TUMOR MARKERS

INTRODUCTION :-
Tumor markers are biochemical substances usually proteins released by tumor cells either due to cause or effect of malignant process. Some are specific while others are seen in several cancers. Many are also seen in non-cancerous conditions. They may be intracellular seen in tissues or released into circulation. Search for suitable markers in serum, tissues or body fluids during neoplastic process is of clinical value. Though an ideal marker should be highly sensitive, specific, reliable with high prognostic value and correlate with staging none of the markers identified so far has all the features. However they are helpful to monitor in risk groups, diagnose the probable source, staging the cancer, determine prognosis, guide & monitor treatment and detect recurrence.

CLASSIFICATION :- Broadly they may be classified as :-
1. Oncofetal antigens:-α-fetoprotein(AFP), carcinoembryonic antigen (CEA), pancreatic oncofetal antigen, fetal sulfoglycoprotein etc.
2. Tumor associated antigen/Cancer antigen e.g. CA-125,CA-19-9,CA 50 etc.
3. Hormones e.g. β human chorionic gonadotrophin, calcitonin, placental lactogen etc.
4. Hormone receptors e.g. estrogen & progesterone receptors.
5. Enzymes and isoenzymes e.g.-PSA(prostate specific antigen),PAP(prostatic acid phospatase),NSE(neuron specific enolase),TDT(terminal deoxy nucleotidyl transferase ),PALP(placental alkaline phospatase), lysozymes, alpha amylase etc.
6. Serum&tissueproteins-β2microglobulin,monoclonalimmunoglobulin/paraproteins, GFAP(glial fibrillary acid protein), proteinS-100, ferritin, fibrinogen degradation products etc.
7. Other biomolecules e.g. polyamines.
Some are commonly in use while others are less common.
IDEAL TUMOUR MARKER An ideal tumor marker should have---
1. Highly sensitive and less false negative.
2. Highly specific and less false positive.
3. Should have high +ve &-ve predictive value.
4. 100% accuracy in differentiating healthy & cancer patients.
5. Differentiate between neoplastic & non-neoplastic conditions showing +ve correlation with tumor volume and extent.
6. Predict early recurrence and have prognostic value.
7 . Clinically sensitive to detect in early stage.
8. Level should precede neoplastic process to screen early.
9. Should be universal to all or specific to one malignancy.
10. Easily assayable , able to indicate all changes during treatment.

DESCRIPTION:-
1.Alpha fetoprotein(AFP)— It is a major fetal serum globulin with a molecular weight of 65000. In fully matured fetus the AFP gene is completely repressed leading to its disappearance soon after birth. Though abundant in fetal blood, in normal adult the value is 15ng/ml. A value of serum AFP >500ng/ml indicate malignancy besides pregnancy. During fetal life AFP is synthesized in liver (main), yolk sac and GI tract. Fetal liver produce AFP about 30mg/day. In first trimester amniotic fluid contain yolksac derived AFP (Concanavalin-A non reactive). Later increased portion of AFP is liver derived(Concanavalin-A reactive). AFP reaches a peak between 30-32 weeks of pregnancy and decline suddenly before term. Clinical significance of AFP level is of value in prenatal diagnosis of open spina bifida, anencephaly, atresia of esophagus and multiple pregnancy.AFP level also aid in diagnosis,prognosis and monitoring primary hepatocellular carcinoma, hepatoblastoma, non seminomatous testicular germ cell tumors like embryonal carcinoma, teratoma, choriocarcinoma, yolksac carcinoma, germ cell tumors of ovary and extragonadal germ cell tumors. Most well differential and highly anaplastic hepatomas do not produce AFP, as AFP synthesis is associated with degree of liver cell differentiation. Significant rise of AFP is rarely seen in malignancy of GIT, pancreas, lungs, kidney and breast etc. Moderate rise of AFP is seen in viral hepatitis, chemical hepatic injury, hepatic necrosis, liver surgery. AFP < 400ng/ml is seen in 10-15% cases of acute and chronic hepatitis, cirrhosis, secondary malignancies. Serial AFP estimation shows steady and progressive rise in malignancies in contrast to fluctuation in nonmalignant condition. Pure seminomas are nonsecretor of AFP whereas in nonseminomatous germ cell tumors the AFP indicate progress, monitor treatment and recurrence. Dysgerminomas are AFP nonsecretors while highly malignant endodermal sinus tumours show raised AFP. Measurement of serum AFP is helpful in diagnosis, prognosis, and monitoring efficiency of chemotherapy, radiotherapy, surgery and recurrence of all malignancies discussed. Yolk sac and liver AFP synthesized during fetal and adult life are immunologically cross reactive but different. Because of their affinity to lectin AFP can be resolved to concannavalin A reactive(R con A) and non-reactive (NR con A) fraction. Quantitive as well as qualitative evaluation of AFP vaiant reveal two types, one specific to liver and other to yolk sac.

2.Human chorionic gonadotrophin(βHCG):- HCG, A marker of germ cell tumors and trophoblastic disease, is 45KD glycoprotein, composed of two dissimilar subunits the αchain(14 KD) and βchain(24 KD). It contains 30% carbohydrate. The beta subunit determines the immunological and hormone specificity. HCG is synthesized by the synctiotrophoblasts of the placenta during pregnancy. The peak HCG concentration is reached between 10th & 12th weeks of gestation. The reference values in serum of healthy men and non-pregnant women are less than 5 IU/ml and post-menopausal women are less than 10IU/ml. HCG is a marker of first choice for gonadal (testes and ovary) choriocarcioma. HCG shows 100% sensitivity for choriocarinoma irrespective of their site in addition to hydatidiform mole. In testicular tumors, the detection of βHCG and AFP correlate with the histological findings and is therefore crucial for the therapeutic procedures with the use of serial determination of βHCG. The biochemical recurrence precedes by 3 months before the patient has symptoms of clinical recurrence/metastasis. The marker also helps in monitoring high-risk group of testicular tumors especially individual with undescended testicle or the healthy monozygotic twin of a testicular tumor patient. High levels of βHCG indicate poor prognosis and frequent assays during therapy level correlate to the clinical response. Serum βHCG levels are rarely elevated in nontrophoblastic tumors such as lung, breast, pancreas and bladder cancers.

3.BETA-2Microglobulin(β2M):- β2M is 11 KD light chain constituent of HLA antigen. The β2M is used clinically as a marker of first choice for B-cell leukemia, lymphomas and multiple myeloma. However, due to its non-specificity its moderate elevation is observed in cases of solid tumors and also in various inflammatory diseases, benign infectious disorders, and primary billiary cirrhosis and in acquired immune deficiency syndrome. It is used routinely for evaluating tumor cell load, disease activity and prognosis. It is also used to monitor efficacy of patient’s response to treatment. Elevated levels of β2M are also reported in cerebrospinal fluid (CSF),in CNS metastasis, acute lymphoblastic leukemia. lymphoma and other lymphoproliferative disorders/diseases. Hence the determination of β2M in CSF helps in identifying and managing CNS metastases. Serum β2M could be clinically relevant marker for Waldenstrom’s macroglobulinemia, secretary and non-secretary multiple myeloma, leukemia and lymphoma. Like other tumor markers, β2M has proven to be the best marker for monitoring therapeutic courses, as it useful serum parameter to monitor tumor progression as well as early biochemical relapse. Serum β2M is the most powerful prognostic marker of monoclonal gammapathies.

4. BRCA 1 &BRCA 2:- BRCA 1and BRCA 2 belong to few tumor suppressor susceptibility genes having high risk to few cancers.BRCA1 predicts high risk for breast, ovary, colon and prostate cancers. BRCA2 gene mutation is seen in 70% of breast cancers in women and men. More than 100 germ line mutations are reported in BRCA gene applying current molecular technology.

5.BTA(Bladder tumor antigen):- Not widely used. Urine level helps in diagnosis and recurrence of bladder tumors. May be raised in kidney stones and urinary tract infection.

6.Carcino-embryonic antigen(CEA): -CEA, is a glycoprotein of 200 KD. Radioimmunoassay (RIA) made it possible to detect very low concentrations of CEA in blood, other body fluids, and also in normal and diseased tissues. It is excreted by certain embryonic and adult tissues in addition to adenocarcinoma of the digestive organs. Extensive studies of patients bearing primary and metastatic colorectal neoplasms have determined that its primary use is in the detection of local and metastatic cancer recurrence after initial resection of the primary tumor, through periodic postoperative analysis of CEA in serum or plasma. The notion that fluids bathing tumors in metastatic sites might contain higher levels of CEA than those found in the blood led to analysis of CEA levels in gallbladder bile from patients bearing colorectal liver metastases. It was observed that CEA levels in gallbladder bile were strikingly higher than those in serum. Furthermore , linear regression analysis of tumor volume versus gallbladder bile CEA levels in patient with liver metastases predicted that tumors as small as 1 cm would produce easily measurable gallbladder bile CEA levels as high as 41ng/ml. This data suggested that measuring biliary CEA levels in patients with primary colorectal lesions might permit detection of small, occult colorectal liver metastasis earlier than now is possible through conventional methods (computed tomography liver scanning, ultrasound, and intraoperative exploration). The results of clinical studies that CEA, although originally thought to be specific for digestive tract cancers, may be elevated in other malignancies and in some nonmalignant disorders. CEA testing is of significant value in the monitoring of patients with diagnosed malignancies in whom changing concentrations of CEA are observed. A persistent elevation in circulating CEA following treatment is strongly indicative of occult metastatic and / or residual disease. A persistently rising CEA value may be associated with progressive malignant disease and a poor therapeutic response. A declining CEA value is generally indicative of a favorable prognosis and a good response to treatment. Clinical relevance of the CEA assay has been shown in the follow-up management of patients with colorectal, breast, lung, prostatic, pancreatic and ovarian carcinoma. CEA testing recommended as a screening procedure to detect cancer in the general population; however, use of the CEA test as an adjunctive test in predicting prognosis and as an aid in the management of cancer patients has been widely accepted.

7.Cancer antigen 125(CA 125):- It is a glycoprotein of more than 200 KD, detected by monoclonal antibody. Healthy women has < 35 U/ml in their serum. It is a first marker of choice in epithelial ovarian carcinoma specially adenocarcinoma (high sensitivity 80% specificity 96%). It is useful for staging, prognosis& recurrence. It may be raised in malignancies of breast, colorectal, gastric, esophagus, liver, billiary tract, pancreas, lungs, and endometrium. After removal of ovarian tumor there is rapid decline within a week and normalize within 3-4 weeks. CA-125 value indicates prognosis, remission or relapse. Nonspecific mild rise may be seen in begin ovarian cyst.(follicular cyst), endometriosis, coelomic epithelium pathologies, cirrhosis, pleural effusion, ascites, peritonitis, pericarditis, during menstruation and last trimester of pregnancy.

8. Cancer Antigen 19-9:- It is a marker of first choice in cancer of pancreas and gall bladder. It is 210 KD glycoprotein antigen having carbohydrate on glycolipid and glycoprotein, detected by monoclonal antibody assay. The antigen is located immunologically in fetal epithelium of colon, small intestine, stomach, pancreas, liver, adult GIT and lung. Appreciable level is seen in mucin rich saliva, seminal fluid, gastric juice, amniotic fluid, urine, ovarian cyst fluid, pancreatic, gallbladder and duodenal secretion. Normal value is < 37U/ml and < 100U/ml is considered as grey zone where malignant and benign disease may overlap. In malignancy value may be > 100,000 U/L. In pancreatic tumor (sensitivity -85%, specificity -95%), cholangiocarcinoma and gall bladder carcinoma ( sensitivity 70%) it is helpful. It may have low sensitivity in colorectal, stomach, primary liver, bronchial, mucinous ovarian, uterus and mammary carcinoma. Besides diagnosis its value predicts recurrence after pancreatectomy. Nonspecific rise may occur after acute or chronic pancreatitis. (8%).

9.CA15-3:- Ca 15-3 is heterogeneous 300 KD glycoprotein antigen. The diagnostic sensitivity of the CA 15-3 for breast carcinoma is low as its elevated level is also observed in benign breast diseases and cirrhosis, acute and chronic hepatitis and in metastatic cancers of pancreas, ovary, colorectal, lung, stomach, uterus.

10.CA72-4:- Its molecular weight is more than 106 KD. This antigen was detected in fetal epithelium and also in serum of patients of various adenocarcinoas. CA 72-4 once emerged as the marker of first choice for gastric carcinoma and is thereby superior to CA19-9 and CEA. The sensitivity of CA 72-4 was found to be 38%. CA 72-4 is considered to be the multiple marker for epithelial cell derived tumors.

11.CA 19-5 & CA-50:- CA 19-5 was found to be associated with colon, pancreatic and hepatocellular carcinoma. Individually both antigens have low sensitivity. However use of both together improves sensitivity in detecting pancreatic and other carcinomas.

12.CA 549:- CA 549 is a high molecular weight circulating glycoprotein antigen associated with breast cancer. Elevated level of CA 549 is observed in serum of advanced breast cancer by using sensitive immunoassay. However, it has very low sensitivity; very low negative predictive value and high positive predict value for early breast cancer.

13.Cytokeratins/Keratins:- Keratins are remarkably diverse, highly resistant and the most conserved cytoskeletal proteins are present in all types of epithelial cells. The composition of keratin filaments ranges from a few polypeptides to 19 different polypeptides ranging from 40 to 68 KD. Keratins have gained importance as marker protein in diagnosis of tumor of epithelial origin. There may be variation in keratin expression compared to normal tissue, depending on degree of differentiation of epithelial tumors. This property of keratin allows their use in combination with other changes as markers for malignant transformation in epithelioid tumors. Keratins has 2 main applications(i)distinguish epithelial from non epithelial tumors and(ii)distinguish type of epithelial tumor. Keratin is reliable marker of (i)undifferentiated and anaplastic carcinoma(ii)infiltrating carcinoma(iii)metastasizing single carcinoma cell in suspension. It may be used for epithelial carcinomas, especially those of stratified and sqamous cell origin e.g. lung , breast, urinary bladder, thymomas and cervical carcinoma. As GItract lining from buccal mucosa to rectum including pancreas and gall bladder is of epithelial origin keratin may serve as an useful marker. Keratin has been used as a differential marker in thyroid, GItract, prostate, lung and breast.

14.Cyfra 21-1:- It is used as a marker for non small cell lung cancer (NSCLC),squamous cell carcinoma(SCC), adenocarcinoma and large cell carcinoma. This marker has highest sensitivity for SCC in lung. Both Cyfra 21-1 and CA19-9 have improved detection of adenocarcinoma of lung.
15.Calcitonin:- Calcitonin a low molecular weight peptide hormone secreted from C cells of thyroid is used as a marker, as increased level is seen in malignancies with skeletal metastasis. It is increased in medullary carcinoma of thyroid, bronchogenic carcinoma, small cell cancer of lung, breast, liver, lung, renal and carcinoid tumors.

16.Catecholamines:- Plasma and urinary epinephrine and norepinephrine are raised in Pheochromocytoma.

17.CathepsinD:- Lysosomal aspartyl protease of lysosomes is considered a potential marker for breast cancer metastasis. Cathepsin D predicts early recurrence. It has high prognostic value in node-ve breast cancer than node+ve breast cancer. Patients with low Cathepsin D value have better survival. High level of Cathepsin D enhances metastasis in breast cancer.

18.Chromogranin A:- Chromogranin A(secretogranin 1) belongs to group of closely related secretary acid protein is used as a marker to asses exocytotic sympathoadrenal activity in Pheochromocytoma. In peptide producing tumors it is raised.

19. CA27.29&CA 15-3:- Usually seen in breast cancers. May be +ve in colonic, gastric, hepatic, lung, ovarian, prostatic cancers and breast, liver, kidney diseases and ovarian cyst.

20. Circulating methylated DNA:- Circulating nucleic acids may be used as marker in early detection, follow progression. DNA is a stable molecule and detected by PCR.

21.Epidermal growth factor receptor(EGFR): -EGFR a 170 KD glycoprotein binds to epidermal growth factor(EGF). It is raised in breast cancer, gliomas, lung cancer, SCC and tumors of female genital tract. Absence of EGFR indicates a good response to Tamoxifan therapy.

22.Estrogen receptor(ER),Progesterone receptor(PR):- ER a 70 KD protein is present in mammary and uterine tissues. ER &PR belongs to receptor super gene family including receptors for thyroid hormone, vitamin D3 and retinoic acid. In breast tumor their level indicate benefit of hormone therapy. 55% to60% ER positive primary breast cancer show good hormone response. Following mastectomy high PR&ER positive tumors have longer survival. PR is more sensitive than ER.

23.Ferritin:- Serum ferritin an acute phase reactant is an intracellular protein playing a role in sequestration and storage of iron. Increased ferritin level is seen in cancers in absence of iron overload. It is increased in advanced breast, ovary, lung, colon, esophagus cancer, acute myelocytic leukemia, teratoblastoma and SCC of head and neck.

24.Homovanillic acid(HVA) & Vanillymandelic acid(VMA): -HVA &VMA are acid metabolites of catecholamines. Their increased excretion is observed in neural crest tumors. They also help in detecting and monitoring therapy in Pheochromocytoma & Neuroblastoma.

25.Hydroxy indole acetic acid (5-HIAA):- Urinary measurement helps in indole secreting tumors. Helps in diagnosis and therapy monitoring in Carcinoid tumors.

26.Her-2/neu(also known as HER,erbB-2,EGFR-2):- Seen in 20-30% of advanced breast cancers. It determine prognosis and guide treatment.
27. Human telomerase reverse transcriptase (hTERT):- It is a novel and newly available biomarker for patients with ovarian and uterine cancers. The hTERT mRNA level has a significant correlation with CA-125 and with histological finding in ovarian cancer. Serum hTERT mRNA is useful for diagnosing gynecological cancer and is superior to conventional tumor markers. Up regulation of hTERT may play an important role in the development of cervical intraepithelial neoplasia (CIN) and cervical cancer. So hTERT could be used as an early diagnostic biomarker for cervical cancer in future.

28.Interleukin-2 receptor/Tac antigen(IL-2R):- IL-2 α a 55KD glycosylated protein is seen in some types of lymphoid malignancies like T-cell leukemia. It my monitor treatment.
29. Inhibin:- Inhibin is a peptide hormone normally produced by ovarian granulosa cells. It inhibits the secretion of follicle-stimulating hormone (FSH) by the anterior pituitary gland. It reaches a peak of 772 +/-38 U/L in the follicular phase of the menstrual cycle and is normally undetectable in the serum of menopausal women. Granulosa-cell tumors produce inhibin and its serum levels reflects the tumor burden. Measurement of inhibin can be used as a marker for primary as well as recurrent granulosa cell tumor.The recent availability of markers of ovarian stroma, including melan-A and inhibin- alpha, has provided a means for the positive identification of ovarian stromal tumors, which can manifest in a myriad of histological appearances.The hormonal activity of granulosa cell tumors permits the use of a variety of serum markers in the diagnostic evaluation. Clinically the most useful serum marker for granulosa cell tumors is inhibin. Inhibin exists in 2 different isoforms. Inhibin-A and Inhibin-B. Both isoforms consists of a dimmer of 2 subunits, the alpha and beta subunits. Inhibin usually becomes no detectable after menopause. However, certain ovarian tumors mostly mucinous epithelial ovarian carcinoma and granulosa cell tumors produce inhibin. An elevated level in a postmenopausal women or a premenopausal women presenting with amenorrhea and infertility is suggestive of the presence of a granulosa cell tumor, but not specific. Inhibin levels can also be used for tumor surveillance after treatment to assess for residual or recurrent disease.

30.Lipid associated sialic acid in plasma(LASA-P):- Increased level is seen in malignancies of breast, GItract, lung, leukemia, lymphoma, Hodgkin’s and melanoma(sensitivity vary -77% to97%). Slight increase is seen in many inflammatory diseases indicating poor specificity.
31. Lysophospatidic acid:- It stimulates cancer cell proliferation, intracellular calcium rise and tyrosine phosporylation. It is found in ascitic fluid of ovarian cancer.

32.L1(CAM):- It correlates with stage and grade of ovarian cancer and response to chemotherapy.

33.LDH(lactate dehydrogenase):- Though one of the first marker clinically used may be raised in many cancers. It is currently used in monitoring some leukemias and lymphomas.

34.Monoclonal immunoglobulin/Paraprotein:- Monoclonal immunoglobulin content is of value in diagnosis and monitoring management of plasma cell tumors like Multiple myeloma, Waldenstrom’s macroglobulinemia, plasma cytoma, B cell leukemias and lymphomas.

35.Mitf (Microphthalmia transcription factor):- It is important in melanocyte development and growth. It is tried in determining disease stage and survival, detect sub clinical metastasis and outcome of treatment.

36.Mullerian inhibiting substance(MIS):- MIS is produced by granulosa cells in the developing follicles. It has emerged as potential tumor marker for granulosa cell tumors. As with inhibin, MIS is typically undectable in postmenopausal women. The elevated MIS level is highly specific for ovarian granulosa cell tumors. However, this test is not commercially available for clinical use.

37.Neuron specific enolase(NSE):- NSE, the gamma subunit of enolase enzyme is present in neurons & neuroendocrine cells.NSE is raised in glucagonoma, insulinomas, carcinoid tumor, pheochromocytoma, medullar carcinoma of thyroid, oat cell carcinoma, small cell and other lung cancers. It is marker of 1st choice in SCLC.NSE monitoring is used in assessing prognosis and therapeutic response in85% of neuroblastoma and SCLC.

38.NMP-22:- Not widely used. Urine level helps in diagnosis and recurrence of bladder tumors(>10 units/ml).

39.Oncogene P21 RAS:- RAS ,one of the transformation inducing gene belonging to family of cellular oncogens(c-ras) frequently seen in human solid tumors like colorectal carcinoma, large adenomas, bladder and lung tumors.

40.Prostate specific antigen(PSA):- PSA known earlier as gammaseminoprotein is 34 KD single chain glycoprotein (93% amino acid, 7% carbohydrate) , a monomer made up of 240 amino acid residue. It is a neutral serine protease, having trypin and chymotrypsin like activities belonging to glandular kalkrein family. Synthesized from prostate epithelium. Small amount of PSA released to circulation form complexes with different protease inhibitors detected in serum and seminal fluid. PSA-ACT complex (major immunoreactive form 80-90%), PSA-AT (α-1 antitrypsin) PSA-PCI(protease C inhibitor ) and PSAα2M(α-2 macroglobulin) are different complexes. The remaining PSA are free immunoreactive form(5-15%). PSA is most useful and clinically relevant marker for prostatic cancer. It is useful for early detection, prevention and assay efficacy of treatment. PSA is synthesized in low quantity by normal prostate, mild quantity in inflamed or hypertrophied prostate, prostatic trauma, after ejaculation and in large quantity by malignant prostate. Due to overlap at times there may be difficulty to distinguish between BPH and early cancer. However combined with digital rectal examination and transrectal ultrasound PSA proves useful in adenocarcinoma besides biopsy. The value of PSA also increases with age and there is correlation between total and free PSA. Indian males have low level as compared to other countries. Though the normal cut off value is 4ng/ml it increases with age. Use of age specific reference value will improve diagnostic efficacy. Clinical analysis of molecular forms of PSA, free PSA, or free PSA/total ratio are useful to differentiate begin from malignant conditions. Other markers in prostatic cancer are PAP, Alkaline phosphates (ALP), PSMA,
Zn-alpha-2-glycoprotein, leucine amino peptidase, lactic dehydrogenase.

41.Prostate acid phospatase(PAP):- Acid phosphates activity is 200 times more abundant in prostate tissue than in any other tissue. Acid phosphatase prostatic fraction is useful only in staging apparently localized disease i.e., primary prostate cancer before definitive therapy such as radical prostatectomy. Its activity in serum can be estimated by several synthetic substrates, but now specific antibodies are available for immunoassay. The enzymatic assay appears superior to the immunoassay in this context. Interest in acid phosphates assay in serum as a measure of prostatic cancer staging has decreased with the availability of more sensitive and specific PSA assay.

42. Parathyroid hormone related peptide(PTH-RP):- Elevated plasma level is seen in cancers having hypercalcemia. It helps to differentiate primary hyperparathyroidism, sarcoidosis, vitamin-D, squamous cell carcinoma of renal, bladder and ovarian cancers.
43.PS 2:- PS2, a low molecular weight cysteine rich protein is raised in 50% of breast tumors. Its expression indicates better prognosis than ER and PR. It is also seen in normal stomach mucosa and ulcerative disease of GItract.

44. PSMA (Prostate specific membrane antigen):- Though not used, may rise with age and serum level indicate prostate disease.

45. S-100:- Though not widely used, may help in diagnosis of metastatic melanomas.

46.Tissue polypeptide antigen(TPA):- TPA regarded as a marker of cell proliferation, is a mixture of proteolytic fragments cytokeratins 8,18,and19. These fragments are released during necrosis and lysis of cancer cells. TPA is regarded as a broad spectrum epithelial marker. Moderate elevation occurs in many diseases and pregnancy. Marked elevation is reported in cancers of breast, lung, gastrointestinal, urological and gynecological conditions.TPA though sensitive but not specific. TPA with CEA help in monitoring lung, breast, bladder, colorectal and ovarian carcinomas.

47. Tumor suppressor gene P53:- P53, a 53 KD nuclear phospoprotein acts as tumor suppressor by inhibiting cell proliferation and plays a role in cellular apoptosis.P 53 gene mutation seen in 50% of all cancers like breast, colon, ovary, lung and esophagus.

48.Squamous cell carcinoma(SCC) antigen:- SCC antigen, a 48KD protein is purified from uterine cervix. It is raised in squamous cell cancer of head & neck, lung, esophagus and anal canal. Highest level is found in metastasis. It is elevated in advanced cervical cancer, determine progression or regression following chemotherapy. Combined use of CEA, NSE, SCC antigen increase sensitivity in detection and monitoring lung cancers.

49. Thyroglobulin:- Used after removal of thyroid to find recurrence. It is elevated in many thyroid diseases. In some antibody is formed against thyroglobulin. So level of antithyroglobulin antibody is measured at the same time.

50. Topoisomerase II:- Topoisomerase II expression is detected in tumor samples by immunohistochemistry and has emerged as a promising, clinically relevant biomarker for survival in patients with advanced epithelial ovarian cancer.

51. TA-90:- Recently on trial to diagnose metastatic melanomas. This protein is found on outer surface of melanoma cells. Its use is studied in colon and breast cancer.

52. Other Gynecological markers:- Other markers in many gynecological conditions are-
Urinary gonadotrophin fragment, Tumor associated trypsin inhibitor, Cyclin E, Mesothelin, HE4, Osteopontin, Ineterleukin 8, Vascular endothelial growth factor(VEGF), Macrophage colony stimulating factor, Insulin like growth factor-binding protein-3, OVX, NB70/K, HMFGR (human milk fat globule)

METHODS:- Common methods used to identify tumor proteins are-
1. Immunohistochemistry- Traditionally most methods have used monoclonal antibodies and immunohistochemistry. They can be used directly in tumors or serum, bonemarrow, lymphnodes.
2. Reversed transcriptase and polymerase chain reaction(RT-PCR)


USEFULNESS:- Tumor markers are usually used for--
1. Detection-Screening in asymptomatic cases for early diagnosis.
2. Diagnosis-Differentiating malignant from benign condition.
3. Monitor-Predict effect of therapy and detect recurrence.
4. Prognosis-Choosing therapy and predict tumor behavior.
5. Therapy-Directing cytotoxic agents to marker containing cells.

SUMMARY:-
Tumor markers are biomolecules released or formed during neoplastic process. Though an ideal marker is yet to be identified they aid in detection, diagnosis, monitor response and recurrence. They may be raised in some nonmalignant conditions.
In urinary bladder tumor BTA and NMP-22 are used along with urine cytology and cystoscopy. In advanced cancers CEA, CA-125,CA 19-9 & TPA are raised.
In breast cancers ER,PR and HER/neu are used for diagnosis. In advanced cases follow-up and recurrence are detected by CA15-3, CA 27-29 & CEA.
In colorectal advanced cancers CEA & ca19-9 are elevated, but neither is helpful for screening test. They are used for follow-up and recurrence.
Gestational trophoblastic diseases show elevated βHCG.
In liver cancers AFP is used for screening, diagnosis and follow-up.
In lung cancers no marker is useful for screening. CEA is raised in non small cell cancer and NSE in small cell cancers and used for evaluation of treatment.
Though no marker is useful for screening TA-90, S-100 and other markers help to find metastasis, follow-up and prognosis.
In multiple myeloma immunoglobulins,β2M are helpful.
In ovarian epithelial cancer CA-125 is usually elevated. Others like CA72-4 & LASA-P are raised. In ovarian germ cell tumor βHCG and AFP are raised.
In pancreatic cancer though no marker is helpful for screening CA 19-9 & CEA are used.
For prostatic malignancy PSA is commonly used. Markers like PSMA, chromogranin-A and PAP are also useful.
Though no marker has developed for stomach cancer CEA,CA 72-4 & 19-9 are raised at times.
For testicular tumor βHCG is elevated in seminomas where as AFP or βHCG or both are raised in nonseminomas.

CONCLUSION:-
Though all tumor marker are not ideal biomarkers their judicious use following evidence based medicine are clinically helpful. Inspite of nonspecificity of wide spectrum of available markers, their potential role in monitoring entire cancer therapeutic course is clinically relevant.

CLINICAL FOCUS:-
 Tumor markers are substances which indicate probable presence of malignancies.
 Few are specific, most of them are nonspecific. Many are seen in nonmalignant conditions.
 All of them are classified into various biochemical groups.
 Though tried since long not a single one fulfill the criteria of ideal marker.
 AFP is specific for liver cancers.
 BTA,NMP-22,CEA,CA125,CA19-9, TPA indicate bladder cancer.
 TA-90,S-100 indicate melanoma.
 ER,PR,HER/neu,CA15-3,CA27-29, CEA are indicative of breast cancers.
 PSA,PSMA,PAP are raised in prostatic conditions.
 CEA,CA72-4,CA19-9 are raised in gastric malignancies.
 CEA,CA 19-9 are increased in pancreatic and colorectal cancers.
 CEA,NSE are raised in lung cancers.
 CA-125,βHCG and AFP are raised in ovarian conditions.
 In testicular tumors βHCG &AFP are raised.
 They are detected by immune assay or RT-PCR.
 Few are used for screening asymptomatic cases while others are helpful for diagnosis, staging, prognosis, response to resection or chemotherapy and recurrence.