AbstractsBiology & Animal Science

For localized colorectal cancer (CRC), lymph node metastases are the most powerful prognostic factor for disease specific and overall survival. In the first part of the thesis, we explore the prognostic role of lymph nodes in patients with stage I/II colon cancer. In these patients, nodal metastases are not detected with conventional pathological examination. Additional immunohistochemistry in the sentinel lymph node can reveal isolated tumour cells and micrometastasis. Studies in this thesis show that patients with micrometastasis have an increased risk of disease recurrence. Isolated tumour cells are not associated with worse prognosis. We also describe a positive correlation between lymph node size, lymph node harvest and prognosis. The second part of the thesis addresses several aspects of a multi-modality approach in the treatment of CRC. The aim of curative surgery for CRC is radical resection of the tumour. This can be difficult when tumours are large and advanced, or when emergency surgery is required because of obstructive tumours. In addition, microscopic tumour seeding within the peritoneal cavity might occur unnoticed. In these situations, surgical treatment alone is not sufficient to cure the patient and a multimodality approach should be applied. We analyzed the chance of a pathological complete tumour response after neoadjuvant chemoradiotherapy (CRT) for rectal cancer and calculated the optimal timing of surgery after (CRT). In addition, we describe the long term oncological follow up of patients that have been treated for obstructive colon cancer, and describe how adjuvant intraperitoneal chemotherapy might prevent the outgrow of peritoneal metastasis.