Non-small cell lung carcinomas with diffuse coexpression of TTF1 and p40: clinicopathological and genomic features of 14 rare biphenotypic tumours.

Thyroid transcription factor 1 (TTF1) and p40 are widely-utilized diagnostic markers of lung adenocarcinoma (LUAD) and squamous cell carcinoma (LUSC), respectively. Diffuse coexpression of TTF1 and p40 has been described in only rare case reports. In a multi-institutional study, we collected the largest cohort of these unusual tumours to-date (n = 14), with the goal of elucidating their clinicopathological and genomic characteristics. Lung tumours with diffuse coexpression (labelling 50-100% tumour cells) of TTF1 clone 8G7G3/1 and p40 clone BC28 were identified. Detailed clinicopathological and immunohistochemical parameters were analyzed. Eight tumours were analyzed by next-generation sequencing (NGS) and the results were compared to those in > 9 K LUAD and > 1 K LUSC. All tumours with diffuse TTF1/p40 coexpression were poorly differentiated non-small cell lung carcinomas (NSCLC), 42% of which had basaloid features. Some tumours exhibited focal keratinization (14%), napsin A and/or mucicarmine labelling (46%) or both squamous and glandular features (7%). NGS revealed a uniquely high rate of FGFR1 amplifications (70%) compared to either LUAD (0.7%, P < 0.0001) or LUSC (11%, P = 0.001). LUAD-type targetable driver alterations were identified in 38% of cases (one EGFR, two KRAS G12C). The tumours were clinically aggressive, exhibiting metastatic disease in most patients. Lung carcinomas with diffuse TTF1/p40 coexpression represent poorly differentiated NSCLCs with frequent basaloid features, but some show evidence of focal squamous, glandular or dual differentiation with a distinctly high rate of FGFR1 amplifications. The presence of targetable LUAD-type alterations (EGFR, KRAS G12C) emphasizes the importance of molecular testing in these tumours.

Superior sulcus non-small cell lung cancers (Pancoast tumors): Current outcomes after multidisciplinary management.

OBJECTIVE: Despite neoadjuvant chemoradiotherapy, Pancoast tumors still present surgical and oncologic challenges. To optimize outcomes, we used a multidisciplinary care paradigm with medical and radiation oncology, and involvement of spine neurosurgery for most T3 and all T4 tumors. Spine neurosurgery permitted resection of transverse process for T3 and vertebral body resection for T4 tumors. METHODS: Retrospective analysis of single institution, prospective database of patients undergoing resection for cT3 4M0 Pancoast tumors. Patients were grouped as cT3 with combined resection with spine neurosurgery (T3 Neuro), cT3 without spine neurosurgery (T3 NoNeuro), and cT4. Overall survival, progression-free survival were analyzed by Kaplan-Meier and compared between groups using log-rank test. Cumulative incidence of local-regional and distant recurrence were compared using Gray test. P value <.05 was considered significant. RESULTS: From 2000 to 2021, 155 patients underwent surgery: median age was 58 years, and 81 were (52%) men. Most patients received neoadjuvant platinum-based neoadjuvant chemoradiotherapy (n = 127 [82%]). Operations were 48 cT3 Neuro, 41 cT3 NoNeuro, 66 cT4. R0 resection was achieved in 49 (94%) cT3 NoNeuro, 35 (85%) cT3 Neuro, and 57 (86%) cT4 patients (P = .4). Complete or major pathologic response occurred in 71 (55%) patients. Lower local-regional cumulative incidence was seen in cT3 Neuro versus cT3 NoNeuro (P = .05) and after major pathologic response. Overall survival and progression-free survival were associated with complete response, pathologic stage, and nodal status but not cT category. CONCLUSIONS: This treatment paradigm was associated with a high frequency of R0 resection, complete response, and major pathologic response. cT3 and cT4 tumors had similar outcomes. Novel therapies are needed to improve complete response.