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e20548 Background: Lung cancer has the highest incidence and mortality worldwide. In Brazil, it is the second most common, and individualized therapy, although more efficient than traditional chemotherapy, is still a challenge for health services, especially in developing countries, as socioeconomic disparities make access to genetic testing difficult or treatment. Thus, it is understood that greater knowledge about the genetic profile and therapeutic response of different populations can contribute to policy changes that guarantee expanded access to individualized therapy. Methods: the EGFR gene mutation status was correlated with clinical-epidemiological, socioeconomic, treatment, and survival parameters of patients with lung adenocarcinoma treated from 2014 to 2021 at an oncology referral center in northeastern Brazil. Data were obtained retrospectively from the patient's charts at the Hospital Haroldo Juaçaba/Instituto do Câncer do Ceará. The X²/Fisher and Log-Rank Mantel-Cox tests were used to associate clinical variables and overall survival curves. The Research Ethics Committee approved the research under protocol number 3.544.754. Results: 586 patients tested, 157 (26.8%) had an EGFR mutation, with exon 19 deletion (n = 83, 52.9%). the most frequent followed by L858R (n = 54, 34.4%) and others (n = 30, 12.8%). The EGFR mutation was inversely associated with smoking history (p < 0.001) and previous use of carboplatin plus paclitaxel (p < 0.001). The median overall survival was 33 (95%CI = 25-41) months, and the presence of a mutation was not associated with a worse outcome (p = 0.146). Interestingly, patients with sensitivity mutation who used gefitinib (64.1%) did not show a significant difference in overall survival (p = 0.218). However, when stratifying analyzes according to mutation type, it was observed that patients with exon 19 deletion treated with gefitinib had greater median overall survival (32, 95%CI = 27-37 months) than patients with this mutation not treated with gefitinib (median = 15, 95%CI = 2-25 months) (p < 0.001). Patients with the L858R type sensitivity mutation (p = 0.523) or other mutations (p = 0.439) did not experience significant benefits from gefitinib use. Conclusions: In the population studied, the exon 19 deletion was the most frequent and the only one associated with a substantial benefit from using gefitinib.

e22529 Background: Genetic tests have been increasingly requested to identify families at risk of hereditary cancer. In a family with a known mutation, the offspring of a carrier, whether male or female, have a 50% risk of inheriting the mutation. Most studies on the psychological implications associated with genetic testing have focused on women and few studies have focused on the male population. Methods: A total of 56 men with a personal history of cancer underwent screening for mutations in a panel of 31 genes associated with hereditary cancer. Assessment of quality of life (QoL) and levels of anxiety and depression was performed after patients received the genetic test result. For this, the HADS and WHOQOL-BREF scales were used. Wilcoxon, X², and Spearman correlation tests were used (SPSS v20.0 for Windows). Results: Of the 56 participants, 28.6% had a pathogenic mutation, 32.1% had a Variant of Undetermined Significance (VUS), and 39.3% had no mutation. The presence of the mutation was not associated with QoL (p = 0.967) or anxiety (p = 0.436) or depression (p = 0.945). Mean QoL was 77.95±7.38 (range = 50.00-95.20), mean anxiety was 5.14±2.62 (range = 1-14) and mean depression scores were 4.14±2.55 (range = 0-14). QoL was inversely correlated with levels of anxiety (p < 0.001, r = -0.496) and depression (p < 0.001, r = -0.494), parameters that were directly correlated (p = 0.037, r = 0.279). Most patients had QoL > 80 (n = 38, 67.9%), and only 16 (28.6%) and 13 (23.2%) men had HAD scores > 5. Conclusions: The result of carrying a mutation did not influence the quality of life and anxiety or depression levels in the male population evaluated. However, it was observed that levels of anxiety and depression can compromise the quality of life. The data from the present study reinforce the importance of considering the psychological aspects in the process of genetic investigation for hereditary cancer. In addition, it suggests that educational levels must be investigated to assess whether the low levels of anxiety and depression observed are associated with a low level of understanding of the clinical significance of carrying a pathogenic mutation.

e22528 Background: The familiar history is indispensable to clinical investigation during genetic counseling and the new molecular techniques allowed the identification of hereditary cancer predisposition syndromes (CPS). However, the classification systems of these syndromes are difficulty and very complex. In 2015, the American College of Medical Genetics and Genomics (ACMG) and the Association for Molecular Pathology (AMP) published guidelines for the assessment of variants in genes associated with Mendelian diseases to reduce the subjectivity bias of mutation variants classified as risk. Methods: To show the difficulty of classification of these variants we describe a case report of a family from countryside of Brazil in which there is a high rate of inbreeding. This family has three brothers with polyposis and colorectal cancer between 51 and 60 years-old. Results: The index-case had multiple polyps, developed colorectal cancer at 51 years-old and had a familiar history of two brother dead by colorectal cancer after polyposis and nine brother without familiar history of cancer, a father dead at 38 years-old by non-specific lung-disease and a mother alive at 83 years-old. There was no description of other cases of cancer among uncles and grandparents. The index-case performe a NSG genetic painel to CPS and showed a homozygosis variant in MUTYH gene: NM_001048174.1: c.253T > C:p.(Trp85Arg), that was classified as variant of uncertain significance (VUS). MUTYH is a base excision repair enzyme, it plays a crucial role in the correction of DNA errors and may be considered a cell protective factor and is associated with MUTYH-related polyposis (MAP). MAP is an autosomal recessive CPS and presents a phenotype that overlaps attenuated polyposis and familial adenomatous polyposis, increasing the risk of colorectal cancer in 43-63% up to 60 years or 80% if there is no surveillance/tracking. In view of the family history that suggests autosomal recessive inheritance, with a homozygous variant absent in the database of population controls (gnomAD) and in which in silico predictors indicate the effect of this variant as deleterious, the management of this family must be carried out considering it as a potential high-risk pathogenic variant. Conclusions: While the classification criteria for the variants are being refined, we reinforce the importance of a careful family history in the approach to CPS in order to offer an appropriate clinal conduct in the prevention of hereditary cancer.

e13670 Background: Loss-of-function mutations in PALB2 gene are associated with increased risk for breast cancer and possibly pancreatic, ovarian, male breast, prostate, colorectal as others cancers. In Brazil it has been estimated that up to 1,516 new cases of hereditary breast cancer for 2020 in the North and Northeast regions. Analysis of susceptibility gene mutations helps identify precisely the high-risk patient and their families, whom need specific and personalized clinical management as high-risk individuals. Methods: Twenty-six patients with pathogenic mutations in PALB2 gene identify by next-generation sequencing from states of Bahia (11), Ceará (9), Pernambuco (5) and Rondônia (1) in the North and Northeast regions were analyzed. Results: Most of the patients analyzed had only breast cancer (80%), including two cases of male breast cancer (9,5%); the others were isolated cases of endometrial cancer (4%), breast and pancreas cancers (4%), breast and lung cancers (4%), only ovarian cancer (4%) and ovarian and breast cancers (4%). Most cancers were stage II or III (65%). Family history of cancer was observed in 22/26 (84%); the most common tumors were breast, prostate, pancreas and thyroid. The founder mutations were more frequent in exons: 4 (58%) and 12 (15%). Eleven variants were found as follow: c.1240C > T (19%); c.3256delC (15%); c.1671_1674delTATT (11.5%); c.355delC (11.5%); NC_000016.9:g.(?_23632673)_(23652488_?)del (11,5%). The greatest variety of mutations was found in the state of Bahia, probably due to the greater number of patients included (42%). Conclusions: These data suggest that changes in clinical management of PALB2 patients are needed since the phenotype observed exhibited pattern of hereditary tumors, including male breast cancer. Besides that, PALB2 gene should be included in painel gene analysis in patients from the North and Northeast of Brazil because its high frequency of pathogenic variants.

e13532 Background: The Lynch syndrome (LS) is the most common inherited syndrome associated with colorectal cancer (CRC). The hallmark of LS is DNA mismatch repair deficiency. The amount of variants of uncertain significance (VUS) in suspected LS confounds diagnosis, requiring surveillance of variant reclassifications. In this paper we describe a new and most likely pathogenic VUS in PMS2. Methods: Patient screened for personal and familial cancer and evaluated with NGS gene panels for 31 genes. The protein structure was analyzed with the software Pymol. Results: A woman diagnosed with breast cancer (BC) at 60 years and CRC at 65 years was investigated due to her extensive family history of cancer (21 maternal relatives), including 6/9 siblings [gastric n = 1, lung n = 1, BC n = 4 (one of whom with BC, endometrium and CRC)], 8/12 aunts and uncles, all of whom died of cancer (gastric n = 4, CRC n = 1, CNS n = 1, BC n = 1; uterus/gallbladder n = 1), and 7 cousins (CNS n = 3, lung n = 1, gastric n = 2, suspected ovary n = 1). The new PMS2 gene variant c.134A > G(p.Asn45Ser), which was also detected in two sisters with CRC submitted to segregation analysis, occupied the same locus as a known pathogenic variant, c.134A > C(p.Asn45Thr). The structural analysis showed that the mutated locus encodes a serine instead of an asparagine in position 45 at the enzyme’s active site. Asn 45 is a conserved amino acid that binds to ATP in protein structure (PDB = 1EA6). Interestingly, this is close to position 42-44, for which another potentially pathogenic VUS (p.Leu42_Glu44del) has been described. Conclusions: Based on our patient’s personal and family history and on the locus variant and protein structure analysis, the new PMS2 gene variant described in this paper is most likely pathogenic.

e13603 Background: Identifying carriers of hereditary cancer predisposition syndromes (HCPS) improves prevention and treatment. However, due to the elevated cost of genetic testing, information on the prevalence and incidence of HCPS is scarce, depriving patients of assertive treatment―a scenario observed worldwide, especially in regions like Northeastern Brazil. In this study, we determined the prevalence of hereditary breast and ovarian cancer (HBOC) in patients from Ceará (Brazil) based on NCCN criteria. Methods: The patients (n = 267) were evaluated using NGS gene panels, while retrospective data were analyzed statistically with the chi-squared test, Fisher’s test and multinomial logistic regressions ( p< 0.05; SPSS 20.0). Results: BRCA1/2 was detected in 21.3% (57/267) of the sample, but BRCA1 was more prevalent than BRCA2 (70%; 40/57 vs 30%; 17/57) ( p< 0.001). Having two or more primary tumors ( p= 0.031) or primary ovarian cancer ( p= 0.029) was associated with the pathogenic mutation BRCA1/2. The latter was detected in patients with bilateral tumors (40%) and male breast cancer (45%), and in patients under 45 years (67%), with familial breast cancer (27%) and familial ovarian cancer (41%). In the multivariate analysis, the triple-negative phenotype was strongly associated with mutated BRCA1/2 ( p= 0.003). Conclusions: The prevalence of HBOC in our sample is compatible with rates reported worldwide. The study variables (bilaterality, male sex, age < 45 years, family history of breast or ovarian cancer, and triple-negative phenotype) reinforce the diagnostic criteria published by the NCCN.

e13602 Background: Breast cancer (BC) is associated with several hereditary syndromes (HS). Patients with clinical criteria for hereditary breast and ovarian cancer (HBOC) should be evaluated for the presence of pathogenic BRCA1/2 variants, although the absence of BRCA1/2 variants does not rule out HS. The purpose of this study was to evaluate the prevalence of pathogenic non- BRCA1/2 variants in patients with suspected HBOC. Methods: Suspected HBOC (NCCN criteria) patients (n = 267) from a Northeastern Brazilian referral cancer hospital were submitted to NGS 31-gene painel. Individuals testing negative for BRCA1/2 mutation (n = 210) remained in the present presentation. Data were analized by the chi-squared test and Fisher’s test ( p< 0.05; SPSS 20.0). Results: Pathogenic/likely pathogenic (P/LP) non- BRCA1/2 variants were detected in 13.3% (n = 28/210) of the patients, all of whom had BC. The most prevalent variant was PALB2 (31%), followed by ATM and MUTYH (14.2%), and TP53 and PMS2 (10.7%). Among these patients 10.7% (n = 3/28) had triple negative tumors. Other gene variants ( BARD1, CHEK2, MLH1, MSH2, PMS1 and XRCC2) were observed at lower frequencies (3.5% each). DNA mismatch repair (MMR)/Lynch syndrome (LS) mutated genes were identified in 4/24 patients with BC. Rare microdeletions were identified in PALB2 (chr16:23652431-23652678 [exons 1-10] and TP53 (chr17:7.573.927-7.579.891 [exons 2-10]) , to our knowledge for the first time in the medical literature (ClinVar). In addition, one patient displayed a double pathogenic variant in ATM (c.67C > T: p.[Arg23*]) and PALB2 (chr16:23652431-23652678 [exons 1-10]). Patients with and without P/LP did not differ with regard to clinical-pathological parameters or therapeutic profile. Conclusions: Patients with suspected HBOC should be evaluated for non- BRCA1/2 variants, including MMR. We also suggest considering BC among the malignancies associated with LS.