TP53 MUTATIONS IN BREAST CANCER TUMORS OF PATIENTS FROM RIO DE JANEIRO, BRAZIL: ASSOCIATION WITH RISK FACTORS AND TUMOR CHARACTERISTICS Tatiana A. SIM˜ AO 1 , Fabiana S. RIBEIRO 1 , Lı ´dia M. F. AMORIM 1,2 , Rodolpho M. ALBANO 1 , Maria J. ANDRADA-SERPA 4 , Lu ´is E. B. CARDOSO 1 , Gulnar A. S MENDONC ¸A 3 and Cl´ audia V. DE MOURA-GALLO 1 * 1 Departamento de Bioquı ´mica, Instituto de Biologia Roberto Alcantara Gomes, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, RJ, Brazil 2 Departamento de Biologia Celular e Molecular, Instituto de Biologia, Universidade Federal Fluminense, Nitero ´i, RJ, Brazil 3 Departamento de Epidemiologia, Instituto de Medicina Social, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, RJ, Brazil 4 Setor de Pesquisa Ba ´sica, Instituto Nacional de Ca ˆncer, Rio de Janeiro, RJ, Brazil Somatic mutations in the TP53 gene are the most fre- quently observed genetic alterations in human malignancies, including breast cancer, which is one of the leading causes of death among women in Brazil. In our study, we determined the frequency and the pattern of TP53 mutations in malig- nant breast tumors from 120 patients living in Rio de Janeiro, Brazil. TP53 mutations were found in 20% of the tumors, which contained a diversity of mutation types: missense (62.5%), nonsense (8.3%), silent (4.2%), intronic (12.5%), in- sertion (4.2%) and deletion (8.3%). Of a total of 15 missense mutations, 4 were observed at Arg248 and 2 at Cys242, which are directly involved in DNA binding and in zinc bind- ing, respectively. A subgroup of 51 patients was analyzed with respect to the relation between the presence of TP53 muta- tions and classical risk factors and with tumor and patient characteristics. For this analysis, we used logistic regression and, in order to obtain more precise confidence intervals, they were recalculated using a bootstrap resampling tech- nique. Our results demonstrate that these mutations are not statistically associated with the risk factors or the patients’ characteristics. However, the presence of TP53 mutations is strongly associated with the aggressiveness of the tumors, measured by Elston classification (OR  11.97 and 95% CI of 2.24 –307.05). This finding is in agreement with previous stud- ies, which report the presence of TP53 mutations in tumors with poor prognosis. This correlation between tumor aggres- siveness and TP53 mutations could be a crucial variable for the treatment and prognosis of breast cancer. © 2002 Wiley-Liss, Inc. Key words: TP53 gene; breast cancer; risk factors; clinicopathologic features; Rio de Janeiro, Brazil; Elston grade Breast cancer is one of the leading causes of death among women in Brazil. The Brazilian expected mortality rate for 2001 is 9.9 women per 100,000, whereas the highest incidence was esti- mated to be in the State of Rio de Janeiro: 82 women per 100,000. 1 The etiology of breast cancer is rather complex and, although 10 –15% of the patients have a family history of the disease, only a small proportion can be explained by mutations in genes such as BRCA1 and BRCA2. The different geographic distribution of cases and evidence from migration studies suggest that some environmental and/or lifestyle factors may be related to the development of breast cancer. 2 Reproductive history, family history of breast cancer, cigarette smoking and alcohol consumption are generally cited as risk factors of breast cancer. However, how these factors contrib- ute to trigger the molecular mechanisms of tumor initiation and progression is not completely understood. 3 Mutations in the tumor suppressor gene, TP53, are the most common genetic alterations seen in human cancer. 4 This gene encodes a 393 amino acid nuclear phosphoprotein that acts as a transcription factor and is implicated in nearly all pathways in- volved in cell proliferation control: modulation of cell-cycle pro- gression, apoptosis, DNA repair, cell differentiation and senes- cence. 5 The type and location of mutations in TP53 are different in distinct human cancers. This variability and the mutation spectrum may represent etiologic factors acting in the malignant transfor- mation process. 4 In breast cancer, the occurrence of TP53 mutations is described to range from 12– 60% of all tumors. 4,6 Furthermore, the presence of TP53 mutations corresponds to a more aggressive tumor phe- notype indicating that the analysis of the mutation pattern may be an interesting tool to study possible correlations with etiologic agents as well as prognostic factors in breast tumors. 7 In our study, we determine the type and location of TP53 mutations among Brazilian breast cancer patients who are resi- dents of Rio de Janeiro City. TP53 mutations were associated with classic risk factors for breast cancer and with the tumor and patients’ characteristics. To our knowledge, this is the first detailed study of TP53 mutation spectrum in breast cancer in Brazil. MATERIAL AND METHODS Study subjects and interviews All of the studied patients (n = 120) were admitted for invasive breast cancer surgery at the National Institute of Cancer, in Rio de Janeiro, from 1995–1997. Fifty-one patients from the group of 120 were interviewed using a structured questionnaire in order to perform a strict analysis of the possible relationship between TP53 mutations and epidemiologic factors or tumor characteristics. Women from this group were eligible for the study only if they lived in the metropolitan area of Rio de Janeiro and were younger than 75 years old. Interviewers, specially trained for the study, elicited detailed information about the patient’s residential area, socioeconomic status, educational level, and about the selected risk factors. The variables included in our study were age, parity status, lactation, family history of breast cancer and other cancers (only for first-degree relatives), tobacco smoking (ever and never) and alcohol consumption. Cancer diagnoses were confirmed his- topathologically and 94% of the tumors were diagnosed as inva- sive ductal carcinoma. Tumor characteristics, grade, size and nodal Grant sponsor: CNPq; Grant sponsor: FAPERJ, Brazil; Grant number: E-26/151.654/1999. *Correspondence to: Departamento de Bioquı ´mica—IBRAG—UERJ, Av. 28 de Setembro, 4 andar, fundos, Vila Isabel, Rio de Janeiro, RJ, Brazil, 20551-013. Fax: +55-21-2587-6136. E-mail: cgallo@uerj.br Received 22 January 2002; Revised 21 May 2002; Accepted 3 June 2002 DOI 10.1002/ijc.10567 Published online 19 July 2002 in Wiley InterScience (www.interscience. wiley.com). Int. J. Cancer: 101, 69 –73 (2002) © 2002 Wiley-Liss, Inc. Publication of the International Union Against Cancer