Cellular interactions of functionalized superparamagnetic iron oxide nanoparticles on oligodendrocytes without detrimental side effects: Cell death induction, oxidative stress and inflammation.

Iron oxide nanoparticles have the capability to cross Blood Brain Barrier (BBB) and hence are widely investigated for biomedical operations in the central nervous system. Before being used for the biomedical purpose, it is necessary to investigate its biocompatibility, dosimetry and biological interaction. In the present study, in-house synthesized superparamagnetic iron oxide nanoparticles (SPIONs) were functionalized using the polymer, PolyEthylene Glycol (PEG) and a fluorophore (Rhodamine). The interaction of these nanoparticles with murine oligodendrocytes 158N was studied using different assays. The nanoparticles were taken up by the cells via endocytosis and there was a dose-dependent increase in the intracellular iron content as revealed by flow cytometry, transmission electron microscopy and confocal microscopy. Nanoparticles remained stable inside cells even after 24 h. Cell sorting capacity using a magnet depended on the number of particles interact per cell. SPIONs exhibited good biocompatibility as no toxicological responses, including morphological changes, loss of viability, oxidative stress or inflammatory response (IL-1ß, IL-6 secretion) were observed. Together, these data show that the in-house synthesized SPIONs have no side effects on 158N cells, and constitute interesting tools for biomedical applications across brain, including cellular imaging and targeting.

Dual effect of docosahexaenoic acid (attenuation or amplification) on C22:0-, C24:0-, and C26:0-induced mitochondrial dysfunctions and oxidative stress on human neuronal SK-N-BE cells.

Increased levels of C22:0, C24:0 and C26:0 were found in cortical lesions of patients with Alzheimer's disease (AD). So, it was of interest to precise the cytotoxic effects of these fatty acids, and to determine whether docosahexaenoic acid (DHA), described to prevent AD, can attenuate their eventual side effects. Human neuronal SK-N-BE cells were cultured in the absence or presence of C22:0, C24:0 or C26:0 (0.1-20 µM) without or with DHA (50-150 µM). C22:0, C24:0 and C26:0 induce an inhibition of cell growth, a loss of Δψm, an overproduction of reactive oxygen species (ROS), a decrease of reduced glutathione, and a lipid peroxidation. DHA attenuates C22:0, C24:0 and C26:0 induced-mitochondrial dysfunctions and/or cell growth inhibition measured with MTT whatever the concentrations considered, whereas it can either decrease or amplify (especially at 150 µM) ROS overproduction. C22:0, C24:0 and C26:0 have neurotoxic activities, and depending on its concentration, DHA attenuates or not fatty acid-induced side effects.

Changes in 18F-FDG tumor metabolism after a first course of neoadjuvant chemotherapy in breast cancer: influence of tumor subtypes.

BACKGROUND: The aim of this study is to evaluate the impact of the different breast cancer subtypes on the tumor (18)F-FDG uptake at baseline and on its changes after the first course of neoadjuvant chemotherapy (NAC). PATIENTS AND METHODS: One hundred and fifteen women with newly diagnosed, large or locally advanced breast cancer undergoing NAC were included. Estrogen receptor (ER), progesterone receptor (PR) and HER2 status were used to define three major tumor subtypes: triple negative (TN) (ER-/PR-/HER2-), luminal (ER+ and/or PR+; HER2-) and HER2 positive (HER2+). Using Fluorine-18 fluorodeoxyglucose positron emission tomography, the tumoral standard uptake value (SUV) maximal index was measured at baseline and just before the second course of NAC. RESULTS: TN tumors presented the highest baseline SUV (11.3 ± 8.5; P < 0.0001). The decrease of SUV after the first course of NAC (ΔSUV) was significantly higher in TN and HER2-positive subtypes (-45% ± 25% and -57% ± 30%, respectively) than in luminal one (-19% ± 35%; P < 0.0001). ΔSUV was a predictive factor of the pathological complete response only in HER2-positive tumors (cut-off = -75%; P < 0.03) with an accuracy of 76%. CONCLUSION: The baseline (18)F-FDG tumoral uptake but also its early response to NAC is different according to the immunohistological subtypes of breast cancer.

[PSA kinetics after radiotherapy]. / Cinétique de PSA après radiothérapie.

The prostate specific antigen (PSA) is the best marker of the prostate cancer today although not very specific of this pathology. The dynamic interpretation of this marker always has to prevail over that of overtaking a threshold. After radiotherapy, PSA can decrease after a mean interval of one to two years to a value less than 1 microg/L (predictive of recurrence-free survival). Biochemical recurrence after radiotherapy is defined by an increase of PSA by 2 microg/L or more above the PSA nadir, whether or not it is associated with endocrine therapy. The time of appearance of the recurrence and the PSA doubling time after total radiotherapy have a diagnostic value on the nature of the site of recurrence, local or metastatic.

[PSA kinetics after total prostatectomy]. / Cinétique du PSA après prostatectomie totale.

The prostate specific antigen (PSA) is the best marker of the prostate cancer today although not very specific of this pathology. The dynamic interpretation of this marker always has to prevail over that of overtaking a threshold. With the lack of residual cancer, PSA becomes undetectable by the first month after total prostatectomy: less than 0.1 microg/L. The type of diminution mono- or biphasic of the marker depends on the chronology of the takings. Faced with residual cancer, PSA either does not become undetectable or increases after an initial undetectable period. A recurrence is defined by a value of PSA higher than 0.2 microg/L and confirmed on two successive assays. The time of appearance of the recurrence and the PSA doubling time after total prostatectomy have, with the initial clinical stage and the Gleason score, a diagnostic value on the nature of the site of recurrence, local or metastatic.

[Germ cell testicular tumors: understanding the kinetics of serum alpha-fetoprotein (AFP) during chemotherapy]. / Tumeurs germinales non séminomateuses du testicule : comprendre les cinétiques d'alpha-foetoprotéine (AFP) sous chimiothérapie.

The analysis of longitudinal series of tumour markers during chemotherapy in patients with germ cells tumors is not easy. The purpose of this work is to present various characteristic profiles of the evolution of serum alpha-fetoprotein during chemotherapy and review the modalities of the dynamic interpretation of this marker.

[Germ cell testicular tumors: understanding the kinetics of serum human chorionic gonadotropin during chemotherapy]. / Tumeurs germinales du testicule : comprendre les cinétiques de la gonadotrophine chorionique humaine (hCG) sérique sous chimiothérapie.

The analysis of longitudinal series of tumour markers during chemotherapy in patients with germ cells tumors is not easy. The purpose of this work is to present various characteristic profiles of the evolution of serum human chorionic gonadotropin during chemotherapy and review the modalities of the dynamic interpretation of this marker.

[Contribution of dynamic interpretation of CA 125 measurements to the understanding of an atypical clinical case]. / Contribution de l'interprétation dynamique du CA 125 dans la compréhension d'un cas clinique atypique.

The dynamic interpretation of the serum concentrations of markers is frequently used to calculate biological indicators of therapeutic efficiency and relapse. But analysis of marker kinetics can also help improve our understanding of the natural history of different types of cancer and their evolution under treatment. This application is illustrated by an analysis of CA 125 kinetics measured in a patient with stage III ovarian cancer treated with multiple lines of chemotherapy and who had a survival time of 9 years.

Prognostic value of serum CA 125 bi-exponential decrease during first line paclitaxel/platinum chemotherapy: a French multicentric study.

BACKGROUND: CA 125 assays enable treatment-response monitoring in ovarian cancer. METHODS: A multicentric study of CA 125 kinetics under paclitaxel/platinum-based chemotherapy was performed in 130 stage IIc-IV patients. CA 125 half-life and nadir concentration were compared to patient outcome. Some patients (n=38, 29.2%) presented a CA 125 bi-exponential decrease and its clinical implication was studied. Survival analyses for disease-free survival (DFS) and overall survival (OS) used univariate (Kaplan-Meier) and multivariate (Cox model). RESULTS: During a median follow-up time of 29 months (range 5-106 months), 111 patients (85%) relapsed and 94 (72%) died from ovarian cancer. Patients were split into 4 groups according to their pattern of CA 125 decrease: non-assessable half-life because of a low pre-chemotherapy CA 125 level (n=38), half-life < or = 14 days and mono-exponential CA 125 decay (n=18), half-life < or = 14 days and bi-exponential CA 125 decay (n=21), and half-life > 14 days (n=53). In Cox models, nadir concentration, residual tumour volume and number of chemotherapy courses were found to be independent prognostic factors for DFS and OS. The group classification was found to be an independent prognostic factor only for DFS. However, when nadir was not introduced in the models, the CA 125 kinetics groups were the most important prognostic factor for OS. CONCLUSION: Characteristics of CA 125 kinetics during first line paclitaxel/platinum chemotherapy have a strong and independent prognostic value. A CA 125 bi-exponential decrease is an indicator of bad prognosis.

Change in CA 125 levels after the first cycle of induction chemotherapy is an independent predictor of epithelial ovarian tumour outcome.

BACKGROUND: CA 125 assays enable treatment response monitoring in ovarian cancer. PATIENTS AND METHODS: This multicentric study was carried out to assess the prognostic value of the CA 125 change after the first and the second courses of induction chemotherapy (CT). Of the 494 stage IIc-IV patients, 194 had a surgical second look, 397 (80.4%) relapsed and 382 (77.3%) died from cancer. Median (range) follow-up time was 34 months (3-215 months). RESULTS: In Cox models, CA 125 change after the first course (P < 0.0001), residual tumour (P = 0.003), CA 125 before the second course (P = 0.025) and patients' age (P = 0.048) were independent prognostic factors for overall survival (OS). A normal CA 125 before each of the two first CT courses or a CA 125 decrease >50% after the first course with a normal CA 125 before the second course identify patients with good prognosis. Both criteria retained a significant value in predicting second-look findings by univariate and multivariate analysis (P < 0.0001). CONCLUSION: Among well-established prognostic factors in ovarian cancers, the CA 125 change after first course of CT was independent prognostic factors for both achievement of pathological complete response and OS.

CA 125 half-life and CA 125 nadir during induction chemotherapy are independent predictors of epithelial ovarian cancer outcome: results of a French multicentric study.

BACKGROUND: CA 125 assays enable treatment-response monitoring in ovarian cancer. PATIENTS AND METHODS: A multicentric study of CA 125 kinetics under induction chemotherapy was performed in 631 patients. CA 125 half-life was calculated by mono-compartmental logarithmic regression. Nadir CA 125 concentration and time to nadir were also studied. Survival analyses for disease-free survival (DFS) and overall survival (OS) used univariate (Kaplan-Meier) and multivariate (Cox) models. RESULTS: For 553 stage IIC-IV patients, 459 (83.0%) relapsed and 444 (80.3%) died from cancer. Median (range) follow up time was 32 months (2-214 months). Median (range) for CA 125 kinetics were: 263 kU/l (5-52000 kU/l) before 1st course, 15.8 days (4.5-417.9 days) for CA 125 half-life, 16 kU/l (3-2610 kU/l) for nadir and 85 days (0-361 days) for time to nadir. Pre-chemotherapy CA 125, its half-life, nadir concentration and time to nadir all had a univariate prognostic value for DFS and OS (P<0.0001). In Cox models, CA 125 half-life, residual tumour (P<0.0001 for both), nadir concentration (P=0.0002) and stage (P=0.0118) were the most powerful prognostic factors for DFS. For OS, the significant variables were similar, with age ranking last (P=0.0319). CONCLUSION: Among well-established prognostic factors in ovarian cancers, CA 125 half-life and nadir concentration bear a strong and independent prognostic value.

[Interpretation of the CA125 kinetics during first line chemotherapy of the ovarian cancer: methodological aspects and characteristic profiles]. / Interprétation des cinétiques du CA125 sous chimiothérapie de première ligne des cancers de l'ovaire: aspects méthodologiques et profils caractéristiques.

Mathematical analysis of CA125 kinetics during first line chemotherapy allows calculation of various biologic parameters which are powerful indicators of the therapeutic efficiency. The purpose of this study is to present an original method of interpretation of CA125 kinetics based on both CA125 profile and its half-life value. The first part of this study reviews the practical modalities of CA125 kinetics analysis, the methods of calculation of the biologic parameters as well as the guidelines of interpretation. The second part of this work is dedicated to the presentation of CA125 profile characteristics in responders to chemotherapy, partially or totally nonresponders to chemotherapy, tumoral growth under treatment and tumor lysis syndrome.

[Standards, options and recommendations for blood tumor markers in thyroid cancers]. / Standards, Options et Recommandations: marqueurs tumoraux seriques des cancers de la thyroide.

CONTEXT: The "Standards, Options and Recommendations" (SOR) project, started in 1993, is a collaboration between the Federation of the French Cancer Centers (FNCLCC), the 20 French Cancer Centers and specialists from French Public Universities, General Hospitals and Private Clinics. The main objective is the development of clinical practice guidelines to improve the quality of health care and outcome for cancer patients. The methodology is based on literature review and critical appraisal by a multidisciplinary group of experts, with feedback from specialists in cancer care delivery. OBJECTIVES: To define, according to the definitions of the Standards, Options and Recommendations project, the characteristics of the main tumor markers in thyroid cancer and the potential role of these markers in the management of patients with this malignancy. METHODS: Data were identified by searching Medline and the personal reference lists of members of the expert groups. Once the guidelines were defined, the document was submitted for review to 55 independent reviewers, and to the medical committees of the 20 French Cancer Centers. RESULTS: The main recommendations are: 1) Thyroglobulin is a serum tumor marker for the monitoring of operated thyroid differentiated neoplasms (standard). 2) It is essential to know if the patient is under TSH stimulation or under thyroid suppression therapy to interpret thyroglobulin results (standard). 3) Thyroglobulin assay must be performed regularly during the monitoring of differentiated thyroid neoplasms (standard, level of evidence B2), should be coupled with the measurement of anti-thyroglobulin antibodies concentration using a sensitive method (standard, level of evidence B2). 4) Thyroglobulin assay should not be performed to detect or diagnose differentiated thyroid neoplasms (standard, level of evidence B2). 5) The methods used to assay thyroglobulin must have a limit of detection lower than 3 mug.l- 1 (standard, expert agreement). 6) Calcitonin is a marker for medullary thyroid cancer (standard). 7) Its assay, associated with RET gene study if indicated, enables medullary thyroid cancer to be diagnosed. 8) The pentagastrin test is essential to diagnose familial forms of medullary thyroid cancer. 9) All analyses for each patient must be performed in the same laboratory, using the same technique (standard, expert agreement). 10) Calcitonin and carcinoembryonic-antigen are serum markers for the monitoring of medullary thyroid cancer and allow the detection of recurrent disease (standard).

[Standards, options and recommendations for tumor markers in colorectal cancer]. / Standards, Options et Recommandations: marqueurs tumoraux sériques dans les cancers du côlon.

CONTEXT: The "Standards, Options and Recommendations" (SOR) project, started in 1993, is a collaboration between the French National Federation of Comprehensive Cancer Centers (FNCLCC), the 20 French Cancer Centers and specialists from French Public University or General Hospitals, and Private Clinics. The main objective is the development of clinical practice guidelines to improve the quality of health care and outcome of cancer patients. The methodology is based on literature review and critical appraisal by a multidisciplinary group of experts, with feedback from specialists in cancer care delivery. OBJECTIVES: To define, according to the definitions of the Standards, Options and Recommendations project, the characteristics of the main tumor markers in colorectal cancer and their potential role in the management of patients with this malignancy. METHODS: Data were identified by searching Medline and the personal reference lists of members of the expert groups. Once the guidelines were defined, the document was submitted for review to 117 independent reviewers, and to the medical committees of the 20 French Cancer Centers. RESULTS: The main recommendations for the tumor markers in colorectal cancer are: 1) The carcinoembryonic antigen (CEA) is the reference serum marker (standard). 2) All the analyses for a given patient must be performed in the same laboratory, using the same technique (standard, expert agreement). 3) CEA or CA 19-9 should not be used for screening or diagnosis (standard, level of evidence B2). 4) High initial serum concentration of CEA is of bad predictive value (standard, level of evidence C). CEA is an independent prognostic factor of survival in colorectal cancers with lymph node metastases (standard, level of evidence B2). 5) CEA is the most sensitive biological parameter for the screening of hepatic metastases (standard, level of evidence B2). 6) CEA serum concentration before palliative chemotherapy is an independent prognostic factor of survival (standard, level of evidence B2). The combination of CEA assay with imagery techniques and clinical examination can help monitor the response to palliative chemotherapy (standard), in particular in non measurable disease (standard, expert agreement). 7) In 65% of the cases, CEA is the first indicator of relapse (standard, level of evidence B2). CEA is the choice marker for monitoring patients with colorectal cancer (standard, level of evidence B2). 8) A sustained biological follow-up including CEA assay can be used to predict the operability of recurring tumors (standard, level of evidence B2). Nevertheless, no survival advantage has been shown (standard).

[Standards, Options and Recommendations (SOR) for tumor markers in breast cancer. SOR Working Group]. / Standards, Options et Recommandations (SOR): marqueurs tumoraux sériques du cancer du sein. Groupe de travail SOR.

CONTEXT: The "Standards, Options and Recommendations" (SOR) project, started in 1993, is a collaboration between the Federation of the French Cancer Centres (FNCLCC), the 20 French Cancer Centres and specialists from French Public Universities, General Hospitals and Private Clinics. The main objective is the development of clinical practice guidelines to improve the quality of health care and outcome for cancer patients. The methodology is based on literature review and critical appraisal by a multidisciplinary group of experts, with feedback from specialists in cancer care delivery. OBJECTIVES: To define, according to the definitions of the Standards, Options and Recommendations project, the characteristics of various tumour markers in breast cancer and the potential role of these markers in the management of patients with this malignancy. METHODS: Data were identified by searching Medline and the personal reference lists of members of the expert groups. Once the guidelines were defined, the document was submitted for review to 43 independent reviewers, and to the medical committees of the 20 French Cancer Centres. RESULTS: The main recommendations are: 1) CA 15.3 and CEA are the serum tumour markers most often used in breast cancer (standard). 2) If the CA 15.3 is raised at presentation, there is no place for the measurement of other tumour markers (standard, expert agreement). 3) All analyses for each patient must be performed in the same laboratory, using the same technique (standard, expert agreement). 4) CA 15.3 should not be used for screening or diagnosis. 5) The level of CA 15.3 before treatment is a recognised prognostic factor, the independent value of which has not been proven (standard, level of evidence C). 6) If the initial value of CA 15.3 is greater than 50 kU.L(-1), disseminated disease should be actively sought before any treatment decisions are made (standard, expert agreement). 7) An initial elevation of CA 15.3 that does not return to normal, reflects a lack of response to treatment and is a strong adverse prognostic factor (standard, level of evidence C). 8) The accuracy of tumours markers (especially CA 15.3) as early indicators of metastatic disease is well recognised (standard) but the clinical benefit has not been established. 9) There is a correlation between tumour markers and clinical response in the treatment of metastatic disease (level of evidence C). The level of CA 15.3 in metastatic disease does not predict response to treatment.

Enhancement of mdr1 gene expression in normal tissue adjacent to advanced breast cancer.

In the present study, mdr1 gene expression was investigated by a sensitive reverse transcriptase-PCR assay in advanced breast cancer and in corresponding adjacent normal tissues obtained before and after treatment with primary chemotherapy. Comparatively to normal tissues, a significant induction of mdr1 expression was observed in untreated tumors (p = 0.0222). Similarly, a significant induction of mdr1 expression was revealed when treated samples were compared to untreated counterparts (p = 0.0222), but no differences were detected between tumor and normal samples (p = 0.3199). Noteworthy, a significant induction of mdr1 gene expression occurred in treated normal samples comparatively to untreated ones (p = 0.0037), and this induction was even more important in normal than in tumoral tissue (p = 0.0627). However, neither the basal expression nor the induction of mdr1 were correlated with subsequent response to chemotherapy or with survival. Thus, in agreement with previous reports, our data show that chemotherapy induce mdr1 gene expression in breast cancer cells, but they also indicate that a similar phenomenon occurs in adjacent normal tissues. Therefore, our results strongly suggest that mdr1 gene overexpression is not a characteristic of breast malignant cells, but rather constitutes a general phenomenon occurring both in normal and tumor cells which could explain at least in part the absence of relationship between mdr1 expression and the clinical outcome of breast cancer patients.

Glutathione S-transferase M1 null genotype: lack of association with tumour characteristics and survival in advanced breast cancer.

BACKGROUND: Glutathione S-transferase (GST)M1, a member of the mu class GST gene family, has been shown to be polymorphic because of a partial gene deletion. This results in a failure to express the GSTM1 gene in 50-60% of individuals. Several studies have demonstrated a possible link with the GSTM1-null genotype and susceptibility to cancer. Furthermore, a GSTM1 isoenzyme has been positively associated with protective effect against mutagenic drugs, such as alkylating agents and anthracyclines. OBJECTIVES: To determine whether GSTM1 polymorphisms are associated with tumour characteristics and survival in advanced breast cancer patients, and whether it may constitute a prognostic factor. METHODS: We genotyped 92 patients receiving primary chemotherapy, which included cyclophosphamide, doxorubicine and 5-fluorouracil. The relationships between allelism at GSTM1 and clinicopathological parameters including age, menopausal status, tumour size, grade hormone receptors, involved nodes and p53 gene mutations were analysed. Of the patients with GSTM1-positive genotype, tissue samples obtained before and after treatment were available from 28 cases, allowing RNA extraction and GSTM1 expression by reverse transcription polymerase chain reaction. Relationships with clinical response to chemotherapy, and disease-free and overall survival were also evaluated. The data obtained was analysed using logistic regression to estimate the odds ratio and 95% confidence interval. RESULTS: Of 92 patients, 57.6% (n = 53) were classified as heritably GSTM1-deficient, and 42.4% (n = 39) were of the GSTM1-positive genotype. There were no statistically significant relationships between GSTM1-null genotype and the clinicopathological parameters analysed. No relationship was observed between GSTM1 RNA expression and objective clinical response to chemotherapy. Objective clinical response to chemotherapy was related only to clinical tumour size (P = 0.0177) and to the absence of intraductal carcinoma (P = 0.0013). GSTM1-null genotype had no effect on disease-free or overall survival. The absence of hormone receptors (P = 0.002), the presence of a mutated p53 gene (P = 0.0098) and lack of response to primary chemotherapy (P = 0.0086) were the only factors associated with reduced disease-free or overall survival. CONCLUSIONS: GSTM1-null genotype alone had no effect on tumour characteristics and outcome of patients with advanced breast cancers. The lack of correlation of GSTM1 genotype with clinical tumour features, clinical response to chemotherapy and survival exclude a role for GSTM1 polymorphism as a prognostic factor in advanced breast cancer.

MDR1 and thymidylate synthase (TS) gene expressions in advanced breast cancer: relationships to drug exposure, p53 mutations, and clinical outcome of the patients.

To characterize the biological features of advanced breast cancer associated with poor chemotherapy response and worse prognosis, sequential tumor samples obtained from 75 patients receiving primary chemotherapy were analysed for MDR1 and TS gene expression before and after treatment. MDR1 gene expression was also analysed in 36 sequential normal samples. The levels of MDR1 and TS genes expression were determined by reverse transcription-PCR method, and examined in relation to p53 gene status, and the clinical outcome of the patients. After treatment, MDR1 expression levels were significantly enhanced in tumor (p = 0.0033) and normal (p = 0.0098) samples, whereas a significant decrease in TS expression was observed (p = 0.0054). There was no significant correlation between MDR1 or TS expressions and the presence of p53 mutations (detected in 24% of the cases), chemoresponsiveness, or survival. Only p53 mutations were associated with reduced disease-free survival (p = 0.0473). These results demonstrate that MDR1 and TS gene expressions were affected by drug exposure, but not by p53 gene status. Furthermore, the increase of MDR1 gene expression in normal and tumor tissues is in favor of an induced MDR1 expression rather than of a selection of resistant tumoral clones, which can be responsible for the absence of relationship of MDR1 expression with clinical outcome of advanced breast cancer patients.

Loss of heterozygosity at the TP53 gene: independent occurrence from genetic instability events in node-negative breast cancer.

TP53 abnormalities have been reported as an early event in the process of cellular transformation of human breast cancers, and involved in mammary-tumor evolution, from in situ to invasive disease. In this study, node-negative (N-) tumors were examined for TP53 allelic loss in relation to different genetic instability events, including allelic loss at chromosome 17p13.3 and c-H-ras-1 loci, as well as alteration of the c-myc and c-erbB-2/neu oncogenes. TP53 allelic loss was analyzed to determine whether such an abnormality was the more important, among other genetic events, in the N- tumors, whether it appeared independently of these genetic events, and whether accumulation of genetic events arises in this group of breast tumors. Clinicopathological parameters were also examined. Loss of heterozygosity (LOH) at the TP53 gene appears the most frequent alteration detected (26% vs. 13%, 8%, 9% and 3% for LOH at D17S30 and c-H-ras-1 loci, and amplification of c-myc and c-erbB-2/neu respectively). There was no association between LOH at the TP53 locus and other genetic events. Among clinicopathological parameters, significant associations were observed only with estrogen-receptor-negative tumors (p = 0.05). Our results demonstrate that LOH at TP53 arises more frequently in the N- breast cancer, thus supporting earlier findings suggesting that TP53 abnormality has a role early in the pathogenesis of breast lesions. Moreover, the data indicate that accumulation of many genetic events occurs at a low level in N- breast tumors, and that TP53 abnormality occurs independently of these genetic events.