
Leiomyosarcoma is not always a good subject for irradiation.  There have been some LMS tumors that have continued to grow splendiferously despite and during heavy irradiation.  Other LMS tumors may have seemed to respond to the radiation, but recur and regrow at a later date.  LMS is considered a radioresistant tumor.  For irradiation of LMS, usually 70 Grays of radiation is used, and this is a very heavy dose.  

While it is not such a good idea to irradiate the liver in its entirety, sometimes tumors on or in the liver grow large.  Radiotherapy that is aimed just at the tumor can be used to shrink such a tumor, to make it operable, or for palliation.  

One football sized liver tumor was irradiated by Fermi Lab with its high-energy fast neutrons, and the woman was still alive, and her tumor was still shrinking, two years later.  

Proton beam, because it is a particle beam that does not go beyond the target area, is also a useful treatment modality if there is one large tumor in the area.  Proton Beam irradiation spares normal tissue posterior to the target area from radiation damage.  Proton Beam Irradiation of tumors is currently done at Loma Linda Hospital in California, and Massachusetts General Hospital in Boston.   There is a new facility opening up at the University of Indiana, as well.

IMRT, gamma knife, and stereotactic radiosurgery are methods which use Xrays [gamma rays] to irradiate tumors.  These rays go through the entire body, so that normal tissue also gets irradiated.  IMRT, gamma knife, and stereotactic modalities try to use so many different angles, so that the tumor gets irradiated heavily, and the surrounding tissues, not so much.


Radiother Oncol 1996 Dec;41(3):233-6 
<b>Clearance of parenchymal tumors following radiotherapy: analysis of hepatocellular carcinomas treated by proton beams.</b> 
Ohara K, Okumura T, Tsuji H, Min M, Tatsuzaki H, Chiba T, Tsujii H, Akine Y, Itai Y. Department of Radiology, University Hospital, University of Tsukuba, Japan. 

Clearance of a parenchymal tumor following radiotherapy was determined by using follow-up CT scans of 18 hepatocellular carcinoma tumors treated with focused proton beams. Regression analysis of the daily decrement (DD) and the diameter (D) of a tumor mass in each CT observation interval, DD = a*Db, showed that the exponent b was 3.0 or larger in early periods and 2.0 or smaller in late periods. This suggests that the clearance depends initially on the tumor volume, subsequently on the tumor surface area, and then it becomes much more moderate, possibly due to radiation damage to the parenchymal tissues. 
&&url PMID: 9027939 
