Diagnostics and histopathology of transverse colon and splenic flexure tumours

Introduction

Left- and right-sided colon cancer differ in many aspects including histopathology. It is unknown whether there may be a gradient within the transverse colon (TC) and splenic flexure (SF).

Methods

All patients in Southern, South-Eastern and Western health-care regions of Sweden diagnosed with cancer in TC or SF 2018–2021 were identified from the Swedish Colorectal Cancer Registry. Data was collected from the registry and meticulous review of medical records. TC was divided into three sections.

Results

Among 1218 patients, 1235 tumours were diagnosed at a median age of 76 years. Synchronous tumours occurred in 10.5% of TC and 6.3% of SF cancers. At presentation, anaemia (47.6%) and abdominal pain (22.2%) were the most common symptoms.

Computerized tomography and colonoscopy were less accurate in localising tumours in TC compared with SF, and localisation was least accurate in the middle part.

T3 tumours occurred somewhat more frequently in SF than TC (P = 0.04). Otherwise, neither stage nor metastatic locations differed significantly between locations.

MMR deficiency and BRAF mutations were more frequent in TC compared with SF tumours, whereas KRAS mutations were more common in SF. Within TC, no clear gradient was observed for either MMR deficiency or KRAS mutations. The frequency of high-grade tumours decreased from TC towards SF. Within TC, a gradual decrease from right to left was observed (P = 0.003).

Discussion

TC tumours differ from those at SF in several characteristics. Notably, synchronous tumours are more common in TC cancer, and tumour localisation is frequently inaccurate.