Background:　Tumor　necrosis　(TN)　is　a　common　feature　in　lung　squamous　cell　carcinoma　(LSCC),　which　could　provide　useful　predictive　and　prognostic　information.Objectives:　This　study　aimed　to　investigate　the　effect　of　pretreatment　pulmonary　TN　(PTN)　on　the　prognosis　of　first-line　anti-programmed　cell　death　1　(PD-1)/PD　ligand　1　(PD-L1)　inhibitor　in　advanced　LSCC.Design:　We　conducted　a　retrospective　study　to　analyze　the　association　between　the　presence　of　PTN　and　clinical　outcomes　in　advanced　LSCC　patients　treated　with　anti-PD-1/PD-L1　inhibitors.Methods:　Data　from　240　eligible　patients　were　collected　from　27　hospitals　across　China　between　2016　and　2020.　The　presence　of　PTN　was　assessed　using　contrast-enhanced　chest　computed　tomography　(CT)　imaging　at　baseline.　We　utilized　the　Cox　proportional-hazards　regression　model　to　analyze　the　association　between　PTN　and　clinical　outcomes.　In　addition,　to　account　for　potential　confounding　factors　and　ensure　comparability　between　groups,　we　employed　propensity　score-matching　(PSM)　analysis.Results:　In　the　overall　patient　cohort,　the　presence　of　PTN　was　39.6%.　The　median　follow-up　duration　was　20.3　months.　The　positive　PTN　group　exhibited　a　notably　inferior　median　progression-free　survival　(PFS;　6.5　months　vs　8.6　months,　p　=　0.012)　compared　to　the　negative　PTN　group.　Within　the　Cox　proportional-hazards　regression　model,　PTN　emerged　as　an　independent　predictor　of　unfavorable　PFS　(hazard　ratio　(HR)　=　1.354,　95%　confidence　interval　(CI):　1.002-1.830,　p　=　0.049).　After　PSM,　the　median　PFS　for　the　positive　PTN　group　(6.5　months　vs　8.0　months,　p　=　0.027)　remained　worse　than　that　of　the　negative　PTN　group.　Multivariate　analyses　also　further　underscored　that　the　presence　of　PTN　independently　posed　a　risk　for　shorter　PFS　(HR　=　1.494,　95%　CI:　1.056-2.112,　p　=　0.023).　However,　no　statistically　significant　difference　in　overall　survival　was　observed　between　the　two　groups.Conclusion:　Our　study　suggests　that　the　presence　of　PTN　on　baseline　contrast-enhanced　chest　CT　is　a　potential　negative　prognostic　imaging　biomarker　for　the　outcome　of　anti-PD-1/PD-L1　inhibitor　therapy　in　advanced　LSCC.　Further　studies　are　warranted　to　validate　these　findings　and　explore　the　underlying　mechanisms.　Predicting　anti-PD-1/PD-L1　inhibitor　treatment　outcomes:　pulmonary　tumor　necrosis　in　lung　squamous　cell　carcinomaOur　study　focused　on　lung　squamous　cell　carcinoma　(LSCC)　patients　receiving　first-line　anti-PD-1/PD-L1　therapy.　We　explored　the　impact　of　a　feature　called　pretreatment　pulmonary　tumor　necrosis　(PTN)　on　their　prognosis.　PTN　was　identified　in　39.6%　of　patients　using　baseline　chest　CT　scans.　Results　revealed　that　patients　with　PTN　had　a　shorter　time　without　disease　progression　(median　PFS　of　6.5　months　compared　to　8.6　months)　and　a　higher　risk　of　unfavorable　outcomes.　This　suggests　that　PTN　may　serve　as　a　negative　prognostic　imaging　marker　for　anti-PD-1/PD-L1　therapy　in　advanced　LSCC.　Further　research　is　needed　to　confirm　and　understand　these　findings　better.