Japanese Journal of Clinical Oncology 32:472-476 (2002)
© 2002 Foundation for Promotion of Cancer Research
Lectin-reactive 
-Fetoprotein (AFP-L3%) Curability and Prediction of Clinical Course after Treatment of Non-seminomatous Germ Cell Tumors
1 Department of Urology, Kyoto University, Graduate School of Medicine, Kyoto, 2 Osaka Research Laboratories, Wako Pure Chemical Industries Ltd, Osaka and 3 Department of Urology, Shiga University of Medical Science, Otsu, Japan
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONPATIENTS AND METHODSRESULTSDISCUSSIONAcknowledgmentsREFERENCES |
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Objective:
-Fetoprotein (AFP) is an important tumor marker for non-seminomatous germ cell tumors (NSGCTs) that greatly affects diagnosis and the evaluations of therapy and therapeutic policy. However, it is sometimes very difficult to make the distinction between tumors and falsely elevated AFP levels due to benign liver disease. We assessed the usefulness of lectin-reactive -fetoprotein (AFP-L3%), which has been reported to be superior to total AFP in both sensitivity and specificity in hepatocellular carcinomas, for the evaluation of predictions of clinical courses after the treatment of NSGCTs. Methods: Frozen sera of 25 tumor-bearing patients with testicular cancers whose AFP levels were 5.0 ng/ml or higher were used. The total AFP levels and the ratio of L3 fraction to total AFP (AFP-L3%) were measured by liquid-phase binding assay (LBA).
Results: The total AFP levels were 6.3–14 907 ng/ml (median: 105.9 ng/ml). The median AFP-L3% was 69.9% (range;: 1.1–88.1%). Except for one patient, 24 patients (96.0%) with evident disease showed high levels of AFP-L3% of >50%, regardless of their total AFP levels. In nine patients whose sera were sequentially measured, AFP-L3% was considered highly useful for the detection of residual tumors (n = 2) and recurrence (n = 1) and for the exclusion of false-positive cases (n = 1).
Conclusions: When the total AFP level increases slightly (e.g. to 5–20 ng/ml), a measurement of AFP-L3% may provide additional useful information for monitoring NSGCT patients and in distinguishing falsely elevated AFP.
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONPATIENTS AND METHODSRESULTSDISCUSSIONAcknowledgmentsREFERENCES |
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The assay of
-fetoprotein (AFP) is integral to the treatment of patients with non-seminomatous germ cell tumors (NSGCTs), from diagnosis and for staging to treatment and long-term follow-up. AFP, a 70 kDa glycoprotein synthesized from fetal yolk sacs, liver and intestines, has a half-life of 5–7 days. Serum AFP is a prognostic indicator of the response and survival of germ cell tumors (1–3). Increased serum tumor markers generally indicate the presence, persistence or recurrence of germ cell tumors, even in the absence of radiographic or clinical evidence. For this reason, a high level of AFP prompts treatment and/or evaluation for disease. In addition, an increased level of AFP that fails to decline according to predicted half-lives during chemotherapy portends a poor prognosis (4,5). However, when an AFP level is slightly elevated, it is especially difficult to evaluate the disease status of testicular cancers because total AFP may be falsely elevated owing to non-neoplastic liver disease. Microheterogeneity of the sugar component of AFP has been studied by affinity chromatography and affinity electrophoresis with several lectins having specificity for different oligosaccharides (6,7). Recently, the AFP-L3 fraction has been reported to be superior to total AFP levels in both sensitivity and specificity in differentiating the AFP elevation between benign and malignant liver disease (8–10). Thus the structure of the sugar chain of AFP was examined in testicular cancers and the usefulness of the AFP-L3 fraction the prediction of the clinical course after treatment of NSGCT was evaluated. |
PATIENTS AND METHODS |
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TOPABSTRACTINTRODUCTIONPATIENTS AND METHODSRESULTSDISCUSSIONAcknowledgmentsREFERENCES |
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Between January 1997 and December 2000, 41 patients with germ cell tumors, including two extragonadal germ cell tumors, were treated at Kyoto University Hospital. Among them, 26 patients were histologically diagnosed as having NSGCTs. All but one case showed increased levels (>5 ng/ml) of total AFP. The clinical characteristics of those 25 patients with elevated serum AFP are summarized in Table 1.
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During the clinical courses, the total serum AFP levels were determined by radioimmunoassay using
-Feto-Riabeads (Dainabot, Tokyo, Japan) with a reference range of <15 ng/ml. In a retrospective study to determine the serum AFP levels and AFP-L3%, frozen sera obtained from the patients were used and both parameters were simultaneously determined using a liquid-phase binding assay (11,12), with LBA Wako AFP-L3 reagent and a LiBASys clinical automatic analyzer (both from Wako, Osaka, Japan). The reference range of AFP-L3% was <10%. Sequential evaluations during treatment and follow-up were possible for nine patients. |
RESULTS |
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TOPABSTRACTINTRODUCTIONPATIENTS AND METHODSRESULTSDISCUSSIONAcknowledgmentsREFERENCES |
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AFP-L3% in Testicular Cancers
The AFP serum levels and the AFP-L3% at initial presentation were summarized according to their histopathological classification (Table 2). The median AFP-L3% in all patients was 69.9% (range: 1.1–88.1%). Except for one patient whose histological type was mainly choriocarcinoma and whose AFP remained elevated at 20–40 ng/ml during treatment, 24 patients (24/25; 96.0%) showed high AFP-L3%s of >50%, regardless of their AFP levels. Although statistical differences were demonstrated in the serum levels of AFP between some histopathological subtypes, no significant difference was observed in AFP-L3% (Table 2). In addition, there was no association between AFP or AFP-L3% and the tumor stage or the clinical outcome (data not shown).
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Clinical Courses of Representative Cases
In nine patients whose sera were sequentially measured during their clinical course, total AFP levels were judged to be useful for evaluating their disease status. Among them, five patients were evaluated satisfactorily in terms of their disease status by their total AFP alone. However, measurements of AFP-L3% were considered highly useful for the detection of residual tumors (n = 2 patients) and recurrence (n = 1) and for the exclusion of false-positive cases (n = 1). The changes in total AFP and AFP-L3 % levels during the clinical courses of these three patients are presented.
Case 1: Stage I NSGCT (Fig. 1)
A 31-year-old man underwent right inguinal orchiectomy. Preoperative AFP was elevated, at 7.2 ng/ml, and declined steadily to an undetectable level (<3.0 ng/ml) after orchiectomy. Three months after the operation, however, computerized tomography (CT) of the abdomen and chest revealed multiple recurrences in the retroperitoneum and lung fields with an increased total AFP level. Combination chemotherapy consisting of cisplatin, etoposide and bleomycin was given for four cycles and the total AFP again fell to an undetectable level. Although there has been no evidence of recurrence of the disease after 3 years of follow-up, the total AFP levels have fluctuated within the normal limits (<15.0 ng/ml), raising suspicions of a recurrence. However, as shown in Fig. 1, AFP-L3% remained consistently at a low level, indicating that this parameter can be a highly specific marker for monitoring disease status.
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Case 2: Stage I NSGCT (Yolk Sac Tumor) (Fig. 2)
A 44-year-old man underwent right inguinal orchiectomy for a right testicular mass. There was no evidence of retroperitoneal or distant metastases at the initial stage of evaluation, which included chest and abdominal CTs and a bone scintigram. His preoperative AFP level was 3467 ng/ml and this steadily declined according to the estimated half-life after orchiectomy. However, 6 weeks after the operation, the AFP level remained at 15–25 ng/ml, whereas all examinations failed to show any metastatic lesions. Despite persistently elevated levels of total AFP, there has been no evidence of the disease during 3 years of a watchful-waiting strategy. In this case, AFP-L3% was <10% at all times during the follow-up period, indicating it to be a more specific marker for disease status.
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Case 3: Stage I NSGCT (Fig. 3)
A 22-year-old man consulted our hospital with an enlarged left testicle that showed signs of a testicular tumor. His preoperative AFP was 28.0 ng/ml and a CT of the abdomen demonstrated a small amount of equivocal lymph node swelling at the left renal hilum. After inguinal orchiectomy, the AFP level steadily declined to 7.6 ng/ml, suggesting that the small amount of lymph node swelling was not a malignant lesion. However, on a follow-up CT of the abdomen, the lymph node swelling increased in size and the AFP was again elevated above the upper normal limit. On a retrospective analysis of sera from the patient, AFP-L3% had remained at a high level (60–70%), despite the normal total AFP levels.
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONPATIENTS AND METHODSRESULTSDISCUSSIONAcknowledgmentsREFERENCES |
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AFP has proved to be of considerable clinical value in the management of patients with NSGCTs. In most cases, increased concentrations of this marker suggest an active disease, but, as has been reported previously, an increase in AFP concentration in the follow-ups of patients is difficult to interpret because total AFP may also rise in non-neoplastic diseases of the liver (10,13). However, there are some recent reports of AFP microheterogeneity (6,7). Concanavalin A (Con-A) affinity assay has been reported to be helpful in determining the etiology of unexplained elevated AFP in patients with GCTs (9). This assay of AFP microheterogeneity may differentiate AFP that is produced by GCTs from that of malignant primary liver lesions and non-malignant liver diseases. Unfortunately, Con-A affinity assay is very complicated. Therefore, we evaluated an automated analytical method for analyzing AFP carbohydrate chain microheterogeneity based on the competitive reaction between lectin and anti-AFP monoclonal antibody in the liquid phase (11,12). Using this method, the ratio of Lens culinaris agglutinin (LCA)-reactive AFP (AFP-L3 fraction) can be easily determined. The present study has shown that this microheterogeneity (AFP-L3%) of testicular cancer was most useful for diseases such as hepatocellular carcinomas (14,15). In almost all testicular cancer patients in whom AFP was used as a tumor marker, the AFP-L3 fraction was also elevated. Hence AFP-L3% could be a very helpful marker for NSGCT. An ideal tumor marker should be sufficiently specific and sensitive to permit an early diagnosis of both primary malignancy and relapse. In our experience, AFP-L3% is such an indicator of disease recurrence (case 1), is able to distinguish false-positive elevation (case 2) and can distinguish between stages I and II (case 3). Although the biological role of AFP is not fully understood and the mechanism of microheterogeneity of AFP is unknown, the AFP-L3 fraction may be the main component of AFP originating from NSGCT cells.
In conclusion, AFP-L3% is a good indicator for the assessment of the clinical courses of patients with NSGCTs who have slightly elevated total AFP levels (e.g. 5–20 ng/ml). AFP-L3 fraction may be a more specific marker than total AFP for both therapeutic evaluation and for the early discovery of any recurrence.
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Acknowledgments |
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TOPABSTRACTINTRODUCTIONPATIENTS AND METHODSRESULTSDISCUSSIONAcknowledgmentsREFERENCES |
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We thank Ms Tomoko Matsushita and Ms Itsuko Fujiwara for their expert technical assistance. This work was supported in part by a grant from the Vehicle Racing Commemorative Foundation.
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FOOTNOTES |
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+ For reprints and all correspondence: Osamu Ogawa, Department of Urology, Kyoto University Graduate School of Medicine, 54 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan. E-mail: ogawao@kuhp.kyoto-u.ac.jp
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REFERENCES |
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1 International Germ Cell Cancer Collaborative Group. International Germ Cell Consensus Classification: a prognostic factor-based staging system for metastatic germ cell cancers. J Clin Oncol 1997;15:594–603.
2 Bosl GJ, Geller NL, Cirrincione C, Vogelzang NJ, Kennedy BJ, Whitmore WF, et al. Multivariate analysis of prognostic variables in patients with metastatic testicular cancer. Cancer Res 1983;43:3403–7.
3 Toner GC, Geller NL, Tan C, Nisselbaum J, Bosl BJ. Serum tumor marker half-life during chemotherapy allows early prediction of complete response and survival in non-seminomatous germ cell tumors. Cancer Res 1990;50:5904–10.
4 Gerl A, Lamerz R, Clemm C, Mann K, Hartenstein R, Wilmanns W. Does serum tumor marker half-life complement pretreatment risk stratification in metastatic non-seminomatous germ cell tumors? Clin Cancer Res 1990;2:1565–70.[Abstract]
5 Doherty AP, Bower M, Christmas TJ. The role of tumour markers in the diagnosis and treatment of testicular germ cell cancers. Br J Urol 1997;79:247–52.[Web of Science][Medline]
6 Breborowicz J. Microheterogeneity of human alphafetoprotein. Tumour Biol 1988;9:3–14.[Medline]
7 Saraswathi A, Malati T. Clinical relevance of alphafetoprotein microheterogeneity in alphafetoprotein-secreting tumors. Cancer Detect Prev 1994;18:447–54.[Web of Science][Medline]
8 Taketa, K, Endo Y, Sekiya, C, Tanikawa K, Koji T, Taga H, et al. A collaborative study for the evaluation of lectin-reactive alpha-fetoprotein in early detection of hepatocellular carcinoma. Cancer Res 1993;53:5419–23.
9 Mora J, Gascon N, Tabernero JM, Germa JR, Gonzalez F. Alpha-fetoprotein–concanavalin A binding as a marker to discriminate between germ cell tumours and liver diseases. Eur J Cancer 1995;31A:2239–42.[Web of Science][Medline]
10 Catalona WJ, Vaitukaitis J, Fair WR. Falsely positive specific human chorionic gonadotropin assays in patients with testicular tumors: conversion to negative with testosterone administration. J Urol 1979;122:126–8.[Web of Science][Medline]
11 Nakamura K, Imajo N, Yamagata Y, Katoh H, Fujio K, Tanaka T, et al. Liquid-phase binding assay of alpha-fetoprotein using a sulfated antibody for bound/free separation. Anal Chem 1998;70:954–7.[Medline]
12 Katoh H, Nakamura K, Tanaka T, Satomura H, Matsuura S. Automatic and simultaneous analysis of lens culinaris agglutinin-reactive alpha-fetoprotein ratio and total alpha-fetoprotein concentration. Chem 1998;70: 2110–4.
13 Yamashiki N, Seki T, Wakabayashi M, Nakagawa T, Imamura M, Tamai T, et al. Usefulness of Lens culinaris agglutinin A-reactive fraction of alpha-fetoprotein (AFP-L3) as a marker of distant metastasis from hepatocellular carcinoma. Oncol Rep 1999;6:1229–32.[Web of Science][Medline]
14 Morris MJ, Bosl GJ. Recognizing abnormal marker results that do not reflect disease in patients with germ cell tumors. J Urol 2000;163:796–801.[Web of Science][Medline]
15 Okuda K, Tanaka M, Kanazawa N, Nagashima J, Satomura S, Kinoshita H, et al. Evaluation of curability and prediction of prognosis after surgical treatment for hepatocellular carcinoma by lens culinaris agglutinin-reactive alpha-fetoprotein. Int J Oncol 1999;14:265–71.[Web of Science][Medline]
Received April 15, 2002; accepted July 17, 2002
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