Reporting of Tumour Deposits in Colorectal Cancer by Radiology and Pathology

Background:

There is increasing evidence that Tumour Deposits (TDs) play an important role in determining prognosis in colorectal cancer patients, both on pathology and on pre-operative imaging (1-2). There is a great variation in their reported prevalence on pathology (1) depending on the staging system and pathology techniques used. Previous work to determine the prevalence of TDs in the UK has relied on the TNM 5 classification, since the 6th and 7th editions were not adopted into UK practice. In TNM 5, all tumour nodules of >3mm were classified as lymph nodes, regardless of whether there was evidence of underlying nodal architecture. Nodules of under 3mm were included in the T stage. Reporting of TDs only took place if the pathologist made specific mention of them in the body of the report, therefore the reported prevalence was very low (6%) compared to when detected on imaging (36%)(2). TNM 8, released in 2017, is the current Tumour Node Metastases staging system used for colorectal cancer (3) and was adopted in the UK from January 2018 onwards. In TNM 8 however, TDs in the subserosa, or in non-peritonealised pericolic or perirectal soft tissue without regional lymph node metastatic disease are reported as N1c. The aim of this multicentre retrospective evaluation is to understand if TDs are being routinely reported in imaging and pathology in rectal cancer patients since the introduction of TNM 8.

Rationale:

There is increasing evidence that TDs impact the recurrence of cancer and cancer death in patients with rectal cancer for the worse. These patients may therefore benefit from additional treatment with chemotherapy or radiotherapy. However, if we are not recording TDs routinely, and don't know at the time of deciding how to treat these patients that they have TDs, then we are not counselling patients properly as well as may not be offering them additional chemotherapy or radiotherapy.

Objectives:

Primary Objectives:

To determine whether, since the introduction of TNM 8, TDs are being routinely reported in staging of rectal cancer on imaging and pathology

Secondary Objective:

To determine if there is as positive association between the reporting of TDs and the reporting of Extramural Venous Invasion.

References:

Please see separate References Section

Inclusion criteria

• Primary adenocarcinoma of the rectum (proven by biopsy)
• Undergone surgical resection between 01st January 2007 to 31st December 2017 inclusive for the TNM 5 cohort
• Undergone surgical resection between 01st January 2022 to 31st December 2024 inclusive for the TNM 8 cohort

• Staging with MRI reports are available 4. Post-operative pathology report available 5. Patients aged 16 years and over

Exclusion criteria

• Synchronous metastatic tumours
• Under the age of 16 years
• MRI and/or pathology reports are not available