The International Association for the Study of Lung Cancer Lung Cancer Staging Project: Application and Interpretation of the Residual Tumor (R) Classification for Lung Cancer. Results from an International Survey among Pathologists and Thoracic Surgeons.

Objective: The study aimed to assess the opinion of pathologists and thoracic surgeons of the International Association for the Study of Lung Cancer (IASLC) regarding application and interpretation of the residual tumor (R) classification for lung cancer.

Methods: Based on their membership-profile a total of n=623 pathologists and thoracic surgeons were identified and contacted by email with a cover letter and a link to an online survey. The questionnaire consisted of 12 questions about various aspects on application and interpretation of the R classification for lung cancer. The response rate (to at least one question) was 72% (144 pathologists and 303 surgeons).

Results: Frequency of use of the R classification varies by geographic region. While R status is regularly reported in Europe and Asia, seventy percent of pathologists in the US or Canada never include R status on reports. Similar variation exists about who assigns the R category for the resection - in Europe and the UK it is mainly the pathologist, whilst in China/Japan and US it is the surgeon. There are some good agreements about margins examined and how to manage staple lines. The category "uncertain resection" R(un) has not been practically implemented in most of the world, except at some centers in Japan and the UK.

Conclusion: This survey shows that surgical resection margins are part of routine reporting in most institutions, but assignment of an R category is not always part of the pathology report, with considerable variation between countries. Application of R(un) has not been taken up by most institutions, despite IASLC proposals, and further evidence is needed.