Abstract 1243P
Background
More than half of NSCLC patients (pts) present with metastatic (met) disease. In this study, we explored relationships between histologic/molecular subtypes and met sites in patients who were initially met NSCLC (de novo) vs. those who were diagnosed at earlier stages (I-III) and then later developed met NSCLC (relapsed).
Methods
Clinico-pathologic and follow-up data on all stage IV NSCLC pts, adenocarcinoma non-EGFR+ (EGFR-WT), EGFR+ adenocarcinoma (EGFR+), and squamous cell carcinoma (SCC) seen at Princess Margaret Cancer Centre diagnosed between 2014-2016 were collected retrospectively. Competing risk cumulative incidence rates were compared between histology/mutation groups.
Results
Of 825 pts with met NSCLC, 53% were diagnosed with EGFR-WT, 26% with EGFR+ and 21% with SCC; 77.5% had de novo mets; 22.5% relapsed to become metastatic. Pts with relapsed met disease were more likely to present with a single site of mets (67%) compared to de novo met disease (40%), independent of histology (p<0.001). In relapsed EGFR+ pts, the predominant locations of single site mets were lung (48%) and brain (32%), whereas patterns of recurrence were more widely distributed amongst common met sites (brain, bone, lung, pleura, adrenal) in patients with EGFR-WT and SCC. Patients with de novo stage IV EGFR+ had a significantly higher risk of presenting with multiple met sites (69%) compared to EGFR-WT (59%) and SCC (51%; p=0.007). Cumulative incidence rates of met sites varied significantly according to histologic/molecular subtypes. In pts with EGFR+ disease, brain (p<0.001), lung (p=0.005), pleural (p<0.001), and bone mets (p=0.012) were more commonly observed compared to EGFR-WT or SCC. Distant lymph node mets (p=0.03) were more commonly seen in EGFR-WT compared to EGFR+ and SCC.
Conclusions
NSCLC pts who relapsed to become metastatic more commonly presented with a single site of mets compared to de novo stage IV. Patients with EGFR+ more commonly presented with multiple met sites compared to other NSCLCs, with differences in cumulative incidences rates and met patterns.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
S. Schmid: Financial Interests, Institutional, Advisory Board: BMS; Financial Interests, Institutional, Advisory Board: MSD; Financial Interests, Institutional, Advisory Board: Boehringer Ingelheim; Financial Interests, Institutional, Research Grant: BMS; Financial Interests, Institutional, Research Grant: AstraZeneca; Financial Interests, Personal, Other, Travel Support: Takeda; Financial Interests, Personal, Other, Travel Support: Boehringer Ingelheim; Financial Interests, Personal, Other, Travel Support: MSD. All other authors have declared no conflicts of interest.