516P - Utility of colonoscopy in diagnosing familial adenomatous polyposis (FAP) among patients (pts) with desmoid tumors (DT)

Date 18 December 2016
Event ESMO Asia 2016 Congress
Session Poster lunch
Topics Hereditary Syndromes
Staging Procedures (clinical staging)
Presenter Zewen Zhang
Citation Annals of Oncology (2016) 27 (suppl_9): ix163-ix168. 10.1093/annonc/mdw597
Authors Z. Zhang1, M. Teo2, K.C. Soo2, M.H. Tan2, A.Y. Chung2, W.L. Goh1, S. Sathiyamoorthy3, K. Sittampalam3, J. Teh4, F. Chin4, S. Li1, J. Ngeow5, M. Farid1, R. Quek1
  • 1Division Of Medical Oncology, National Cancer Center, 169610 - Singapore/SG
  • 2Division Of Surgical Oncology, National Cancer Center, 169610 - Singapore/SG
  • 3Department Of Anatomical Pathology, Singapore General Hospital, 169856 - Singapore/SG
  • 4Division Of Radiation Oncology, National Cancer Center, 169610 - Singapore/SG
  • 5Dept. Medical Oncology, National Cancer Center, 169610 - Singapore/SG



Desmoid tumors are rare mesenchymal neoplasms and account for less than 3 percent of soft tissue tumors. The etiology of DTs is unclear. DT may arise sporadically or in association with FAP. Data of FAP among DT pts is limited, with prevalence varying between 4.8 to 16%. We aim to (1) study the clinical characteristics and treatment outcomes and (2) evaluate the clinical utility of colonoscopy in screening for FAP in pts with DT.


We undertook a retrospective chart review of DT pts seen in our centre. 22 pts with complete clinical, treatment and follow up data were enrolled.


Median age at diagnosis of DT was 32yrs (range 10 – 52yrs). 82% of patients were females. Primary sites of DT were as follows: intra-abdominal (IA; n = 3), abdominal wall (AW; n = 12), extra-abdominal (EA, n = 6) or concomitant IA/AW (n = 1). 20 pts presented to our centre with primary disease while 2 pts presented with recurrent disease. Primary DT treatment at our centre was surgery alone in 16 pts, systemic chemotherapy in 2 pts, radiotherapy in 1 pt, surgery plus radiotherapy in 2 pts and surgery plus chemotherapy in 1 pt. Of those who underwent surgery, 26% (n = 5) had complete R0 resection, 58% (n = 11) had microscopic R1 margin while 16% (n = 3) had macroscopic residual disease (R2). Median tumor size was 9.8 cm (range, 2.5-22.0 cm). At a median follow-up of 34 months, of 16 pts who had R0/R1 surgery, 31% (4 R1, 1 R0 margin) relapsed. 2 had IA, 2 AW and 1 had EA DT. Median relapse-free survival was 23 mths. 1 pt was known to have FAP, and had a procto-colectomy 12mths prior to the diagnosis of DT. 10 of the 22 pts had screening colonoscopies performed after diagnosis of DT was made; only 1 resulted in FAP diagnosis. This patient had a positive family history of FAP. Notably, 1 pt with a negative colonoscopy screen was subsequently diagnosed with FAP after APC gene aberration was confirmed on genetic testing.


In this small cohort of DT pts, 1 FAP was detected on colonoscopy. Interestingly, 1 pt without polyposis on colonoscopy was diagnosed with FAP on genetic testing raising the question of APC gene testing in DT pts.

Clinical trial indentification

Legal entity responsible for the study

National Cancer Center




R. Quek: Grants/research support: Novartis Pfizer Janssen Bayer Eisai Honoraria or consultation fees: Novartis Bayer BMS Merck Roche Eisai Participation in a company sponsored speaker’s bureau: Novartis Bayer Merck Eisai. All other authors have declared no conflicts of interest.