Early-onset (<50 years old) colorectal cancer (CRC) has been increasing worldwide and is associated with poor outcomes. Over 85% of the Saudi population are <50 years old, which put them at heightened risk of early-onset CRC. No study assessed the trends in CRC incidence rates among the Saudis. The Joinpoint Regression software by the Surveillance, Epidemiology, and End Results (SEER) program was used to estimate the magnitude and direction of CRC incidence trends by age and gender. The annual percentage change (APC) and the average annual percentage change (AAPC) between 2001 and 2016 were computed. In a sensitivity analysis, we also assessed trends using various age groups. Between 2001 and 2016, the early-onset CRC incidence (per 105) increased from 1.32 (95% CI: 1.11, 1.54) to 2.02 (95% CI: 1.83, 2.22) with AAPC (2.6, 95% CI: -0.4, 5.7). At same period, the late-onset incidence increased from 3.54 (95% CI: 3.10, 3.97) to 9.14 (95% CI: 8.62, 9.66) with AAPC (6.1, 95% CI: 3.5, 8.8). Among early-onset CRC patients, age 40–49 has the highest rates and women in this age group has higher rate than men. Our national data showed a gradual increase in CRC incidence rates, which reflect the global concern of early-onset CRC. Further research is needed to understand the etiology of early-onset CRC. Primary health care providers must be alerted about the increasing rate of early-onset CRC. To reduce the future burden of the disease, initiating CRC screening before age 50 is warranted.

Colorectal cancer (CRC) is the most common cancer in males and third in females in Saudi Arabia, with the majority (66%) diagnosed at a late stage. We evaluated the effect of marital status on stage at diagnosis and CRC survival. We hypothesized that married patients would be more likely to present at an early stage and have higher survival than unmarried patients. The Ministry of National Guard-Health Affairs (MNG-HA) cancer registry was used to identify patients diagnosed with CRC from 2009 to 2017. A competing risk analysis was performed to assess the 5-year CRC-specific survival, adjusting for potential confounders. The Kaplan–Meier method and the Cox regressions were used to assess survival. Two-thirds (76.50%) of the 936 CRC patients were married, 11.64% were unmarried, and 11.86% had an unknown marital status. With multiple imputation-based analysis, the multivariate analysis indicated that unmarried patients were 52% more likely to present at an advanced stage [adjusted odds ratio (aOR) 1.52; 95% CI 1.33–1.73], and had a 30% higher risk of death due to CRC compared to the married patients (aHR 1.30; CI 1.17, 1.44). Future CRC screening and survivorship programs should assess the needs of the vulnerable unmarried population. Interventions supporting the early detection of CRC in this population may be beneficial in the long term and lead to improved cancer outcomes.

e16186 Background: Nivolumab, an immune checkpoint inhibitor, has improved the outcomes of patients with hepatocellular carcinoma (HCC). It is approved for HCC patients previously treated with sorafenib. Outcomes have been reported in previous studies, in malignancies other than HCC, to be worse when patients have been exposed to antibiotics while receiving immune checkpoint inhibitors. We aimed to evaluate the effects of antibiotics on survival in HCC patients treated with nivolumab. Methods: We performed a retrospective review of 59 patients with advanced HCC that have been treated with nivolumab in two academic centers in Saudi Arabia. Patient characteristics, tumor data, antibiotic use (2 weeks prior, during, and 4 weeks after nivolumab therapy), survival data, and other factors were collected. Log-rank test analysis was performed to test the difference in overall survival (OS) time with and without antibiotics use. Results: The majority of patients were males (n=51, 85%), and 38 were Child-Pugh A (64%). A large number of patients had Barcelona Clinic Liver Cancer (BCLC) stage C tumors (n=42, 71%), and 20 patients (34%) used antibiotics. Most patients received nivolumab as second-line therapy after exposure to sorafenib (n=49, 83%). In patients who received nivolumab as first- or second-line therapy (n=57) and did not receive antibiotics, the median OS was double that of patients who received antibiotics (10 vs. 4.5 months, P=0.04). In child A patients who received nivolumab as second-line therapy (n=32), those who were exposed to antibiotics had a statistically significant shorter median OS compared to those who did not (5.5 vs. 20 months, P=0.04). More patients achieved partial response, or complete response (as per modified RECIST criteria) in the cohort that did not receive antibiotics compared to patients who received antibiotics (21% vs. 15%) but that was not statistically significant (P=0.6). Conclusions: This study shows that HCC patients receiving nivolumab have worse survival if they received antibiotics. Antibiotic mediated alteration of the gut microbiome may impact nivolumab response and shorten patient survival. Although this finding may warrant a prospective larger study but it is consistent with other previous studies. Antibiotics should be used very cautiously when treatment with checkpoint inhibitors is considered.

Purpose Hospital readmissions in the first weeks following surgery are common, expensive, and associated with increased mortality among colorectal cancer patients. This study is designed to assess the 30-day hospital readmission after colorectal cancer surgery and evaluate the risk factors that affect hospital readmission. Methods The study uses data from the Ministry of National Guard-Health Affairs Cancer Registry. All colorectal cancer patients who underwent colorectal cancer surgery between January 1, 2016, and November 31, 2021, were investigated. Factors examined were age, gender, marital status, Body Mass Index, Charlson Comorbidity Index, chemotherapy, radiotherapy, tumor stage, grade, site, surgical approach, length of stay, and discharge location. Kaplan–Meier curves were constructed to assess survival rates between readmitted and non-readmitted patients, and logistic regressions were performed to assess predictors of readmission. Results A total of 356 patients underwent tumor resection and 49 patients were readmitted within 30-day of index discharge. The most common reasons for hospital readmissions were gastrointestinal (22.45%), urinary tract infection (16.33%), and surgical site infection (12.24%). In the multivariable analysis, females were 89% more likely to be readmitted compared to males (odds ratio 1.89, 95% confidence intervals 1.00–3.58). Patients with distant metastatic tumors have higher odds of readmission (odds ratio 4.52, 95% confidence intervals 1.39–14.71) compared to patients with localized disease. Conclusions Colorectal cancer readmission is more common in patients with metastatic disease. Strategies to reduce readmission include planned transition to outpatient care, especially among patients with a high risk of readmission.

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Liposarcomas are a group of malignancies that mainly affect adults. Myxoid pleomorphic liposarcoma (MPL) is a newly added subtype of liposarcomas [1]. It is extremely rare and mostly affects infants and children, and it has a predilection for the mediastinum. We report a case of a 58-years-old female with MPL originating from the falciform ligament who presented initially with vague abdominal pain. MPLs have an aggressive pathology and high metastasis and recurrence potential.

Background: Fasting during the holy month of Ramadan is a religious ritual practiced by the majority of Muslims around the globe. This daytime fasting is short-term or intermittent fasting, which may be associated with valuable health benefits, particularly in cancer patients.Methods: A prospective cohort study of pre-and post-fasting evaluation of 37 colorectal cancer (CRC) patients was conducted at King Abdulaziz Medical City (KAMC) and King Abdullah Specialized Children's Hospital (KASCH)-oncology outpatient clinics. The study aimed to assess the impact of fasting during the holy month of Ramadan on the tolerability of chemotherapy side effects and to assess changes in the levels of carcinoembryonic antigen (CEA) and lactate dehydrogenase (LDH) tumor biomarkers, which are primarily associated with certain types of carcinomas, including CRC.Results: A total of 33 patients (89.2%) had fasted at least part of the month of Ramadan. Twenty-seven patients (73%) reported "Serenity" after fasting during Ramadan with improved tolerability of chemotherapy side effects. However, the results did not reveal any significant difference in the measured laboratory variables between pre-fasting values and by the end of the 30 days of Ramadan. Although statistically insignificant, the levels of CEA and LDH were reduced in 46.9% and 55.6% of patients, respectively. The mean level of CEA in the fasting group was substantially reduced by more than 40%, attributed to the highly significant decline of CEA levels in three patients (p=0.0283). Moreover, there were no significant differences between pre-and post-fasting blood creatinine levels or estimated glomerular filtration rates, ruling out any possible adverse effects of fasting on renal function. Conclusion:The current study confirms the safety and tolerability of intermittent fasting in CRC patients actively receiving chemotherapy, which is consistent with several reports. Nonetheless, the results did not reveal a significant decrease in CEA and LDH tumor biomarkers.

Introduction: Molecular Tumor Boards (MTB) are essential in Precision Oncology Programs. Gaps, however, remain in interpreting comprehensive genomic profiling (CGP) results, and determining their actionability. Our MTB, established in October 2020 and conducted at a tertiary cancer center in Saudi Arabia, focused on discussing patients with complex CGP results and recommending genomic based therapies. Meetings occurred virtually, every month, with oncologists, pathologists and genomicists attending. Methods: This is a retrospective cohort study of patients discussed in our MTB from October 2020 till October 2022. We report the outcomes of these patients who had progressive disease on standard of care (SOC) therapies, and have had non Tier 1 alterations (ESCAT classification) in their CGP reports. We chose an FDA approved, commercially available CGP, which tests 324 genes (FoundationOne CDX). We present the demographics, clinical characteristics, CGP results, recommendations of the MTB, and patient outcomes. Results: Sixty patients fitting the criteria above have been discussed. Median number of prior systemic therapy lines was 2 (range 0-8). The most common primary diagnosis was soft tissue sarcoma (25%), followed by liver and pancreato-biliary cancers (20%), followed by head and neck cancers (15%) and skin cancers (8%). Of the 60 patients, 48 patients had response evaluations. Thirty five patients (out of 48, 73%) have had recommendations for genomic based therapies based on their CGP results. Only 16 patients (out of 35, 46%) received MTB recommended therapies. Eight patients (out of 16, 50%) have remained progression free and on MTB recommended genomic therapy for 6 months and above. The commonest reasons for not receiving MTB recommended therapy were patient clinical deterioration or death (9 patients, 47%) followed by patients responding on current line of therapy (7 patients, 37%). Most common pathogenic targetable alterations were CDKN2A/B mutations (6 patients), followed by alterations in FGFR (5 patients), PTEN (4 patients), BRAF (4 patients), PIK3CA (2 patients) and ERBB2 (2 patients) followed by others (will be presented). Conclusion: Following recommendations, of the first MTB in Saudi Arabia, resulted in improved outcomes of cancer patients who had progressive disease on SOC therapies. Consideration of performing CGP and discussing patients early in their cancer journey may allow them to receive, and benefit from recommended genomic therapies earlier. Citation Format: Kanan Alshammari, Fouad Sabatin, Mehlika Hazar-Rethinam, Faizah Alotaibi, Reham Ajina, Hussam Shehata, Mohammad Alkhayyat, Abdullah Alsaleh, Mohammed Algarni. Outcomes of molecular tumor board recommendations for cancer patients with progression on standard of care therapies in Saudi Arabia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 938.