A new human chromogranin A (CgA) immunoradiometric assay involving monoclonal antibodies raised against the unprocessed central domain (145-245).

Chromogranin A (CgA), a major protein of chromaffin granules, has been described as a potential marker for neuroendocrine tumours. Because of an extensive proteolysis which leads to a large heterogeneity of circulating fragments, its presence in blood has been assessed in most cases either by competitive immunoassays or with polyclonal antibodies. In the present study, 24 monoclonal antibodies were raised against native or recombinant human CgA. Their mapping with proteolytic peptides showed that they defined eight distinct epitopic groups which spanned two-thirds of the C-terminal part of human CgA. All monoclonal antibodies were tested by pair and compared with a reference radioimmunoassay (RIA) involving CGS06, one of the monoclonal antibodies against the 198-245 sequence. It appears that CgA C-terminal end seems to be highly affected by proteolysis and the association of C-terminal and median-part monoclonal antibodies is inadequate for total CgA assessment. Our new immunoradiometric assay involves two monoclonal antibodies, whose contiguous epitopes lie within the median 145-245 sequence. This assay allows a sensitive detection of total human CgA and correlates well with RIA because dibasic cleavage sites present in the central domain do not seem to be affected by degradation. It has been proved to be efficient in measuring CgA levels in patients with neuroendocrine tumours.

[Diagnostic value of SCC-TA4 determination in 4 localizations of epidermoid cancers. An experience of the FNCLCC subgroup of radio-analysis]. / Intéret diagnostique du dosage du SCC-TA4 dans quatre localisations de cancers épidermoïdes. Expérience du sous-groupe de radio-analyse de la FNCLCC.

A multicenter and retrospective study of the diagnosis value of SCC-TA4 in squamous cell carcinomas of 4 localisations was made with the 2 thresholds of 2 and 2.5 ng/ml. However, 3.1% of controls have a SCC value above 2.5 ng/ml. Sixteen benign gynecologic pathologies had no positive level. The benign digestive (N = 73), bronchial (N = 345) pathologies and no squamous cell carcinomas (N = 93, N = 220 respectively), had SCC-TA4 mean levels significantly lower than corresponding squamous cell carcinomas (N = 153, N = 128 respectively). Sensitivity of the test varied from 40% in the squamous cell carcinomas of the lung, to 72% in the squamous cell carcinomas of the uterine cervix. Specificity was always very high and varied from 91% in the SCC of lung, to 100% in the SCC of uterine cervix. For the SCC of uterine cervix, oesophagus and head and neck, the mean values and incidence of positive levels increased significantly with increasing tumor size and advancing disease stage. For the SCC of uterine cervix, mean SCC-TA4 levels and percentages of positive levels above 2 ng/ml were significantly higher for the patients with recurrence (22.5 +/- 4.6 ng/ml; 76%) or with metastasis appearance (23.6 +/- 5.4 ng/ml; 77%) than for the patients in remission (less than 1.5 ng/ml; 0%). In the SCC of oesophagus, we report levels before treatment that are significantly higher for the patients with metastasis at the first attempt (4.2 +/- 5.1 ng/ml; 59%), and an elevated SCC level at the diagnosis evoked a SCC of lung already disseminated (8.8 +/- 12.1 ng/ml; 50%) that will fail to respond to treatment (4.0 +/- 4.2 ng/ml; 48%).

[Systematic study of various tumoral markers in prevalent bone metastasis]. / Apport de l'étude systématique de différents marqueurs tumoraux dans les métastases osseuses prévalentes.

In the presence of prevalent bone metastases, the precise histo-pathological diagnosis of the primary tumor is often difficult. The authors study the diagnostic value of systematic serum assay of a series of tumoral tracers (ACE, AFP, PAP and PSA, SCC, CA 19:9, CA 15:3, CA 125) which until now were used in evolutive and therapeutic monitoring. 34 patients were selected for this preliminary retrospective study (including 20 with a demonstrated histopathological diagnosis). 70 p. cent of prevalent bone metastases express a target tracer corresponding to the initial location. In some cases, an elevated tracer, because of its specificity, may bring about a diagnostic or therapeutic decision (always according to the context). No conclusion may currently be drawn in case of discordance between the anatomo-clinical context and the "profile" of the markers (1 case in our series).

Evaluation of prostate-specific antigen in prostate cancer.

Prostate-specific antigen (PSA) was assayed retrospectively in 131 prostate cancer patients. Pretreatment levels at primary tumor diagnosis were above 5 ng/ml in 13/16 (81%) of stage B and C patients and in 28/28 (100%) of stage D (D1 and D2) patients. At the discovery of metastasis in treated patients, they were above this value in 12/17 (71%) of patients. To determine the value of PSA assays when physical exams were negative, 52 patients were reevaluated at a maximum interval of 12 months as a function of their initial PSA concentration. When the initial PSA was negative, there was no clinical evolution during the next 6 months; when PSA was positive, patients had a 55% risk of progression in the next 4 months. All PSA assays were coupled with prostatic acid phosphatase (PAP) measurements. No PAP values were positive when PSA was negative.

Value of CA 15:3 in the follow-up of breast cancer patients.

CA 15:3, a new tumour marker detectable by two monoclonal antibodies (115 D 8 and DF 3), was measured by an immunoradiometric technique on the ELSA solid phase. Sixteen percent of patients with localized breast cancer had CA 15:3 levels greater than 25 U ml-1, and levels increased with tumour size. CA 15:3 levels greater than 25 U ml-1 were found in 54% of patients with nodal involvement and in 91% of patients with metastatic breast disease. Measurement of CA 15:3 in 70 women with metastatic breast cancer and a normal CEA revealed positive CA 15:3 levels at diagnosis of the first metastasis in 66% of cases; 63% of these patients could be monitored with CA 15:3.