Abstract P3-12-13: Breast Cancer Genomic Profile in a Consecutive Series of a Breast Healthcare Service in South Brazil

Abstract

Background: Prognostic factors, such as breast cancer (BC) genomic profile, are cornerstone for the understanding of the disease, especially in the orientation of its treatment. The majority of studies reporting BC genomic profile were conducted in developed countries. Research in the developing world is needed, in order to investigate if BC profile in these countries is similar to the one seen in the developed world. Moreover, it is important to evaluate possible differences in the genomic profile between pre-and post-menopausal women. Finally, it is also important to appraise if there was any temporal trend in BC genomic profile in the last decade. Methods: A consecutive sample of patients who were diagnosed with BC between 2000 and 2010 were analyzed. All patients were diagnosed and treated at Núcleo Mama Moinhos, a specialized BC service in South Brazil. Comparisons were made between women below and above the age of 50, and between the period of 2000-2005 and 2006-2010. The Fisher exact test was used for comparisons. Ki-67 was considered as positive when > 5%. Results: 439 patients were included. Mean age was 55 ± 13 years, 37% of the sample was younger than 50 years old and 10% than 40 years old. 57% were diagnosed between 2000-2005 and 43% between 2006-2010. Tumor staging was as follows: 61% stage 0/I, 22% stage IIA, 9% stage IIB, 7% stage III and 1% stage IV. Median tumor size was 1.6 cm (IQR 1.0 — 2.5), 26% of patients had positive lymph nodes. 75% were invasive ductal carcinomas and 10% were in situ ductal carcinomas. Tumor histologic grades were as follows: 15% grade I, 42% grade 2 and 22% grade 3. Surgery type was mastectomy in 43.5% and setorectomy in the remainder. 56% of patients were submitted to chemotherapy, of which 25% were neoadjuvant. Regarding the genomic profile, 82% of the sample had positive estrogen receptor (ER) or progesterone receptor (PR), 18% were HER2 positive, and 11% were triple negative. Ki 67 was positive in 68% of the sample, median value was 10% (IQR 5% — 20%); p53 mutation was seen in 26%. When compared to patients diagnosed between 2000-2005, the sample from 2006-2010 had a lower prevalence of hormone receptors (76% vs 86%, p = 0.01) and a higher proportion of triple negative cases (16% vs 8%, p=0.01). This difference was more marked in women below the age of 50 (6% until 2005 and 18% afterwards, p = 0.02). There were no other temporal trends in the other evaluated variables (staging, histologic grade and type, age, HER2, type of surgery). In the comparison of women diagnosed after versus before 50 years of age, the former had a more favorable staging: 86% were in stages 0/I/IIA, as compared to 78% in the latter (p=0.03). Conclusions: The profile seen in this population has some similarities with other series from developed countries. The increase in triple negative and hormone negative tumors in women older than 50 is worrisome and does not reflect the common sense that the large majority of cases in this age group are hormone sensible. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P3-12-13.