59 Background: Over the last decades the incidence of EOCRC (age 50 or less) has dramatically increased, and so has the scientific interest in this field, given that clinical and molecular characteristics in these patients are not well understood, and may be critical to identify prognostic factors. Methods: We conducted a retrospective analysis of 554 patients with metastatic colorectal cancer (mCRC), analyzing the PFS and OS of 68 (12.25%) patients with EOCRC, as well as their clinical and molecular characteristics. We used a log-rank test to compare PFS and OS, and the estimate of hazard ratio (HR) between the studied groups was calculated by means of Cox proportional hazard model. We also used the exact test of Fisher to identify significant association between categoric variants, while Mann-Whitney test was applied to identify significant differences between numeric values. Results: We performed a survival analysis: those patients with EOCRC had significantly higher median PFS in first line of treatment (16.2 vs. 11.3 months, p = 0.042) and significantly higher median OS (121.5 vs. 58.1 months, p = 0.011). Several characteristics were significantly more frequent in patients with EOCRC (n=68): BMI < 18.5 (n = 16, OR = 1.9, p = 0.046), primary tumor site at transverse colon (n = 9, OR = 2.61, p = 0.03) and ECOG 0 (n = 32, OR = 2.21, p = 0.003). Having peritoneal metastases almost reached statistical signification (n = 17, OR = 1.82, p = 0.055). Some other characteristics were less frequent: BMI 25-30 (n = 13, OR = 0.51, p = 0.046), primary tumor site at sigmoid colon (n = 14, OR = 0.49, p = 0.038) and former-smoker status (n = 7, OR = 0.44, p = 0.048). Moreover, mean values of LDH at diagnosis were significantly higher in EOCRC patients (359 U/L vs. 280 U/L, p = 0.015). EOCRC patients received a significantly higher number of lines of chemotherapy (2.94 vs. 2.38, p = 0.027) and underwent more surgeries (2,42 vs. 1.24, p < 0,001) than patients with > 50 years. Significant differences in tumor mutational status (BRAF, KRAS, NRAS, MSI, PI3K and HER2), sex, primary tumor resection or number of metastatic sites between groups were not found. Conclusions: This retrospective analysis showed that EOCRC patients had significant higher rates of PFS in first-line treatment and OS. Moreover, EOCRC patients had more frequently BMI < 18.5, primary tumor located at transverse colon and ECOG 0.

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We present the case of a 38-year-old female who, in the context of a 22-week gestation, attended the hospital due to epigastric pain and hematemesis. She underwent gastroscopy (Fig. 1A), which revealed two ulcers with a neoplastic aspect in the gastric body, and the biopsy confirmed the finding of diffuse gastric adenocarcinoma. Considering the patient's desire to continue with her pregnancy, the tumor was staged by thoracic computed tomography (CT), endoscopic ultrasound (EUS) (Fig. 1B) and abdominal and pelvic magnetic resonance imaging (MRI) (Fig. 1C).One month later, a cesarean section was performed, followed by FLOT induction cytostatic treatment (a combination based on fluoropyrimidines, platinum salts and taxanes); after four cycles, the patient underwent Roux-en-Y total gastrectomy. The anatomopathological finding, ypT3ypN3b, reflected the poor response of the tumor to chemotherapy, and foreshadowed the poor outcome of the young mother.

e15552 Background: BRAF mutated mCRC patients have worse prognosis compared with BRAF wildtype mCRC. Within this group, those with resectable disease have a better prognosis compared to those with unresectable disease. However, it is not well known whether there are clinical differences that may help clinicians to identify this subgroup of patients. Methods: We conducted a retrospective analysis of 24 patients with BRAF mutated mCRC, describing their clinical characteristics and the differences between those who have undergone metastatic surgery (n = 18) versus those who have not (n = 6). We applied the exact test of Fisher to identify significant association between categoric variables, while we used Mann-Whitney test to identify significant differences between quantitative variables. PFS and OS were compared using a long-rank test, and the estimate of hazard ratio (HRs) between studied groups was calculated by means of Cox proportional hazards model. Results: Twenty-four patients with BRAF mutated mCRC have been identified. 58% (n = 14) of them were < 65 years old; 54% (n = 13) had BMI > 25, and all of them had a good PS at diagnosis (0 or 1). The most frequent tumor location was the right colon (58%; n = 14) and in 79% (n = 19) of the cases the primary tumor was resected. Most of the patients presented peritoneal (41%, n = 10) or liver (41%, n = 10) disease, and 70% of them (n = 17) had synchronous disease. Within the 18 patients who underwent surgery, the most frequent surgery was liver metastasectomy (50%, n = 9) followed by peritoneal metastasectomy (28%, n = 5). Regarding first-line chemotherapy treatment, only 12% (n = 3) presented disease progression in the first reassessment. No statistically significant differences were found between surgical and non-surgical patients regarding the following variables: age, BMI, ECOG, primary tumor side, location of the metastases, synchronous presentation of the metastatic disease, analytical parameters (CEA, Ca 19.9 and LDH), response to chemotherapy treatment and first line progression-free survival. However, we found significant differences in overall survival with an HR for mortality of 0.22 (95% CI 0.049-0.99; p = 0.031) in patients undergoing metastases surgery, with a median of 38 months in patients who underwent surgery vs 20 months in those who did not. Conclusions: BRAF mutated mCRC who receive surgery for metastases have better prognosis with higher overall survival, compared to those who have not undergone surgery. Still, no other statistically significant differences were found in the rest of the clinical characteristics analyzed to identify a subgroup with better prognosis.