<jats:p>The number of oncological patients (OP) admitted to intensive care units (ICU) for sepsis/septic shock has dramatically increased in recent years. The definition of septic shock has been modified, adding hyperlactatemia as a severity biomarker for mortality. However, it remains poorly reported in septic OP. We performed a retrospective analysis from a prospective database of sepsis/septic shock patients admitted to our ICU between September 2017 and September 2019 and followed until day 90. We identified 251 patients and 31.9% had active oncological comorbidity, mainly solid tumor (81.3%). Septic shock criteria were met for 112 (44.6%). Hyperlactatemia was observed in 136 (54.2%) patients and this was associated with a lower survival rate. Overall 90-day mortality was 15.1%. In OP vs. non-OP, hyperlactatemia was more frequent (65% vs. 49.1%, <jats:italic>p</jats:italic> = 0.013) and associated with lower survival (65.4% vs. 85.7%, <jats:italic>p</jats:italic> = 0.046). In OP, poor performance status was also associated with lower survival (HR 7.029 [1.998–24.731], <jats:italic>p</jats:italic> = 0.002) In an adjusted analysis, cancer was associated with lower 90-day survival (HR 2.690 [1.402–5.160], <jats:italic>p</jats:italic> = 0.003). In conclusion, septic OP remains a high mortality risk group in whom lactate levels and performance status could help with better risk stratification.</jats:p>
