Dose Reduction of Preoperative Radiotherapy in Myxoid Liposarcomas

- A Bayesian approach is considered for the analysis of this trial. The aim is to provide
a stopping rule for inefficacy of the new dose.

- Two aspects are important to elucidate the mechanism of this treatment: dynamic
investigations of perfusion and vasculature. Apart from participation to the dose
reduction paragraphs of this study, patients will be also asked to undergo, at
clinically relevant dose points, dynamic contrast enhanced (DEC) MRI scans and
separately tumor biopsies.

Inclusion Criteria:

1. Age above or equal to 18 years

2. Biopsy proven MLS (including the reciprocal chromosomal translocation
t(12;16)(q13;p11); A the primary sarcoma in case of non-metastatic disease for
management is with curative intent (regimen to be chosen = 18 x 2 GY) B in case of
oligometastatic patients, the metastasis may also be irradiated to a dose of 36 GY in
order to postpone the time interval to next systemic chemotherapy. These patients are
usually not operated upon and the total dose may also be reached in 12 times 3 Gy, for
convenience purposes (see paragraph 10 for radiobiological considerations).

3. ECOG (Eastern Cooperative Oncology Group) PS (Performance Status) 0-2

4. Patients must be able (physically, mentally and socially) to complete a series of RT,
followed by an observation period of 4-6 weeks and undergo surgery.

5. Written informed consent

Exclusion Criteria:

1. Prior radiotherapy to the target area.

2. Anticoagulant medication of any kind; especially Ascal®(and derivates), coumarines
(Sintrom® and Marcoumar®), all heparin and heparin-like formulations. (Note: this
exclusion criterion only applies for patients consenting to the translational research
part of the study; patients on anticoagulant medication as described above may take
part in the dose reduction part of the study, but the repeat biopsies may not be
taken.)

3. Pregnancy -