Desmoïdtumoren bij patiënten met familiaire adenomateuze polyposis

- Desmoid tumours (DT) are slow-growing tumours that consist of proliferations of well-differentiated fibroblasts. Although the typical characteristics of malignant tumours, such as distant metastases, are absent, the tumours are locally aggressive and grow into neighbouring structures.

- The prevalence of desmoid tumours in patients with FAP is 7-12. The lifetime risk of developing desmoid tumours is about 20. In FAP, most tumours are intra-abdominal or located in the abdominal wall. Next to colorectal cancer, desmoid tumours are the most frequent cause of death in FAP.

- Possible risk factors for the development of desmoid tumours are previous surgical procedures, pregnancy, female sex, a family history of desmoid tumours, and specific mutations in the APC-gene.

- Both CT scanning and MRI can be used to detect the tumours. An excision biopsy is needed to establish the diagnosis.

- Medicinal treatment with NSAIDs is the treatment of first choice, followed by hormonal treatment (e.g. tamoxifen) in combination with NSAIDs. Both forms of treatment lead to a response in about 30-50 of the patients.

- Surgery is the preferred treatment for extra-abdominal tumours or tumours located in the abdominal wall. Surgical treatment of intra-abdominal tumours is only indicated in patients with obstruction of the bowel or ureter.

- Chemotherapy is indicated in patients with progressive desmoid tumours when non-cytotoxic treatment has failed. Radiotherapy may play a role in the treatment of irresectable extra-abdominal or abdominal wall tumours, or as adjuvant treatment of tumours with positive margins.