Preliminary Experience with Proton Radiotherapy for Pelvic Bone Sarcomas

English

Reviewer: William Levin
Abramson Cancer Center of the University of Pennsylvania
Ultima Vez Modificado: 29 de mayo del 2007

Presenter: T. Delaney
Presenter's Affiliation: Massachusetts General Hospital
Type of Session: Scientific

Background

Surgery is commonly used for the definitive treatment of pelvic bone sarcomas.
However, acceptable surgical margins are difficult to achieve in this location.
Furthermore, surgical morbidity can be quite high in that amputation or disarticulation may be required.
Accordingly, radiation therapy plays and important role both in a definitive and adjuvant setting.
Control of microscopic disease requires a dose of at least 66Gy while in some bone sarcomas a control of residual disease requires a dose in the neighborhood of 75Gy.
These doses may in fact be difficult to achieve while still respecting tolerance doses to nearby normal tissue.
Proton therapy, therefore may offer an excellent alternative to the use of conventional photon radiotherapy.

Materials and Methods

This is a retrospective chart review of three patients with peri-acetabular chondrosarcomas managed with primary radiation therapy after biopsy or curettage/packing without radical surgery.
Tumor size ranged from 3.6 to 14 cm with a median size of 3.7 cm. Radiation therapy was given completely with protons.
50 Gy equivalent was given in 25 fractions to the CTV.
A GTV boost was composed of 24 Gy equivalent in 12 fractions.
Follow-up ranged from 16-36 months with the median follow-up of 36 months.

Results

All patients completed proton therapy without significant acute morbidity.
To date, no tumor or late morbidity has been seen in any patients.
Two of the patients are symptom free and carrying out extremely active lives (cycling, hiking) without any restriction.
Patient number 3 with the 14 cm lesion no longer needs narcotic pain medication and is now able to work part-time.

Author's Conclusions

Protons can deliver high radiation doses to pelvic sarcomas with little morbidity and might offer an alternative if radical surgery is declined.
The author is interested in collaborative studies given the scarcity of these tumors.
Tumor types to be included in these studies should include chondrosarcoma, osteosarcoma, MFH of bone, and Ewing 's sarcoma.

Clinical/Scientific Implications

Although this study is limited in the number of patients evaluated and in the length of follow up, proton radiation seems to offer excellent disease control of pelvic tumors with minimal long-term toxicity.
It also appears that the use of proton radiation after biopsy and curettage may offer a less morbid treatment than the use of definitive surgery, allowing patients to maintain active and productive lifestyles.