METHODS
We retrospectively evaluated the data of 46 patients with metastatic NSCLC (adenocarcinoma) and
EGFR mutation (exon 19 deletion, exon 21 mutation, and exon 18 activating mutation) treated with
EGFR-TKI between 2012 and 2017.
RESULTS
Median age was 61 (range 30-80), and 56.5% (26/46) was female. Median follow-up was 39 months. The
rate of smoking was 41.3% (19/46). The EGFR mutations were present in the patients, exon 19 deletion
in 29 patients (64%), exon 21 mutation in 13 patients (28%) and exon 18 activating mutations in four
patients (8%). Progression-free survival (PFS) was 21 months in smokers, whereas it was 25 months in
non-smokers (p=0.330). Median PFS was 21 months for patients using EGFR TKI in the first-line (35
patients), and 13 months in the second-line setting (11 patients).
CONCLUSION
There were no statistically significant PFS differences between the smoker and non-smoker groups.
Smokers should be tested for EGFR mutations, as some patients may benefit from EGFR TKI treatment
for longer than reported in the literature.
Keywords: Epidermal growth factor receptor; smoking; tyrosine kinase inhibitors
EGFR mutations are more prevalent in certain subpopulations
of patients with NSCLC, such as women,
patients in East Asia, patients with adenocarcinoma histologic types, and non-smokers.[
Treating NSCLC patients having activating EGFR
mutations with tyrosine kinase inhibitor (TKI) significantly
prolongs progression-free survival compared to
standard chemotherapy and is more tolerable.[
Preclinical studies in recent years have shown that
cigarette smoking abnormally activates the EGFR pathway
and that active EGFR cells are resistant to smoking
and EGFR-TKIs.[
Few studies directly focus on the relationship between
EGFR-TKI"s response and cigarette smoking history
in NSCLC EGFR-mutant patients. In this study,
we aimed to evaluate the effects of smoking cessation
on anti-EGFR treatment in the Turkish patient population.
We compared the clinicopathologic features (age,
gender, 1st or 2nd line usage, LDH or CEA levels,
ECOG PS, smoking, weight loss, mutation status) of
smokers and non-smokers, and there was no significant
difference. LDH elevation was found in 63% and
CEA elevation was found in 50% of the patients. Sixty
four percent (n=29) of the patients had exon 19 deletion,
28% (n=13) had exon 21 mutation, and 8% (n=4)
had activating exon 18 mutations (Table
Median PFS was 21 months (2-35) for patients using
Erlotinib in the first-line (35 patients) and 13 months (5-
30) in the second-line setting (11 patients). There were 27 patients with PFS 12 months or more and 19 patients
with less than 12 months. No statistically significant
difference was found for PFS when clinicopathologic
features (age, gender, 1st or 2nd line usage, LDH or CEA
levels, ECOG PS, smoking, weight loss, mutation status)
of these patients were compared (Table
Median overall survival time (mOS) for metastatic
disease was 39 months (range 4-65). The negative effects
of ECOG-PS and weight loss on OS were shown
by univariate analysis and the negative effects of
ECOG-PS in multivariate analysis (Table
Skin toxicity was observed in 18 patients (43%), which resulted in treatment interruption, and the dose was reduced in six patients (14%) due to side effects.
In a meta-analysis of Zhang et al. in 2015, for advanced
NSCLC patients with EGFR mutations, non-smoking
is associated with longer PFS than ever smoking after
EGFR-TKIs treatment. However, there was no difference
in objective response rates (ORR) and disease control rate
(DCR). Smoking-related lung cancer is linked to multiple
carcinogenic mechanisms. EGFR mutation may be
one of the carcinogenic pathways of NSCLC in smokers,
but not a single activated signaling pathway. EGFR-TKI
may be effective for patients with EGFR mutation at the
onset of treatment but cannot block other carcinogenic
pathways induced by cigarette smoking, which may be
due to that ORR and DCR are not different, although
there are short PFSs in smokers.[
A meta-analysis conducted by Mitchell et al. concluded
that smoking and its effect on the EGFR-TKI
response were still not determined because no data
were available on smoking history and relationship to
treatment response.[
There were no statistically significant PFS and OS
differences between the smoker and non-smoker groups
in our study. PFS was 21 months in smokers whereas it
was 25 months in non-smokers. Overall survival was
26 months in the smoker group and 47 months in the
non-smoker group (p=0.475). In our study, the overall
median PFS time was 21 months, whereas median PFS
is 21 months in patients using erlotinib in the first-line
and 13 months in the second-line setting. Our PFS time
results are much longer than the literature.
Our study had some limitations. This study was
performed retrospectively with a limited sample. In addition,
smoking history was only collected at the first
diagnosis and smoking status during treatment was not
followed up.
Peer-review: Externally peer-reviewed. Conflict of Interest: None declared.
Ethics Committee Approval:The authors declare that this research was conducted in accorda
nce with the ethical principles of the Declaration of Helsinki.
Financial Support: Financial support was not received.
Authorship contributions: Concept - Ö.E., T.A.T.; Design - Ö.E.; Supervision - Ö.E.; Funding - Ö.E.; Materials - Ö.E.; Data collection and/or processing - Ö.A., E.T.Ş., R.H.; Data analysis and/or interpretation - Ö.E.; Literature search - N.B., Ö.E.; Writing - S.K., Ö.E.; Critical review - P.F.Y., F.D.