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MINI 01 - Pathology (ID 93)
- Event: WCLC 2015
- Type: Mini Oral
- Track: Biology, Pathology, and Molecular Testing
- Presentations: 1
- Moderators:W.A. Franklin, A.G. Nicholson
- Coordinates: 9/07/2015, 10:45 - 12:15, Mile High Ballroom 2c-3c
MINI01.06 - Pathological Second-Predominant Component Predicts Recurrence in Lung Adenocarcinoma (ID 1070)
10:45 - 12:15 | Author(s): T. Mimura
Lung adenocarcinoma is pathologically subdivided according to its predominant component. Approximately 50–70% of invasive adenocarcinomas are diagnosed as adenocarcinomas of either papillary or acinar predominant subtype. The prognostic difference between these subtypes has not been revealed, and these 2 similar subtypes may further be classified. This study aimed to investigate whether the pathological second-predominant component that follows the most predominant component predict recurrence in adenocarcinoma.
We retrospectively reviewed 347 consecutive cN0 lung adenocarcinoma cases resected between April 2006 and December 2010 at Hiroshima University Hospital and Kanagawa Cancer Center. We further classified papillary and acinar predominant adenocarcinomas into either the papillary/acinar-lepidic type (Pap/Aci-Lep type) or the papillary/acinar-nonlepidic type (Pap/Aci-NonLep type). Tumor recurrence and the frequency of each invasion status such as lymphatic, vascular, and pleural invasion were compared between Pap/Aci-Lep type and Pap/Aci-NonLep type adenocarcinomas. In addition, we estimated the correlation between the radiological and pathological characteristics of these subtypes. Whole-tumor size, ground-glass opacity (GGO) ratio, solid size, and tumor disappearance ratio (TDR) on high-resolution computed tomography and maximum standardized uptake value (SUVmax) on positron emission tomography (CT) were measured as radiological parameters.
Papillary (n = 70) and acinar predominant adenocarcinomas (n = 61) were subdivided into the Pap/Aci-Lep type (n = 72) and Pp/Aci-NonLep type (n = 59). Compared with the Pap/Aci-NonLep type, the Pap/Aci-Lep type showed a significantly higher disease-free survival rate (5-year DFS: 89.4% vs 70.6%, p = 0.0374) and fewer cases of lymphatic invasion (15.3% vs 30.5%, p = 0.037), vascular invasion (15.3% vs 33.9%, p = 0.013), and pleural invasion (9.72% vs 25.4%, p = 0.031). Furthermore, radiological findings significantly differ between the Pap/Aci-Lep and Pap/Aci-NonLep types as follows: GGO ratio (μ ± 1 ´ SD: 34.4% ± 25.2% vs 3.81% ± 18.0%, p < 0.01), CT solid size (μ ± 1 ´ SD: 1.35 ± 0.65 cm vs 1.73 ± 0.55 cm, p = 0.015), TDR (μ ± 1 ´ SD: 41.8% ± 26.7% vs 17.5% ± 22.6%, p < 0.01), and SUVmax (μ ± 1 ´ SD: 2.37 ± 2.15 vs 3.96 ± 3.06, p < 0.01). Significant recurrence-free survival and prevalences of lymphatic and vascular invasion were observed between the lepidic predominant type (n = 109) and Pap/Aci-Lep type.
The pathological second-predominant component allows for subclassification of papillary and acinar predominant adenocarcinomas with prognostic significance. Pathological features of these subtypes can be represented on clinical imaging. Not only the most predominant component but also the second-predominant component should be given clinical and pathological attention in order to predict malignant potential or decide indication for adjuvant therapy.
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