485P - LDCT lung cancer screening of never-smokers meta-analysis subgroup analysis: Adenocarcinoma is the highly predictive histology identified in never-smokers

Background

We demonstrated LDCT lung cancer screening significant improved mortality benefit among Asian never-smokers (NS) compared to ever-smokers (ES). We compared age at diagnosis and characteristics of lung cancer between NS and ES.

Methods

Subgroup analysis were performed from the 14 studies from our previous meta-analysis which included both NS and ES participants and published by April 30, 2021. Our aims were to assess age at lung cancer diagnosis and histology between the 2 groups.

Results

Out of the 14 studies, 4 studies (729 patients/77568 ES, 155 patients/30834 NS) reported age at diagnosis. Eight studies reported histology of lung cancer per patient (5 studies, 207 patients/46,679 ES, 162 cases/35,771 NS) and lung cancer lesion (3 studies, 216 lesions in 192 patients/28898 ES, and 276 lesions in 241 patients/34857NS). Compared to lung cancer in ES, lung cancer in never smokers (LCINS) were diagnosed at younger age though mean year of diagnosis was significantly 1.98 years younger (95% CI -3.38 to – 0.58, I² 0.00%); had a higher proportion of adenocarcinoma (ADC), per patient: 96.58% vs. 69.70% with RR=1.16 (95%CI 0.98 – 1.38, I² 0.00%) and per lesions: 96.81% vs. 68.88% with RR=1.20 (95%CI 1.03 – 1.40, I² 0.00%). Conversely, a lower proportion of squamous cell carcinoma (SqCC), per patient case: 1.37% vs. 16.28% with RR=0.31 (95%CI 0.12 – 0.80, I2 12.41%), and per lung cancer lesions: 0% vs. 14.54% with RR=0.05 (95% CI 0.01 – 0.23, I² 0.00%)). There was a significantly higher RR of ADC over SqCC per patient case: 11.14 (95%CI 2.93 – 42.35, I² 52.10%) among NS vs. 2.49 (95%CI 1.20 – 5.18, I² 69.15%) among ES. The lung cancer lesion ADC/SqCC ratio was also significant per lesion: 73.21 (95%CI 14.83 – 361.54, I²0.00%) among NS vs. 3.01 (95%CI 1.98 – 4.57, I² 22.37%) among ES. Two studies reported 3 interval cancers among 8530 ES and none among 9061 NS.

Conclusions

LCINS is predominantly ADC as expected with frequently seen multifocal adenocarcinoma. LCINS was diagnosed on average about 2 years younger in NS than ES suggesting that the age limit to initiate lung cancer screening in NS may be set lower compared to ES.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

M. Nagasaka: Financial Interests, Personal, Advisory Board: AstraZeneca, Caris Life Sciences, Daiichi Sankyo, Novartis, EMD Serono, Janssen, Lilly, Pfizer, Genentech, Mirati, Regeneron, Silverback; Financial Interests, Personal, Invited Speaker: Takeda, Blueprint; Financial Interests, Personal, Other, Travel: AnHeart. E. Shum: Financial Interests, Personal, Advisory Board: AstraZeneca, Genentech, Boehringer-Ingleheim, Janssen, Regeneron; Financial Interests, Institutional, Funding: Delfi Diagnostics. S.I. Ou: Financial Interests, Personal, Invited Speaker: Pfizer, Roche; Financial Interests, Personal, Advisory Board: JNJ/Janssen, Elevation Oncology, AnHeart Therapeutics; Financial Interests, Personal, Ownership Interest: MBrace Therapeutics, BlossomHill Therapeutics; Financial Interests, Institutional, Local PI: Pfizer, Mirati, JNJ/jassen, Merus, Revolution Medicine, Nuvalent. All other authors have declared no conflicts of interest.