PhD Defence by Laurids Østergaard Poulsen
Laurids Østergaard Poulsen will defend his PhD thesis: "Diagnostic, Predictive and Therapeutic Aspects on Adenocarcinoma of the Rectum"
26.10.2018 kl. 13.00 - 17.00
Each year, approximately 1400 new patients are diagnosed with rectal cancer (RC) in Denmark. In the interest of ensuring an optimal clinical outcome, accurate diagnostic and predictive information are essential to avoid overtreatment and, consequently, unnecessary side effects.
In paper I, the accuracy of preoperative diagnostic MRI staging of RC according to tumour height was assessed. The ability to accurately stage RC by MRI is not influenced by tumour height; however, staging is still uncertain in daily clinical practice, with many patients being over- or understaged, potentially leading to over- or undertreatment of RC.
In paper II, the value of gene expression for predicting resistance to long-course preoperative chemoradiation therapy was investigated in a strictly selected cohort of patients with advanced tumours (cT4). A total of 9 genes and 3 miRNAs were found and validated as predictors of chemoradiation therapy resistance. This result provides a foundation for further studies that would allow diagnostic biopsy to yield much more information that it currently does.
In paper III, the value of postoperative adjuvant chemotherapy for RC patients was assessed by means of a systematic review. In patients treated with surgery alone, a clear gain in disease-free survival was observed, whereas in patients treated with preoperative chemoradiation, no gain from postoperative adjuvant chemotherapy was identified. These findings have contributed to evidence that has led to an updated version of the Danish guidelines.
In paper IV, the impact of the strictly designed Danish selection of RC patients for preoperative chemoradiation on local recurrence and overall survival was evaluated in a national cohort. The local recurrence rate was equal to those reported in corresponding international studies. Given the results from other Nordic countries, supporting evidence continues to mount for a restrictive use of preoperative radiotherapy in RC patients.
In conclusion, this thesis provides indications that RC patients need better preoperative staging. Diagnostic imaging is still suboptimal and should be further improved. Prediction of response or resistance to preoperative chemoradiation therapy in RC patients may be possible using molecular genetic assessments. The low actual local recurrence rate of RC justifies restricted use of preoperative chemoradiation in Denmark, and the use of postoperative adjuvant chemotherapy may be recommended only for a subgroup of RC patients.
Aalborg University Hospital – Room: Auditoriet Afsnit Syd