Gerald Saldanha1,2, Rokiah Ali3, Arti Bakshi4, Ahmed Basiouni5, Rachael Bishop2, Peter Colloby6, Paul Craig7, Philip Da Forno2, Sara Edward8, Olivia Espinosa de Los Monteros9, Alan Evans10, Lynne Jamieson11, Ed Rytina12, Mark Bamford2. 1. Leicester Cancer Research Centre, University of Leicester, Leicester, UK. 2. University Hospitals of Leicester NHS Trust, Leicester, UK. 3. The Rotherham Hospital NHS Foundation Trust, Rotherham, UK. 4. Royal Liverpool University Hospital NHS Trust, Liverpool, UK. 5. Royal United Hospitals, Bath NHS Foundation Trust, Bath, UK. 6. University Hospitals Birmingham NHS Trust, Birmingham, UK. 7. Gloucestershire Hospitals NHS Foundation Trust, Gloucester, UK. 8. St James's University Hospital, Leeds, UK. 9. Oxford University Hospitals NHS Foundation Trust, Oxford, UK. 10. Ninewells Hospital and Medical School, Dundee, UK. 11. Salford Royal Hospital, Salford, UK. 12. Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK.
Abstract
AIMS: Staging is the gold standard for predicting malignant melanoma outcome but changes in its criteria over time indicate ongoing evolution. One notable recent change from the 8th edition of the American Joint Committee on Cancer (AJCC) staging manual was removal of mitotic count. We explore the extent to which this feature is limited by interobserver error in order to find ways to improve its fitness for use should it be revisited in future staging versions. METHODS AND RESULTS: In a cohort of 476 patients with melanoma ≤1.0 mm, a mitotic count of 0 versus 1 was significant for metastasis-free survival, but not melanoma-specific or overall survival. In 10 melanomas that were 0.9-1.0 mm thick, the mitotic count intraclass correlation coefficient for histopathologists was 0.58 (moderate agreement). Uniquely, we also assessed agreement for specific putative mitotic figures, identifying precise reasons why specific mitotic figures qualified for scoring or elimination. A kappa score was 0.54 (moderate agreement). We also gathered data on other staging features. Breslow thickness had an intraclass correlation coefficient of 0.41 (moderate agreement) and there was a systematic difference between histopathologists among cases (P = 0.04). Every case had a range that crossed the AJCC8 0.8-mm pT1a/pT1b staging boundary. Ulceration was only identified in two of the 10 cases. For ulceration, kappa agreement score was 0.31 (fair). CONCLUSION: This study supports the removal of mitotic count from staging, but shows that its scoring is substantially affected by interobserver variation, suggesting that more prescriptive guidelines might have a beneficial impact on its prognostic value.
AIMS: Staging is the gold standard for predicting malignant melanoma outcome but changes in its criteria over time indicate ongoing evolution. One notable recent change from the 8th edition of the American Joint Committee on Cancer (AJCC) staging manual was removal of mitotic count. We explore the extent to which this feature is limited by interobserver error in order to find ways to improve its fitness for use should it be revisited in future staging versions. METHODS AND RESULTS: In a cohort of 476 patients with melanoma ≤1.0 mm, a mitotic count of 0 versus 1 was significant for metastasis-free survival, but not melanoma-specific or overall survival. In 10 melanomas that were 0.9-1.0 mm thick, the mitotic count intraclass correlation coefficient for histopathologists was 0.58 (moderate agreement). Uniquely, we also assessed agreement for specific putative mitotic figures, identifying precise reasons why specific mitotic figures qualified for scoring or elimination. A kappa score was 0.54 (moderate agreement). We also gathered data on other staging features. Breslow thickness had an intraclass correlation coefficient of 0.41 (moderate agreement) and there was a systematic difference between histopathologists among cases (P = 0.04). Every case had a range that crossed the AJCC8 0.8-mm pT1a/pT1b staging boundary. Ulceration was only identified in two of the 10 cases. For ulceration, kappa agreement score was 0.31 (fair). CONCLUSION: This study supports the removal of mitotic count from staging, but shows that its scoring is substantially affected by interobserver variation, suggesting that more prescriptive guidelines might have a beneficial impact on its prognostic value.
Authors: Giovanni Damiani; Alessandra Buja; Enzo Grossi; Michele Rivera; Anna De Polo; Giuseppe De Luca; Manuel Zorzi; Antonella Vecchiato; Paolo Del Fiore; Mario Saia; Vincenzo Baldo; Massimo Rugge; Carlo Riccardo Rossi; Gianfranco Damiani Journal: Acta Derm Venereol Date: 2020-11-18 Impact factor: 3.875
Authors: Ian A Cree; Puay Hoon Tan; William D Travis; Pieter Wesseling; Yukako Yagi; Valerie A White; Dilani Lokuhetty; Richard A Scolyer Journal: Mod Pathol Date: 2021-06-02 Impact factor: 7.842