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Post-treatment survival difference between lobectomy and stereotactic ablative radiotherapy in stage I non-small cell lung cancer in England
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  • Published on:
    Response to Kennedy et al

    We thank Dr Kennedy and colleagues for their interest in our recent
    paper comparing outcomes after surgery and SABR radiotherapy in
    stage I non-small cell lung cancer (1,2) .
    We agree that intraoperative nodal upstaging can be a cause of stage
    migration in the surgical arm but not the SABR arm, and so could act
    as a potential bias in an observational study. This might
    overestimate the benefit of surgery compared to SABR. The Society
    for Cardiothoracic Surgery Database Project reported 2155 patients
    undergoing lung cancer resections in England from 2014-16, and
    found that over 13% of patients underwent nodal upstaging when
    their resection pathology was analysed (3) .
    The information bias inherent in having full pathological data
    available for surgical but not SABR cases leads to other potential
    problems with analysis. All patients undergoing surgery have a
    pathological analysis confirming the cancer and its stage, while 240
    of the 476 patients treated with SABR were treated without a
    pathological diagnosis. A recent prospective UK study found that
    14% of patients operated on for presumed lung cancer had benign
    disease on intraoperative frozen section biopsy or final pathology (4) .
    Assuming that this surgical false negative rate approximates the rate
    in the suspected early clinical stage patients treated with SABR, then
    around 7% of our SABR arm may...

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    Conflict of Interest:
    None declared.
  • Published on:
    Nodal staging should not be left out of the equation
    • Martyn P T Kennedy, Consultant Respiratory Physician Leeds Teaching Hospitals NHS Trust
    • Other Contributors:
      • Katie L Spencer, Specialist Trainee in Oncology
      • Alesandro Brunelli, Consultant Thoracic Surgeon
      • Kevin Franks, Consultant Oncologist
      • Matthew E J Callister, Consultant Respiratory Physician

    We read with interest the report from Khakwani and colleagues comparing real-world outcomes for patients with stage I NSCLC undergoing surgery and stereotactic radiotherapy (SABR) (Ref 1), together with the accompanying editorial (Ref 2). Given the failure to recruit to previous randomised trials designed to compare these treatments, analyses of large national datasets are vital to improve our understanding of how best to manage this patient group.

    One additional possible explanation for the worse outcome in the SABR cohort relates to occult nodal involvement. Inaccuracies in clinical staging are well described; one analysis documented that 34% of patients are under-staged by pre-operative work-up (Ref 3). Patients with occult nodal disease would have been identified in the surgical group by intraoperative systematic nodal staging, and would therefore have been excluded from analysis of the Stage I cohort presented here (Ref 1). Patients who are similarly under-staged prior to SABR treatment will remain in the Stage I cohort for analysis, yet will have worse outcomes by virtue of their more advanced disease. Comparing outcomes on an intention-to-treat basis using pre-treatment stage may minimise this bias.

    We agree with the authors that residual confounding may be an important factor explaining these results, and that examination of cause of death is instructive. In our single centre study, cause of death was compared (on an intention to treat basis) between...

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    Conflict of Interest:
    None declared.