Abstract B080: Assessment of the molecular mechanisms of a protective variant for breast cancer in Latinas

The incidence of breast cancer is lower in women of Latin American origin in the U.S. compared to European American and African American women. Among Latinas, the rs140068132A>G variant, which is common in women with IAA, has been associated to a lower risk of breast cancer. The frequency of the G allele is 0% for non-Latinos while 12% in Latinos, being highest in the Peruvian population (23%). This variant is located on chromosome 6 near the Estrogen Receptor 1 gene (ESR1) and even though experimental evidence suggests that this variant might be functional, the molecular mechanisms that explain its protective effect are unknown. We hypothesize that the rs140068132-G variant decreases ESR1 expression, which affects the expression or function of genes involved in associated pathways. We aim to test the association of the rs140068132 variant and gene expression in breast cancer tumors from patients with high IAA. We collected 47 breast tumors and blood samples from the Instituto Nacional de Enfermedades Neoplásicas in Lima, Peru. These patients were genotyped for IAA estimation and determination of the rs140068132 genotype. Total RNA was extracted from tumor samples and used for a paired-end sequencing (2 × 75bp paired-end,100 million reads per sample) in the Illumina NextSeq500. Differential gene expression between genotypes was performed by DEseq2 R package and statistical significance was determined using FDR<0.05 for samples with at least log2 1.5-fold change. Differentially expressed isoforms were detected by EBseq R package using FDR<0.05. Tumor intrinsic subtypes were obtained using PAM50 as implemented in the genefu R package. The average IAA for the 47 Peruvian patients was 77% (SD=0.17). Twenty-seven patients were homozygous AA, 19 heterozygous AG and 1 GG for the rs140068132 variant. According to PAM50 classification, 10 tumors were Luminal A, 12 Luminal B, 15 HER2+ and 10 Basal. Among luminal tumors there was a suggestive trend towards lower expression of the ESR1 gene in patients carrying the protective allele (p=0.16). Including all subtypes, 27 genes were differentially expressed according to the rs140068132 genotype. Four of these genes are ER dependent or associated with ER status. The expression of the top gene, which is a transcriptional target of ER, is lost in patients with the protective allele. This association is mainly driven by its expression in luminal tumors and remained significant after adjusting for IAA. ESR1 isoforms were not differentially expressed by genotype, however significant differences were detected in the expression of isoforms for 115 genes, of which 18% have been reported to be transcriptional targets of ER or functionally related. Our preliminary results suggest that the rs140068132 variant decreases ER expression and affects the expression of functionally associated genes in luminal tumors. Further allele-specific expression analysis will elucidate if this variant is part of a cis-regulatory module.

Note: This abstract was not presented at the conference.

Citation Format: Valentina A. Zavala, Tatiana Vidaurre, Katie Marker, Sandro Casavilca, Lizeth Tamayo, Carlos Castañeda, Jeannie Vásquez, Fernando Valencia, Zaida Morante, M. Calderon, J. Abugattas, H. Gomez, H. Fuentes, C. Monge-Pimentel, Silvia Neciosup, Jovanny Zabaleta, Laura Fejerman. Assessment of the molecular mechanisms of a protective variant for breast cancer in Latinas [abstract]. In: Proceedings of the Twelfth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2019 Sep 20-23; San Francisco, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl_2):Abstract nr B080.

Abstract 4184: Tumor and risk factor characteristics among breast cancer patients from different geographic regions in Peru

There are few Latin American cohorts with available biospecimens that include women of high Indigenous American ancestry. The Peruvian population is characterized by a high degree of Native American (NA) ancestry, with this ancestral component varying between 56 to 100% on average, depending on the region. We have collected 1199 Peruvian samples from the Instituto Nacional de Enfermedades Neoplasicas in Lima. This cohort of patients represents a unique opportunity to study the molecular characteristics of breast cancer in the NA genetic and genomic background. Here we present a basic description of the women in the study and a comparison of tumor subtypes distribution and risk factor information of the patients by place of birth and residence.

We explored differences in tumor subtype distribution and risk factors in relation to place of birth or residence in the three main geographical region of Peru. To test differences in proportions we used Chi2 or Fisher-exact tests. To test differences in means for continuous variables we used ANOVA or t-tests. Genetic ancestry was estimated using genome wide genotypes and the program ADMIXTURE. Tumor subtypes were defined using the following criteria: ER+/PR+/HER2- as luminal A, ER+/PR+/HER2+ as luminal B, ER-/PR-/HER2+ as HER2+ and ER-/PR-/HER2- as triple negative.

Overall, the patients included in the study were relatively young (50 yrs, SD=11.0). The average number of full-term pregnancies was 3 (SD=1.8), the average age at first pregnancy 22 (SD=5.7) and age at menarche was 13 (SD=1.8). The tumor subtype distribution was 31% of Luminal B tumors, 24% luminal A, 12% HER2 and 12% triple negative and did not differ by place of birth or residence. We found that patients from the Coastal region were heavier and taller than those born in the Andean region (p<0.005). Women born in the Coastal region had the lowest age at menarche and a lower number of full-term pregnancies (p<0.0001). Similar trends were observed when we compared women by place of residence. Patients born in Lima, the Capital of Peru, smoke more (p<0.05), were heavier, had lower age at menarche, lower number of full term pregnancies and were diagnosed at a younger age, compared to women born outside the city (p<0.05). The distribution of NA genetic ancestry also varied by place of birth: patients born outside Lima had higher proportion of NA ancestry (78% SD=0.15 vs. 74%, SD=0.18, p<0.05).

The distribution of tumor subtypes among women in the Peruvian breast cancer cohort did not differ by place of birth or residence. However, we found that for some breast cancer risk factors, exposures differed between women from different regions. Finally, given the relatively low observed values for reproductive and lifestyle related exposures and the high proportion of Indigenous American ancestry of Peruvian women, this cohort is likely to be particularly informative to study genetic predisposition to breast cancer.

Citation Format: Valentina Zavala, Tatiana Vidaurre, Katie Marker, Jeannie Vásquez, L Tamayo, Renzo Florez, Sandro Casavilca, M Calderon, J Abugattas, H Gómez, H Fuentes, C Monge-Pimentel, S Song, D Cherry, Laura Fejerman. Tumor and risk factor characteristics among breast cancer patients from different geographic regions in Peru [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4184.

Abstract P3-01-07: Comparison of the prognostic value of lymph node ratio versus residual lymph node status in triple negative breast cancer

Background: Triple negative breast cancer (TNBC) patients with residual disease are characterized for a bad outcome. In these patients nodal involvement after neoadjuvant chemotherapy (NAC) is one of the most important prognostic determinants. In this study we compare two prognostic variables based on nodal status, the lymph node ratio (LNR=#positive nodes/#resected nodes) and residual lymph node status (ypN) in TNBC who received NAC.

Methods: We evaluated a retrospective cohort of TNBC patients with residual disease in the lymph nodes (at least 4 resected nodes) and treated with NAC between 2000-2014 at the Instituto Nacional de Enfermedades Neoplasicas (Lima-Peru). Patients were grouped in three LNR groups (≤0.20, 0.20-0.69 and ≥0.70). Survival differences were calculated by the log rank test. Prognostic factors for progression free survival (PFS) and overall survival (OS) were assessed by the Cox regression analysis.

Results: Overall, 189 were evaluated. Mean age was 48y (range: 26-73) where 53.5% were premenopausal and 16.5% had breast/ovary cancer familial background. A total of 175 pts (92.6%) had clinical T3-T4 tumors and 85.2% had nodal involvement at diagnosis. Indeed, the majority of patients had III CS (94.2%). Regarding to the LNR, 48.2% (n=91), 29.6% (n=56) and 22.2% (n=42) (22.2) had LNR ≤0.20, 0.21-0.69 and ≥0.70, respectively. Distribution of clinical differences was similar between groups, except for the clinical N stage (N2-N3: 15.4%, 46.4%, 52,3%, respectively; p<0.001). The median follow-up was 7 years. Progression risk was higher in patients with LNR ≤0.20 than 0.20-0.69 and ≥0.70 (HR=1.77, 95%CI:1.21-2.59, p=0.003 and HR=2.22, 95%CI:1.47-3.35, respectively, p<0.001). It was similar for the risk of death (HR=1.78, 95%CI: 1.17-2.70, p=0.007 and HR=2.95, 95%CI:1.91-4.56, respectively, p<0.001). LNR groups were associated to progression events (P=0.02) in contrast to ypN groups (P=0.07). In the multivariate analysis, pre-menopausal status, a higher LNR and ypT with non-complete response were prognostic factors of worse DFS. Only a higher LNR has a negative impact on OS (table 1).

Conclusion: LNR was an independent prognostic factor for TNBC in patients with residual disease with better capability than ypN to predict progression events. LNR should be considered in the risk stratification after NAC among these patients.

Table 1. Multivariate Cox Regression AnalysisCharacteristicsDFS  OS   HR95%CIp valueHR95%CIp valuePremenopausal status1.931.37-2.73<0.001nsnsnsLNR 0.20 vs 0.21-0.692.011.36-2.970.0011.781.17-2.700.007LNR 0.20 vs 0.701.751.57-3.74<0.0012.921.88-4.55<0.001ypT complete vs partial1.751.13-2.710.012nsnsnsypT complete vs non-response2.041.20-3.480.009nsnsnsns=not significant

Citation Format: De la Cruz-Ku G, Morante Z, Pinto J, Enriquez D, Eyzaguirre E, Saavedra A, Luján M, Luque R, Ramírez M, Araujo J, Fuentes H, Flores C, Moller M, Yakoub D, Neciosup S, Gomez H. Comparison of the prognostic value of lymph node ratio versus residual lymph node status in triple negative breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P3-01-07.

Abstract P3-10-11: Triple negative breast cancer in young Peruvian patients: 15-years' experience in a public hospital

Background: The incidence of breast cancer (BC) is low in young women and is characterized by a high prevalence of triple-negative tumors, representing a group of high risk. In this work, we describe the clinicopathological and epidemiological features of triple-negative breast cancer (TNBC) in patients aged ≤35 years.

Methods: We reviewed information of TNBC patients diagnosed at ≤35 years old and treated at the Instituto Nacional de Enfermedades Neoplasicas (between 2000 and 2014). The Cox proportional hazard model was used to identify prognostics factors for DFS and OS.

Results: In total, of 243 out 2007 cases (12.11%) were very young TNBC patients. The median follow-up was 9 years. The median age was 32 years (range: 19-35); 14.8% had obesity. A total of 40 (16.5%) patients had a family history of breast-ovary cancer (FHBOC). Regarding to the clinical-pathological characteristics, 59.4% presented T-Stages 3/4; 65.2% had nodal involvement and 7 patients (2.9%) had bilateral BC. Most of patients were diagnosed at Clinical Stage (CS) III (50.8%). The most common histological subtype the was ductal invasive carcinoma (92.1%), followed by medullar (4.5%) and lobulillar (1.7%). A high histological grade was frequent (84.7%), while 71 cases (49%) were diagnosed with vascular permeation and 55 (48.2%) with macrometastasis in lymph nodes. The majority of patients underwent mastectomy (60.2%) compared to lumpectomy (39.8%). Locoregional relapse and distant metastasis were reported in 30.9% and 49.4% of cases, respectively. The most frequent sites of metastases were lung (14.8%) and brain (11.5%). In the multivariate analysis, only N3 stage was associated with a poor outcome in terms of (N0 vs N3, HR=7.89, 95%CI:2.76-22.56, p<0.001). Variables associated with the risk of death were N stage (P<0.001 for N0 vs N3), neoadjuvant chemotherapy (P<0.027), adjuvant chemotherapy (P<0.001), and radiotherapy (P=0.008).

Conclusions: TNBC in very young Peruvian women was characterized by advanced stage at diagnosis. In these patients, nodal involvement was the most important prognostic factor for DFS. It presents distinctive characteristics and poorer outcomes in terms of DFS and OS.

Table 1. Multivariate Cox Regression Analysis.CharacteristicsPFS  OS   HR95% CIp valueHR95% CIp valueN0 vs N11.820.74-4.480.191.510.88-2.590.14N0 vs N22.260.69-7.360.183.031.69-5.46<0.001N0 vs N37.892.76-22.56<0.0013.581.83-7.01<0.001Adjuvant chemotherapynsnsns0.340.20-0.55<0.001Neo-Adjuvant Chemotherapynsnsns0.590.37-0.940.027Radiotherapynsnsns0.560.37-0.860.008ns = not significant

Citation Format: Morante Z, De la Cruz-Ku G, Pinto J, Araujo J, Eyzaguirre E, Saavedra A, Lujan M, Enriquez D, Ramirez M, Fuentes H, Neciosup S, Gomez H. Triple negative breast cancer in young Peruvian patients: 15-years' experience in a public hospital [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P3-10-11.

Abstract P1-15-02: Benefit of adjuvant chemotherapy in disease-free survival for T1N0 triple negative breast cancer

Background: Although chemotherapy is not recommended in low-risk early breast cancer, triple-negative breast cancers (TNBC) have twice risk of recurrence despite an aggressive treatment. In this study we evaluated the role of chemotherapy in the outcome of T1N0 TNBC patients in terms of disease-free survival (DFS) and overall survival (OS).

Methods: We evaluated a retrospective cohort T1N0 TNBC patients diagnosed between 2000 to 2014 at the Instituto Nacional de Enfermedades Neoplasicas (Lima-Peru). Survival rates differences were assessed by Log-rank test and prognostic factors were identified using the Cox proportional hazards model.

Results: We identified 123 T1N0 TNBC patients. The median age was 51 years (range: 28-85), where 38.5% were premenopausal. Thirty-six (29.3%) were pT1a/b and 87 were pT1c (70.7%). ACT was administered more frequently in pT1c patients (74.7% vs 55.6%; P=0.036). Locoregional relapse and distant metastases rates were 8.3% vs 19.5% and 5.6% vs 16.1% for tumors pT1a/b and pT1c, respectively. The median of follow-up was 8.8 years. Independent prognostic factors were pT stage and treatment with ACT. In relation to pT stage, DFS rates were 97% vs 78% (at 5-years) and 97% vs 70% (at 8-years) for pT1a/b vs pT1c patients, respectively (HR=4.8; 95%CI:1.46-17.0; P=0.015). In the other hand, patients treated with ACT had a better outcome with DFS rates to 5-years of 86% vs 74% and 8-years of 81% vs 65% (HR: 0.41, 95%CI: 0.17-0.97, p=0.043). Our study had not statistical power to evaluate benefit of ACT in pT1a/b patients. In cases with pT1c tumors, treatment with ACT was the only factor associated with a better DFS (HR=0.29, 95%CI: 0.11-0.77, p=0.012). Because the low mortality in our cohort, OS was not evaluable.

Conclusions: Treatment with adjuvant chemotherapy reduces the recurrence risk in 71% among pT1cN0 TNBC.

Citation Format: Morante Z, De la Cruz-Ku G, Pinto J, Araujo J, Fuentes H, Enriquez D, Luque R, Eyzaguirre E, Saavedra A, Luján M, Neciosup S, Gomez H. Benefit of adjuvant chemotherapy in disease-free survival for T1N0 triple negative breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P1-15-02.

Abstract P6-08-26: Outcomes and prognostic factors in 2000 patients with TNBC: Long-term results covering 10 years

Background: Triple-negative breast cancer (TNBC) is characterized by being a heterogeneous disease with different risk factors and poor survival rates. TNBC have a higher prevalence in the Peruvian population (21.3%) than in Caucasian groups. Our study aims to determine the outcome and identify prognostic factors in Peruvian women with TNBC.

Methods: We retrospectively analyzed TNBC patients treated at the “Instituto Nacional de Enfermedades Neoplasicas” between 2000 and 2014. Survival rates and differences were calculated by the Kaplan-Meier method and Log-rank test, respectively. With the Cox regression, in univariate and multivariate analysis, we identified prognostic factors in for our TNBC population.

Results: In total, 2007 patients were diagnosed.The mean age was 50 years (range: 19-95 years); 44.8% were premenopausal and 26.2% had obesity at diagnosis. A family history of breast and/or ovarian cancer was present in 266 (28.9%) patients. Regarding the clinical-pathological features, 1860 (93.5%) had ductal invasive carcinoma and 1024 (51.6%) patients were in Stage (S) III. Local relapse and distant metastasis affected to 34.5% and 51.4% of our patients, respectively. Lung (14.5%) and bone (9.7%) were the most frequent sites of metastasis. The median follow-up was 9 years. The 5 and 10 yrs DFS/OS rates are shown in table 1. In the multivariate analysis, adjuvant chemotherapy (ACT) (HR: 0.60, 95%CI: 0.44-0.82, p=0.001) and radiotherapy (RT) (HR:0.72, 95%CI:0.55-0.93, p=0.014) were associated with a reduced risk of recurrence, while nodal involvement were associated to a high recurrence risk. Factors associated to a reduction in the risk of death were ACT (HR:0.73, 95%CI:0.61-0.88, p=0.001), RT (HR: 0.70, 95%CI: 0.60-0.92, p<0.001), and Neoadjuvant CT (HR: 0.61, 95%CI: 0.51-0.73, p<0.001); in contrast, a NLR≥3 (HR:1.60,95%CI: 1.36-1.87, p<0.001), N stage were associated with a higher risk of death.

Conclusions: Sociodemographic features of Peruvian patients with TNBC resemble other populations; however, our population is diagnosed at more advanced clinical stages, hence DFS and OS were lower than international reports while prognostic factors were similar to previous studies.

Table 1. 5- and 10-years DFS/OS ratesClinical StageIIIIIIIVTotalp (value)DFS (%)     <0.0015-years837540-63 10-years696429-52 OS (%)     <0.0015-years938239655 10-years837532550 

Citation Format: De la Cruz-Ku G, Morante Z, Pinto J, Enriquez D, Araujos J, Luque R, Eyzaguirre E, Saavedra A, Fuentes H, Neciosup S, Gomez H. Outcomes and prognostic factors in 2000 patients with TNBC: Long-term results covering 10 years [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P6-08-26.

Abstract P6-10-18: Phyllodes tumor of the breast, clinicopathological features and prognostics factors in a retrospective cohort with 7-year follow-up

BACKGROUND: The phyllodes tumor of the breast is a rare neoplasm that represent less than 1% of all breast tumors and between 2.5% of fibroepithelial tumors. Often develop local recurrence and more infrequently metastatic capability. OBJECTIVE: The aim of this study was to describe clinical pathological characteristics and identify prognostics factors in terms of local recurrence-free survival (LRFS), distant metastasis-free survival (DMFS) and overall survival (OS) in patients with phyllodes tumors of the breast.

METHODS: We retrospectively analyzed 157 patients diagnosed and treated at the "Instituto Nacional de Enfermedades Neoplasicas" between January 2005 to December 2010. In order to evaluate the relationship between clinical features and histology of the tumors, the Pearson χ2 test was used. Kaplan-Meier method with Log-rank test or Breslow test (when it was applicable) was used to identify prognostic factors in terms of LRFS, DMFS and OS. RESULTS: The median age was 42 years (range: 13-81 years), 98 (62.4%) cases ≤ 45 years and 59 (37.6%) cases > 45 years; 88 (56.1%) had tumors in the right breast, 67 (42.7%) in the left breast and 2 (1.3%) had bilateral tumor. The mean of tumor size was 6.3 cm (range: 0.7-30 cm). Sixty three (40%) tumors were ≤5 cm and 94 (59.9%) were >5cm. Regarding the histological classification, 100 (63.7%) cases were benign, 35 (22.3%) were borderline and 22 (14%) were malignant. Age (p=0.047), tumor size (p=0.001), atypical stromal (p=0.066), stromal cellularity (p<0.001), pleomorphism (p<0.001) and tumor necrosis (p=0.003) were associated to the histological type. Local recurrence occurred in 9 patients, 2 developed distant recurrence and 1 patient presented synchronously local and metastatic recurrence. In the univariate analysis, histological subtype (p=0.006) and pleomorphism (p<0.001) were identified as prognostic factors of LRFS, while the surgical approach (p=0.008), histological type (p<0.001) and some histological features such as stromal cellularity (P<0.001), pleomorphism (p<0.001), heterologous elements (p<0.001) and tumor necrosis (p=0.004) were identified as prognostic factors for DMFS. In regard to the OS, we found as prognosis factors, histology (p= 0.044), pleomorphism (p<0.001) and tumor necrosis (p=0.001).

CONCLUSIONS: In our institution we have a low incidence (2.3%) of Phyllodes tumors of the breast and the majority of our patients were benign tumors and had good prognosis. We found that histological type and degree of pleomorphism are prognostic factors at LRFS and OS. Surgical approach, histological type and some histological characteristics were predictors for DMFS.

Keywords: Phyllodes tumor, local recurrence, distant recurrence, overall survival.

Citation Format: Morante Z, Araujo J, Fuentes H, Neciosup S, Gomez H. Phyllodes tumor of the breast, clinicopathological features and prognostics factors in a retrospective cohort with 7-year follow-up. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P6-10-18.