Project details

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Rectal cancer and the suspicious posttherapy presacral mass

Keywords:
MRI PET rectal cancer

Researchers:
Dr. T.C. Kwee
Dr. R.J. de Haas

Nature of the research:
Retrospective evaluation

Fields of study:
surgery gastroenterology radiology

Background / introduction
After surgery and chemoradiation for rectal cancer, almost 50% of patients develop a presacral soft tissue mass. In the majority of patients, this soft tissue mass represents fibrosis (scar tissue). However, in patients with rising CEA levels (carcinoembryonic antigen, a blood marker that can suggest disease recurrence) during follow-up, and a positive nuclear FDG-PET scan (i.e., increased metabolic activity in this presacral mass), there is a suspicion of a local recurrence. Invasive biopsy is necessary for confirmation. Based on experience, however, the value of the FDG-PET scan in this setting is overestimated and frequently false-positive; there is no recurrent rectal cancer, but only fibrosis/inflammation. A new advanced MRI scan that can detect the motion of water molecules at a microscopic level (diffusion-weighted MRI) may improve the differentiation between fibrosis/inflammation and recurrent carcinoma, and thus reduce the need for invasive biopsies in these patients.
Research question / problem definition
1. What is the positive predictive value of FDG-PET for recurrent rectal cancer in a presacral mass?
2. Can diffusion-weighted MRI improve the differentiation between recurrent rectal cancer and fibrosis/inflammation in patients with an FDG-PET positive presacral mass?
Workplan
This project is suited for a medical student in his/her senior Bachelor (2nd or 3rd year) or Master phase for a period of 8-12 weeks. The final product will be a co-authored scientific article. Time schedule: part 1: familiarisation with the topic; part 2: data collection (retrospective data from our digital Picture Archiving and Communication System); part 3: data analysis and manuscript writing. Attendance of weekly clinical multidisciplinary gastro-entero-oncological meetings (with surgeons, gastro-enterologists, radiation oncologists, and imaging physicians) is also possible.
References
1. Even-Sapir E, Parag Y, Lerman H, Gutman M, Levine C, Rabau M, Figer A, Metser U. Detection of recurrence in patients with rectal cancer: PET/CT after abdominoperineal or anterior resection. Radiology 2004;232:815-822
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