Abstract Background: A meta-analysis of COVID-19 shows that the pooled prevalence of cancer is 1.4%. Febrile illness during COVID-19 is caused by cytokine release syndrome energized by innate inflammatory immune cells, neutrophils, monocytes, and macrophages. Cancer has a worse clinical outcome with COVID-19 due to a potential contribution of the disordered inflammatory microenvironment and immune system. This study aimed to determine the impact of peripheral inflammatory responses on clinical outcome and severity of COVID-19 patients with and without cancer and compare their clinical spectra. Methodology: This IRB-approved, retrospective chart review performed at PNOC included patients 18 years or older with PCR-confirmed COVID-19 from April 2020 to April 2021. Histopathology-confirmed cases identified excluded cranial metastases, pregnancy, or ICU-ineligible due to advanced malignancy or missing data. We collected the first clinical encounter data following a positive COVID-19 test, including CDC-defined COVID-19 symptoms, co-morbidities, cancer status, and treatment—clinical outcomes and death from any cause within30 days of COVID-19 diagnosis. We determined peripheral blood inflammatory cells of neutrophils, lymphocytes, monocytes, platelets and the ratios between lymphocytes and the other three. According to INH guidelines, we ranked clinical severity as presymptomatic, mild, moderate, severe, or critical. Results: Of 3745 people with PCR-confirmed COVID-19, 65 (1.7%) had cancer. We randomly selected 130 non-cancer subjects, homogeneously distributed across each month. The median age was 59 years. Of all, 52.3% were women, 43% were diabetic, 45% were hypertensive, and 35% had the cardiopulmonary disease. Dyspnea occurs in 30.8% of those with cancer but in 59.2% of those without cancer (P < .001). High neutrophil was significantly associated with severity (P = .038), but there was no significant difference between cancer and non-cancer groups. High lymphocytes, MPV, and Neutrophil/Lymphocyte ratio were associated with symptoms but not outcome or severity. Death from any cause was more in the group with cancer 23.1% vs. 6.9%, P= .001. Only 2% of study participants with cancer continued chemotherapy after the diagnosis of COVID-19 was confirmed. Conclusion: Mortality significantly remains higher when cancer is comorbid with COVID-19, as seen in international groups. Further studies are needed to confirm whether cancer immunomodulation is a factor. Peripheral inflammatory response modestly predicts a worse outcome, particularly with elevated neutrophils, known for its proinflammatory rule by polarization and neutrophil extracellular trap (NET) formation with platelet activation. There was a modest increase in symptoms severity in non-cancer COVID19 but more mortality in cancer comorbid COVID-19 Citation Format: Amer N. Radwi, Zahra H. Alshardi, Rakan H. Alelyani, Raha M. Garout, Lojain N. Alruwaili, Muhammad T. Bakhsh. The peripheral proinflammatory responses in COVID-19: Clinical spectrum and outcome in patients with and without cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5273.