Detection of melanoma cells in peripheral blood by means of reverse transcriptase and polymerase chain reaction

Increased sensitivity for the detection of malignant melanoma cells in peripheral blood using an improved protocol for reverse transcription-polymerase chain reaction

Conflicting results have been obtained by various research groups using tyrosinase reverse transcription-polymerase chain reaction (RT-PCR) for detecting micrometastases in the blood of melanoma patients, with positive results ranging from 0 to 100% in disseminated melanoma. Methodological differences in the processing of blood samples may in part account for these discrepancies. The aim of this study was to standardize and optimize the experimental conditions for RT-PCR detection of melanoma cells in peripheral blood. We analysed the effect of different parameters of sample processing on the sensitivity of the tyrosinase RT-PCR using peripheral blood spiked with defined numbers of SKMEL28 melanoma cells. Purification of the mononuclear cell fraction using a Ficoll gradient with a density of 1.077 g/mL prior to RNA isolation gave the highest sensitivity, with the detection of two SKMEL28 cells in 5 mL of blood. In addition, the RNA isolation method and the kind of RT enzyme used had a significant impact on the sensitivity and reproducibility of tyrosinase detection, whereas variations in the PCR conditions had only a minor influence. Furthermore, we showed that amplification of MelanA in addition to tyrosinase resulted in an approximately 10% enhanced sensitivity of melanoma cell detection, whereas gp100/pMel17 and MUC18 gene products were also detected in blood from non-melanoma patients. MelanA could serve as a sensitive marker in addition to tyrosinase for detecting micrometastases.

Amplification of MelanA messenger RNA in addition to tyrosinase increases sensitivity of melanoma cell detection in peripheral blood and is associated with the clinical stage and prognosis of malignant melanoma

An improved protocol for reverse transcription-polymerase chain reaction (RT-PCR), amplifying tyrosinase and MelanA/MART-1 mRNA from peripheral blood, was used to test 340 blood samples from 225 patients with malignant melanoma for the presence of circulating tumour cells. Positive results for tyrosinase or MelanA were obtained in 19% of patients in stage I (n = 74), 31% in stage II (n = 45), 29% in stage III (n = 48) and 52% in stage IV (n = 58). Amplification of MelanA in addition to tyrosinase resulted in a 30% enhanced sensitivity of melanoma cell detection compared with amplification of tyrosinase alone. The sensitivity was further enhanced by analysis of at least two blood samples per patient and performing at least two PCR analyses per sample. During a median follow-up of 4 months, patients with a positive PCR showed a 2. 4-fold increased risk for relapse compared with PCR-negative patients. These data indicate that the detection of circulating melanoma cells in peripheral blood using our optimized protocol for RT-PCR correlated with the clinical stage of disease and is therefore likely to be a prognostic marker for recurrence. MelanA is a sensitive additional marker to tyrosinase in detecting micrometastases using RT-PCR.

Detection of melanoma micrometastasis in sentinel nodes by reverse transcription-polymerase chain reaction correlates with tumor thickness and is predictive of micrometastatic disease in the lymph node basin

The sentinel node has been reported to be representative for the presence or absence of metastatic melanoma in the draining lymph node basin. In this study, for the first time sentinel nodes and adjoining nonsentinel nodes were analyzed for micrometastatic disease using tyrosinase reverse transcription-polymerase chain reaction (RT-PCR) in comparison with standard immunohistochemistry. Successful identification of the sentinel nodes using a gamma probe-guided surgery was achieved in 73 (92%) of 79 patients with cutaneous stage I and II melanoma (tumor thickness > or =0.75 mm). A total of 794 regional lymph nodes, 148 sentinel nodes, and 646 adjoining nonsentinel nodes were evaluated. Tyrosinase RT-PCR was shown to increase the sensitivity for melanoma cell detection in sentinel nodes significantly (49% positivity) as compared with immunohistochemistry using antibodies against HMB-45 antigen and S-100 protein (18% positivity). Examination of sentinel nodes was highly predictive in determining the presence of regional lymph node micrometastasis by immunohistochemistry (99%) and RT-PCR (89%). Interestingly, detection of nodal micrometastasis by RT-PCR showed a strong positive correlation with tumor thickness of primary cutaneous melanoma. These results suggest the clinical significance and emphasize the importance of tyrosinase RT-PCR for detection of melanoma micrometastasis in sentinel nodes.

Detection of regional melanoma metastases by ultrasound B-scan, cytology or tyrosinase RT-PCR of fine-needle aspirates

Physical examination and ultrasound B-scan screening are important follow-up procedures in melanoma patients with regional disease. However, they do not allow definite diagnosis of suspicious lesions. Fine-needle aspiration cytology (FNAC) enhances the diagnostic accuracy in such patients but, unfortunately, reaches its technical limits, particularly when very small or necrotic lesions are examined. We therefore tested whether tyrosinase reverse transcription polymerase chain reaction (RT-PCR) of fine-needle aspirates (FNA-PCR) could help to increase diagnostic sensitivity. With clinical follow-up in 69 melanoma patients 81 regional lymph nodes were detected by ultrasound B-scan examination, nine of whom appeared to be palpable. Technically, FNAC was successful in all 81 lymph nodes, while FNA-PCR failed to obtain RNA at detectable levels in two lymph nodes of two patients. Of 79 lesions which have been completely evaluated by B-scan, FNAC and FNA-PCR, 44 proved to be melanoma metastases by histopathology, while the remaining 35 lesions were finally classified as non-specific lymph nodes. Of the 44 melanoma metastases 80% (n = 35) have been detected by B-scan, 90% (n = 39) by FNAC and 100% (n = 44) by FNA-PCR (P < 0.05 vs FNAC, P < 0.005 vs B-scan). In the subclass of lesions with diameters below 10 mm the sensitivities were 72% (n = 13), 78% (n = 14) and 100% (n = 18) respectively. In 35 regional lymph nodes classified as benign lesions, FNAC was always negative while FNA-PCR produced one positive result. Neither of these methods did produce false positive results in 15 control lymph nodes of non-melanoma patients. We conclude, that FNA-PCR might have superior sensitivity as compared to FNAC or ultrasound B-scan, particularly in melanoma lesions with diameters below 10 mm.

Detection of messenger RNA for the beta-subunit of chorionic gonadotropin in urinary cells from patients with transitional cell carcinoma of the bladder by reverse transcription-polymerase chain reaction

We studied whether detection of messenger-RNA (mRNA) for the beta-subunit of chorionic gonadotropin (CGbeta) in urinary cells from bladder cancer patients could be used as a marker of disease activity. Sixty-eight urine samples from patients under follow-up for bladder cancer and 23 samples from patients with other malignancies and non-malignant surgical conditions, as well as 14 samples from healthy controls were analyzed. RNA was isolated from urinary cells collected by centrifugation. Reverse transcription-polymerase chain reaction (RT-PCR) was used to detect CGbeta mRNA. The results were compared to those obtained by cystoscopy and urinary cytology. For comparison, we determined CG and CGbeta in serum and urine and the core fragment of CGbeta (CGbeta cf) in urine by immunofluorometric assays. CGbeta mRNA was detected in 29 of 68 urine samples from patients with a history of bladder cancer, whereas all 14 samples from healthy controls tested negative. Elevated levels of CGbeta were observed in serum in 18 of 45 bladder cancer patients, but the association with CGbeta mRNA was weak. However, CGbeta mRNA expression in the absence of detectable cancer also occurred in some conditions associated with cellular atypia such as urinary tract infection, instrumentation and certain therapies. There was a highly significant association between histologically verified transitional cell carcinoma of the bladder and CGbeta mRNA in urine (p = 0.0014), implying CGbeta mRNA expression in tumor tissue. We conclude that CGbeta mRNA is a potential new marker for monitoring of bladder cancer. Further studies are needed to evaluate whether it provides independent clinical information.

Quantitative Reverse Transcription-PCR Measurement of Thyroglobulin mRNA in Peripheral Blood of Healthy Subjects

Background: Thyroglobulin mRNA can be detected qualitatively in the peripheral blood of patients with metastatic thyroid cancer, thyroid cancer patients with residual thyroid bed uptake, and individuals with no known thyroid disease with intact thyroid glands by use of a lengthy, highly sensitive extraction technique. To improve and broaden the clinical usefulness of this assay, we developed a quantitative reverse transcription (RT)-PCR assay for thyroglobulin mRNA, using RNA recovered from whole blood with a simplified extraction technique.

Methods: Whole blood was drawn from 32 healthy subjects in standard EDTA blood collection tubes. Total RNA was extracted from whole blood, using the PUREscript RNA Isolation Kit. RT-PCR using intron-spanning primers was used to quantitatively amplify thyroglobulin mRNA, using the ABI PRISM 7700 Sequence Detection System with a fluorescent-labeled, thyroglobulin-specific oligonucleotide probe. Thyroid RNA calibration curves were created using total RNA recovered from a single nondiseased thyroid gland.

Results: Qualitative RT-PCR demonstrated the presence of thyroglobulin mRNA in the whole blood sample of each healthy subject. The mean concentration of thyroglobulin mRNA detected in these subjects was 433 ± 69 ng of total thyroid RNA per liter of whole blood (range, 26–1502 ng/L). Overall assay imprecision (CV) was 24% for five samples analyzed 10 times each in separate analytical runs on different days.

Conclusions: Thyroglobulin mRNA can be accurately detected and quantified in peripheral blood from healthy subjects. This new quantitative technique may improve the clinical utility of circulating thyroglobulin mRNA detection in patients with thyroid disease.

The detection of tyrosinase-specific mRNA in bone marrow is not more sensitive than in blood for the demonstration of micrometastatic melanoma

Recent reports suggest that as a marker of progression of malignant melanoma, the detection of tyrosinase mRNA in blood is of limited value. In the present study, we investigated whether the detection of tyrosinase mRNA by reverse transcription-polymerase chain reaction (RT-PCR) in bone marrow samples might be a more useful method for the detection of micrometastatic melanoma. The presence of tyrosinase mRNA was analysed in blood and in bone marrow samples from 20 melanoma patients with widespread clinical metastases. Of these 20 patients, 12 were negative for tyrosinase mRNA in both blood and bone marrow. The remaining eight patients had tyrosinase mRNA in either blood or bone marrow: six in bone marrow and blood, one in bone marrow but not blood, and one in blood but not bone marrow. The sensitivity of tyrosinase mRNA detection by RT-PCR in bone marrow samples apparently does not exceed that in blood samples from metastatic melanoma patients. This seems to be independent of prior chemotherapy or immunotherapy. In contrast to different solid tumours, in melanoma, bone marrow seems not to be a significant reservoir for micrometastatic tumour cells.

Predictive value of serum S100B for monitoring patients with metastatic melanoma during chemotherapy and/or immunotherapy

In the immunohistology of malignant melanoma the use of polyclonal antibodies against protein S100 is well established. Recently, it was shown that S100B, a subunit of the S100 protein family, is detectable in the serum of melanoma patients and correlates with the stage of the disease in patients with metastatic melanoma. In the present study, the first evaluation of a large number of treatment observations (n = 77) in 64 different patients during chemotherapy and/or immunotherapy for advanced metastatic melanoma (stage IV) is presented. All patients received treatment according to standardized protocols comprising 8 weeks of treatment followed by routine staging procedures to evaluate therapeutic outcome. In 13 patients with tumour enlargement after first-line therapy, a second-line treatment was subsequently given. S100B immunoradiometric assay (IRMA) tests were performed before, during and after treatment at scheduled time points. In the interim analysis at 4 weeks 29 of 37 (78%) patients with tumour progression during treatment showed a raised S100B level. In the final analysis at 8 weeks, 31 of these 37 patients (84%) demonstrated rising S100B values (P < 0.001). Patients who responded to treatment (stable or regressing metastatic disease) showed constant or declining S100B levels in 38 of 40 patients (95%) at the interim analysis, at 8 weeks this was further increased to 39 of 40 patients (98%; P < 0.001). Thus, the use of S100B for monitoring treatment is adequate in the majority of cases. Our observations are of great interest for therapeutic trials of adjuvant and palliative therapies as the rise of S100B levels might indicate that re-staging and/or changes in therapy strategies should be chosen.

S100B protein detection in serum is a significant prognostic factor in metastatic melanoma

The serum detection of S100B, a new melanoma marker, has shown clinical significance in early studies. The aim of our study of 1, 339 serum samples from 412 different melanoma patients and 107 control patients was to prove the prognostic value of serum S100B levels in melanoma patients at different stages of disease and at follow-up (median: 30 months). Using a cutoff level of 0.2 microgram/l S100B, 5 of 286 patients (1.7%) with primary tumors (stage I/II), 14/73 (19.2%) patients with locoregional metastasis (stage III) and 57/84 (67.9%) patients with advanced disease (stage IV) were S100B positive (statistically significant differences for stage I/II vs. III, I/II vs. IV, and III vs. IV, p < 0.001). The estimated overall survival time was significantly longer (p < 0.001) for patients with S100B values below 0.2 microgram/l compared to patients with elevated S100B levels (>/=0.2 microgram/l), which was independent of the stage of disease (I-IV). Regarding prognosis, we were furthermore able to distinguish different subgroups among stage III and IV patients using S100B serum levels (p < 0.01). Patients with different cutaneous non-melanoma diseases served as S100B-negative controls. S100B serum evaluations using the Sangtec(R)100 IRMA are highly specific and sensitive for the detection of metastatic melanoma. S100B has been shown to be a relevant prognostic factor for survival in a study with a large sample size of melanoma patients including close follow-up evaluations.

Predictive power of screening tests for metastasis in uveal melanoma

PURPOSE

Uveal melanoma undergoes haematogenous dissemination, particularly to the liver. It is routine practice to screen for metastatic disease. The purpose of this study was to evaluate such screening tests and to determine their value in detecting metastatic disease at presentation.

METHODS

In this study of a series of 245 patients with uveal melanoma of whom 55 (22%) died, the sensitivity, specificity, positive and negative predictive powers and likelihood ratio of the blood tests, chest radiographs and liver ultrasound investigations performed at diagnosis were determined.

RESULTS

All the screening investigations were found to have a low yield, but the most sensitive were those for gamma-glutamyl transpeptidase (gamma GT; sensitivity 21%) and alkaline phosphatase (sensitivity 25%), with gamma GT being more specific (specificity 92%). No blood test had a positive predictive power greater than 50%. The chest radiograph and liver ultrasonography were both 100% specific but had sensitivities of 2% and 14% respectively.

CONCLUSIONS

Only the chest radiograph and liver ultrasonography had positive predictive powers greater than 50% and these tests had very poor sensitivity. We conclude that there is no good test available for screening for metastatic uveal melanoma.

No-touch isolation technique reduces intraoperative shedding of tumor cells into the portal vein during resection of colorectal cancer

BACKGROUND

The mutant-allele-specific amplification (MASA) method is capable of detecting 1 genetically altered tumor cell among thousands of normal cells. The MASA enabled us to detect occult tumor cells undetectable by histopathologic examination of lymph nodes and blood samples.

METHODS

To investigate whether tumor manipulation during operation enhances cancer cell dissemination into the portal vein with use of MASA and to assess the effect of the no-touch isolation technique in the treatment of colorectal cancers, 27 colorectal cancers (17 were operated on conventionally and 10 were operated on according to the no-touch isolation technique) were screened for mutations in K-ras or p53. We next examined blood samples of the portal vein collected before, during, and after manipulation of tumors, using MASA to look for the specific mutation found in the primary tumors.

RESULTS

Somatic mutations were identified in 18 of these primary tumors (11 were in the conventional resection technique group and 7 were in the no-touch isolation technique group). In 8 of 11 (73%) conventional resection technique cases, we identified the same genetic alteration of the primary tumor in the portal blood during operation, whereas only 1 patient (14%) in the no-touch isolation technique group had a positive result.

CONCLUSIONS

The no-touch isolation technique may be useful to prevent cancer cells from being shed into the portal vein during surgical manipulation.

Reproducibility of detection of tyrosinase and MART-1 transcripts in the peripheral blood of melanoma patients: a quality control study using real-time quantitative RT-PCR

In recent years, large discrepancies were described in the success rate of the tyrosinase reverse transcription polymerase chain reaction (RT-PCR) for detecting melanoma cells in the peripheral blood of melanoma patients. We present a quality control study in which we analysed the reproducibility of detection of tyrosinase and MART-1 transcripts in 106 blood samples from 68 melanoma patients (mainly stages III and IV). With this study, we aimed to improve insight in the reproducibility of a RT-PCR for the detection of (minimal) amounts of circulating melanoma cells. We performed two reverse transcriptions on each mRNA sample and performed tyrosinase and MART-1 nested PCRs in duplicate per cDNA sample. Thus, four tyrosinase and four MART-1 measurements were performed per blood sample. In our study, the majority of blood samples was negative for tyrosinase (80%) or MART-1 (66%). Only four samples were positive in all four determinations for tyrosinase and seven for MART-1. Variable results (1-3 times positive results) were obtained for tyrosinase and MART-1 in 16% and 27% respectively. MART-1 PCR had a better performance than tyrosinase PCR. Sensitivity increased when both markers were used. We reasoned that the low number of melanoma marker PCR-positive blood samples can be explained by differences in mRNA quality. By using real-time quantitative PCR, we found that this was not the case: amplification of porphobilinogen deaminase (PBGD), a low copy household gene, was not different in blood samples in which a melanoma marker was not detected from groups in which this marker was detected more or less consistently (1-4 times). When applying real-time quantitative PCR for tyrosinase and MART-1, we found that a low amount of SK-MEL-28 cell equivalents was present in the blood of melanoma patients, with a higher number of equivalents in the group with a consistently positive result. We conclude that low reproducibility of a repeated assay for the detection of circulating melanoma cells is not caused by differences in mRNA quality between the samples, but due to low numbers of amplifiable target mRNA molecules in the mRNA sample. Use of more than one marker and repetition of the assay will increase the probability of finding positive PCR results.

Simultaneous analysis of tyrosinase mRNA and markers of tyrosinase activity in the blood of patients with metastatic melanoma

Determination of blood tyrosinase mRNA by RT-PCR and markers of tyrosinase activity (L-DOPA/L-tyrosine ratio) by HPLC have been proposed as biological tools for the detection of metastases in melanoma patients. We prospectively evaluated their significance and clinical value in a group of 30 stage III (n = 10) and IV (n = 20) melanoma patients and one with melanosis of Dubreuilh. L-DOPA/L-tyrosine ratio was elevated in 30% of stage III, 41% of stage IV patients (range: 7.5-261.0 x 10(5)) and in melanosis of Dubreuilh (184.8) (reference values: 6-16 X 10(5)). One stage III and four stage IV melanoma patients were positive for tyrosinase mRNA. In stage IV patients, tyrosinase mRNA positivity was associated with disease progression (P<0.01). The presence of tyrosinase mRNA in blood is more related to clinical status than level of melanin precursors, which probably reflects tumor burden.

Detection of tyrosinase mRNA by reverse transcription-polymerase chain reaction in melanoma sentinel nodes

BACKGROUND

Sentinel lymph node (SLN) biopsy is an alternative to elective dissection or observation for management of lymph node basins in patients with cutaneous melanomas. The detection of tyrosinase mRNA in melanoma SLN specimens by reverse transcription-polymerase chain reaction (RT-PCR) has been reported to be a more sensitive method to detect subclinical metastases, compared with histological analysis. The aims of this study were to (1) define the yield of RT-PCR in assessing SLNs, compared with histological analysis, (2) identify the incidence of false-positive results in SLNs, and (3) report the rate of actin PCR negativity (i.e., samples with degraded RNA) in SLNs.

METHODS

Twenty-eight patients with 1.2-9.6-mm cutaneous melanomas underwent SLN biopsy (between October 1996 and March 1997). One half of each SLN was analyzed by nested RT-PCR for tyrosinase mRNA. The other half of the SLN was examined by routine microscopy. Twenty-one lymph nodes from patients without melanoma were evaluated as controls.

RESULTS

Two of the 28 patients with melanoma were excluded because of RNA degradation, as indicated by actin negativity. Six of the remaining 26 patients exhibited melanoma metastases in routine histological examinations. All histologically positive lymph nodes were RT-PCR-positive. Thirteen of the 20 (65%) histologically negative cases were RT-PCR-positive. Of 21 control lymph nodes, 3 were actin-negative and were not assessable for tyrosinase mRNA. Two of the remaining 18 (11%) negative-control nodes were RT-PCR-positive.

CONCLUSIONS

Among patients undergoing SLN biopsy, tyrosinase mRNA was detectable in 73% of SLNs from patients at risk for regional nodal metastases, including all of those with histologically positive SLNs. There is a definable false-positive rate for tyrosinase mRNA detection in the lymph nodes of patients who do not have melanoma. Actin verification of RNA integrity is necessary to ensure the accuracy of this test in detecting tyrosinase mRNA. Ongoing follow-up monitoring will define the prognostic value of this assay.

K-ras mutations in DNA extracted from the plasma of patients with pancreatic carcinoma: diagnostic utility and prognostic significance

PURPOSE

Previous studies have demonstrated the presence of K-ras mutations in the plasma of patients with pancreatic carcinoma. However, the diagnostic utility and the prognostic significance of this finding have never been addressed.

PATIENTS AND METHODS

Forty-four consecutive patients with histologically confirmed primary pancreatic ductal adenocarcinoma were included. A control group of 37 patients with chronic pancreatitis, 10 patients with other tumors of the pancreatic area, nine patients with acute pancreatitis, and four healthy volunteers was also included. Plasma DNA was isolated and K-ras codon-12 mutations were analyzed by means of restriction fragment length polymorphism-polymerase chain reaction and single-strand conformation polymorphism techniques. Patients were followed up to establish their clinical outcome.

RESULTS

The mutant-type K-ras gene was found in plasma DNA samples of 12 (27%) of 44 patients with pancreatic ductal adenocarcinoma; this finding was related to the tumor stage (P = .05), mainly in the presence of distant metastases (P = .02). In addition, K-ras mutations were detected in the plasma DNA of two (5%) of 37 patients with chronic pancreatitis. In the subset of patients with pancreatic masses, the sensitivity and specificity of plasma K-ras analysis for pancreatic adenocarcinoma were 27% and 100%, respectively. Finally, pancreatic carcinoma patients with the mutant-type K-ras gene in plasma DNA exhibited a shorter survival time than patients with the wild-type gene (P<.005), and plasma K-ras mutations were identified as the only independent prognostic factor (odds ratio, 1.51; 95% confidence interval, 1.02 to 2.23).

CONCLUSION

Plasma K-ras analysis is a highly specific, low-sensitivity approach that has diagnostic and prognostic clinical implications in patients with pancreatic carcinoma.

Polymerase chain reaction-based detection of circulating melanoma cells as an effective marker of tumor progression. Melanoma Cooperative Group

PURPOSE

Reverse transcriptase (RT) polymerase chain reaction (PCR) with multiple markers has been demonstrated to be highly sensitive in detecting circulating cells from patients with malignant melanoma (MM). We evaluated the clinical significance of the presence in peripheral blood of specific PCR-positive mRNA markers as an expression of circulating melanoma cells.

PATIENTS AND METHODS

Total cellular RNA was obtained from the peripheral blood of 235 patients with either localized (n = 154) or metastatic (n = 81) melanoma. We performed RT-PCR using tyrosinase, p97, MUC18, and MelanA/MART1 as gene markers. The PCR products were analyzed by gel electrophoresis and Southern blot hybridization. In addition, 20 healthy subjects and 21 patients with nonmelanoma cancer were used as negative controls.

RESULTS

Although detected at various levels among assessable patients, each mRNA marker was significantly correlated with disease stage. A significant correlation with disease stage was demonstrated for patients who were positive to all four markers (P < .0001) or to at least three markers (P < .001). Univariate analysis showed a significant correlation between risk of recurrence (evaluated in stage I, II, and III patients) and increasing number of PCR-positive markers (P = .0002). Logistic regression multivariate analysis indicated that each single marker (except tyrosinase) and, more especially, the presence of four PCR-positive markers remained statistically independent prognostic factors for tumor progression.

CONCLUSION

Our data establish the existence of a significant correlation among clinical stages, tumor progression, and presence of circulating melanoma-associated antigens in peripheral blood of MM patients. Preliminary assessment of a subset of patients with a higher risk of recurrence needs longer follow-up and further studies to define the role of RT-PCR in monitoring MM patients.

Perioperative change in albumin messenger RNA levels in patients with hepatocellular carcinoma

A quantitative assay of albumin messenger RNA (mRNA) in blood samples was designed using the competitive reverse-transcription polymerase chain reaction, and the significance of measuring albumin mRNA levels in the blood of patients with hepatocellular carcinoma (HCC) in hepatic resection was evaluated. Albumin mRNA levels were measured in the following: (1) peripheral blood in 11 patients with HCC and 20 control subjects without liver disease, (2) blood in the portal and hepatic veins in five patients with HCC immediately after laparotomy, and (3) a perioperative series of peripheral blood in eight patients with HCC. Two patients with HCC whose albumin mRNA level in peripheral blood was markedly high were both at stage IVa. On the other hand, 20 control subjects showed negative or <5 x 10(3) transcripts/microgram RNA of albumin mRNA expression. Immediately after laparotomy, the albumin mRNA levels in the tumor-draining hepatic vein were greater than in the portal and non-tumor-draining hepatic veins in four of five patients with HCC. Albumin mRNA levels in peripheral blood showed a marked increase after mobilization and/or resection of the liver and, thereafter, gradually decreased at postoperative day 7 in all eight patients with HCC. A new method to measure the albumin mRNA levels in blood samples was developed, and high albumin mRNA levels in the peripheral blood of patients with advanced-stage HCC suggest the presence of HCC cells in the circulation. Increased levels in the tumor-draining hepatic vein could indicate the spontaneous release of tumor cells or nontumorous hepatocytes or an increased albumin transcription in activated blood mononuclear cells. An increase in the levels in peripheral blood during an operation is intermittent. Therefore, an increased albumin mRNA level in the tumor-draining vein suggests, but does not prove, that the increased albumin mRNA level reflects tumor cells entering the systemic circulation. This alone does not prove that the prognosis is worsened.

Ex vivo staining of metastatic lymph nodes by class I major histocompatibility complex tetramers reveals high numbers of antigen-experienced tumor-specific cytolytic T lymphocytes

Characterization of cytolytic T lymphocyte (CTL) responses to tumor antigens has been impeded by a lack of direct assays of CTL activity. We have synthesized reagents ("tetramers") that specifically stain CTLs recognizing melanoma antigens. Tetramer staining of tumor-infiltrated lymph nodes ex vivo revealed high frequencies of tumor-specific CTLs which were antigen-experienced by surface phenotype. In vitro culture of lymph node cells with cytokines resulted in very large expansions of tumor-specific CTLs that were dependent on the presence of tumor cells in the lymph nodes. Tetramer-guided sorting by flow cytometer allowed isolation of melanoma-specific CTLs and confirmation of their specificity and their ability to lyse autologous tumor cells. Our results demonstrate the value of these novel reagents for monitoring tumor-specific CTL responses and for generating CTLs for adoptive immunotherapy. These data also indicate that strong CTL responses to melanoma often occur in vivo, and that the reactive CTLs have substantial proliferative and tumoricidal potential.

Specificity of reverse transcriptase polymerase chain reaction assays designed for the detection of circulating cancer cells is influenced by cytokines in vivo and in vitro

Several reverse transcriptase polymerase chain reaction (RT-PCR) assays have been described for the detection of circulating tumour cells in blood and bone marrow. Target mRNA sequences for this purpose are the cytokeratins (CK) 19 and 20, the carcinoembryonic antigen (CEA), and the prostate-specific antigen messages. In this study, we investigated biological factors influencing the specificity of the CK19 and CEA RT-PCR assays. Bone marrow, granulocyte colony-stimulating factor (G-CSF)-mobilized blood stem cells and peripheral blood samples obtained from healthy volunteers (n = 15; CEA n = 7), from patients with epithelial (n = 29) and haematological (n = 23) cancer and from patients with chronic inflammatory diseases (n = 16) were examined. Neither CEA nor cytokeratin 19 messages could be amplified from bone marrow samples from healthy subjects and from patients with haematological malignancies. In contrast, specimens from patients with inflammatory diseases scored positive up to 60%. To investigate the influence of inflammation on target mRNA expression, haemopoietic cells were cultured with and without cytokine stimulation in vitro. CK19 messages could be easily detected in cultured marrow cells without further stimulation, CEA messages only after gamma-interferon (gamma-INF) stimulation. In contrast, G-CSF-mobilized peripheral blood stem cells were positive for CK19 messages only after stem cell factor (SCF) or interleukin stimulation. We conclude that transcription of so-called tissue-specific genes is inductible in haemopoietic tissues under certain conditions. These factors have to be considered in future applications of RT-PCR for the detection of minimal residual disease.

High expression of immunotherapy candidate proteins gp100, MART-1, tyrosinase and TRP-1 in uveal melanoma

In the treatment of cutaneous melanoma, provisional therapeutic strategies have been designed to combat tumour load using T cells that are sensitized with peptides derived from melanoma autoantigens, such as glycoprotein 100 (gp100), melanoma antigen recognized by T cells 1 (MART-1 or MelanA), tyrosinase and tyrosinase-related protein 1 (TRP-1). We recently found that gp100, MART-1 and tyrosinase are heterogeneously expressed in human cutaneous melanoma (De Vries et al (1997) Cancer Res 57: 3223-3229). Here, we extended our investigations on expression of these immunotherapy candidate proteins to uveal melanoma lesions. Cryostat sections from 11 spindle-type, 21 mixed and epithelioid tumours and four metastasis lesions were stained with antibodies specifically recognizing gp100, MART-1, tyrosinase and TRP-1. In addition, we used the DOPA reaction to detect tyrosinase enzyme activity as a confirmation of the tyrosinase immunohistochemical results. High expression of gp100, MART-1 and tyrosinase was found in the uveal melanoma lesions: 80% of the lesions displayed 75-100% positive tumour cells. TRP-1 positivity was slightly less: approximately 65% of the lesions stained in the 75-100% positive tumour cell category. All uveal melanoma lesions were positive for the four markers studied, this being in contrast to cutaneous melanoma where 17% of the advanced primary lesions and metastases were negative. The presence of these antigens was a little lower in metastases. We conclude that uveal melanomas and their metastases express melanocyte-lineage immunotherapy candidate proteins very abundantly. Uveal melanomas differ in this respect from cutaneous melanoma, in which the expression of these immunotherapy antigens was much more heterogeneous. This makes uveal melanoma a suitable candidate tumour for immunotherapeutic approaches.

Enhanced melanogenesis induced by tyrosinase gene-transfer increases boron-uptake and killing effect of boron neutron capture therapy for amelanotic melanoma

Specific and powerful cancer killing effect for melanoma by boron neutron capture therapy (BNCT) using DOPA analogue, 10B-p-boronophenylalanine (10B-BPA), has been established, but amelanotic melanoma is insufficiently responsive to 10B-BPA BNCT in comparison with actively melanin-producing melanoma. Although the accumulation mechanism of 10B-BPA within melanoma was not established, we have recently obtained findings suggesting that melanin monomers, key intermediates for melanin polymer formation, play a critical role in 10B-BPA accumulation. In addition, there are some kinds of human amelanotic melanomas, such as MEL2A, in which expression of tyrosinase is repressed or lacking though tyrosinase-related protein (TRP)-1 and TRP-2 are well expressed. Thus, by using a similarly tyrosinase-lacking mouse amelanotic melanoma cell line, A1059, we constructed TA1059 cells by transfecting human tyrosinase-cDNA into these cells. TA1059 cells acquired higher DOPA-oxidase and DOPAchrome tautomerase activity as well as eumelanin content at even higher levels than those of B16F10 cells. TA1059 cells showed about 2.5 times higher P-boronophenylalanine (BPA) uptake than A1059 cells in culture. In animal experiments, by using these cell lines, tumor growth of TA1059 was significantly suppressed by 10B-BPA BNCT as compared with A1059. These findings indicate that the induction of active melanin biosynthesis by melanogenic gene-transfer effectively improves the treatment of amelanotic melanoma by BNCT.

Expression of cytokeratin-20 in endometrial carcinoma

OBJECTIVE

Cytokeratins are constituents of the intermediate filaments of epithelial cells which are expressed in various combinations depending on the epithelial type and the degree of differentiation. The recently identified cytokeratin-20 (CK-20) was found with immunohistochemical methods to be expressed in gastrointestinal epithelium, uroepithelial cells, and Merkel cells. Clues were also found for low expression of CK-20 in endometrial carcinoma cells. The aim of this study was to examine whether CK-20 expression can be measured in endometrial carcinoma with the more sensitive reverse transcriptase-polymerase chain reaction (RT-PCR) methods and therefore used as a potential diagnostic tumor biomarker for endometrial carcinoma.

METHODS

In the present study we have used RT-PCR methods to determine expression of CK-20 in endometrial epithelial cells. Endometrial specimens were collected from 18 patients with endometrial carcinoma and 22 patients that underwent hysterectomy due to benign diseases. The specimens were prepared for both RT-PCR and immunohistochemical analysis. RNA, of the various cell pellets, was extracted and RT-PCR was performed with CK-20 and CK-19 primers (CK-19 was used as a marker for normal epithelial cells). Immunohistochemistry was carried out with the avidin-biotin-peroxidase complex method on formalin-fixed paraffin sections using CK-20 antibody.

RESULTS

CK-20 amplification band (370 bp) was obtained with mRNA extracted from endometrial carcinoma cells of 17 of the patients with endometrial carcinoma (sensitivity, 94.4%). CK-20 was negative in 21 patients with benign endometrial disease (specificity, 91.3%). No positive results were obtained with the immunohistochemical methods.

CONCLUSION

These results indicate that RT-PCR of CK-20, because of its high sensitivity, is a potential biomarker for detecting endometrial carcinoma.

Non-specificity of messenger RNA of alpha-fetoprotein in peripheral blood in detecting early spread of hepatocellular carcinoma in black Africans

Awareness of early spread of hepatocellular carcinoma is crucial in selecting patients for surgical intervention. Alpha-fetoprotein is widely used as a serum marker for hepatocellular carcinoma. Our aim was to evaluate the specificity of alpha-fetoprotein-mRNA transcription in cells in the peripheral blood for diagnosing early spread of hepatocellular carcinoma in black Africans. Alpha-fetoprotein-, albumin- and prothrombin-mRNA were detected in peripheral blood mononuclear cells by reverse transcription-polymerase chain reaction. Alpha-fetoprotein-mRNA was shown in peripheral blood mononuclear cells in 53% (35/66) of patients with hepatocellular carcinoma, but also in 45% (10/22) of healthy blacks, 64% (14/22) of black patients with acute hepatitis, 55% (11/20) of those with chronic hepatitis or cirrhosis and 75% (9/12) of those with hepatic metastases (from a number of primary sites). Specificity of albumin- and prothrombin-mRNA was better than that of alpha-fetoprotein-mRNA, although the sensitivity was reduced. The corresponding prevalence of albumin-mRNA for each group of patients or controls was 30% (20/66), 9% (2/22), 41% (9/22), 10% (2/20), and 17% (2/12), respectively, and for prothrombin-mRNA 27% (18/66), 4.5% (1/22), 27% (6/22), 20% (4/20) and 17% (2/12), respectively. We conclude that the non-specificity of alpha-fetoprotein-mRNA transcription in peripheral blood in recognizing malignant hepatocytes in the circulation severely limits its usefulness in diagnosing the early spread of hepatocellular carcinoma in black Africans.

Expression of uroplakin Ib and uroplakin III genes in tissues and peripheral blood of patients with transitional cell carcinoma

Uroplakins (UPs), urothelium-specific transmembrane proteins, are present only in urothelial cells. We have determined the nucleotide sequences of human UP-Ib and UP-III and synthesized specific primer pairs. The two UP genes were expressed in both cancerous and noncancerous urothelial taken from all patients examined by reverse transcription-polymerase chain reaction (RT-PCR). These genes were also detected in the peripheral blood of 3 patients with metastatic transitional cell carcinoma (TCC), but not in that from 9 patients with non-metastatic TCC or 3 healthy volunteers. The sensitivity of our assay was sufficient to detect one cancer cell in 5 ml of peripheral blood. Detection of UP gene-expression in blood by RT-PCR may provide helpful information for the diagnosis and management of TCC.

Molecular assessment of tumour stage and disease recurrence using PCR-based assays

Solid cancers arise as a consequence of the accumulation of genetic and epigenetic alterations within a single cell or group of cells. Their ongoing characterization is providing a range of acid-based molecular markers for neoplasia. This, together with continuous refinements to the polymerase chain reaction (PCR), had led to the emergence of PCR-based assays as potential aids in the clinical management of cancer patients. Although the sensitivity of molecular diagnosis has the potential to aid clinicians in therapeutic decision making, problems with its specificity mean that the predictive value of molecular staging is still unproved. Its role in the identification of minimal residual disease after curative surgical resection requires clinical validation in further prospective studies.

Lymph node micrometastases of cutaneous melanoma: increased sensitivity of molecular diagnosis in comparison to immunohistochemistry

The presence of regional lymph node metastases is one of the most significant prognostic factors for predicting survival in patients with clinical stage I or II cutaneous melanoma. For accurate staging of the primary tumor a sensitive technique is required to detect occult nodal micrometastases. This prospective diagnostic study was designed to evaluate the incidence of nodal micrometastases using nested reverse transcription-polymerase chain reaction (RT-PCR) for tyrosinase in comparison to immunohistochemical examination. Furthermore, the incidence of melanoma micrometastases detected by RT-PCR was analysed in correlation to major prognostic factors. A total of 466 regional lymph nodes from 79 patients with primary cutaneous melanoma (tumor thickness > 0.75 mm) were investigated. In 49 lymph nodes from 31 patients immunohistochemistry demonstrated melanoma metastases. Using tyrosinase RT-PCR, nodal micrometastases were detected in 136 lymph nodes from 52 patients including all lymph nodes positive by immunohistochemical examination. Out of the 417 lymph nodes negative by immunohistochemistry, 87 nodes (21%) were identified to express tyrosinase by the RT-PCR technique. Among the 48 patients negative by immunohistochemical assessment, 21 (44%) had nodal micrometastases (n = 40) using RT-PCR. All 68 lymph nodes from 46 non-melanoma patients serving as negative controls for tyrosinase RT-PCR were negative. The detection of melanocytic nodal micrometastases by tyrosinase RT-PCR is a highly specific method with a sensitivity significantly higher than that achieved by immunohistochemistry (p < 0.0001). Patients with nodal micrometastases identified exclusively by RT-PCR had significantly higher tumor thickness as compared to patients with negative results by RT-PCR (p < 0.01).

Detection of carcinoembryonic antigen mRNA in the mesenteric vein of patients with resectable colorectal cancer

The detection of tumor cells in the drainage venous blood of patients with colorectal cancer was made feasible by demonstrating carcinoembryonic antigen (CEA) mRNA in the mononuclear cell component of the blood, using a nested reverse transcription-polymerase chain reaction. CEA mRNA was detected in the drainage venous blood from 11 (42%) of 26 patients, and the rate of detection increased according to the grade of vessel invasion. CEA mRNA was detected in all patients with synchronous liver metastases, even though there was no significant correlation between the presence of CEA mRNA in the drainage venous blood and the clinicopathological findings. As the presence of CEA mRNA in the drainage venous blood is an indicator of the spread of tumor cells in patients with colorectal cancer, this assay can be used to assess the possible outcome of patients with colorectal cancer, providing one more tool for the physician-oncologist to use in designing appropriate treatments.

Prognosis in malignant melanoma

A uniform and practical classification and staging system for melanoma must exist and be widely adopted if useful comparisons between different treatment centers and databases are to be made. This article reviews the 1992 American Joint Committee on Cancer pTNM staging system. In this classification, localized disease without regional nodal involvement is defined as stage I or II, depending on the tumor thickness of the primary melanoma. Regional lymph node involvement and/or in-transit metastasis is defined as stage III, and systemic metastatic disease is defined as stage IV.

Minimally invasive staging of patients with melanoma: sentinel lymphadenectomy and detection of the melanoma-specific proteins MART-1 and tyrosinase by reverse transcriptase polymerase chain reaction

BACKGROUND

A minimally invasive standard has yet to be developed for sentinel lymphadenectomy, and many patients undergo this procedure in the main operating room under general anesthesia. These patients often have microscopic metastases in sentinel nodes that could be missed by histopathologic examination. Techniques of reverse transcriptase polymerase chain reaction (RT-PCR) could detect these metastases if the nodes could be preserved intraoperatively.

STUDY DESIGN

Fifty patients with melanoma > or = mm thick underwent sentinel lymphadenectomy under local anesthesia in an outpatient surgical unit. Sentinel nodes were identified using blue dye and technetium-99 sulfur colloid and a hand-held gamma probe. Each node was sectioned, with half sent for routine histopathologic study and half preserved in liquid nitrogen. We used RT-PCR to detect mRNA for tyrosinase and Melanoma Antigen Recognized by T cells-1 (MART-1).

RESULTS

All patients were able to tolerate sentinel lymph node biopsy under local anesthesia. Sentinel lymph nodes were obtained in 100% of our patients, and usable mRNA was harvested from all but five. Ten patients had positive sentinel node(s) by standard histopathologic examination, and all of these nodes were also positive for MART-1 and tyrosinase. Three patients with negative results by histopathology had positive results by RT-PCR analysis. The average cost of these outpatient operations was 38% less than the same operations performed in the main operating room under general anesthesia.

CONCLUSIONS

Sentinel lymphadenectomy under local anesthesia in an outpatient setting and intraoperative lymph node preservation in liquid nitrogen are both feasible. Both tyrosinase and MART-1 are promising markers in the detection of occult melanoma in lymph nodes.

Lymphatic mapping and selective lymphadenectomy as an alternative to elective lymph node dissection in patients with malignant melanoma

This article reviews the use of selective lymphadenectomy, otherwise known as sentinel lymph node biopsy, as a clinical alternative in patients with malignant melanoma. This represents a compromise between the two traditional treatment modalities, elective lymph node dissection or observation of the regional nodal basin followed by therapeutic lymph node dissection once disease becomes clinically apparent.

Classification and staging of melanoma

Although a standardized and uniformly accepted cancer staging system is an essential and fundamental requirement to enable meaningful comparisons across patient populations, the sometimes capricious biologic behavior of melanoma makes developing such a staging system particularly difficult. Since the earliest well-documented attempts at classifying patients with cutaneous melanoma were described more than 50 years ago, the identification of increasingly powerful prognostic factors has led to sequential modifications of the cutaneous melanoma staging system. The current AJCC staging system is based on relatively well-established prognostic factors; however, several recent reports have identified additional prognostic factors not included in the current system, and other studies support the re-evaluation of some of the currently employed staging criteria. Some of the more controversial areas include the relevance of level of invasion versus tumor thickness, optimal cutoffs for tumor thickness, importance of ulceration, the grouping of satellites with in-transit metastases, the inclusion of microsatellites and local recurrences as a separate staging criterion, the replacement of size of nodal mass with number of positive nodes, the importance of nodal metastases in more than one nodal basin, and the prognostic significance of distant metastases. Therefore, future modifications of the staging system are anticipated to better incorporate these observations. Stage-specific staging recommendations for the patient with melanoma provide the clinician with a framework to most efficiently assess extent of disease in an era of cost-conscious clinical practice. In the asymptomatic patient with primary melanoma (stage I or II), we recommend a chest roentgenogram and evaluation of alkaline phosphatase and LDH levels; extensive radiologic evaluations are not indicated, because the rate of detection in this population is extremely low. Additional staging information should also be obtained by the technique of lymphatic mapping and sentinel lymphadenectomy. For patients with local-regional disease (stage III, satellites, and local recurrence), a selective approach to imaging studies is warranted. For this patient population, we recommend complete blood count, liver function tests including alkaline phosphatase and LDH, a chest roentgenogram, and a CT scan of the abdomen. Although the yield of these tests, particularly CT of the abdomen, in detecting distant metastases in asymptomatic patients is low, they may identify false-positive abnormalities and provide an important baseline for future studies in this high-risk population. For patients with disease below the waist or in the head and neck region, we recommend CT of the pelvis and CT of the neck, respectively. Additional studies should be done only if clinically indicated. Finally, patients with known systemic disease (stage IV) should be more comprehensively evaluated, because the likelihood of detecting asymptomatic metastases is higher. Accordingly, in addition to the work-up outlined previously for stage III patients, we also perform a CT scan of the chest and MR imaging of the brain; other studies (e.g., bone scan, gastrointestinal series) are performed on the basis of symptoms.

Polymerase chain reaction and immunohistochemistry frequently detect occult melanoma cells in regional lymph nodes of melanoma patients

AIMS

To evaluate immunohistochemistry and reverse transcriptase polymerase chain reaction (RT-PCR) for melanoma associated antigens (MAA) in detecting occult melanoma cells in lymph nodes which were missed on routine pathology.

METHODS

Occult melanoma cells were sought in 436 lymph nodes from 32 patients with cutaneous melanoma of the lower extremities by immunohistochemistry using the melanoma specific antibody HMB-45. The detection sensitivity of routine histology, immunohistochemistry, and RT-PCR was also compared in 23 lymph node samples from six patients.

RESULTS

Immunohistochemistry showed that 15 of 24 patients (62.5%) who had no detectable metastasis by routine histology had at least one lymph node containing HMB-45 positive cells, mostly seen singly in the medullary sinus. No difference was found in known clinicopathological prognostic factors and recurrence rates between the two groups of patients with and without occult HMB-45 positive cells. RT-PCR analyses showed that the nested PCR for tyrosinase was more sensitive than a combination of single round PCR for five different MAA, including tyrosinase, MART-1/Melan A, Pmel-17, TRP-1, and TRP-2, detecting tyrosinase mRNA in six nodes which were negative by HMB-45 immunohistochemistry.

CONCLUSIONS

Immunohistochemistry + RT-PCR is more sensitive than routine histology in detecting occult melanoma cells in lymph nodes. The nested PCR for tyrosinase should be used in future studies investigating the prognostic significance of such lymph node micrometastases.

Micrometastases and survival in stage II colorectal cancer

BACKGROUND

Standard treatment of colorectal cancer includes adjuvant chemotherapy for patients with stage III disease (defined by the presence of lymph-node metastases), but not for patients with stage II tumors (who have no lymph-node metastases). However, 20 percent of patients with stage II tumors die of recurrent disease. We investigated whether the detection of micrometastases can be used to identify patients with stage II disease who are at high risk for recurrence.

METHODS

We analyzed 192 lymph nodes from 26 consecutive patients with stage II colorectal cancer, using a carcinoembryonic antigen-specific nested reverse-transcriptase polymerase chain reaction. Five-year follow-up information was obtained on all patients. Observed and adjusted survival rates were assessed in the patients with and the patients without micrometastases.

RESULTS

Micrometastases were detected in one or more lymph nodes from 14 of 26 patients (54 percent). The adjusted five-year survival rate (for which only cancer-related deaths were considered) was 50 percent in this group, whereas in the 12 patients without micrometastases, the survival rate was 91 percent (P=0.02 by the log-rank test). The observed five-year survival rates were 36 percent and 75 percent, respectively (P=0.03). The groups were similar with respect to age, sex, tumor side (location in relation to the flexura lienalis), degree of tumor differentiation (grade), and diameter of the primary tumor.

CONCLUSIONS

Molecular detection of micrometastases is a prognostic tool in stage II colorectal cancer.

New prognostic factors in melanoma: mRNA tumour markers

Circulating tumour cells in the peripheral blood may be important for haematogenous spread of malignant disease. Monitoring these cells may therefore be of prognostic value. Reverse transcriptase-polymerase chain reaction (RT-PCR)-based assays to detect occult neoplastic cells offer the highest sensitivity for the study of tumour dissemination and minimal residual disease. This review summarises technical considerations and clinical investigations in melanoma patients of various disease stages. The clinical data are promising, but to clearly define the clinical usefulness of messenger RNA (mRNA) tumour markers, methodological issues must be resolved and the clinical value must be assessed prospectively in sufficiently large patient cohorts.

The sequence of vessel ligation affects tumor release into the circulation

OBJECTIVE

Whether the sequence of pulmonary vein and artery ligation in pulmonary lobectomy for carcinoma affects intraoperative hematogenous cancer cell dissemination is not known. We examined whether vessel ligation sequence affects the presence of circulating cancer cells as reflected by carcinoembryonic antigen messenger ribonucleic acid.

METHODS

We assayed for the transcripts of carcinoembryonic antigen messenger ribonucleic acid by reverse-transcriptase polymerase chain reaction in peripheral blood taken before, during, and after operation from 30 patients with non-small-cell lung cancer who underwent a curative lobectomy and from six patients with limited-stage small-cell lung cancer who were treated initially with chemotherapy followed by lobectomy. Each patient was randomly assigned before the operation to have either pulmonary vein ligation or pulmonary artery ligation first. Blood taken from 10 patients with interstitial pulmonary fibrosis who underwent an open lung biopsy and 41 healthy subjects served as a control.

RESULTS

No control samples were positive for transcripts. Sixteen of the preoperative blood samples from the 30 patients with non-small-cell cancers were positive. Of these 16, eight samples remained positive even after lobectomy was performed; the remaining eight samples (four in each ligation group) became negative. Of the 14 initially negative samples (seven in each ligation group), nine samples became positive during the operation. Such conversion during the operation was more common with arterial ligation first (six patients, 85.7%) than with venous ligation first (three patients, 42.9%). Samples from all six patients with small-cell cancer were positive before the operation, and five of six samples remained positive after the operation.

CONCLUSIONS

Many patients with non-small-cell lung cancer have systemic disease even when they were thought to have resectable tumors. Ligating the pulmonary vein before ligating the artery may lessen intraoperative hematogenous dissemination. Most small-cell lung cancers represent systemic disease even when considered resectable.

Elevated pretreatment serum levels of soluble vascular cell adhesion molecule 1 and lactate dehydrogenase as predictors of survival in cutaneous metastatic malignant melanoma

Very rapid progression of disease with a median survival of 6-9 months is a common feature of metastatic cutaneous malignant melanoma. Nevertheless, substantial variability of survival suggests that metastatic cutaneous malignant melanoma can be divided into several biological subgroups. Pretreatment serum levels of soluble adhesion molecules and various clinical parameters in cutaneous metastatic malignant melanoma were evaluated to determine their prognostic value. In this study pretreatment serum levels of soluble vascular cell adhesion molecule 1 (sVCAM-1), soluble intercellular cell adhesion molecule 1 (sICAM-1), soluble endothelial leukocyte adhesion molecule 1 (sE-selectin) and multiple clinical factors were assessed in relation to overall survival of 97 consecutive patients with metastatic cutaneous malignant melanoma seen at our institution between May 1990 and April 1996. For statistical analysis, both univariate and multivariate Cox proportional-hazards models were used. Elevated pretreatment serum levels of sVCAM-1 (P < 0.005) and of lactate dehydrogenase (P < 0.002) were rendered statistically independent and were significantly associated with unfavourable outcome. Patients were assigned to one of three risk categories (low, intermediate and high) according to a cumulative risk score defined as the function of the sum of these two variables. There were significant differences in overall survival (P < 0.0001) between low- (n = 53, 5-year survival probability of 23.3%), intermediate- (n = 29, 5-year survival probability of 9.9%) and high-risk (n = 15) patients. Elevated pretreatment serum levels of sVCAM-1 and of lactate dehydrogenase correlate with poor outcome in metastatic cutaneous malignant melanoma. These data support risk stratification for future therapeutic trials and identify factors that need to be validated in prospective studies and may potentially influence decision-making in palliative management of patients with disseminated cutaneous malignant melanoma.

Detection of colorectal cancer cells in peripheral blood by reverse-transcriptase polymerase chain reaction for cytokeratin 20

The staging of colorectal cancer currently depends on pathological examination of the surgical specimen and regional lymph nodes, accompanied by imaging tests such as computed tomography (CT) scanning. However, alternative molecular methods to detect circulating tumour cells in blood or bone marrow may provide additional information about the extent of disease and prognosis. We have previously reported the development of a reverse-transcriptase polymerase chain reaction (RT-PCR) for cytokeratin 20 (CK 20) mRNA to detect circulating epithelial tumour cells. In this study, we report on the application of this method for detecting circulating tumour cells in patients with colorectal cancer. Using this method, CK 20 mRNA was detected in 8/8 human colorectal cancer cell lines, in 8/9 biopsies from primary colorectal tumours and in 9/10 biopsies of liver metastasis in patients with metastatic colorectal cancer, suggesting that CK 20 may be a useful target for the detection of circulating tumour cells in this patient group. In spiking experiments, 10 cells were consistently identified in 2 ml of whole blood (1 x 10(6)-1 x 10(7) mononuclear cells). In 12/25 (48%) peripheral blood samples from patients with known metastatic colorectal cancer, CK 20 mRNA was detected. However, there was no correlation between the detection of CK 20 mRNA in the peripheral blood and disease progression and survival in this group of patients. CK 20 mRNA was detected in 1/12 normal blood samples, which raises questions about the absolute specificity of CK 20 expression.

Quantitative analysis of alpha-fetoprotein mRNA in circulating peripheral blood of patients with hepatocellular and alpha-fetoprotein-producing gastric carcinomas

In conjunction with strategies introduced in recent years to identify cancer micrometastasis through amplification of cancer-associated mRNA, we developed a highly sensitive system to detect alpha-fetoprotein mRNA in circulating peripheral blood of hepatocellular carcinoma patients. The aim of the present study was to make our original system quantitative. Peripheral venous blood from patients with hepatocellular carcinoma and alpha-fetoprotein-producing gastric carcinoma was subjected to reverse transcription followed by our original three-step polymerase chain reaction co-amplifying both the original sequence and our synthetic competitor. We succeeded in modifying our system for quantitative analysis, and investigated the perioperative change, the postoperative change and the change after chemotherapy in order to illustrate the possible application of this method. The quantitative analysis of alpha-fetoprotein mRNA present in the peripheral blood represents a useful tool for analyzing the relationship of surgery to recurrence, the effect of chemotherapy, and to predict impending recurrence in patients with hepatocellular and alpha-fetoprotein-producing gastric carcinomas.

Utilization of polymerase chain reaction technology in the detection of solid tumors

BACKGROUND

Most cancer detection tests currently performed are based on either antibody assays to a marker protein with altered expression in cancer patients or on imaging studies to identify characteristic lesions. Generally, for a positive result, these detection assays require that a tumor have a significant volume of cancer cells. Advances in diagnostic techniques and technology may allow for cancer detection at earlier stages, when the tumor burden is smaller and potentially more curable. The molecular techniques of polymerase chain reaction (PCR) and reverse transcriptase PCR (RT-PCR) are highly sensitive methods for detecting a small number of cancer cells. Over the past few years, numerous clinical studies have used PCR techniques to detect physical alterations of genes, such as mutations, deletions, translocations and amplification, the presence of oncogenic viruses, and the expression of genes specific to tissue, cancer, and metastasis. The current status of PCR as a method for detecting marker genes in the management of solid tumors is reviewed.

METHODS

A review of the literature on the clinical utility of PCR and RT-PCR in the detection of solid tumor micrometastasis was conducted.

RESULTS

Amplification by PCR is a highly sensitive method to determine gene expression. A single cell expressing a tumor marker among 10-100 million lymphocytes can be detected by the PCR assay. This approach has been used to detect tumor cells in approximately 18 different solid tumor types, with melanoma and carcinoma of the breast and prostate the most widely investigated to date. PCR-based assays have been used to detect cancer cells in biopsies of solid tissue, lymph nodes, bone marrow, peripheral blood, and other body fluids. Several studies have reported a high specificity and sensitivity of tumor marker detection and a high correlation between PCR results and the presence of metastatic disease. However, in a few studies, PCR assays have not consistently demonstrated a higher sensitivity and specificity of detection than traditional modalities for many types of cancer. There has been a wide range in sensitivity and specificity among the studies, which may be partly attributed to the lack of uniformity among the PCR protocols used in different studies.

CONCLUSIONS

PCR can detect tumor marker-expressing cells that are otherwise undetectable by other means in patients with localized or metastatic cancer. Reports from various study groups have lacked uniformity in their protocols, and this has prevented adequate comparison. The clinical utility of this assay as a tool for the prognosis and management of cancer patients remains and area of active investigation. PCR is a powerful tool in the study of the biology of cancer metastasis and will likely serve as a useful adjunct to clinical decision-making in the future.

Utilization of polymerase chain reaction technology in the detection of solid tumors

BACKGROUND

Most cancer detection tests currently performed are based on either antibody assays to a marker protein with altered expression in cancer patients or on imaging studies to identify characteristic lesions. Generally, for a positive result, these detection assays require that a tumor have a significant volume of cancer cells. Advances in diagnostic techniques and technology may allow for cancer detection at earlier stages, when the tumor burden is smaller and potentially more curable. The molecular techniques of polymerase chain reaction (PCR) and reverse transcriptase PCR (RT-PCR) are highly sensitive methods for detecting a small number of cancer cells. Over the past few years, numerous clinical studies have used PCR techniques to detect physical alterations of genes, such as mutations, deletions, translocations and amplification, the presence of oncogenic viruses, and the expression of genes specific to tissue, cancer, and metastasis. The current status of PCR as a method for detecting marker genes in the management of solid tumors is reviewed.

METHODS

A review of the literature on the clinical utility of PCR and RT-PCR in the detection of solid tumor micrometastasis was conducted.

RESULTS

Amplification by PCR is a highly sensitive method to determine gene expression. A single cell expressing a tumor marker among 10-100 million lymphocytes can be detected by the PCR assay. This approach has been used to detect tumor cells in approximately 18 different solid tumor types, with melanoma and carcinoma of the breast and prostate the most widely investigated to date. PCR-based assays have been used to detect cancer cells in biopsies of solid tissue, lymph nodes, bone marrow, peripheral blood, and other body fluids. Several studies have reported a high specificity and sensitivity of tumor marker detection and a high correlation between PCR results and the presence of metastatic disease. However, in a few studies, PCR assays have not consistently demonstrated a higher sensitivity and specificity of detection than traditional modalities for many types of cancer. There has been a wide range in sensitivity and specificity among the studies, which may be partly attributed to the lack of uniformity among the PCR protocols used in different studies.

CONCLUSIONS

PCR can detect tumor marker-expressing cells that are otherwise undetectable by other means in patients with localized or metastatic cancer. Reports from various study groups have lacked uniformity in their protocols, and this has prevented adequate comparison. The clinical utility of this assay as a tool for the prognosis and management of cancer patients remains and area of active investigation. PCR is a powerful tool in the study of the biology of cancer metastasis and will likely serve as a useful adjunct to clinical decision-making in the future.

Reliability of reverse transcription-polymerase chain reaction (RT-PCR)-based assays for the detection of circulating tumour cells: a quality-assurance initiative of the EORTC Melanoma Cooperative Group

Reverse transcription-polymerase chain reaction (RT-PCR)-based assays detecting occult neoplastic cells are increasingly being used for the study of tumour dissemination and minimal residual disease. However, different methods are employed by various research groups and the results are heterogenous. We prospectively assessed the results from nine laboratories performing tyrosinase RT-PCR assays for the detection of melanoma cells on a series of blind samples. After complete analysis, the results were compared for sensitivity and specificity. All laboratories reported correct results for cDNA standards. Five laboratories attained acceptable specificity and a sensitivity detecting 10 cells in 10 ml of whole blood. Four laboratories had unacceptable specificity and/or sensitivity. This blind study highlights the difficulty of RT-PCR data interpretation and the need for quality assurance between laboratories. Measures to increase the reliability of RT-PCR assays are proposed, which have to be prospectively evaluated in future studies.

Putative markers for the detection of breast carcinoma cells in blood

The aim of this study was to investigate certain genes for their suitability as molecular markers for detection of breast carcinoma cells using the reverse transcriptase-polymerase chain reaction (RT-PCR). RNA was prepared from MCF-7 breast carcinoma cells and peripheral blood leucocytes of healthy female volunteers. This RNA was screened for mRNA of MUC1, cytokeratin 19 (CK19) and CD44 (exons 8-11) by RT-PCR and the results validated by Southern blots. Variable degrees of expression of MUC1 and CD44 (exons 8-11) were detected in normal peripheral blood, rendering these genes non-specific for epithelial cells and therefore unsuitable for use as markers to detect breast carcinoma cells. Although CK19 mRNA was apparently specific, it was deemed unsuitable for use as a marker of breast cancer cells in light of its limited sensitivity. Furthermore, an attempt at using nested primers to increase sensitivity resulted in CK19 mRNA being detected after two amplification rounds in blood from healthy volunteers.

The use of molecular technology in the differentiation of pancreatic cancer and chronic pancreatitis

CONCLUSION

It is concluded that currently there are limitations in the use of some of the proposed tests, whereas in the future, further progress in our understanding of the molecular biology of pancreatic disease and the development and application of existing techniques should have a greater impact on clinical practice.

BACKGROUND

Fifteen to 20% of patients with pancreatic cancer present with a resectable mass in the head of the pancreas, but there is a subgroup of patients for whom it is difficult to reach the correct diagnosis.

METHOD

This article addresses how molecular technology can be used to aid in the diagnosis of this group of patients. The clinical and scientific literature is reviewed by accessing papers through the Medline database.

RESULTS

This article reviews the limitations of conventional imaging techniques and the limitations of fine needle aspiration cytology and cytological examination of pancreatic duct secretions. The molecular biology of both pancreatic cancer and chronic pancreatitis is then reviewed with emphasis on the common molecular defects seen in these diseases. The current use of molecular techniques in the examination of cytological and histological specimens, stool, blood, and pancreatic duct secretions and how this helps discriminate between benign and malignant lesions of the pancreas is addressed. Finally, the use of novel serum screening tests in groups at high risk of pancreatic cancer is discussed.

RT-PCR for tyrosinase-mRNA-positive cells in peripheral blood: evaluation strategy and correlation with known prognostic markers in 123 melanoma patients

Reverse transcriptase polymerase chain reaction for the detection of tyrosinase-mRNA-positive cells in peripheral blood of melanoma patients, as a possible marker of hematogenous dissemination, has demonstrated varying detection rates. This study examined the sensitivity and reproducibility of the technique using a protocol of multiple polymerase chain reaction to determine circulating melanocytic cells. For each of the 123 melanoma patients included in this study, four nested polymerase chain reactions were performed from two blood specimens requiring both polymerase chain reactions from at least one blood sample to be positive to consider a patient as positive. Thus, a definitive result was obtained in 98% of the cases, whereas only 1.6% lacked conclusive findings. Thus, we found a correlation between the tyrosinase detection rate and the clinical stage. Circulating tyrosinase-mRNA-positive cells were detected in 13% of patients with primary tumor, 17% with regional skin/lymph node metastasis, and 44% with distant metastasis. Positivity also correlated with known melanoma progression markers such as gender, tumor thickness, and histologic type. Positive results were obtained more frequently in (i) men compared with women, (ii) patients with thick primary melanomas (> 4 mm: 38%) compared with those with thinner tumors (1.1-4 mm, 22%; < or = 1 mm, 5%), and (iii) patients with nonclassifiable (38%), nodular (34%), and occult primary melanomas (30%) compared with those with acrolentiginous (17%), superficial spreading (9%), or lentigo maligna melanoma (0%). These findings suggest that detection of tyrosinase-mRNA-positive cells in peripheral blood is not an adequate marker for identifying melanoma patients with distant metastasis. Reverse transcriptase polymerase chain positivity in early melanoma stages, however, as corresponding to other prognostic parameters, may indicate increased risk for the development of hematogenous metastasis and may be of value as a progression marker.