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• 33549

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  IASLC Pre-Conference School of Pathology (ID 4)

  • Event: LALCA 2019
  • Type: Invited Speaker Session
  • Track:
  • Presentations: 2
  • Moderators:
  • Coordinates: 10/17/2019, 08:15 - 15:30, Feria 2-3

  • 33623

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    PC4.02 - Update of Staging, Challenges for Pathologists (ID 42)

    08:15 - 15:30  |  Author(s): Mercedes Liliana Dalurzo
    • Abstract
    • Slides

    Clinical and pathological staging play a crucial role in predicting survivor and influencing treatment option in lung cancer patients. The last revision of AJCC and UICC, 8th edition of lung cancer staging, was released in 2017 and has being effective internationally from 2018.
    One of the most important changes in the 8th Staging Edition for pTNM are related with the size of the tumor (pT) and the application of 2015 WHO Lung Cancer Classification of adenocarcinoma. (1)
    
    Several published studies demonstrated that the size of the tumor from 1 to 5 cm is very important in lung cancer, each centimeter increase in tumor diameter is associated with worsening survival. According to these studies, for (T) descriptors of 8th edition of TNM the new tumor-size groups were created: T1a, ?1 cm; T1b, >1 to 2 cm; T1c, >2 to 3 cm; T2a, >3 to 4 cm; T2b, >4 to 5 cm; T3, >5 to 7 cm; and T4, >7 cm.
    
    In 2011, new entities of adenocarcinoma as adenocarcinoma in situ, minimally invasive adenocarcinoma, and lepidic predominant adenocarcinoma were defined and subsequently incorporated into the 2015 World Health Organization classification of lung cancer. To fit these entities into the T classification of the staging system, Tis and T1mi were introduced for adenocarcinoma in situ and minimally invasive adenocarcinoma, respectively.
    
    In non-mucinous lung adenocarcinomas with a lepidic component, total gross tumor size should be recorded but only the invasive component is used as a descriptor of the T-categories. The lepidic component of the tumor as the amount of this growth, may potentially be difficult or could be underestimated grossly. To help to find and evaluate grossly these lesions we can carefully inflate the specimen with a mixture of optimal cutting temperature medium (OCT) before sectioning or we can make serial section followed by washing of the specimen before formalin fixation. To complete the evaluation of tumor size in non-mucinous lung adenocarcinomas with lepidic growth it is also important the microscopic reexamination of the specimen with a careful correlation with radiographic findings.
    
    In microscopic evaluation, each adenocarcinoma subtype component of the tumor could be difficult to determine and the interpretation could be potentially different for different pathologists. There are interesting studies about intra observer and inter observer lung pathologists reproducibility of the classification of adenocarcinoma.(2) They represent the challenge that sometimes pathologists face with the application of 2015 adenocarcinoma classification, especially important when the subtype of the tumor evaluated impacts over the size of the invasive tumor and in consequence the pT for staging.
    
    If the invasive and lepidic components are mixed in different areas and the size of the invasive component cannot be measured in a single discrete focus, the pT can be estimated by multiplying the total size by the percentage of the invasive components: invasive size = % of invasive component x tumor diameter.
    
    For separate tumor nodules (intrapulmonary metastasis), the classification recommended in the 7th edition has not changed: T3 for ipsilateral separate cancer nodules in the same lobe, T4 for ipsilateral separate cancer nodules in a different lobe, and M1a for a separate cancer nodule(s) in a contralateral lobe(s). The reported incidence of lung carcinoma patients presenting with multiple nodules ranges from 0.2% to 20%. Classification of multiple lung nodules as either multiple primary tumors or intrapulmonary metastases can be challenging. The 8th edition of the AJCC staging manual categorized multifocal lung cancer into four disease patterns. (I) two or more distinct and histologically different masses (considered unrelated and staged as individual cancers); (II) multiple ground-glass or part-solid nodules, histologically with lepidic growth pattern (considered separate tumors, T staged based on highest T stage lesion); (III) patchy areas of ground-glass and consolidations, histologically often invasive mucinous adenocarcinomas (considered single tumor with diffuse "pneumonic-type" involvement); and (IV) separate nodules with the same histologic features based on comprehensive histologic subtyping (considered intrapulmonary metastases). These patterns are based on clinical presentation (including radiologic impression and distribution of disease), histological assessment, and outcomes. Histologic and molecular features, in conjunction with clinical and radiological information, can all be tools to assist with staging of multiple nodules. Histologic features of adenocarcinomas are best characterized using histologic subtyping (percentage of lepidic, acinar, solid, papillary and micropapillary pattern) and comprehensive histologic assessment. Genomic alterations are commonly assessed using fluorescence in-situ hybridization and next generation sequencing (NGS). The AJCC considers exactly matching breakpoints by comparative genomic hybridization (CGH) as the only evidence for intrapulmonary metastases, and clearly different histologic types or subtypes as the only evidence for separate primary tumors. (3)
    Involvement of the Pleura: When the visceral pleura is infiltrated by cancer, a pT1 cancer by size (3 cm or less) continues to be upstaged to pT2a. Elastic stains are of value in identifying pleural invasion in this setting. Beside there is no difference in staging between PL1 and PL2, this should be documented, tumor with neoplastic cells on the visceral pleural surface (PL2) have higher recurrence and worse prognosis.
    
    The nodal stages have been able to consistently separate the patients into different prognostic group and remain unchanged from the earlier edition. The explorative analysis of pathologically-classified cases suggested that prognosis can be more accurately defined if combined with the number of stations in N1 and N2 location. Subdividing the N1 and N2 descriptors into involvement of single or multiple lymph node may help future studies on prognostication.
    
    For metastatic disease (M descriptor) the new M1b category comprises patients with only one metastasis in one distant organ, whereas M1c implies multiple distant metastases in one or several organs.
    
    1- Nicholson AG, et al. Eight Edition Staging of Thoracic Malignancies: Implications for the Reporting Pahtologist. Arch Pathol Lab Med. 2018 May;142 (5):645-661.
    2- Shih AR, et al. Problems in the reproducibility of Classification of small lung adenocarcinoma: An International Interobserver Study. Histopathology. 2019 May 20. doi: 10.1111/his.13922.
    3- Schenider F, Dacic S. Histopathologic and Molecular Approach to staging of multiple lung nodules. Transl Lung Cancer Res. 2017 Oct: 6(5): 540-549.

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  • 33631

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    PC4.10 - Case Presentations: 3 or 4 Cases (ID 50)

    08:15 - 15:30  |  Author(s): Mercedes Liliana Dalurzo
    • Abstract

    Abstract not provided