enzyme variants may be of greater diagnostic value, although possibly not in the early diagnosis of cancer; study of enzymatic activity in body fluid may offer valuable help in specific situations; and occasionally, determination of enzymes may be of help in establishing susceptibility to malignancies.

Placental alkaline phosphatase as a tumour marker in seminoma using the H17 E2 monoclonal antibody assay

Serum samples from 62 patients with seminoma were assayed for placental alkaline phosphatase-like activity using the monoclonal antibody H17 E2, in order to evaluate its utility as a serum tumour marker. Fifteen of 16 patients (94%) with active seminoma had elevated serum PLAP levels. Sixteen of 46 (35%) of patients considered to be in remission had elevated PLAP levels (false positive rate 35%). Fifteen false positive results were considered attributable to concomitant smoking, and if these patients are excluded, only one false positive case was detected. In 7 out of 7 patients sequential PLAP assays reflected clinical response to treatment.

The biological and clinical significance of HCG-containing cells in seminoma

The morphological appearance, incidence and prognostic significance of human chorionic gonadotrophin (HCG)-containing cells in seminomas were examined in a retrospective series of 228 orchidectomy specimens, obtained between 1958 and 1972. Sections from each tumour were stained with haematoxylin and eosin (H & E) and immunocytochemically for HCG. In 33 (14.5%) of the tumours HCG-containing cells were observed, but in only 12 were these recognised in an initial study of the H & E stained sections. HCG staining was seen predominantly in syncytiotrophoblastic giant cells and rarely in "mulberry" cells and mononuclear seminoma cells. Of the patients whose tumours included HCG-containing cells 23% died of their disease within 2 years of orchidectomy, compared with only 8% of the patients whose tumours lacked this feature. It is concluded that immunocytochemical staining for HCG should form part of the routine histological assessment of seminomas, and that the presence of HCG-containing cells indicates a more aggressive disease.

Evaluation of an amplified enzyme-linked immunoassay of placental alkaline phosphatase in testicular cancer

The levels of serum placental alkaline phosphatase (PLAP) have been examined in 81 male controls, 51 untreated testicular tumours (41 seminomas and ten non-seminomatous testicular tumours) and 34 patients in complete remission (11 seminoma and 23 non-seminoma). Smoking induced a significant rise of serum PLAP in the controls, with a median level of 0.055 U/1 in non-smokers compared to 0.25 U/l in smokers. The levels found in pre-treatment seminoma (median 1.7 U/1) were significantly higher than in untreated teratoma (median 0.7 U/1). Treatment produced a significant fall in seminomas in remission (median 0.07 U/1). The role of PLAP in routine monitoring of seminomas was evaluated in 17 patients studied for 1-4 yr. PLAP shows similar trends to beta HCG but is an independent variable. The main role of PLAP is to help determine that the response to treatment has been satisfactory and that there are no unexpected foci of tumour.

Testicular carcinoma. A curable malignancy

The progress in the management of testicular germ cell tumours is reviewed. A marked improvement of the treatment results has been obtained in non-seminomas, especially by the use of cis-platinum based chemotherapy. At present long term survival can be expected in 85 per cent of all non-seminomas and in 95 per cent of all seminomas after adequate treatment. The natural history of the disease, symptomatology, diagnostic procedures, staging and different treatment modalities, as surgery, radiation therapy, chemotherapy and their combination, are discussed.

Eutopic expression of placental-like alkaline phosphatase in testicular tumors

Very high levels of placental-like alkaline phosphatases (PLAP-like enzymes) were observed in tissues from 13 typical seminomas. Four tumors with seminoma components contained these enzymes to varying degrees, and other testicular tumors had them in smaller or non-detectable amounts. Analysis using monoclonal antibodies produced against the common placental alkaline phosphatase (PLAP) phenotypes and enzyme inhibition studies with amino acids and peptides showed the PLAP-like enzymes present in seminoma to be similar to those PLAP-like enzymes which are expressed in lower amounts in two embryonal carcinomas and in trace amounts in normal testicular tissue. These similarities suggest that the increased expression of PLAP-like enzymes in seminomas results from enhanced eutopic expression of enzymes found in normal testis.

Tumour and cellular localization by use of monoclonal and polyclonal antibodies to placental alkaline phosphatase

Monoclonal and polyclonal antibodies against placental alkaline phosphatase (PLAP) were evaluated for tumour immunolocalization of human PLAP-producing Hep 2 tumours in nude mice. The antibodies were labelled with 125I and injected i.p. in mice with developing Hep 2 tumours. The distribution of 125I-anti PLAP in various tissues showed that the labelled antibody was enriched in the tumour, the mean concentration ratio being 7.1 and 6.8 for polyclonal and monoclonal antibodies, respectively. A PLAP negative tumour (RD) showed a mean ratio of 1.2. There was a positive correlation between PLAP content and uptake of labelled antibody in the tumours. Hep 2 tumour cells in tissue culture showed 100% positivity for PLAP, while imprints of the tumour after passage in nude mice showed 40-50% positivity. PLAP offers potential as a useful marker for localizing tumours in humans.