Systematic endoscopic staging of mediastinum to determine impact on radiotherapy for locally advanced lung cancer (SEISMIC): protocol for a prospective single arm multicentre interventional study

A prospective analysis of the management practices for patients with Stage-III-N2Non-Small-Cell lung cancer (OBSERVE IIIA-B GFPC 04-2020Study)

BACKGROUND

Management of stage-III-N2 non-small-cell lung cancer (NSCLC) based on a multimodal strategy (surgery or radiotherapycombined with systemic drugs) remains controversial. Patients are treated with a curative intent, and available data suggestprolonged survival after complete resection. However, no consensual definition of "tumor resectability" exists. This study aimed to analyze the concordanceamong French tumor board meeting (TBM)-emittedtherapeutic decisions forstage-III-N2 NSCLC.

METHODS

Six patients with stage-III-N2 NSCLC discussed at Saint-Etienne University Hospital'sthoracic TBMs were selected, anonymouslyreported, and submitted to the participating TBMs. The primary goal of this multicenter, prospective, observational study was to assess the consistency of TBMpanel decisions for each case. The secondary endpointwas identifying the demographic or technical factors that potentiallyaffected decision-making.

RESULTS

Twenty-seven TBMs from university hospitals, a cancer center, general hospitals, and a private hospitalparticipated in this study. None of their decisions for the six cases were unanimous.The decisions were homogenous for three cases (78%, 85%, and 88% TBMs opted for medical treatment, respectively),andmore ambivalent for the other three (medical versus surgical strategies were favored by 44%/56%, 46%/54%, and 58%/42% TBMs, respectively). Interestingly, decisions regarding chemoradiationand perioperative chemotherapyinthe medical and surgical strategies, respectively, were also discordant. Hospital type, specialist participation in TBMs, and activity volumes were not significantly associated with therapeutic decisions.

CONCLUSION

The results of this study highlight substantial disparities amongFrench TBMs regarding therapeutic management of stage-III-N2 NSCLC. The decisions were not associated with local conditions.

Systematic endoscopic staging of mediastinum to guide radiotherapy planning in patients with locally advanced non-small-cell lung cancer (SEISMIC): an international, multicentre, single-arm, clinical trial

BACKGROUND

Systematic mediastinal lymph node staging by endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) improves accuracy of staging in patients with early-stage non-small-cell lung cancer (NSCLC). However, patients with locally advanced NSCLC commonly undergo only selective lymph node sampling. This study aimed to determine the proportion of patients with locally advanced NSCLC in whom systematic endoscopic mediastinal staging identified PET-occult lymph node metastases, and to describe the consequences of PET-occult disease on radiotherapy planning.

METHODS

This prospective, international, multicentre, single-arm, international study was conducted at seven tertiary lung cancer centres in four countries (Australia, Canada, the Netherlands, and the USA). Patients aged 18 years or older with suspected or known locally advanced NSCLC underwent systematic endoscopic mediastinal lymph node staging before combination chemoradiotherapy or high-dose palliative radiotherapy. The primary endpoint was the proportion of participants with PET-occult mediastinal lymph node metastases shown following systematic endoscopic staging. The study was prospectively registered with Australian New Zealand Clinical Trials Registry, ACTRN12617000333314.

FINDINGS

From Jan 30, 2018, to March 23, 2022, 155 patients underwent systematic endoscopic mediastinal lymph node staging and were eligible for analysis. 58 (37%) of patients were female and 97 (63%) were male. Discrepancy in extent of mediastinal disease identified by PET and EBUS-TBNA was observed in 57 (37% [95% CI 29-44]) patients. PET-occult lymph node metastases were identified in 18 (12% [7-17]) participants, including 16 (13% [7-19]) of 123 participants with clinical stage IIIA or cN2 NSCLC. Contralateral PET-occult N3 disease was identified in nine (7% [2-12]) of 128 participants staged cN0, cN1, or cN2. Identification of PET-occult disease resulted in clinically significant changes to treatment in all 18 patients. In silico dosimetry studies showed the median volume of PET-occult lymph nodes receiving the prescription dose of 60 Gy was only 10·1% (IQR 0·1-52·3). No serious adverse events following endoscopic staging were reported.

INTERPRETATION

Our findings suggests that systematic endoscopic mediastinal staging in patients with locally advanced or unresectable NSCLC is more accurate than PET alone in defining extent of mediastinal involvement. Standard guideline-recommended PET-based radiotherapy planning results in suboptimal tumour coverage. Our findings indicate that systematic endoscopic staging should be routinely performed in patients with locally advanced NSCLC being considered for radiotherapy to accurately inform radiation planning and treatment decision making in patients with locally advanced NSCLC.

FUNDING

None.

Systematic mediastinal staging in non-small cell lung cancer: Filling in the guideline evidence gap

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