The data were collected in the Medical Spectrum Twente, a large community teaching hospital in the regional capital of a foremost rural area in the eastern part of the Netherlands. It functions as a regional referral center for liver and lung surgery, but has no facilities for the treatment of peritoneal carcinomatosis with hyperthermic intraperitoneal chemotherapy (HIPEC).
The study design is a prospective observational cohort study evaluating the outcome of routine staging with abdominal CT concerning the ability to find liver metastases (LM), peritoneal carcinomatosis (PC) and T4-stage in colon cancer (LACC). All patients in our hospital who where treated for CRC from January 2007 till December 2009 were included in the analysis; all surgical patients with CRC in the study hospital were prospectively registered in a database designed for colorectal surgery, including patient characteristics, staging and surgical procedures, the clinical M stage and pathological TNM stage, post-operative mortality, treatment of metastases and follow-up; patients with the diagnosis of CRC in the same 3 years who did not undergo surgery were identified by the regional cancer registry and retrospectively added to the database. The clinical T stage of colon cancer on abdominal CT (cT4 or non-cT4) was retrospectively scored based upon the original radiology reports.
Routine pre-operative staging with a CT of chest and abdomen for patients with CRC was introduced as a regional CRC guideline in 2007 and preceded similar national guideline recommendations (2008). CT scanning was performed on a 16 and 64 slice scanner (Toshiba Aquillion 16 and 64) after intravenous contrast injection (visipaque 320, 90 ml, 3 ml/s.) in the portal venous phase, with a slice thickness of 1 mm and a reconstruction of 0.8 mm. When preoperative scanning was omitted, staging with abdominal CT was intended within 3 months after surgery. Patients with rectal cancer, defined as localization below the peritoneal reflection, were additionally staged with a pelvic MRI for determination of the local invasion and possible lymph node metastases (cTN stage) and received neo-adjuvant (chemo)radiation according to the Dutch guidelines on rectal cancer. Follow-up after curative treatment of non-metastatic CRC consisted of serum CEA measurements every 3 months combined with bi-annual ultrasound of the liver.
Pathological staging was based upon the TNM classification 2002 (6th edition) and classified according to the American Joint Committee on Cancer (AJCC) stages. Advanced CRC was defined as either locally advanced disease, presence of distant metastases or both. Locally advanced colon cancer (LACC) was defined by pT4 stage; meaning the tumor showed invasion through the serosal layer or into surrounding organs. Locally advanced rectal cancer (LARC) was defined as all patients that had either a T4 tumor or a T3 tumor with a threatened circumferential margin on pelvic MRI. The final diagnosis of liver metastases was based upon radiological (CT, contrast-enhanced ultrasound and/or PET scanning) and per-operative findings. In case of resection or in case of persistent uncertainty, histological confirmation was obtained. The final diagnosis of peritoneal carcinomatosis was by histological confirmation. The final diagnosis of lung lesions was on radiological grounds (chest CT). In case of resection or indeterminate lung lesions, histological confirmation was obtained when feasible. Several lung lesions remained indeterminate: these were followed by repeat CT scanning and considered positive when growth was observed . Incurable CRC was defined as all macroscopical irradical (R2) resections of the primary tumor, when the patient had no resection of the primary tumor, or when no intended curative treatment of distant metastases was done.
Emergency presentation in the surgical patients was defined as all non-planned admissions to the hospital due to symptoms related to the tumor, with a subdivision into 'urgent' defined as surgery imperative within 5 days and 'acute' procedures within 6 hours.
The ability of the staging abdominal CT to detect advanced disease was analyzed in surgical patients that were staged with CT before treatment; the gold standard for PC and LACC were per-operative findings confirmed with histology. For LM the findings on CT (negative for liver metastases or indeterminate lesions) were related to per-operative findings and follow-up.