Author of

• 11866

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  P2.18 - Poster Session 2 - Pathology (ID 176)

  • Event: WCLC 2013
  • Type: Poster Session
  • Track: Pathology
  • Presentations: 1
  • Moderators:
  • Coordinates: 10/29/2013, 09:30 - 16:30, Exhibit Hall, Ground Level

  • 11869

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    P2.18-003 - Spread Through Alveolar Spaces (STAS): A Newly Recognized Pattern of Invasion in Lung Adenocarcinoma Associated with Increased Recurrence in Patients Undergoing Limited Resection for ≤2cm Tumors (ID 295)

    09:30 - 09:30  |  Author(s): H. Ujiie
    • Abstract

    Background
    We have recently demonstrated that presence of the micropapillary pattern increases the risk of local recurrence after limited resection for ≤2 cm lung adenocarcinoma (ADC). In cases of tumors with the micropapillary pattern, a detached collection of tumor cells is frequently identified within an alveolar space separate from the main tumor, which we have named “Spread Through Alveolar Spaces” (STAS). However, the prognostic significance of this finding is not known. The purpose of this study is to investigate whether the presence of STAS correlates with an increased risk of recurrence after limited resection versus lobectomy.

    Methods
    All available tumor slides from patients with therapy-naive, surgically resected solitary lung ADC ≤2 cm in size (1995-2009) were reviewed (n=697; stage IA/IB, 600/97; limited resection/lobectomy, 226/471). Comprehensive histologic subtyping was performed according to the IASLC/ATS/ERS classification. STAS was defined as isolated tumor islands (morphologically solid or micropapillary pattern) or single cells within alveolar spaces separate from the main tumor. The distance between the tumor surface and the STAS was measured by a ruler (mm) and by the number of alveolar spaces. Recurrence-free probability (RFP) was estimated using the Kaplan-Meier method.

    Results
    STAS was identified in 224 cases (32%). The morphologic types of STAS were as follows: 119 micropapillary, 91 solid, and 14 single cell. Presence of the micropapillary or solid pattern (>5%) in the main tumor and presence of lymphatic invasion were significantly associated with presence of STAS (p<0.001 for each). Presence of STAS correlated with an increased risk of recurrence (5-year RFP, 75.6%), compared with absence of STAS (5-year RFP, 83.5%; p=0.022). In the limited resection group, tumors with STAS were associated with an increased risk of recurrence, compared with those without STAS (5-year RFP, 58.3% vs 81.9%; p=0.004); this did not follow in the lobectomy group (5-year RFP, 84.1% vs 84.2%; p=0.658) (Figure). The distance between the tumor surface and the STAS did not correlate with risk of recurrence (p=0.992). Figure 1

    Conclusion
    Presence of STAS correlated with an increased risk of recurrence in patients treated with limited resection for ≤2 cm lung ADC. This finding may guide surgeons to choose lobectomy over limited resection for the treatment of these patients.