The value of BRCA-1-associated protein 1 expression and cyclin-dependent kinase inhibitor 2A deletion to distinguish peritoneal malignant mesothelioma from peritoneal location of carcinoma in effusion cytology specimens.

OBJECTIVE: Diffuse malignant peritoneal mesothelioma (DMPM), represents 30% of all malignant mesothelioma, and is characterised by a difficult diagnosis and different presentations. Immunohistochemistry has improved the diagnostic sensitivity and specificity in the differential diagnosis between metastatic adenocarcinoma and malignant mesothelioma, and loss of BRCA-1-associated protein 1 (BAP1) expression is correlated with BAP1 somatic or constitutional genetic defects. Furthermore, cyclin-dependent kinase inhibitor 2A (CDKN2A) is frequently lost in DMPM. In the present study, we assessed the value of integrating BAP1 in the panel of antibodies used for the diagnosis of DMPM in cytological samples. Since p16 fluorescent in situ hybridisation (FISH) assay could constitute an additional useful adjunct, results of BAP1 immunostaining and p16 FISH assays have been compared. METHODS: Forty-eight DMPM patients and 71 peritoneal carcinomatosis patients were included. BAP1 immunohistochemical and CDKN2A FISH techniques were performed on tissue specimens of DMPM (n = 48) and peritoneal carcinomatosis (n = 71) then on cell-block of DMPM (n = 16), peritoneal carcinomatosis (n = 25) and peritoneal benign effusion (n = 5). RESULTS: Loss of BAP1 expression was observed in 56.3% of DMPM while none of the peritoneal carcinoma specimens showed BAP1 loss of expression. CDKN2A loss was observed in 34.9% DMPM and 2.1% peritoneal carcinoma. Although BAP1 immunostaining was successful in 100% of cytological DMPM samples, CDKN2A deletion status could be obtained for 75% of DMPM cases. CONCLUSION: BAP1 immunostaining represents an objective and reproducible diagnostic biomarker for peritoneal mesothelioma in effusion cytology specimens and should be preferred to CDKN2A FISH analysis on these precious samples.

A Simplified Version of the IASLC Grading System for Invasive Pulmonary Adenocarcinomas With Improved Prognosis Discrimination.

Tumor grading enables better management of patients and treatment options. The International Association for the Study of Lung Cancer (IASLC) Pathology Committee has recently released a 3-tier grading system for invasive pulmonary adenocarcinoma consisting of predominant histologic patterns plus a cutoff of 20% of high-grade components including solid, micropapillary, and complex glandular patterns. The goal of this study was to validate the prognostic value of the new IASLC grading system and to compare its discriminatory performance to the predominant pattern-based grading system and a simplified version of the IASLC grading system without complex glandular patterns. This was a single-site retrospective study based on a 20-year data collection of patients that underwent lung cancer surgery. All invasive pulmonary adenocarcinomas confirmed by the histologic review were evaluated in a discovery cohort (n=676) and a validation cohort (n=717). The median duration of follow-up in the combined dataset (n=1393) was 7.5 years. The primary outcome was overall survival after surgery. The 3 grading systems had strong and relatively similar predictive performance, but the best parsimonious model was the simplified IASLC grading system (log-rank P =1.39E-13). The latter was strongly associated with survival in the validation set ( P =1.1E-18) and the combined set ( P =5.01E-35). We observed a large proportion of patients upgraded to the poor prognosis group using the IASLC grading system, which was attenuated when using the simplified IASLC grading system. In conclusion, we identified a histologic simpler classification for invasive pulmonary adenocarcinomas that outperformed the recently proposed IASLC grading system. A simplified grading system is clinically convenient and will facilitate widespread implementation.

Prognostic value of complex glandular patterns in invasive pulmonary adenocarcinomas.

Prognostic stratification of patients surgically resected with invasive pulmonary adenocarcinoma must be improved. Previous studies reported that complex glandular patterns (CGPs), cribriform and fused gland growth patterns, are associated with unfavorable prognosis. The goal of this study is to evaluate the prognostic value of CGPs in patients with resected stage I-IV lung adenocarcinoma. The presence of CGPs as a minor to predominant component was tested for association with overall survival (OS, n = 676) and relapse-free survival (RFS, n = 463) after surgery. CGPs were observed in 284 tumors (42.0%). Cribriform and fused gland were the predominant patterns in 35 and 37 cases, respectively. The presence of cribriform pattern was associated with worse RFS, but not OS. The fused gland pattern alone or grouped into CGPs with the cribriform pattern was not associated with OS and RFS. As a predominant pattern, cribriform was associated with the worse survival compared to the 5 recognized histologic patterns. Patients with fused gland-predominant tumors had 5-year survival that ranged between papillary- and micropapillary-predominant tumors. We conclude that cribriform-predominant, but not fused gland-predominant, is a subtype with poor prognosis similar to the solid and micropapillary subtypes. In contrast, the presence of a minor component of fused gland or CGPs (cribriform + fused gland) is not associated with survival. The cribriform pattern alone offers prognosis stratification improvement, but this effect is attenuated when combined into CGPs to define a subset of acinar-predominant tumors with poor prognosis. This argues against combining cribriform and fused gland into CGPs to summarize high-grade patterns.

Uncommon EGFR mutations in lung adenocarcinoma: features and response to tyrosine kinase inhibitors.

BACKGROUND: EGFR mutant non-small cell lung cancer (NSCLC) is a heterogeneous disease. The treatment for frequent EGFR mutations relies on tyrosine kinase inhibitors (TKIs); the clinical and therapeutic significance of uncommon EGFR mutations is uncertain. METHODS: This is a single-center retrospective study of patients with EGFR-mutant lung cancer (2009-2017). Molecular analyses of EGFR exons 18-21 were performed. Only patients with uncommon mutations were included (p.Glu709X, p.Gly719X, p.Ala767_Val769 dup, p.Ser768Ile, and p.Leu861Gln). RESULTS: Among 6,747 tumor samples, 95 out 820 patients (11.6%) harbored 113 uncommon EGFR mutations. There were 50 metastatic NSCLC patients for whom the median OS was 18.0 months (95% CI: 15, 32). In this population, the p.Leu861Gln uncommon exon 21 EGFR mutation was associated with poor prognosis (HR: 2.96, 95% CI: 1.39, 6.31; P=0.003). Among those harboring a single uncommon EGFR mutation, median OS was 27.6 months (95% CI: 10.8, not attained) in patients who were treated by chemotherapy only (n=13) versus 6.0 months (95% CI: 2.4, not attained) in patients exclusively treated with a first or second-EGFR-TKI (n=9; HR: 0.27, 95% CI: 0.09, 0.78; P=0.01. In patients with a single uncommon EGFR mutation, first-line chemotherapy was associated with a better overall survival than TKIs (HR: 0.31, 95% CI: 0.15, 0.68; P=0.002). In patients who received first or second-EGFR-TKI as first-line treatment (n=26), OS was significantly better for those with two uncommon EGFR mutations than those with a single uncommon mutation (HR: 0.07, 95% CI: 0.009, 0.54; P=0.001). CONCLUSIONS: In conclusion, uncommon EGFR mutations may be associated with a poor outcome and the data challenge the use of first-generation TKI in such patients, however first-line TKI is more effective in cases of double uncommon mutations and such patients should be treated accordingly.