Effect of surface penetrating sealant on surface texture and microhardness of composite resins

The application of Fortify (Bisco, Lombard, IL), an unfilled resin, to the surface of composite resin restorations is intended to fill in defects in the surface that persist despite polishing, improve marginal integrity, and increase these materials' resistance to abrasion. The aim of this study was to observe the surface texture by scanning electron microscopy and measure the microhardness of the surface. For each sample of composite resin covered with glaze, 40 measurements were made of the thickness of the resin. Measurements of the Vickers microhardness included three samples of composite resin, three samples of glaze, and six samples of composite resin covered with glaze. A relationship was established between microhardness and thickness. Scanning electron microscopy showed a noticeable improvement in the surface texture. Nevertheless, areas were seen in which glaze seemed very thin or even completely absent. Measurements of the thickness ranged from 0-70 microm. The mean microhardness of composite resin was 65.8 +/- 0.7, while the mean hardness of glaze was 7.3 +/- 0.7. The microhardness of the double layer was reduced, depending on the thickness of the glazing resin. The capacity of glaze to mask surface defects of composite resin was shown, but it was difficult to obtain a regular surface with liquid resin. The application of this product caused a decrease of the microhardness of the composite resin's surface.

Patient set-up using portal images: 2D/2D image registration using mutual information

OBJECTIVE

Conformal radiation therapy requires accurate patient set-up for each fraction delivery. Electronic portal imaging devices allow the acquisition of portal images just before and even during dose delivery. However, the quantitative interpretation of these images in determining and correcting the patient's position remains uncertain, and automated methods are therefore being developed. Such methods must be usable for the different radiation therapy techniques. They must be robust and as automated as possible for use in clinical routines. This work was undertaken to establish the feasibility of 2D/2D registration for portal/portal and portal/simulator images in radiotherapy.

MATERIALS AND METHODS

This paper describes an automated method based on the combination of calibration algorithms and pixel-based registration algorithms. We present experiments with the different imaging techniques, some of which use a phantom with and without a gold standard. Preliminary results obtained using patient data are also presented and discussed.

RESULTS

The results obtained with a phantom demonstrated that this automated method for 2D/2D registration is fast, accurate, and robust, even in the case of blurred images for small treatment fields.

CONCLUSIONS

Mutual information is a feasible method for 2D/2D portal/portal and portal/simulator image registration in radiotherapy.

Leukotriene D4-induced activation of smooth-muscle cells from human bronchi is partly Ca2+-independent

Cysteine-containing leukotrienes (cysteinyl-LTs) are potent bronchoconstrictors and play a key role in asthma. We found that histamine and LTD4 markedly constrict strips of human bronchi (HB) with similar efficacy. However, in human airway smooth-muscle (HASM) cells, LTD4, at variance with histamine, elicited only a small, transient change in intracellular calcium ion concentration. HASM cells express both Ca2+-dependent and -independent isoforms of protein kinase C (PKC) (i.e., PKC-alpha and PKC-alpha ). Western blot analysis showed that PKC-alpha is activated by histamine and, to a lesser extent, by LTD4, whereas only LTD4 translocates PKC-alpha. This translocation was specifically inhibited by the LTD4 antagonist pobilukast. Phorbol-dibutyrate ester (PDBu) (a PKC activator) contracted HB strips to the same extent in the presence as in the absence of extra- and intracellular Ca2+. In the absence of Ca2+, LTD4 contracted HB strips to the same extent as did PDBu, suggesting the involvement of a Ca2+-independent PKC in LTD4-mediated signal transduction. PDBu-induced desensitization and the PKC inhibitor H7 abolished the slow and sustained LTD4-triggered contraction of HB strips in the absence of Ca2+, although H7 did not greatly affect the response in the presence of the ion. Thus, in human airways, we identified a novel LTD4 transduction mechanism linked to bronchial smooth-muscle contraction, which is partly independent of Ca2+ and involves the activation of PKC-alpha.

[Absorbed dose during helical acquisition CT. Effect of acquisition parameters]

PURPOSE

European directive 97/43 specifies that the dose delivered to the patient during a radiological procedure should be estimated. In order to prepare for implementation of this new regulation, we have studied the dose delivered during spiral CT acquisition.

MATERIALS AND METHODS

We have studied the influence of slice thickness, pitch, tube voltage and intensity, and acquisition volume length. We present measurements for single and dual detector CT scanners. We used a pencil ionization chamber to measure air kerma. We measured absorbed dose in water with a waterproof ionization chamber set in a semi-customized phantom filled with water. Chambers were set on the rotation axis of the CT scanners. We studied the dose outside the acquisition volume.

RESULTS

We quantified the influence of each parameter on the absorbed dose. We used our measurements to calculate the dose for different acquisition protocols. Also we evaluated the dose to organs distant from the acquisition area.

CONCLUSION

This study is one step toward a systematic estimation of the dose delivered to patient during helical CT exams. To use these results in daily practice, we have to develop software using our measurements.

Effect of endogenous and exogenous prostaglandin E(2) on interleukin-1 beta-induced cyclooxygenase-2 expression in human airway smooth-muscle cells

We studied the effect of endogenous and exogenous prostaglandin E(2) (PGE(2)), a metabolite of arachidonic acid through the cyclooxygenase (COX) pathway, on interleukin (IL)-1 beta-induced COX-2 expression, using primary cultures of human bronchial smooth-muscle cells (HBSMC). Treatment with exogenous PGE(2) resulted in enhanced expression of IL-1 beta-induced COX-2 protein and messenger RNA (mRNA) as compared with the effect of the cytokine per se. Inhibition of PGE(2) production with a nonselective COX inhibitor (flurbiprofen, 10 microM) resulted in a significant reduction in IL-1 beta- induced COX-2 expression, supporting a role of endogenous COX metabolites in the modulation of COX-2 expression. None of the experimental conditions used in the study affected the expression of constitutive cyclooxygenase (COX-1). Treatment with cycloheximide to inhibit translation, and with dexamethasone or actinomycin D to inhibit transcription, linked the effect of PGE(2) to the transcriptional level of COX-2 mRNA rather than to a potential effect on protein and/or mRNA stabilization. PGE(2) increased adenylate cyclase activity in a concentration dependent manner, and forskolin, a direct activator of adenylate cyclase, caused a marked increase in IL-1 beta-dependent COX-2, suggesting the existence of a causal relationship between the two events. The same results were observed with salbutamol, a bronchodilator that acts by increasing cyclic adenosine monophosphate. The effect of PGE(2) on COX-2 expression may contribute to the hypothesized antiinflammatory role of PGE(2) in human airways, providing a self-amplifying loop leading to increased biosynthesis of PGE(2) during an inflammatory event.

[Multidisciplinary approach in the treatment of localized forms of cancer of the prostate]

Localized prostate cancer can be treated by surgery, 3D conformal radiotherapy, brachytherapy: age, clinical stage, Gleason grade, baseline PSA, multidisciplinary approach enable physicians to tailor the therapeutic strategy. Patients are more informed of therapeutic morbidity and health related quality of life and want to give their feeling. Clinical research remains mandatory to set up the treatment policy with more objectivity.

[Image fusion methods for the repositioning of the patient in radiotherapy]

Conformal radiotherapy requires the accurate and reproducible setup of the patient for each fraction delivery. Megavoltage imaging could enable this. This requires the development of image processing and data fusion algorithms. We describe an automated method based on the use of mutual information for registration. Such a method does not require any preliminary segmentation of the images. This method has been extensively tested on phantom as well as on some patient data. The obtained results demonstrated that this automated method for 2D/2D registration is rapid, accurate and robust even in the case of blurred images for small treatment fields.

Adjuvant hormonal treatment with radiotherapy for locally advanced prostate cancer

OBJECTIVES

Long-term results of radiotherapy in locally advanced prostate cancer are poor due to local and distant failures. Since prostate cancer is hormone dependent, tumor androgen deprivation may enhance tumor eradication.

METHODS

Three randomized phase III trials, RTOG and EORTC are reported: they assess androgen suppression by using a luteinizing hormone-releasing hormone analogue (LH-RHa) with or without androgen blockade before and during, or during and after external irradiation.

RESULTS

A gain in disease-free, local relapse-free and metastasis-free survival has been obtained (p < 0.001). Only the EORTC 22863 trial has reported a significant improvement in overall survival (p = 0.001) with an LH-RHa started the first day of radiotherapy and administered every 4 weeks over 3 years. In the RTOG 85-10 trial, and LH-RHa, initiated in the last week of radiation therapy and continued until relapse, increased overall survival only in patients with poorly differentiated tumor with a Gleason score of 8-10 (p = 0.03).

CONCLUSION

Androgen suppression prior to and during radiation improves disease-free survival; adjuvant hormonal therapy with an LH-RHa during and after radiation improves overall survival.

Prognostic of DNA-synthesizing enzyme activities (thymidine kinase and thymidylate synthase) in 908 T1-T2, N0-N1, M0 breast cancers: a retrospective multicenter study

Among the methodological approaches of tumor proliferation, thymidine kinase (TK) and thymidylate synthase (TS) assays take into account the specific pathways of pyrimidine synthesis. Studies pointing to a prognostic value of TK and TS in breast cancer involved small numbers of patients. We investigated the prognostic value of these enzymes and their combination in a large retrospective multicenter study. Nine hundred eight T1T2, N0N1, M0 primary breast cancer samples (median follow-up 68 months) were tested. TK and TS were measured in cytosols by using standardized radioenzymatic methods. Although a positive correlation was obtained between TK and TS (p<10(-5)), major discrepancies were observed in some tumors. High levels of both enzymes were associated with large tumor size, histological grade III and steroid receptor-negative tumors. Univariate analysis showed that TK, TS and their combination were predictive of poor metastasis-free (MFS) (p < 10(-4); p=0.004; p < 10(-4)) and disease-free survival (DFS) (p < 10(-4); p=0.007; p=0.0001). TK was selected as an independent factor for MFS in Cox analysis. It was the only variable selected in node-negative patients. Subgroups with specific outcomes, with possible therapeutic implications, were identified: a) in node-negative patients not receiving adjuvant treatment, TK values in the 4th quartile were associated with poor MFS (p=0.0002) and DFS (p=0.0005) as compared to the other quartiles; b) in node-positive patients receiving adjuvant chemotherapy, low levels of both TK and TS were associated with the highest survival rates (MFS: p=0.04; DFS: p=0. 03).

Post-radiation severe xerostomia relieved by pilocarpine: a prospective French cooperative study

BACKGROUND AND PURPOSE

The aim of the study was: (1) to confirm the action of pilocarpine hydrochloride (Salagen) against xerostomia: (2) to correlate the response to dose/volume radiotherapy parameters.

MATERIALS AND METHODS

From June 1995 to February 1996, 156 patients with severe radiation induced xerostomia received pilocarpine hydrochloride orally. IS mg per day with a 5 mg optional increase at S weeks up to a daily dose of 25 mg beyond 9 weeks.

RESULTS

One hundred and forty five patients are fully evaluable. Treatment compliance was 75%. Thirty eight patients (26%) stopped treatment before week 12 for acute intolerance (sweating, nausea, vomiting) or no response. No severe complication occurred. Ninety ses en patients (67%) reported a significant relief of symptoms of xerostomia at 12 weeks. Within 12 weeks, the size of the subgroup ith normal food intake almost doubled (13-24 patients) while the size of the subgroup with (nearly) impossible solid food ingestion decreased by 38% (47 vs. 29 patients). The impact on quality of life was considered important or very important by 77% of the responders.

CONCLUSIONS

No difference was found according to dose/volume radiotherapy parameters suggesting that oral pilocarpine hydrochloride: (1) acts primarily by stimulating minor salivary glands: (2) can be of benefit to patients suffering of severe xerostomia regardless of radiotherapy dose/volume parameters: (3) all responders are identified at 12 weeks.

[Breast, cervical and colo-rectal simultaneous mass screening program for women 50 to 69 years old in Isere]

A cervical screening campaign is implemented in the Isere department since 1990 for women aged 50 to 69, together with breast cancer and colo-rectal cancer screening. The attendance rate is about 30% but a survey performed among this population shows that 68.6% of these women did presented for screening during the year following their invitation. One and a half per cent of all smears were abnormal or ASCUS smears. Cancer detection rate for invasive cancer and CIN III was 1.3/1000. General practitioners and gynaecologists took the same part in the programme. During a postal survey conducted among them, they declared that they felt concerned with cancer screening, even if they met some difficulties. This results suggest that nominative invitations and a good cooperation of GPs may improve the coverage of eligible women. For the future success of the National Programme, which is to be implemented in France, organisational arrangements have to be set up. The review of positive points and difficulties met by Isere's local programme may help to discuss it.

Fast growing cervical carcinomas. A retrospective analysis of 20 IB-IIB FIGO

INTRODUCTION

Fast growing cervix carcinomas have a pejorative outcome: they may occur quickly after cervical smears qualified as normal - within an interval from 12 to 18 months in women less than 50 years old, and involveing the endocervix. This retrospective analysis is aimed at assessing 5-year outcomes.

MATERIALS AND METHODS

Twenty cases of fast-growing cancer of the uterine cervix classified according to the FIGO clinical staging system as IB (n=14), IIA (3), and IIB (3), have been reviewed and compared to a cohort of 160 cases not having this feature. As regard to fast-growing carcinoma, the median age was 41 years (range 25-50), and the median follow-up 22 months (8-213) as compared to 54 years (27-79) and 80 months (5-199) for the reference cohort. The comparison of the two cohorts shows only a difference of breakdown which concerns the histological pelvic lymph nodes status (P<0.05), more often positive in fast-growing forms. The treatment policy was equally distributed between a radio-surgical approach, cesium 137 intracavitary irradiation followed by radical hysterectomy and lymphadenectomy, or a definitive irradiation with pelvic external irradiation followed by cesium 137 intracavitary irradiation.

RESULTS

Thirteen deaths are reported in the fast-growing series instead of 54 in the other series. The 5-year overall survival is, respectively, 34 (13-55) vs. 74% (68-82) (P<0.001), the loco-regional-free survival 58 (33-84) vs. 85% (79-81) (P<0.001), the 5-year metastasis-free survival 61 (38-84) vs. 84% (78-90) (P=0. 004).

CONCLUSION

These poor results emphasize the need to intensify loco-regional therapy with a concurrent cisplatin-based chemotherapy within the framework of a multidisciplinary approach.

Phase II trial of up-front accelerated thoracic radiotherapy combined with chemotherapy and optional up-front prophylactic cranial irradiation in limited small-cell lung cancer. Groupe d'Oncologie Thoracique des Régions Alpines

PURPOSE

To investigate the feasibility and outcome of bifractionated, up-front thoracic radiotherapy (TR) (45 Gy in 30 fractions of 1.5 Gy twice daily over 3 weeks) combined with chemotherapy (CT) (six cycles of cisplatin and etoposide) and optional low-dose, up-front prophylactic cranial irradiation (18 Gy in 10 fractions of 1.8 Gy twice daily over 5 days) in limited small-cell lung cancer.

PATIENTS AND METHODS

CT (etoposide 100 mg/m(2) for 3 days and cisplatin 25 mg/m(2) for 3 days) was started on day 8 or 15 after the first TR treatment. In the five subsequent cycles, cisplatin was given as a single 100-mg/m(2) dose on day 1 every 4 weeks. A total of 52 patients were entered (41 men and 11 women); the median age was 55 years (range, 33 to 67 years). World Health Organization performance status was 0 in 34 patients, 1 in 16 patients, and 2 in two patients. Thirty-six patients (69%) received the full planned six cycles of CT.

RESULTS

All treated patients were assessable for response. Thirty-one patients (60%) achieved a complete response, and 16 (30%) had a partial response. One-, 3-, and 4-year survival rates were 74% (95% confidence interval [CI], 60% to 84%), 34% (95% CI, 21% to 49%), and 32% (95 CI, 16% to 46%), respectively. The median survival time was 18 months. Event-free survival at 1 year was 45% (95% CI, 32% to 58%) and at 3 years, 30% (95% CI, 18% to 44%). The main radiation-related acute toxicity was esophageal: 38% of the patients experienced grade 3 or 4 acute toxicity. CT was well tolerated. Although grade 3/4 neutropenia was observed in 86% of the patients, only 4% presented with associated fever. Grade 3/4 nausea and vomiting was seen in 35% of patients.

CONCLUSION

This trial demonstrates that up-front accelerated TR associated with CT is feasible, has acceptable toxicity, and shows considerable long-term survival potential.

Clinical impact of dosimetry quality assurance programmes assessed by radiobiological modelling of data from the thermoluminescent dosimetry study of the European Organization for Research and Treatment of Cancer

The European Organization for Research and Treatment of Cancer (EORTC) Radiotherapy Group initiated its mailed thermoluminescence dosimetry (TLD) programme in 1986. The aim of the present study was to evaluate the clinical relevance of variations in beam output detected in the period 1993 to 1996. A total of 140 beam outputs were checked (26 for cobalt-60 units and 114 for linear accelerators) in 35 centres. Clinical dose-response data for tumour control and normal tissue morbidity were used to assess the variation in clinical outcome resulting from variability in beam output. For 75 checked beams with nominal accelerating potentials (n. a.p.) of 6 MV or less the mean ratio, +/- standard deviation (S.D.) of measured to stated output was 1.004+/-0.020. For 65 beams with n. a.p. of 8 MV or more, the ratio was 1.009+/-0.021. Even with this relatively high level of precision, broad distributions of estimated tumour control or normal tissue morbidity were found. In the 10% of the beams with the most pronounced underdosage, the loss in tumour control probability was estimated at 7-8 percentage points. Likewise, in the 10% of the beams with the most pronounced overdosage, the increase in mild/moderate morbidity was 19-22 percentage points. For severe morbidity the same beams raised the estimated incidence of severe complications from 5% to 9-10%. An estimation of the loss of uncomplicated cure probability was about 1% for both high and low energy beams. Sequential mailings considerably improved the uniformity of clinical outcome. We conclude that small deviations in beam output may lead to clinically important variations in outcome. Substantial reductions in the variation between measured and stated output can be achieved by sequential mailings. Mailed TLD checks should be an integral part of a continuously ongoing quality assurance activity in radiotherapy.

Pathological prognostic factors in a series of 137 stage I TNM/UICC endometrial carcinomas

PURPOSE

We report on the long-term results of combination surgery-radiotherapy in cT1 carcinoma of the endometrium according to prognostic factors.

PATIENTS AND METHODS

From 1974 to 1993, 130 women suffering from cT1Nx-O Mo endometrial carcinoma, underwent surgical resection. The median age was 62 years. Thirteen received pre-operative irradiation, two pre-operative brachytherapy followed by post-operative external irradiation and 115 patients (88.35%) underwent post-operative irradiation therapy by brachytherapy or external beam irradiation.

RESULTS

The median follow-up is 67 months. Overall and specific survival rates for patients with cT1pT1 tumours were 71.1 and 85% at 10 years. For overall survival, lymph node invasion was the most powerful prognostic factor in the multivariate analysis (P = 0.02). If lymph node invasion is not taken into account, the WHO histological grade exerts a significant prognostic impact (P = 0.001).

CONCLUSION

For stage cT1 endometrial carcinoma, primary surgery allows radiotherapy to be adjusted according to the WHO histological grade, myometrial invasion and the pelvic lymph node status.

The use of a semi-customized phantom for verification of conformal plans

We have developed a technique for inverse treatment planning of prostate therapy designed to improve the degree of conformation between the dose distribution and the target volume. We compared the inverse plan with a "standard" four-field box technique as well as a four-field technique using oblique fields ("cross technique"). We validated the dosimetry of the inverse plan using Fricke gel solution in phantom specifically designed for this purpose. The phantom is a Plexiglas tank with a cross section, which approximates the dimensions of the pelvis. Anatomical data from computed tomography (CT) images of a patient were used to simulate organs in our phantom. This allows us to calculate dose distributions with the external geometry of the phantom and internal anatomy of the patient. Dose-volume histograms (DVHs) for the three different plans were calculated. The phantom containing the Fricke gel was irradiated according to the inverse plan. Magnetic resonance (MR) images was used to determine the dose distribution delivered to the phantom. We observe, on DVHs, that the inverse plan significantly reduces the dose to the rectum and the bladder but slightly increases the inhomogeneity inside the target volume. Correlation is good between isodoses on MR images and calculated isodoses. We conclude that inverse planning software can greatly improve the conformal degree of treatment to the prostate. This technique could be applied to other complex anatomic sites at which dose to organs at risk is a limiting factor and increased dose to the target volume is indicated. Our phantom and the Fricke gel solution are convenient to carry out validation of conformal treatments.

Accelerated radiotherapy, carbogen, and nicotinamide in glioblastoma multiforme: report of European Organization for Research and Treatment of Cancer trial 22933

PURPOSE

A three-step phase I/II trial associating accelerated radiotherapy with carbogen (step 1, ARCO), with nicotinamide (step 2, ARN), or with both (step 3, ARCON) was conducted, the aim of which was to overcome the effects of proliferation and hypoxia as potential causes of tumor radioresistance in glioblastoma multiforme.

PATIENTS AND METHODS

Radiotherapy consisted of 60 Gy delivered over 4 weeks in 1.5-Gy fractions twice daily, 5 days a week. Carbogen breathing was started 5 minutes before each fraction and continued until the end of each treatment session. Nicotinamide was given daily as a single oral dose of 85 mg/kg.

RESULTS

A total of 115 patients with a median age of 55 years were registered. Of 107 eligible patients, 23 were registered in step 1, 28 in step 2, and 56 in step 3. The planned treatment was administered without any interruption in 72% of patients (86% in ARCO but 68% in ARN and ARCON). The incidence and severity of acute skin and mucous membrane toxicity were higher in patients who received nicotinamide (ie, the ARN and ARCON groups). Grade 1 to 2 gastrointestinal toxicity was observed in 44% of patients in the ARN group and 32% of patients in the ARCON group, but only in 8% of patients in the ARCO group. Eight percent of evaluated patients presented with abnormal liver test results at treatment completion. The dose of corticosteroids had to be increased in 44% of patients. Late neurologic side effects were similar in all treatment steps and were observed mostly in patients with disease progression. Median survival times for patients treated with ARCO, ARN, and ARCON were 10.1, 9.7, and 11.1 months, respectively.

CONCLUSION

Feasibility of ARCO treatment was good but that of ARN and ARCON was only fair. This probably reflected the higher acute toxicity rate, particularly gastrointestinal, for patients receiving nicotinamide. The dose of corticosteroids had to be increased frequently during treatment, suggesting a higher than expected acute neurologic toxicity. Overall survival was similar in the three treatment steps and not different when compared with results of other series that used radiotherapy alone.

[Conformal radiotherapy of prostatic cancer: a general review]

Recent progress in radiotherapeutic management of localized prostate cancer is reviewed. Clinical aspects--including dose-effect beyond 70 Gy, relative role of conformal radiation therapy techniques and of early hormonal treatment--are discussed as well as technical components--including patient immobilization, organ motion, prostate contouring, beam arrangement, 3-D treatment planning and portal imaging. The local control and biological relapse-free survival rates appear to be improved by high dose conformal radiotherapy from 20 to 30% for patients with intermediate and high risk of relapse. A benefit of overall survival is expected but not yet demonstrated. Late reactions, especially the rectal toxicity, remain moderate despite the dose escalation. However, conformal radiotherapy demands a high precision at all steps of the procedure.

[Standardization and quality control in the evaluation of proliferation parameters in T1T2, N0N1, M0 breast cancer: multicentric retrospective study II. DNA-ploidy and S-phase fraction]

As part of a clinical research project, proliferative parameters were studied in primary breast cancer: standardization and technical validation of thymidine kinase (TK), thymidylate synthase (TS) and protein tyrosine kinase (PTK) are described. A total of 633 frozen tumor specimens, available in four institutions, was analyzed in three flow cytometry laboratories for DNA content and percentage of S-phase cells (%S) measurement. 1) The standardization step consisted in developing a common protocol for sample preparation; then, common cell suspensions were analyzed in order to perform an inter-laboratory control. Objective guidelines were elaborated to interpret DNA histograms in breast carcinoma. 2) DNA-aneuploidy was observed in 61% of cases of the retrospective series. Compared with DNA-aneuploid tumors, mean %S was significantly lower in case of DNA-diploidy (respectively: 6.4% and 2.2%, p < 0.001). When compared between the four institutions, %S distributions did not differ significantly. 3) %S is strongly correlated with TK, TS and PTK and high percentages were also observed in high grade tumors or tumor without hormone receptors. These results show that a standardization in using flow cytometers and DNA software allows multicenter studies.

[Standardization and quality control in the evaluation of proliferation parameters in T1T2, N0N1, M0 breast cancer : multicentric retrospective study I. DNA synthesis enzyme activities]

As part of a clinical research project co-ordinated in Grenoble, six French institutions (CRLCC Angers, CHU Grenoble, Hospices civils Lyon, AP Marseille, CRLCC St-Cloud, CHU Tours) grouped together in order to study the following proliferative parameters in primary breast cancer: DNA synthesis enzymes [thymidine kinase (TK), thymidylate synthase (TS)], signal transduction enzyme [protein tyrosine kinase (PTK)] and S-phase fraction (%S). TK, TS and PTK were measured in cytosols using radio-enzymatic biochemical methods. S-phase was estimated using flow cytometry. The first step consisted in standardization and technical validation of the measurements. The second step consisted in the clinical validation by using a retrospective series of 1,003 breast cancers T1T2, N0N1, M0. We report the results of the first step, together with the distributions of the variables and their relationship with classical clinical variables: 1) Using standardized methods and a cytosolic control, a good reproducibility of measurements was obtained, whether assays were performed in one (TS, PTK) or in several laboratories (TK). 2) Significantly different distributions of TK and TS were observed between the different centres mainly due to different conditions of storage of tumours and cytosols. 3) A highly significant correlation was observed between TK, TS and PTK. Highest TK, TS and PTK levels were observed in tumours with high histological grade or receptor negative tumors. This study clearly illustrates the importance of quality assurance of multicentre studies.