Background: Immunodeficiency in patients (pts) with cancer can lead to the progression of common respiratory viral infections to lower respiratory tract disease (LRTD) with potentially high mortality. Understanding risk factors of SARS-CoV-2 related LRTD in pts with cancer is imperative for the development of preventive measures. Methods: We examined all patients aged 18 years or older with cancer and laboratory-confirmed SARS-CoV-2 infection reported between March 16, 2020 and February 6, 2021 in the international CCC19 registry. We examined frequency of LRTD (pneumonia, pneumonitis, acute respiratory distress syndrome, or respiratory failure), demographic and clinicopathologic factors associated with LRTD, and 30-day and overall mortality in pts with and without LRTD. Results: Of 7,289 pts with a median follow-up time of 42 (21-90) days, 2187 (30%) developed LRTD. Pts of older age (65 yrs or older), male sex, pre-existing comorbidities, baseline immunosuppressants, baseline corticosteroids, and ECOG performance status of 2 or more had substantially higher rates of LRTD compared to those without these risk factors (Table). We did not observe differences in LRTD rates between pts of different racial/ethnic groups, smoking history, hypertension, obesity, cancer status, timing or type of anti-cancer therapy. LRTD was more likely in pts with thoracic malignancy (39%), hematological malignancy (39%) compared to those with other solid tumors (27%). The majority of pts (86%) had symptomatic presentation; however, 8% of pts with asymptomatic presentation developed LRTD. 30-day and overall mortality rates were significantly higher in pts with LRTD than those without LRTD (31% vs. 4% and 38% vs. 6%, P < 0.05). Conclusions: COVID-19 related LRTD rate is high and associated with worse mortality rates in pts with cancer. The majority of risk factors associated with LRTD demonstrate underlying immunodeficiency or lung structural damage as a driving force in this population. Identifying pts at high-risk for developing LRTD can help guide clinical management, improve pt outcomes, increase the cost-effectiveness of antiviral therapy, and direct future clinical trial designs for vaccine or antiviral agents.