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Mahmoud Yousef

Weill Cornell Medical College in Qatar

ORCID: 0009-0007-2550-4837

Publishes on Intraperitoneal and Appendiceal Malignancies, Cancer Genomics and Diagnostics, Pancreatic and Hepatic Oncology Research. 59 papers and 246 citations.

59Publications
246Total Citations

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Top publicationsby citations

Impact of KRAS mutations and co-mutations on clinical outcomes in pancreatic ductal adenocarcinoma
Abdelrahman Yousef, Mahmoud Yousef, Saikat Chowdhury et al.|npj Precision Oncology|2024
Cited by 79Open Access

Abstract The relevance of KRAS mutation alleles to clinical outcome remains inconclusive in pancreatic adenocarcinoma (PDAC). We conducted a retrospective study of 803 patients with PDAC (42% with metastatic disease) at MD Anderson Cancer Center. Overall survival (OS) analysis demonstrated that KRAS mutation status and subtypes were prognostic ( p < 0.001). Relative to patients with KRAS wildtype tumors (median OS 38 months), patients with KRAS G12R had a similar OS (median 34 months), while patients with KRAS Q61 and KRAS G12D mutated tumors had shorter OS (median 20 months [HR: 1.9, 95% CI 1.2–3.0, p = 0.006] and 22 months [HR: 1.7, 95% CI 1.3–2.3, p < 0.001], respectively). There was enrichment of KRAS G12D mutation in metastatic tumors (34% vs 24%, OR: 1.7, 95% CI 1.2–2.4, p = 0.001) and enrichment of KRAS G12R in well and moderately differentiated tumors (14% vs 9%, OR: 1.7, 95% CI 1.05–2.99, p = 0.04). Similar findings were observed in the external validation cohort (PanCAN’s Know Your Tumor® dataset, n = 408).

The relative prevalence of the Omicron variant within SARS-CoV-2 infected cohorts in different countries: A systematic review
Aparajita Sarkar, Sara Omar, Aya Alshareef et al.|Human Vaccines & Immunotherapeutics|2023
Cited by 35Open Access

The Omicron variant of SARS-CoV-2 was detected in October 2021 and exhibited high transmissibility, immune evasion, and reduced severity when compared to the earlier variants. The lesser vaccine effectiveness against Omicron and its reduced severity created vaccination hesitancy among the public. This review compiled data reporting the relative prevalence of Omicron as compared to the early variants to give an insight into the existing variants, which may shape the decisions regarding the targets of the newly developed vaccines. Complied data revealed more than 90% prevalence within the infected cohorts in some countries. The BA.1 subvariant predominated over the BA.2 during the early stages of the Omicron wave. Moreover, BA.4/BA.5 subvariants were detected in South Africa, USA and Italy between October 2021 and April 2022. It is therefore important to develop vaccines that protect against Omicron as well as the early variants, which are known to cause more severe complications.

Serum Tumor Markers and Outcomes in Patients With Appendiceal Adenocarcinoma
Cited by 29Open Access

Importance: Serum tumor markers carcinoembryonic antigen (CEA), carbohydrate antigen 19-9 (CA19-9), and cancer antigen 125 (CA125) have been useful in the management of gastrointestinal and gynecological cancers; however, there is limited information regarding their utility in patients with appendiceal adenocarcinoma. Objective: To assess the association of serum tumor markers (CEA, CA19-9, and CA125) with clinical outcomes and pathologic and molecular features in patients with appendiceal adenocarcinoma. Design, Setting, and Participants: This is a retrospective cohort study at a single tertiary care comprehensive cancer center. The median (IQR) follow-up time was 52 (21-101) months. Software was used to query the MD Anderson internal patient database to identify patients with a diagnosis of appendiceal adenocarcinoma and at least 1 tumor marker measured at MD Anderson between March 2016 and May 2023. Data were analyzed from January to December 2023. Main Outcomes and Measures: Association of serum tumor markers with survival in patients with appendiceal adenocarcinoma. Cox proportional hazards regression analyses were also performed to assess associations between clinical factors (serum tumor marker levels, demographics, and patient and disease characteristics) and patient outcomes (overall survival). Results: A total of 1338 patients with appendiceal adenocarcinoma were included, with a median (range) age at diagnosis of 56.5 (22.3-89.6) years. The majority of the patients had metastatic disease (1080 patients [80.7%]). CEA was elevated in 742 of the patients tested (56%), while CA19-9 and CA125 were elevated in 381 patients (34%) and 312 patients (27%), respectively. Individually, elevation of CEA, CA19-9, or CA125 were associated with worse 5-year survival; elevated vs normal was 81% vs 95% for CEA (hazard ratio [HR], 4.0; 95% CI, 2.9-5.6), 84% vs 92% for CA19-9 (HR, 2.2; 95% CI, 1.4-3.4), and 69% vs 93% for CA125 (HR, 4.6; 95% CI, 2.7-7.8) (P < .001 for all). Quantitative evaluation of tumor markers was associated with outcomes. Patients with highly elevated (top 10th percentile) CEA, CA19-9, or CA125 had markedly worse survival, with 5-year survival rates of 59% for CEA (HR, 9.8; 95% CI, 5.3-18.0), 64% for CA19-9 (HR, 6.0; 95% CI, 3.0-11.7), and 57% for CA125 (HR, 7.6; 95% CI, 3.5-16.5) (P < .001 for all). Although metastatic tumors had higher levels of all tumor markers, when restricting survival analysis to 1080 patients with metastatic disease, elevated CEA, CA19-9, or CA125 were all still associated worse survival (HR for CEA, 3.4; 95% CI, 2.5-4.8; P < .001; HR for CA19-9, 1.8; 95% CI, 1.2-2.7; P = .002; and HR for CA125, 3.9; 95% CI, 2.4-6.4; P < .001). Interestingly, tumor grade was not associated with CEA or CA19-9 level, while CA-125 was slightly higher in high-grade tumors relative to low-grade tumors (mean value, 18.3 vs 15.0; difference, 3.3; 95% CI, 0.9-3.7; P < .001). Multivariable analysis identified an incremental increase in the risk of death with an increase in the number of elevated tumor markers, with an 11-fold increased risk of death in patients with all 3 tumor markers elevated relative to those with none elevated. Somatic mutations in KRAS and GNAS were associated with significantly higher levels of CEA and CA19-9. Conclusions and Relevance: In this retrospective study of serum tumor markers in patients with appendiceal adenocarcinoma, CEA, CA19-9, and CA125 were associated with overall survival in appendiceal adenocarcinoma. Given their value, all 3 biomarkers should be included in the initial workup of patients with a diagnosis of appendiceal adenocarcinoma.

Molecular, Socioeconomic, and Clinical Factors Affecting Racial and Ethnic Disparities in Colorectal Cancer Survival
Cited by 25Open Access

Importance: Disparity in overall survival (OS) and differences in the frequency of driver gene variants by race and ethnicity have been separately observed in patients with colorectal cancer; however, how these differences contribute to survival disparity is unknown. Objective: To quantify the association of molecular, socioeconomic, and clinical covariates with racial and ethnic disparities in overall survival among patients with colorectal cancer. Design, Setting, and Participants: This single-center cohort study was conducted at a tertiary-level cancer center using relevant data on all patients diagnosed with colorectal cancer from January 1, 1973, to March 1, 2023. The relative contribution of variables to the disparity was determined using mediation analysis with sequential multivariate Cox regression models. Main Outcome: OS, from diagnosis date and from start of first-line chemotherapy. Results: The study population of 47 178 patients (median [IQR] age, 57.0 [49-66] years; 20 465 [43.4%] females and 26 713 [56.6%] males; 3.0% Asian, 8.7% Black, 8.8% Hispanic, and 79.4% White individuals) had a median (IQR) follow-up from initial diagnosis of 124 (174) months and OS of 55 (145) months. Compared with White patients, Black patients had worse OS (hazard ratio [HR], 1.16; 95% CI, 1.09-1.24; P <.001), whereas Asian and Hispanic patients had better OS (HR, 0.66; 95% CI, 0.59-0.74; P <.001; and 0.86; 95% CI, 0.81-0.92; P <.001, respectively). When restricted to patients with metastatic disease, the greatest disparity was between Black patients compared with White patients (HR, 1.2; 95% CI, 1.06-1.37; P <.001). Evaluating changes in OS disparity over 20 years showed disparity decreasing among Asian, Hispanic, and White patients, but increasing between Black patients and White patients (HRs, 1.18; 95% CI, 1.07-1.31 for 2008-2012; 1.24, 95% CI, 1.08-1.42 for 2013-2017; and 1.50; 95% CI, 1.20-1.87 for 2018-2023). Survival outcomes for first-line chemotherapy were worse for Black patients compared with White patients (median OS, 18 vs 26 months; HR, 1.30; 95% CI, 1.01-1.70). Among 7628 patients who had clinical molecular testing, APC, KRAS, and PIK3CA showed higher variant frequency in Black patients (false discovery rate [FDR], 0.01; < 0.001; and 0.01, respectively), whereas BRAF and KIT were higher among White patients (FDR, 0.001 and 0.01). Mediation analysis identified neighborhood socioeconomic status as the greatest contributor to OS disparity (29%), followed by molecular characteristics (microsatellite instability status, KRAS variation and BRAF variation, 10%), and tumor sidedness (9%). Conclusions: This single-center cohort study identified substantial OS disparity and differing frequencies of driver gene variations by race and ethnicity. Socioeconomic status had the largest contribution but accounted for less than one-third of the disparity, with substantial contribution from tumor molecular features. Further study of the associations of genetic ancestry and the molecular pathogenesis of colorectal cancer with chemotherapy response is needed.

Mutational and co-mutational landscape of early onset colorectal cancer
Cited by 21Open Access

INTRODUCTION: Colorectal cancer (CRC) incidence and mortality before 50 have been rising alarmingly in the recent decades. METHODS: Using a cohort of 10,000 patients, this study investigates the clinical, mutational, and co-mutational features of CRC in early-onset (EOCRC, < 50 years) compared to late-onset (LOCRC, ≥ 50 years). RESULTS: . CONCLUSION: This study highlights the significance of age-specific molecular profiling, offering insights into the unique biology of EOCRC and potential clinical applications.