Early rectal cancer and screening for colorectal cancer

Abstract

Colorectal cancer (CRC) is the second most common form of cancer in Europe, and population based screening for colorectal cancer is recommended by the European Union. Screening enables detection of precursor lesions, i.e. adenomas, and cancer at an early stage, and randomised trials have demonstrated that screening reduces mortality in colorectal cancer. In rectal cancer, oncological results after abdominal resection surgery have improved over many years, but the morbidity, mortality and negative functional side effects following surgery and oncological treatment are considerable. Local excision techniques, on the other hand, demonstrate excellent functional results and a low morbidity and mortality but have high local recurrence rates, mainly since the technique does not allow for excision of mesorectal lymph nodes, which could be exposed to metastatic disease not detectable in the preoperative radiological staging. Since further expansion of population based screening programs for CRC will increase the detection of early cancer, local excision techniques are of great interest, provided that an adequate oncological out-come can be ensured.

In paper I all patients in Sweden undergoing surgery for stage I rectal cancer 1995-2006 were assessed regarding survival, local recurrence rates and risk factors for death. Patients undergoing local excision had a higher local recurrence rate and a poor survival, especially in the age group ≥ 80 years, compared to patients undergoing abdominal resection surgery.

Paper II analysed risk factors for lymph node metastases in patients with rectal cancer. All patients in Sweden 2007-2010 with histopathologically confirmed radical resections of pT1-2 rectal cancer follow-ing abdominal resection surgery without (neo)adjuvant treatment were included. T2 stage, poor differen-tiation and vascular infiltration were identified as risk factors for lymph node metastases. A model calcu-lating the total risk depending on the number of risk factors included, displayed a risk range of 6-65 % and 11-78 % in T1 and T2 tumours respectively.

In paper III all Swedish patients aged 60-69 years with screening detected colorectal cancer were com-pared to those with non-screening detected cancer diagnosed 2008-2012. Pre- and postoperative staging, MDT-assessment, surgical and oncological treatment were compared between the groups. Patients with screening detected cancer were staged and MDT-assessed to a higher extent compared to those with non-screening detected cancer and tumours were found at an earlier stage in the screening group. Surgical and oncological treatment did not differ between the groups. Patients with endoscopically resected can-cer did not undergo staging and MDT-assessment to the same extent as did patients with surgically re-sected cancer.

Paper IV included all individuals with a positive FOBT in the Stockholm screening programme, January 2008 - June 2012. Complications and mortality within 30 days after interventions, i.e. colonoscopies or surgery for adenomas or cancer, subsequent to a positive screening test were assessed. Total complica-tion rates were acceptable and mortality was low, but the rate of anastomotic leakage, which was 13 % and 12 % in the adenoma and cancer surgery groups respectively, was higher than expected.