High practice variation in risk stratification, baseline oncological staging, and follow-up strategies for T1 colorectal cancers in the Netherlands

Abstract

<b>Background and study aims</b> Based on pathology, locally resected T1 colorectal cancer (T1-CRC) can be classified as having low- or high-risk for irradicality and/or lymph node metastasis, the latter requiring adjuvant surgery. Reporting and application of pathological high-risk criteria is likely variable, with inherited variation regarding baseline oncological staging, treatment and surveillance. <b>Methods</b> We assessed practice variation using an online survey among gastroenterologists and surgeons participating in the Dutch T1-CRC Working Group. <b>Results</b> Of the 130 invited physicians, 53 % participated. Regarding high-risk T1-CRC criteria, lymphangio-invasion is used by 100 %, positive or indeterminable margins by 93 %, poor differentiation by 90 %, tumor-free margin ≤ 1 mm by 78 %, tumor budding by 57 % and submucosal invasion > 1000 µm by 47 %. Fifty-two percent of the respondents do not perform baseline staging in locally resected low-risk T1-CRC. In case of unoperated high-risk patients, we recorded 61 different surveillance strategies in 63 participants, using 19 different combinations of diagnostic tests. Endoscopy is used in all schedules. Mean follow-up time is 36 months for endoscopy, 26 months for rectal MRI and 30 months for abdominal CT (all varying 3-60 months). <b>Conclusion</b> We found variable use of pathological high-risk T1-CRC criteria, creating risk for misclassification as low-risk T1-CRC. This has serious implications, as most participants will not proceed to oncological staging in low-risk patients and adjuvant surgery nor radiological surveillance is considered. On the other hand, oncological surveillance in patients with a locally resected high-risk T1-CRC who do not wish adjuvant surgery is highly variable emphasizing the need for a uniform surveillance protocol.