The most important application of AFP testing in cancer management is for testicular cancer. Although not present in pure seminoma,¹ elevated serum AFP is closely associated with nonseminomatous testicular cancer.^2-4 The measurement of AFP in serum, in conjunction with serum hCG, is an established regimen for monitoring patients with nonseminomatous testicular cancer.^5-8 In addition, monitoring the rate of AFP clearance from serum after treatment is an indicator of the effectiveness of therapy.^9,10 Conversely, the growth rate of progressive cancer can be monitored by serially measuring serum AFP concentration over time.¹¹ Serial serum AFP testing is a useful adjunctive test for managing nonseminomatous testicular cancer.

The measured AFP value of a patient's sample can vary depending on the test procedure used. The laboratory finding must, therefore, always contain a statement on the AFP assay method used. AFP values determined on patient samples by different test procedures cannot be directly compared with one another and could be the cause of erroneous medical interpretations.

As with all tests containing monoclonal mouse antibodies, erroneous findings may be obtained from samples taken from patients who have been treated with monoclonal mouse antibodies or who have received them for diagnostic purposes.¹² In rare cases, interference due to extremely high titers of antibodies to streptavidin and ruthenium can occur.¹² The test contains additives, which minimize these effects.

For diagnostic purposes, the results should always be assessed in conjunction with the patient's medical history, clinical examination, and other findings.

The Elecsys AFP assay is intended for the in vitro quantitative determination of α₁-fetoprotein in human serum and plasma to aid in the management of patients with nonseminomatous germ cell tumors.¹² The determination of AFP to screen the general population for cancer is, however, not to be recommended.

A₁-fetoprotein, an albumin-like glycoprotein with a molecular weight of 70,000 daltons, is formed in the yolk sac, nondifferentiated liver cells, and the fetal gastrointestinal tract.^13-15 Seventy percent to 95% of patients with primary hepatocellular carcinoma have elevated AFP values.¹⁶ The later the stage of nonseminomatous germ cell tumors, the higher the AFP values. Human chorionic gonadotropin (hCG) and AFP are important parameters for estimating the survival rate of patients with advanced, nonseminomatous germ cell tumors.^17-19

No correlation between the AFP concentration and tumor size, tumor growth, stage, or degree of malignancy has so far been demonstrated. Greatly elevated AFP values generally indicate primary liver cell carcinoma. When liver metastasis exists, the AFP values are generally <350-400 IU/mL.²⁰ As the AFP values rise during regeneration of the liver, moderately elevated values are found in alcohol-mediated liver cirrhosis and acute viral hepatitis as well as in carriers of HBsAg.^20,21

1. Javadpour N, McIntire KR, Waldmann TA. Human chorionic gonadotropin (HCG) and alpha-fetoprotein (AFP) in sera and tumor cells of patients with testicular seminoma: A prospective study. Cancer. 1978 Dec; 42(6):2768-2772. PubMed 83187

2. Lange PH, McIntire KR, Waldmann TA, Hakala TR, Fraley EE. Serum alpha fetoprotein and human chorionic gonadotropin in the diagnosis and management of nonseminomatous germ-cell testicular cancer. N Engl J Med. 1976 Nov 25; 295(22):1237-1240. PubMed 62281

3. Javadpour N, McIntire KR, Waldmann TA, Scardino PT, Bergman S, Anderson T. The role of the radioimmunoassay of serum alpha-fetoprotein and human chorionic gonadotropin in the intensive chemotherapy and surgery of metastatic testicular tumors. J Urol. 1978 Jun; 119(6):759-762. PubMed 77918

4. Kohn J, Orr AH, McElwain TJ, Bentall M, Peckham MJ. Serum-alpha1-fetoprotein in patients with testicular tumours. Lancet. 1976 Aug 28; 2(7983):433-436. PubMed 73740

5. Perlin E, Engeler JE Jr, Edson M, Karp D, McIntire KR, Waldmann TA. The value of serial measurement of both human chorionic gonadotropin and alpha-fetoprotein for monitoring germinal cell tumors. Cancer. 1976 Jan; 37(1):215-219. PubMed 55299

6. Scardino PT, Cox HD, Waldmann TA, Mcintire KR, Mittemeyer B, Javadpour N. The value of serum tumor markers in the staging and prognosis of germ cell tumors of the testis. J Urol. 1977 Dec; 118(6):994-999. PubMed 72833

7. Javadpour N. The role of biologic tumor markers in testicular cancer. Cancer. 1980 Apr 15; 45(7 Suppl):1755-1761. PubMed 6154517

8. Mason MD. Tumour markers. In: Horwich A, ed. Testicular Cancer Investigation and Management. Baltimore, Md: Williams and Wilkins;1991:35-50.

9. Toner GC, Geller NL, Tan C, Nisselbaum J, Bosl GJ. Serum tumor marker half-life during chemotherapy allows early prediction of complete response and survival in nonseminomatous germ cell tumors. Cancer Res. 1990 Sep 15; 50(18):5904-5910. PubMed 1697503

10. Kirkpatrick AM, Kirkpatrick KA. Clearance-corrected differencing and other analytic techniques useful in the interpretation of serum AFP values. In: Kirkpatrick AM, Nakamura RM, eds. Alpha-Fetoprotein: Laboratory Procedures and Clinical Applications. New York, NY: Masson;1981:135-148.

11. Price P, Hogan SJ, Horwich A. The growth rate of metastatic non-seminomatous germ cell testicular tumours measured by marker production doubling time--I. Theoretical basis and practical application. Eur J Cancer.1990; 26(4):450-453. PubMed 1694086

12. AFP on Elecsys 1010/2010 and Modular Analytics E170, package insert 2006-05, V2, Indianapolis, Ind: Roche Diagnostics; 2006.

13. Taketa K. Alpha-Fetoprotein in the 1990s. In: Sell SS, ed. Serological Cancer Markers. Humana Press;1992:31-46.

14. Ruoslathi E, Engvall E, Kessler MJ. Chemical properties of alpha-fetoprotein. In: Herberman RB, McIntire KR, eds. Immunodiagnosis of Cancer. New York: Marcel Dekker Inc;1979:101-117.

15. Diamandis EP, Fritsche HA, Lilja H, et al. Tumor Markers: Physiology, Pathobiology, Technology, and Clinical Applications. Washington, DC: AACC Press;2002.

16. Ramsey WH, Wu GY. Hepatocellular carcinoma: Update on diagnosis and treatment. Dig Dis. 1995 Mar-Apr; 13(2):81-91. PubMed 7586635

17. Sato Y, Nakata K, Kato Y, et al. Early recognition of hepatocellular carcinoma based on altered profiles of alpha-fetoprotein. N Engl J Med. 1993 Jun 24; 328(25):1802-1806. PubMed 7684823

18. Klepp O. Serum tumor markers in testicular and extragonadal germ cell malignancies. Scand J Clin Lab Invest Suppl. 1991; 206:28-41. PubMed 1947758

19. Sturgeon C. Practice guidelines for tumor marker use in the clinic. Clin Chem. 2002 Aug; 48(8):1151-1159. PubMed 12142367

20. Fateh-Moghadam A, Stieber P. Sensible Use of Tumor Markers. Boehringer Mannheim;1994. Catalog N° 1536869.

21. Stuart KE, Anand AJ, Jenkins RL. Hepatocellular carcinoma in the United States. Prognostic features, treatment outcome, and survival. Cancer. 1996 Jun 1; 77(11):2217-2222. PubMed 8635087