Cellular senescence is associated with the spatial evolution toward a higher metastatic phenotype in colorectal cancer

In this study, we explore the dynamic process of colorectal cancer progression, emphasizing the evolution toward a more metastatic phenotype. The term "evolution" as used in this study specifically denotes the phenotypic transition toward a higher metastatic potency from well-formed glandular structures to collective invasion, ultimately resulting in the development of cancer cell buddings at the invasive front. Our findings highlight the spatial correlation of this evolution with tumor cell senescence, revealing distinct types of senescent tumor cells (types I and II) that play different roles in the overall cancer progression. Type I senescent tumor cells (p16INK4A+/CXCL12+/LAMC2-/MMP7-) are identified in the collective invasion region, whereas type II senescent tumor cells (p16INK4A+/CXCL12+/LAMC2+/MMP7+), representing the final evolved form, are prominently located in the partial-EMT region. Importantly, type II senescent tumor cells associate with local invasion and lymph node metastasis in colorectal cancer, potentially affecting patient prognosis.

Differential efficacy of tyrosine kinase inhibitors according to the types of EGFR mutations and agents in non-small cell lung cancer: a real-world study

BACKGROUND

Both first and second-generation EGFR-TKIs are recommended in advanced NSCLC with common EGFR mutations. However, there are few data on the difference in efficacy of EGFR-TKIs based on the type of EGFR mutation and agents.

METHODS

This retrospective real-world study evaluated the outcomes and clinicopathologic characteristics, including the type of EGFR mutations, of 237 advanced NSCLC patients treated with first- or second-generation (afatinib) EGFR-TKIs as first-line therapy.

RESULTS

The median progression-free survival (PFS) and overall survival (OS) of all patients were 11 months (M) and 25M, respectively. In the univariate analysis, patients with exon 19 deletion (del) (n=130) had significantly longer median OS compared to those with other mutations (L858R: 84, others: 23) (30 vs. 22 M, p=0.047), without a difference in PFS (p=0.138). Patients treated with afatinib (n=60) showed significantly longer median OS compared to those treated with first-generation TKIs (gefitinib: 159, erlotinib: 18) (30 vs. 23 M, p=0.037), without a difference in PFS (p=0.179). In patients with exon 19 del, there was no significant difference in median PFS (p=0.868) or OS (p=0.361) between patients treated with afatinib and those treated with first-generation TKIs, while significantly better PFS (p=0.042) and trend in OS (p=0.069) were observed in patients receiving afatinib in other mutations. Exon 19 del was independently associated with favorable OS (p=0.028), while age >70 years (p=0.017), ECOG performance status ≥2 (p=0.001), primary metastatic disease (p=0.007), and synchronous brain metastasis (p=0.026) were independent prognostic factors of poor OS.

CONCLUSIONS

The EGFR exon 19 del was associated with favorable OS in advanced NSCLC patients receiving first-line EGFR-TKIs. Moreover, in patients with exon 19 del, first-generation TKIs seem to be a reasonable treatment option if osimertinib is unavailable.

CDK4/6 inhibitors induce breast cancer senescence with enhanced anti-tumor immunogenic properties compared with DNA-damaging agents

Since therapy-induced senescence (TIS) can either support or inhibit cancer progression, identifying which types of chemotherapeutic agents can produce the strongest anti-tumor TIS is an important issue. Here, cyclin-dependent kinase4/6 inhibitors (CDK4/6i)-induced senescence was compared to the TIS induced by conventional DNA-damaging agents. Despite both types of agents eliciting a similar degree of senescence, we observed increased expression of the senescence-associated secretory phenotype (SASP) and ligands related to pro-tumor immunity (IL6, CXCL8, TGFβ, CD274, and CEACAM1) and angiogenesis (VEGFA) mainly in TIS induced by DNA-damaging agents rather than by CDK4/6i. Additionally, although all agents increased the expression of anti-tumor immunomodulatory proteins related to antigen presentation (MHC-I, B2M) and T cell chemokines (CXCL9, 10, 11), CDK4/6i-induced senescent cells still maintained this expression at a similar or even higher intensity than cells treated with DNA-damaging agents, despite the absence of nuclear factor-kappa-B (NF-κB) and p53 activation. These data suggest that in contrast with DNA-damaging agents, which augment the pro-tumorigenic microenvironment via pro-inflammatory SASP, CDK4/6i can generate TIS only with antitumor immunomodulatory proteins.

Thromboembolic events in patients who received adjuvant chemotherapy for gastric cancer: a single-center retrospective study

BACKGROUND

Thromboembolic events (TEEs) are significant adverse events that can cause serious morbidities and mortality in cancer patients receiving chemotherapy. Patients with gastric cancer (GC) treated with palliative chemotherapy have been reported to experience a TEE incidence of 5-27%. However, very few reports have addressed TEEs in adjuvant chemotherapy (AC) for GC.

METHODS

This study retrospectively analyzed 611 GC patients (stage II: 309, III: 302) who started AC with capecitabine/oxaliplatin (167 patients) or S-1 (444 patients) after undergoing curative resection between January 2013 and June 2020 at a single center. The incidence of TEEs during AC or within 1 year after AC completion was investigated, while analyzing the factors that influenced the TEEs' occurrence.

RESULTS

TEEs were confirmed in 20 patients (3.3%), and TEEs occurred in almost all patients in the S-1 group (19 patients). The most common TEE types were cerebral infarction and pulmonary thromboembolism (five patients each). Although old age (≥ 70 years, p < 0.0001), S-1 treatment (p = 0.021), and hypertension (p = 0.017) were identified as significant risk factors for TEEs in univariate analysis, only old age showed a statistically significant correlation with TEEs' occurrence in multivariate analysis (odds ratio: 3.07; 95% confidence interval 1.11-8.48; p = 0.031).

CONCLUSIONS

TEEs occurred in fewer patients with GC who had been treated with AC than patients who had received palliative chemotherapy in previous reports. However, elderly GC patients who are undergoing AC require more careful surveillance for possible TEEs, considering relatively higher incidence of them.

Pericardial diverticulum arising from the right lateral superior aortic recess: a mimicker of cystic anterior mediastinal mass

AIM

To report the prevalence of pericardial diverticulum of the right lateral superior aortic recess (RSAR) on computed tomography (CT), to analyse the structural CT findings of whether or not the structure is large enough to be seen on chest radiographs, and to describe changes in size and shape of RSAR on follow-up CT.

MATERIALS AND METHODS

A well-circumscribed, fluid-attenuation lesion in the anterior mediastinum with the following CT features was defined as a pericardial diverticulum of the RSAR: no enhancing wall, communication with the RSAR, abutment to the heart with an acute angle, and moulding by adjacent structures. Chest CT images of 31 patients with the diverticulum were evaluated, including four selected from 1,130 consecutive patients (0.4%).

RESULTS

The diverticulum projected ventrally from the RSAR and its largest size on axial CT ranged between 12-56 mm. Although the RSAR and the largest diverticular portion were usually seen on the same axial image (n=19), the latter sometimes lay above (n=1) or below (n=11) the former. On sagittal images, the last 11 diverticula resembled teardrops hanging from the RSAR by small stems. All of the 24 patients, each with 1-31 follow-up CT examinations, showed size fluctuations ranging between 1-46 mm (mean, 16 mm) during a follow-up period of 0.5-172 months (mean, 65 months). The diverticulum was not identifiable in five cases and was identifiable but did not show a connection with the RSAR in three cases when the diverticulum was smallest in size.

CONCLUSIONS

In cases of cystic anterior mediastinal mass, a deliberate search for its connection with the RSAR on all available CT images including previous studies is necessary for the diagnosis of pericardial diverticulum of the RSAR.

p15INK4B is an alternative marker of senescent tumor cells in colorectal cancer

Senescent tumor cells are nonproliferating tumor cells which are closely related to cancer progression by secreting senescence-related molecules, called senescence-associated secreting phenotypes. Therefore, the presence of senescent tumor cells is considered a prognostic factor in various cancer types. Although senescence-associated β-galactosidase staining is considered the best marker for detection of senescent tumor cells, it can only be performed in fresh-frozen tissues. p16^INK4A, a cyclin-dependent inhibitor, has been used as an alternative marker to detect senescent tumor cells in formalin-fixed paraffin-embedded tissues. However, other reliable markers to detect senescent tumor cells is still lacking. In the present study, using public single-cell RNA-sequencing data, we found that p15^INK4B, a cyclin-dependent kinase inhibitor, is a novel marker for detection of senescent tumor cells. Moreover, p15^INK4B expression was positively correlated with that of p16^INK4A in colorectal cancer tissues. In in vitro studies, mRNA expression of p15^INK4B was increased together with that of p16^INK4A in H₂O₂- and therapy-induced cancer senescence models. However, the mRNA level of p15^INK4B did not increase in the oncogene-induced senescence model in primary colonic epithelial cells. In conclusion, p15^INK4B is a potential alternative marker for detection of senescent tumor cells together with conventional markers in advanced stages of colorectal cancer.

Analysis of treatment outcomes according to the cycles of adjuvant chemotherapy in gastric cancer: a retrospective nationwide cohort study

Background

One-year S-1 or six-month capecitabine/oxaliplatin (CAPOX) has been the standard adjuvant chemotherapy for gastric cancer (GC). We investigated outcomes according to the cycles of adjuvant chemotherapy, using data from the Korean Health Insurance and Assessment Service.

Methods

A total of 20,552 patients, including 13,614 patients who received S-1 and 6,938 patients who received CAPOX extracted from 558,442 patients were retrospectively analyzed. The five-year overall survival rate was evaluated according to the duration of adjuvant chemotherapy.

Results

The five-year overall survival rate gradually increased according to the increase in adjuvant chemotherapy cycles in both the S-1 (≤ 5 cycles: 48.4%, hazard ratio [HR] 4.06, 95% confidence interval [CI] 3.74–4.40, P < 0.0001; 5 < cycles ≤ 6: 55.4%, HR 3.08, 95% CI 2.65–3.57, P < 0.0001; 6 < cycles ≤ 7: 64.1%, HR 2.11, 95% CI 1.84–2.41, P < 0.0001; 7 < cycles < 8: 71.1%, HR 1.60, 95% CI 1.39–1.84, P < 0.0001; ≥ 8 cycles: 77.9%) and the CAPOX groups (≤ 4 cycles: 43.5%, HR 3.20, 95% CI 2.84–3.61, P < 0.0001; 5 cycles: 45.3%, HR 2.63, 95% CI 2.11–3.27, P < 0.0001; 6 cycles: 47.1%, HR 2.09, 95% CI 1.76–2.49, P < 0.0001; 7 cycles: 55.3%, HR 1.63, 95% CI 1.35–1.96, P < 0.0001; ≥ 8 cycles: 67.2%).

Conclusions

Reducing the treatment cycles of adjuvant chemotherapy in GC with S-1 or CAPOX showed inferior survival outcomes. Completing the standard duration of adjuvant chemotherapy with S-1 or CAPOX would be strongly recommended.

Analysis of thromboembolic events in head and neck cancer patients who underwent concurrent chemoradiotherapy with cisplatin

BACKGROUND/AIMS

The study investigated the incidence of thromboembolic events (TEE) in head and neck (H&N) cancer patients who received concurrent chemoradiotherapy (CCRT) with cisplatin, and analyzed the factors affecting TEE occurrence.

METHODS

Two hundred and fifty-seven patients who started CCRT with cisplatin for H&N cancer from January 2005 to December 2019 were analyzed.

RESULTS

TEE occurred in five patients, an incidence rate of 1.9%. The 2-, 4-, and 6-month cumulative incidences of TEE were 0.8%, 1.6%, and 1.9%, respectively. Khorana score was the only factor associated with TEE occurrence (p = 0.010).

CONCLUSION

The incidence of TEE in H&N cancer patients who underwent CCRT with cisplatin was relatively low when compared to other types of cancer. However, patients with a high Khorana score require more careful surveillance for possible TEE occurrence.

The efficacy of EGFR-tyrosine kinase inhibitor in non-small cell lung cancer patients with synchronous brain metastasis: a real-world study

BACKGROUND/AIMS

The optimal treatment (Tx) for epidermal growth factor receptor (EGFR)-mutant non-small cell lung cancer (NSCLC) patients with brain metastasis (BM) remains to be determined.

METHODS

A retrospective review was conducted on 77 NSCLC patients with synchronous BM who underwent first-line EGFR-tyrosine kinase inhibitor (TKI) Tx. The outcomes of patients were analyzed according to the clinicopathological characteristics including local Tx modalities.

RESULTS

Fifty-nine patients underwent local Tx for BM (gamma knife surgery [GKS], 37; whole brain radiotherapy [WBRT], 18; others, four) concurrently or sequentially with EGFR-TKI. Patients treated with TKI alone showed significantly lower incidence of central nervous system (CNS) symptoms. The median progression-free survival (PFS) and overall survival (OS) after the initiation of EGFR-TKI for all patients were 9 and 19 months, respectively. In 60 patients with follow-up brain imaging, the median time to CNS progression was 15 months. Patients with EGFR exon 19 deletion had a significantly longer median OS than those with other mutations including L858R (23 months vs. 17 months). Other clinical characteristics, including CNS symptoms, number of BM, and the use of local Tx were not associated with OS, as well as PFS. In terms of the local optimal Tx modality, no difference was found between GKS and WBRT in the OS and PFS.

CONCLUSION

This study suggests that EGFR-TKI may result in a favorable outcome in NSCLC patients with synchronous BM, especially in deletion 19 mutant, regardless of the extent of BM lesions or local Tx modalities. Patients with asymptomatic BM can be treated with EGFR-TKI and careful surveillance.

The chromatin remodeler RSF1 coordinates epigenetic marks for transcriptional repression and DSB repair

DNA lesions impact on local transcription and the damage-induced transcriptional repression facilitates efficient DNA repair. However, how chromatin dynamics cooperates with these two events remained largely unknown. We here show that histone H2A acetylation at K118 is enriched in transcriptionally active regions. Under DNA damage, the RSF1 chromatin remodeling factor recruits HDAC1 to DSB sites. The RSF1-HDAC1 complex induces the deacetylation of H2A(X)-K118 and its deacetylation is indispensable for the ubiquitination of histone H2A at K119. Accordingly, the acetylation mimetic H2A-K118Q suppressed the H2A-K119ub level, perturbing the transcriptional repression at DNA lesions. Intriguingly, deacetylation of H2AX at K118 also licenses the propagation of γH2AX and recruitment of MDC1. Consequently, the H2AX-K118Q limits DNA repair. Together, the RSF1-HDAC1 complex controls the traffic of the DNA damage response and transcription simultaneously in transcriptionally active chromatins. The interplay between chromatin remodelers and histone modifiers highlights the importance of chromatin versatility in the maintenance of genome integrity.

Early removal of central venous catheter may not impact the in-hospital mortality in patients with acute leukemia

Central venous catheters (CVCs) are generally required for chemotherapy in patients with acute leukemia, but catheter-related infection is one of the common causes of neutropenic fever. We investigated the in-hospital mortality according to early removal of CVCs and the factors influencing the mortality in patients with acute leukemia undergoing remission induction chemotherapy. This study retrospectively analyzed the hospital record data of 278 patients with acute leukemia treated with non-tunneled CVCs and remission induction chemotherapy in a single institution. Bloodstream infection was more common (p < 0.0001) and median peak C-reactive protein (CRP) levels after neutropenic fever were significantly higher (23.3 vs. 14.5 mg/dl, p = 0.003) in the group with early removal than in the group with maintenance of the CVC. Multivariate analysis of the patients revealed a significant decrease in the mortality with female gender (odds ratio (OR): 0.19, 95% confidence interval (CI): 0.06-0.54, p = 0.002) and a significant increase in the mortality according to the peak CRP (OR 1.12, 95% CI: 1.07-1.17, p < 0.0001). By contrast, early removal of the CVC had no significant effect on the mortality (OR = 1.16, 95% CI: 0.54-2.47, p = 0.706) in univariate analysis. Furthermore, subsequent bloodstream infection after clinical decision for maintenance or early removal of the CVC was confirmed more frequently in the group with early removal (early removal, 22.6%; maintenance, 7.6%, p < 0.0001). Early removal of the CVC had no benefit regarding the mortality and prophylaxis of bloodstream infection in patients with acute leukemia undergoing remission induction chemotherapy. Therefore, maintaining a CVC for as long as possible may be considered, if catheter-related bloodstream infection is not strongly suspected.

Clinical Benefits of Oral Anticoagulant Use in Cancer Patients at Increased Risk for Venous Thromboembolism per Khorana Index

Background

Cancer patients are at increased risk for venous thromboembolism (VTE) due to cancer-induced hypercoagulability. However, current guidelines do not routinely recommend prophylactic use of oral anticoagulants to prevent VTE in cancer patients.

Objective

To evaluate the efficacy and safety of novel oral anticoagulants (NOACs) versus no anticoagulant use (no-use) and, additionally, differential effects between NOACs and warfarin, in VTE and adverse bleeding prevention among cancer patients, in consideration of risk stratification by gender, high-risk chemotherapy exposure, and Khorana index.

Methods

This national health insurance data-based study with a 180-day follow-up enrolled cancer patients with or without oral anticoagulant use in 2017. The primary outcome was VTE risk in oral anticoagulant users vs non-users. Four propensity score-matched comparison pairs were designed: use vs no-use, NOAC vs no-use, warfarin vs no-use, and NOAC vs warfarin. A logistic regression model was used to investigate between-group differences in VTE and bleeding risk.

Results

When compared to no-use, NOACs showed substantial effects in preventing VTE complications (OR=0.40, p<0.001), primarily deep vein thrombosis (DVT) events (OR=0.38, p<0.001), in both male and female cancer patients as well as those with a Khorana score ≥1. Adverse bleeding risk was comparable or lower in NOAC-receiving female patients (p=0.13) and male patients (p=0.04), respectively. In contrast, no protective effects were found with warfarin compared to no-use in controlling thrombosis and adverse bleeding risk. In a head-to-head comparison of NOACs versus warfarin, DVT risk in those patients exposed to high-risk chemotherapy was significantly decreased with NOAC use (OR=0.19, p=0.03).

Conclusion

NOACs can be a promising thromboprophylactic option in both male and female cancer patients with VTE risk.

Decontamination of SARS-CoV-2 contaminated N95 filtering facepiece respirators using artificial sun lamps

Aims

Assess the feasibility of using light from artificial sun lamps to decontaminate N95 filtering facepiece respirators (FFRs) contaminated with SARS‐CoV‐2.

Methods and Results

FFR coupons or whole FFRs contaminated with 5 log₁₀ TCID₅₀ (target concentration) SARS‐CoV‐2 in culture media, simulated saliva, or simulated lung fluid were dried for 1–2 h, then exposed to light from tanning and horticulture lamps to assess decontamination. Exposed coupons and whole FFRs showed SARS‐CoV‐2 inactivation for all matrices tested. Furthermore, FFRs still met performance specifications after five decontamination cycles.

Conclusions

It is feasible that artificial sunlight from these sun lamps can be used to decontaminate FFRs provided the UV dose is sufficient and the light is unobstructed. Furthermore, decontamination can be performed up to five times without degrading FFR performance.

Significance and Impact of the Study

This research shows a proof of principle that artificial sun lamps may be an option to decontaminate SARS‐CoV‐2 on N95 FFRs. UV doses required for inactivation to levels below detection ranged from 4 to 37·8 J cm⁻² depending on the light source, virus matrix and FFR type.

Trastuzumab-based palliative chemotherapy for HER2-positive gastric cancer: a single-center real-world data

Background

Since the results of the ToGA trial were published, trastuzumab-based chemotherapy has been used as the standard first-line treatment for HER2-positive recurrent or primary metastatic gastric cancer (RPMGC). However, the real-world data has been rarely reported. Therefore, we investigated the outcomes of trastuzumab-based chemotherapy in a single center.

Methods

This study analyzed the real-world data of 47 patients with HER2-positive RPMGC treated with trastuzumab-based chemotherapy in a single institution.

Results

With the median follow-up duration of 18.8 months in survivors, the median overall survival (OS) and progression-free survival were 12.8 and 6.9 months, respectively, and the overall response rate was 64%. Eastern Cooperative Oncology Group performance status 2 and massive amount of ascites were independent poor prognostic factors for OS, while surgical resection before or after chemotherapy was associated with favorable OS, in multivariate analysis. In addition, 5 patients who underwent conversion surgery after chemotherapy demonstrated an encouraging median OS of 30.8 months, all with R0 resection.

Conclusions

Trastuzumab-based chemotherapy in patients with HER2-positive RPMGC in the real world demonstrated outcomes almost comparable to those of the ToGA trial. Moreover, conversion surgery can be actively considered in fit patients with a favorable response after trastuzumab-based chemotherapy.

Senescent Tumor Cells Build a Cytokine Shield in Colorectal Cancer

Cellular senescence can either support or inhibit cancer progression. Here, it is shown that intratumoral infiltration of CD8+ T cells is negatively associated with the proportion of senescent tumor cells in colorectal cancer (CRC). Gene expression analysis reveals increased expression of C-X-C motif chemokine ligand 12 (CXCL12) and colony stimulating factor 1 (CSF1) in senescent tumor cells. Senescent tumor cells inhibit CD8+ T cell infiltration by secreting a high concentration of CXCL12, which induces a loss of CXCR4 in T cells that result in impaired directional migration. CSF1 from senescent tumor cells enhance monocyte differentiation into M2 macrophages, which inhibit CD8+ T cell activation. Neutralization of CXCL12/CSF1 increases the effect of anti-PD1 antibody in allograft tumors. Furthermore, inhibition of CXCL12 from senescent tumor cells enhances T cell infiltration and results in reducing the number and size of tumors in azoxymethane (AOM)/dextran sulfate sodium (DSS)-induced CRC. These findings suggest senescent tumor cells generate a cytokine barrier protecting nonsenescent tumor cells from immune attack and provide a new target for overcoming the immunotherapy resistance of CRC.

Decontamination of SARS-CoV-2 contaminated N95 filtering facepiece respirators (FFRs) with moist heat generated by a multicooker

Decontamination of N95 filtering facepiece respirators (FFRs) is a crisis capacity strategy allowed when there are known shortages of FFRs. The application of moist heat is one decontamination method that has shown promise and is the approach approved in the Steris Steam Emergency Use Authorization (EUA). This effort examines the use of multicookers to apply moist heat, as they are available in retail stores and more affordable than methods requiring more sophisticated equipment. Four of five multicooker models examined met the acceptance criteria for the test and one model was selected for inactivation testing. Tests were performed on four different FFR models with SARS‐CoV‐2 suspended in culture media, simulated saliva or simulated lung fluid. Moist heat treatment reduced recoverable titres of SARS‐CoV‐2 virus to levels below the limit of detection in all tests. Furthermore, these four FFR models showed no loss in collection efficiency, inhalation resistance or visual damage after up to 10 decontamination cycles. Two (2) FFR models showed a slight change in strap elasticity (<9%). These data show that moist heat treatment using a multicooker is a viable option for FFR decontamination in a crisis capacity strategy.

Combination versus single-agent as palliative chemotherapy for gastric cancer

BACKGROUND

Although combination chemotherapy (CC) is generally recommended in recurrent or primary metastatic gastric cancer (RPMGC), the results of randomized trials are conflicting.

METHODS

A retrospective review was conducted on 687 RPMGC patients who received palliative chemotherapy. We compared the overall survival (OS) between CC and single-agent chemotherapy (SC) among these patients, and we analyzed the clinicopathological characteristics affecting outcome including neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR).

RESULTS

Although 521 patients (75.8%) underwent CC, SC was more frequently performed in elderly patients (57.6%) and ECOG performance status (PS) 2 or 3 (65.8%) patients (p < 0.0001, in each case). The median OS of patients who received CC was significantly longer than that of patients who received SC (11 vs. 8 months, p < 0.0001). No difference in OS between CC and SC was observed in elderly patients (p = 0.583), poor PS (p = 0.810), signet ring cell (p = 0.347), palliative surgical resection (p = 0.307), and high PLR (p = 0.120), with a significant interaction between age and type of regimen (p = 0.012). Moreover, there was no difference in OS between CC and SC after propensity score matching (p = 0.322). Multivariate analysis revealed that palliative resection and ≥ second-line chemotherapy were independently associated with favorable OS (p < 0.0001, in each case), whereas poor PS (p = 0.004), signet ring cell (p < 0.0001), peritoneal metastasis (p = 0.04), high NLR (p = 0.001), and high PLR (p = 0.033) were independent prognostic factors of poor OS.

CONCLUSIONS

Although CC is the standard of care in RPMGC, SC can be considered a reasonable option in certain subgroups, such as elderly patients.

Abrogation of B-RafV600E induced senescence by FoxM1 expression

B-Raf^V600E oncogene mutation occurs in various cancers and is associated with tumor initiation. However, genetic modification of B-Raf^V600E in cells induces MAPK activation and results in oncogene-induced senescence. Overcoming the oncogene-induced senescence by B-Raf^V600E requires activation of another oncogene pathway, such as AKT signaling. In the present study, we explored the factors involved in overcoming the senescence program in cells activated by B-Raf^V600E and AKT signaling. B-Raf^V600E activation caused a feedback inhibition of AKT phosphorylation and resulted in downregulation of FoxM1, one of the AKT downstream components. AKT activation by PTEN downregulation induced FoxM1 expression, and co-expression of B-Raf^V600E and FoxM1 overcame the cellular senescence. These observations suggested that FoxM1 is critical downstream gene of AKT and functions to overcome B-Raf^V600E-induced senescence.

Anaphylaxis to Chlorpheniramine Maleate and Literature Review

Chlorpheniramine maleate is commonly used antihistamine. Since antihistamines are the main therapeutic agents for symptomatic treatment of urticaria, anaphylaxis to antihistamines may lead to errors in diagnosis and treatment. We report a case of anaphylaxis induced by chlorpheniramine maleate confirmed by intradermal test. A 35-year-old female experienced history of anaphylaxis after intramuscular injection of chlorpheniramine maleate. Skin prick test was negative, but intradermal test was positive. Patient also experienced mild dizziness after intradermal test and refused to perform any further evaluation such as oral challenge test. Anaphylaxis for chlorpheniramine maleate is very rare but should be considered.

Cutaneous Lymphangioma Circumscriptum Occurred Seven Years after Surgery with Soft Tissue Cystic Lymphangioma

Lymphangiomas are rare benign congenital lymphatic malformations. They can be divided into three groups: cutaneous lymphangioma circumscriptum (CLC), cavernous, and cystic. CLC is the most common type, and rarely occurs with cavernous or cystic lymphangioma under the lesion. Here, we describe the case of a 9-year-old girl who presented with an asymptomatic vesicular lesion on her back. She was finally diagnosed with CLC by clinical manifestations, dermoscopic findings, and histologic findings. Seven years ago, there was a history of surgical operation in the department of general surgery, and the surgery was soft tissue cystic lymphangioma removal surgery. There was no skin lesion for seven years after surgery, but one occurred a month ago. Herein, we present a case of CLC that occurred after a long interval after surgery for soft tissue cystic lymphangioma.

Cowden Disease: Case Report and Review of the Literature

Cowden's disease is a rare autosomal dominant, multiple hamartoma syndrome with characteristic mucocutaneous lesions. It is associated with abnormalities of the breast, thyroid, and gastrointestinal tract; and is characterized by multiple hamartomas in the gastrointestinal tract and mucocutaneous lesions such as trichilemmomas, oral papillomatosis, facial papules, and acral keratosis. A 21-year-old male patient presented with erythematous facial papules, oral mucosal papillomatosis, and punctate palmoplantar hyperkeratosis indicating a definite case of Cowden's disease. This disease derives from variable expression resulting from a mutation in the PTEN gene. Gastrointestinal endoscopy and colonoscopy revealed multiple hamartomas in the stomach and colon. On thyroid ultrasonography, several probable benign nodules were noted in the right thyroid gland. He had no pertinent family history and no other systemic findings. Further regular laboratory and image studies will be planned for our patient, as well as his family members. Sporadic Cowden's disease is rarely observed. Herein, we report a case of Cowden's disease without known family history. Dermatologists should be aware of the possibility of Cowden syndrome based on its several dermatologic findings.

Comparison of preoperative and prechemotherapy lymphocyte counts to predict outcome of non-small cell lung cancer patients treated with adjuvant chemotherapy

e20002

Background: Several systemic inflammatory markers in blood have been suggested as prognostic factors in various cancers. We investigated the prognostic significance of neutrophil-to-lymphocyte ratio (NLR) and absolute lymphocyte count (ALC) in patients (pts) with non-small cell lung cancer (NSCLC) treated with adjuvant chemotherapy. Methods: A retrospective review was conducted on 108 pts who received adjuvant chemotherapy after surgical resection of NSCLC. Disease-free survival (DFS) and overall survival (OS) of pts with high NLR and ALC ( > median value) before surgery or chemotherapy were compared to those of pts with low NLR and ALC (≤median value). Results: The number of pts at AJCC stage IB, IIA, IIB, IIIA, and IIIB were 1, 38, 9, 58, and 2, respectively. Adenocarcinoma, squamous cell carcinoma, and other histologic types were present in 66 (61.1%), 32 (29.6%), and 10 (9.3%) pts, respectively. The most frequently used chemotherapy regimen was vinorelbine/cisplatin (81 pts), followed by paclitaxel/carboplatin (22 pts), and others (5 pts). A total of 61 (56.5%) pts received adjuvant radiotherapy (before adjuvant chemotherapy: 53 pts). Preoperative NLR and ALC were not associated with clinicopathologic characteristics including stage and histologic types. High prechemotherapy NLR and low ALC were more frequently observed in pts who underwent radiotherapy before chemotherapy (p < 0.0001). The median follow-up duration was 70 (38-162) months for survivors. Pts with stage III demonstrated poor DFS (p = 0.019) and OS (p = 0.028) compared to those with stage IB or II. The shorter median DFS was observed in pts with low prechemotherapy ALC (20 vs. 65 months, p = 0.021), without significant difference in OS (p = 0.088). On the other hand, NLR and preoperative ALC were not associated with outcome of pts. Conclusions: The present study suggests that high prechemotherapy ALC is associated with poor outcome in stage IB-III NSCLC pts who received adjuvant chemotherapy after surgical resection.

Does the extent of brain metastasis affect outcome of non-small cell lung cancer patients treated with chemotherapy?

e20616

Background: More than one third of advanced non-small cell lung cancer (NSCLC) patients (pts) experience brain metastases in the course of their disease. Although the outcome of NSCLC pts with brain metastasis is generally poor, identifying subgroups of pts that could benefit from appropriate therapeutic approach is clinically important, particularly in EGFR tyrosine kinase inhibitor (TKI) era. Methods: A retrospective review was conducted on 85 NSCLC pts with synchronous brain metastasis who underwent at least first-line chemotherapy, after treatment (Tx) for brain metastasis (gamma knife surgery or fractionated stereotactic radiotherapy : 42, whole brain radiation therapy : 38, surgical resection : 1, and no Tx : 4) from Jan 2002 to Dec 2013. Overall survival (OS) of all pts was analyzed according to the clinicopathological characteristics, Tx modality for brain metastasis, and chemotherapy. Results: The median OS for all pts after the initiation of first-line chemotherapy was 9 months. In univariate analysis, pts who received TKI (13 months versus 6 months, p= 0.001) and third- or further-line chemotherapy (15 months versus 6 months, p< 0.001) had significantly longer median OS. The presence of extracranial extrathoracic metastasis, number of brain metastasis, and Tx modality for brain metastasis showed no significant association with OS. In multivariate analysis, third- or further-line chemotherapy (24 pts) was the only independent prognostic factor for favorable OS ( p< 0.001). Pts who underwent third- or further-line chemotherapy were characterized by high proportion of non-squamous histology ( p= 0.016), extracranial extrathoracic metastasis ( p= 0.015), and TKI Tx ( p< 0.001). Conclusions: The present study suggests that judicious but active use of chemotherapy after appropriate Tx for brain metastasis may result in favorable outcome in NSCLC pts with synchronous brain metastasis, regardless of the number of brain metastatic lesions or local Tx modalities.

Nail Dystrophy in Patients with Atopic Dermatitis and Its Association with Disease Severity

Background

Nail dystrophy arises from various inflammatory dermatologic diseases. However, there have been few reports on the prevalence of nail abnormality in atopic dermatitis (AD) or on the relationship of this condition with the severity of the disease.

Objective

This study was intended to determine the prevalence and types of nail abnormalities associated with AD and to evaluate the relation between nail abnormalities and the severity of AD.

Methods

AD patients aged 2 to 19 who visited the outpatient clinic were thoroughly examined for nail abnormalities. Demographic information was collected and eczema area and severity index (EASI) score for severity of AD were checked.

Results

A total of 235 AD patients (children and adolescents) were investigated. There were 24 (10.2%) patients with nail abnormalities: transverse groove (Beau's line) (25.0%), nail pitting (16.7%), koilonychia (16.7%), trachyonychia (12.5%), leukonychia (12.5%), brachyonychia (8.3%), melanonychia (8.3%), onychomadesis (8.3%), onychoschizia (8.3%), and onycholysis (8.3%). There was no statistically significant difference in the total EASI score associated with development of nail abnormalities (p=0.236). However, when the EASI score was confined to the lower extremities, it showed a relation to the prevalence of toe nail dystrophy (odds ratio, 1.115; 95% confidence interval, 1.014~1.316; p=0.030).

Conclusion

Nail abnormalities in AD are thought to be caused mainly by pathologic change in the nail matrix region, and the EASI score confined to lower limbs, might be used as a predictor of toe nail changes in patients with AD.

The role of surgical resection before palliative chemotherapy in advanced gastric cancer

The role of palliative surgical resection in recurrent or metastatic gastric cancer is still controversial. A retrospective review was conducted on 689 patients who received palliative chemotherapy for recurrent (n = 307) or primary metastatic (n = 382) gastric cancer. Among 131 patients (89 primary metastatic and 42 recurrent) with surgical resection before chemotherpay, 75 underwent gastrectomy, 42 metastasectomy, and 14 gastrectomy with metastasectomy. The median overall survival (OS) of patients who underwent surgical resection was significantly longer than that of patients who received chemotherapy alone (18 vs. 9 months, p < 0.0001). The OS benefit of surgical resection was consistent across subgroups. In multivariate analysis, surgical resection was independently associated with favorable OS (hazard ratio = 0.42, p < 0.0001). Moreover, patients with surgical resection showed favorable OS both in univariate (p < 0.0001) and multivariate (p < 0.0001) analysis even after propensity score matching. In addition, the median OS of patients who underwent gross complete resection (n = 54) was significantly longer than that of patients who underwent incomplete resection (n = 77) (30 vs. 15 months, p = 0.002). The present study suggests that judicious use of surgical resection before chemotherapy in recurrent or metastatic gastric cancer patients may result in a favorable outcome, especially when complete resection is achievable.

The Risk of Rosacea According to Chronic Diseases and Medications: A 5-Year Retrospective, Multi-Institutional Case-Control Study

Background

Rosacea is associated with chronic systemic disease. However, research is lacking in Asian countries.

Objective

To evaluate the association between rosacea and cardiovascular diseases (CVDs) related systemic comorbidities, and the use of antihypertensive and antihyperlipidemic drugs in Korea.

Methods

A five-year retrospective study, using hospital database, was conducted in five medical centers for five years. Totally 1,399,528 patients were evaluated.

Results

The overall frequency for diagnosed rosacea was 0.18% over five years (2,536 rosacea patients). Patients with diabetes and patients with dyslipidemia were more likely to have rosacea (odd ratio [OR] 2.724, 95% confidence interval [CI] 1.295~5.730, p=0.016; OR 1.788, 95% CI 1.445~2.212, p<0.001). Patients with CVD were less likely to have rosacea (OR 0.431, 95% CI 0.244~0.760, p=0.003). Patients with α-blocker prescriptions and patients with β-blocker prescriptions showed a tendency diagnosed with rosacea frequently (OR 1.963, 95% CI 1.200~3.212, p=0.006; OR 3.939, 95% CI 3.512~4.419, p<0.001). Patients with [beta]-hydroxy-[beta]-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, and those with fibrate, were prone to have rosacea (OR 1.599, 95% CI 1.390~1.839, p<0.001; OR 1.660, 95% CI 1.056~2.609, p=0.026). As adjusted results, among the patients who took HMG-CoA reductase inhibitor without dyslipidemia, rosacea was less likely to be diagnosed (OR 0.780, 95% CI 0.620~0.982, p=0.034).

Conclusion

Rosacea is associated with chronic diseases and drugs.

The role of third-line chemotherapy in recurrent or metastatic gastric cancer: A cohort study with propensity score matching analysis

In recurrent or metastatic gastric cancer, second-line chemotherapy is generally recommended in current guidelines. Although third-line therapy is often performed in daily practice in some countries, there are only a few reports about its benefits.A retrospective review was conducted on 682 patients who underwent at least first-line chemotherapy for recurrent (n = 297) or primary metastatic (n = 385) disease. Clinicopathological characteristics and overall survival (OS) were analyzed according to lines of chemotherapy.One hundred sixty-seven patients (24.5%) underwent third- or further-line therapy. Third- or further-line therapy was frequently performed in patients with young age (<70) (P < .0001), Eastern Cooperative Oncology Group (ECOG) performance status (PS) 0 or 1 (P < .0001), surgical resection before first-line therapy (P = .007), and first-line combination regimen (P = .001). The median OS for all patients after the initiation of first-line therapy was 10 months. The median OS of patients who received third- or further-line therapy was significantly longer than that of patients who received second- or lesser-line therapy (18 vs 8 months, P < .0001). The multivariate analysis revealed that third- or further-line therapy was independently associated with favorable OS (hazard ratio = 0.58, P < .0001). Moreover, patients who received third- or further-line therapy demonstrated better OS both in univariate (P = .002) and multivariate (P < .0001) analysis even after propensity score matching using baseline characteristics. The median OS after the start of third-line chemotherapy was 6 months. In addition, ECOG PS 0 or 1 at the initiation of third-line therapy (P < .0001) and surgical resection (P = .009) were independently associated with longer OS after third-line therapy.The current study suggests that third-line therapy could be recommended for recurrent or metastatic gastric cancer patients with good PS after progression from second-line chemotherapy in clinical practice.

Abstract 469: Therapy-induced senescence associated secretory phenotype enhances breast cancer cell invasion and stemness via CXCR1/2-CXCR1/2 ligands axis

Various chemotherapeutic agents have been demonstrated to induce senescence of cancer cells in vitro and in vivo. This therapy-induced senescence (TIS) has been regard as a favorable therapeutic response, although it is not a cell death but a permanent cell cycle arrest. However, adverse aspects of TIS have been also suggested since senescence-associated secretory phenotype (SASP) enables to affect microenvironment of senescent cancer cells. Nonetheless, when senescent cancer cells are intermingled with non-senescent cells after chemotherapy, the effects of SASP from senescent cancer cell to non-senescent cell have not yet been fully elucidated. Therefore, TIS, confirmed by measuring senescence associated β-galactosidase activity and cell cycle arrest, was induced by the treatment with adriamycin and cisplatin in variable breast cancer cell lines in vitro. To evaluate the effects of SASP from senescent cancer cell to non-senescent cell, conditioned media (CM) from TIS of MCF7 (poorly-aggressive and non-invasive cell line) was treated in parent non-senescent MCF7 and their invasiveness and stemness were measured by invasion assay and mammosphere forming assay, respectively. In MCF7 treated with CM from TIS, invasiveness and mammosphere forming ability were significantly increased. To discover the mediators of the observed effects, cytokine array was performed by collecting CM from non-senescent control and therapy-induced senescent cells. In the secretome of TIS, CXCR2 ligands, including growth-related protein-α (CXCL1) and interleukin-8 (CXCL8) were focused on for further analysis. Increased mRNA of CXCR2 ligands (CXCL1, 2, 3 and CXCL8) in TIS and increased secretion of CXCL8 protein in CM of TIS were confirmed by real time PCR and ELISA, respectively. To investigate the contribution of CXCR1/2-CXCR1/2 ligands axis in enhanced invasion and stemness ability by CM of TIS, a CXCR1/2 specific inhibitor, SCH-527123, was applied. The pretreatment of SCH-527123 in the concentration without affecting cell proliferation and survival (25, 50μM), significantly inhibited the enhanced invasion and mammosphere forming ability by CM of TIS. The potential mechanisms of cancer cell invasion and stemness enhancement by CXCR1/2-CXCR1/2 ligands axis, are currently under investigated. In summary, SASP of TIS can be harmful by augmenting invasion and stemness of surrounding non-senescent cancer cell thorough the CXCR1/2-CXCR1/2 ligands axis and CXCR1/2 inhibitors can be used as therapeutic agents, by antagonizing the adverse effects of TIS.

Citation Format: Yong Won Choi, Hyun-Young Cha, Tae Jun Park, Mi Sun Ahn, Hyun Woo Lee, Seong Hyun Jeong, Seok Yun Kang, Joon Seong Park, Jin-Hyuk Choi. Therapy-induced senescence associated secretory phenotype enhances breast cancer cell invasion and stemness via CXCR1/2-CXCR1/2 ligands axis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 469.

Strong immunoexpression of dickkopf-1 is associated with response to bortezomib in multiple myeloma

The predictive significance of osteolysis-related proteins was evaluated in bortezomib-treated multiple myeloma. The clinicopathological characteristics were collected retrospectively. Immunohistochemistry was performed for analyzing receptor activator of NF-κB ligand (RANKL), osteoprotegerin (OPG), macrophage inflammatory protein 1 alpha (MIP1α), and dickkopf-1 (DKK1) expression. Among clinicopatholgical characteristics, osteolytic lesion was associated with higher response to bortezomib treatment (79% vs. 46%). High DKK1 expression was significantly correlated with osteolytic lesion (p = .003), whereas RANKL, OPG, and MIP1α were not. In high DKK1 expression, higher response to bortezomib was observed (84% vs. 44%). In multivariate analysis, high DKK1 expression was associated with better response to bortezomib (p = .005). Patients with high DKK1 expression had longer median progression-free survival (PFS) and overall survival (OS) after bortezomib treatment. In multivariate analysis, high DKK1 expression was an independent prognostic factor of favorable PFS (p = .027) and OS (p = .035). In multiple myeloma treated with bortezomib, expression status of DKK1 may be a useful predictive marker.

Post-Translational Regulation of the RSF1 Chromatin Remodeler under DNA Damage

Chromatin remodeling factors are involved in many cellular processes such as transcription, replication, and DNA damage response by regulating chromatin structure. As one of chromatin remodeling factors, remodeling and spacing factor 1 (RSF1) is recruited at double strand break (DSB) sites and regulates ataxia telangiectasia mutated (ATM) -dependent checkpoint pathway upon DNA damage for the efficient repair. RSF1 is overexpressed in a variety of cancers, but regulation of RSF1 levels remains largely unknown. Here, we showed that protein levels of RSF1 chromatin remodeler are temporally upregulated in response to different DNA damage agents without changing the RSF1 mRNA level. In the absence of SNF2h, a binding partner of RSF1, the RSF1 protein level was significantly diminished. Intriguingly, the level of RSF1-3SA mutant lacking ATM-mediated phosphorylation sites significantly increased, and upregulation of RSF1 levels under DNA damage was not observed in cells overexpressing ATM kinase. Furthermore, failure in the regulation of RSF1 level caused a significant reduction in DNA repair, whereas reconstitution of RSF1, but not of RSF1-3SA mutants, restored DSB repair. Our findings reveal that temporal regulation of RSF1 levels at its post-translational modification by SNF2h and ATM is essential for efficient DNA repair.

Effect of Different Cooking Methods on Histamine Levels in Selected Foods

BACKGROUND

Histamine in food is known to cause food poisoning and allergic reactions. We usually ingest histamine in cooked food, but there are few studies about the influence of cooking method on the histamine level.

OBJECTIVE

The purpose of this study was to determine the influence of cooking methods on the concentration of histamine in foods.

METHODS

The foods chosen were those kinds consumed frequently and cooked by grilling, boiling, and frying. The histamine level of the food was measured using enzyme-linked immunosorbent assay.

RESULTS

Grilled seafood had higher histamine levels than raw or boiled seafood. For meat, grilling increased the histamine level, whereas boiling decreased it. For eggs, there was not much difference in histamine level according to cooking method. Fried vegetables had higher histamine levels than raw vegetables. And fermented foods didn't show much difference in histamine level after being boiled.

CONCLUSION

The histamine level in food has changed according to the cooking method used to prepare it. Frying and grilling increased histamine level in foods, whereas boiling had little influence or even decreased it. The boiling method might be helpful to control the effect of histamine in histamine-sensitive or susceptible patients, compared with frying and grilling.

Is third-line chemotherapy routine practice in recurrent or metastatic gastric cancer?

e15558

Background: Patients (pts) with recurrent or metastatic gastric cancer eventually experience disease progression during or after completion of first-line chemotherapy. Second-line therapy is generally recommended in the current guidelines. Although third-line therapy is often performed in daily practice in some countries, there are few reports about the benefit of third-line therapy. Methods: A retrospective review was conducted on 683 pts who underwent at least first-line palliative chemotherapy for recurrent (n = 297) or primary metastatic (n = 386) gastric cancer. Clinicopathological characteristics and overall survival (OS) were analyzed according to the lines of chemotherapy as well as for all study pts. Results: One hundred and forty-nine pts (21.8%) underwent third- or further-line therapy. Third- or further-line therapy was more frequently performed in pts with young age ( < 70) (p < 0.0001), ECOG PS 0 or 1 (p < 0.0001) at the initiation of first-line therapy, first-line combination regimen (p = 0.006), and palliative surgical resection before first-line therapy (p = 0.029). The median follow-up duration was 62 months (24-151 months) for the survivors. The median OS for pts after first- and third-line therapy was 10 and 6 months, respectively. The median OS of pts who received third-line therapy was significantly longer than that of pts who received second- or lesser-line therapy (18 vs. 8 months, p < 0.0001). Multivariate analysis revealed that third- or further-line therapy was independently associated with favorable OS (hazard ratio = 0.56, p < 0.0001) along with surgical resection (p < 0.0001) and first-line combination regimen (p = 0.008), whereas signet ring cell histology (p = 0.002) and peritoneal metastasis (p = 0.027) were independent prognostic factors of poor OS. Conclusions: This study suggests that recurrent or metastatic gastric cancer pts may benefit from third-line chemotherapy, although careful selection is essential.

Is surgical resection beneficial in recurrent or metastatic gastric cancer?

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Background: Although chemotherapy is currently established as a standard treatment in recurrent or metastatic gastric cancer, the role of palliative surgical resection is still controversial. We investigated the survival benefit of surgical resection in patients (pts) with recurrent or metastatic gastric cancer who received systemic chemotherapy. Methods: A retrospective review was conducted on 698 pts who received palliative chemotherapy for recurrent (n = 307) or primary metastatic (n = 391) gastric cancer. Overall survival (OS) of pts who underwent surgical resection followed by chemotherapy was compared to that of pts who received chemotherapy alone. Results: Among 140 pts (primary metastatic: 97, recurrent: 43) with surgical resection, gastrectomy, metastasectomy, and gastrectomy with metastasectomy were performed in 83 (primary metastatic: 81), 44, and 13 pts, respectively. Higher surgical resection rate was observed in pts with young age ( < 70) (p = 0.010), ECOG PS 0 or 1 (p = 0.010), primary metastatic (p < 0.0001), absence of liver metastasis (p = 0.002), and signet ring cell histology (p = 0.002). The median OS of pts who underwent surgical resection before chemotherapy was significantly longer than that of pts who received chemotherapy alone (19 vs. 9 months, p <0.0001). The OS benefit of surgical resection was consistent across subgroups in terms of baseline characteristics including age, ECOG PS, disease status (primary metastatic vs. recurrent), peritoneal metastasis, and first-line chemotherapy regimen (single vs. combination). In multivariate analysis, surgical resection was independently associated with favorable OS (hazard ratio = 0.41, p < 0.0001) along with ≥second-line chemotherapy (p < 0.0001), whereas ECOG PS 2 or 3 (p = 0.013), signet ring cell histology (p < 0.0001), and peritoneal metastasis (p = 0.046) were independent prognostic factors of poor OS. Conclusions: The present study suggests that judicious use of surgical resection before chemotherapy in recurrent or metastatic gastric cancer pts may result in favorable outcome, although large scale phase III trials are essential to establish this treatment approach as a standard practice.

Does the efficacy of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor differ according to the type of EGFR mutation in non-small cell lung cancer?

An exon 19 deletion and a L858R mutation in exon 21 of the epidermal growth factor receptor (EGFR) are the two most common mutations that predict favorable efficacy of EGFR tyrosine kinase inhibitors (TKIs) in patients with non-small cell lung cancer (NSCLC). Many retrospective and prospective studies, as well as meta-analyses including patients with NSCLC with various lines of EGFR TKI treatment, have demonstrated longer progression-free survival and sometimes more favorable overall survival in patients with an exon 19 deletion than those with the L858R or other mutations. In contrast, some clinical studies, including phase III trials, have demonstrated no difference in the efficacy of EGFR TKIs according to the EGFR mutation type. Therefore, the existence of clinically significant differences in sensitivity to EGFR-TKIs among different EGFR mutation subtypes remains controversial. In this review, we summarize the evidence suggesting different outcomes according to the type of EGFR mutation in patients with advanced NSCLC who were treated with EGFR-TKIs, along with their clinical significance. We also discuss possible mechanisms that can explain the different sensitivities to EGFR TKIs between cases with an exon 19 deletion and those with the L858R mutation.