Clinical consequences of diagnostic variability in the histopathological evaluation of early rectal cancer

• Published in: European journal of surgical oncology Vol. 49; no. 7; pp. 1291 - 1297
• Main Authors: Smits, Lisanne J.H., van Lieshout, Annabel S., Bosker, Robbert J.I., Crobach, Stijn, de Graaf, Eelco J.R., Hage, Mariska, Laclé, Miangela M., Moll, Freek C.P., Moons, Leon M.G., Peeters, Koen C.M.J., van Westreenen, Henderik L., van Grieken, Nicole C.T., Tuynman, Jurriaan B., Bastiaansen, B.A.J., Beets, G., Bonsing, B.A., Borstlap, W.A.A., Bruin, S., Burger, J.W.A., de Hingh, I., de Wilt, J.H.W., Demirkiran, A., Denost, Q., Didden, P., Dunker, M.S., Fabry, H.F.J., Gerhards, M.F., Grotenhuis, B.A., Hoff, C., Hompes, R., Koedam, T.W.A., Leijtens, J.W.A., Mol, L., Pronk, A., Sietses, C., Smits, A., Spillenaar Bilgen, E.J., Talsma, A.K., Tanis, P.J., Toorenvliet, B.R., Tuech, J., van de Ven, A., van der Bilt, J., van der Schelling, G., van Duijvendijk, P., van Grevenstein, W.M.U., van Leerdam, M., van Oostendorp, S.E., Verdaasdonk, E.E.G., Vogels, S., Vuylsteke, R.J.C.L.M., Zimmerman, D.D.E.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.07.2023
• Subjects: Clinical consequences; Diagnostic variability; Digestive System Surgical Procedures; Early rectal cancer; Humans; Lymphatic Metastasis; Lymphovascular invasion; Neoplasm Staging; Prospective Studies; Rectal Neoplasms - pathology; Rectal Neoplasms - surgery; Diagnostic variability; Early rectal cancer; Clinical consequences; Lymphovascular invasion
• ISSN: 0748-7983; 1532-2157
• DOI: 10.1016/j.ejso.2023.02.008

In early rectal cancer, organ sparing treatment strategies such as local excision have gained popularity. The necessity of radical surgery is based on the histopathological evaluation of the local excision specimen. This study aimed to describe diagnostic variability between pathologists, and its impact on treatment allocation in patients with locally excised early rectal cancer. Patients with locally excised pT1-2 rectal cancer were included in this prospective cohort study. Both quantitative measures and histopathological risk factors (i.e. poor differentiation, deep submucosal invasion, and lymphatic- or venous invasion) were evaluated. Interobserver variability was reported by both percentages and Fleiss’ Kappa- (ĸ) or intra-class correlation coefficients. A total of 126 patients were included. Ninety-four percent of the original histopathological reports contained all required parameters. In 73 of the 126 (57.9%) patients, at least one discordant parameter was observed, which regarded histopathological risk factors for lymph node metastases in 36 patients (28.6%). Interobserver agreement among different variables varied between 74% and 95% or ĸ 0.530–0.962. The assessment of lymphovascular invasion showed discordances in 26% (ĸ = 0.530, 95% CI 0.375–0.684) of the cases. In fourteen (11%) patients, discordances led to a change in treatment strategy. This study demonstrated that there is substantial interobserver variability between pathologists, especially in the assessment of lymphovascular invasion. Pathologists play a key role in treatment allocation after local excision of early rectal cancer, therefore interobserver variability needs to be reduced to decrease the number of patients that are over- or undertreated.