(p.127)- Neutrons have been used for PCa since 1977. One study from RTOG (Radiation Therapy Oncology Group) clinical trial comparing neutrons+photons versus photons alone on patients T3-4, N0-1, M0 . Out comes at 10 yrs. for patients with mixed beam treatment found superiority in overall survival, disease-specific survival and freedom from clinical local tumor recurrence.
A subsequent study done in locally advanced PC comparing RT photons at 70-72 Gy (prostate) and approx. 50 Gy (pelvic nodes) vs. neutron RT using 20 Gy (prostate) and 13.6 Gy (pelvic nodes). (note lower doses on neutron, because of power of the ray). Median follow up was 68 months, the 5 yr. actuarial clinical local-regional failure rate was 32% for photons and only 11% for neutron patients. PSA values were elevated in 17% of neutron patients and 45% in photon patients (p<0.001).
(p.124) Neutrons are a form of high linear engery transfer (high LET) radiation because they deposit 20-100 times more engery-pre-unit of traversed tissue than megavoltage photons. High LET radiation such as neutron results in DNA damage to a tumor that is less repairable than to a tumor cell damaged by low LET radiation, which has a significant chance to repair itself and continue to grow. (like we wanted to hear that factor)
(p.126) Neutrons do not depend on the presence of oxygen to kill the tumor(other radiations do apparently), thus have the ability to eradicate bulky tumors, unlike low LET radiations. In such settings, NBRT would have a better chance of eradicating high volume tumors than would photon, proton or electron RT. (very interesting to note)
On electron rays, these are commonly used on mens boob radiations (usually 4 sessions) to prevent Gynecomastia (breast enlargement caused by using certain PCa drugs- i.e. casodex(flutamides), proscar/avodart, des (any estrogenics). Yes I had this done too besides the Primary treatment of Neutron/Photon back in 2002, I got the electron rays later when switching to DES around early 2004 (causes temporary red like sunburn around the boobs 4"+, you don't want to take your shirt off ), lasts maybe 1-2 months and then you are good to go. I have some photos for laughs.
Note on Neutron rays (maybe 3-4 centers in the USA have Cyclotrons to deliver this) I saw a photo of the machine (gigantic and unreal, of course it was made probably in the 70's?)
The room I was placed into to get Neutron sessions (10 in total for primary radiation use) the door was about 2' thick lead and like a bank vault, the doctor was the only one administering these sessions (I presume handle with care). My other sessions with IMRT-photon (24) had assistants doing all the proceedures that were set up by the radiologist.
This might be worth looking into for salvage patients as maybe having a better control or efficacy like it seems to show on the studies done above. Maybe we will hear from someone whom has done this, besides me as a primary treatment. Might be worth an SRT patient getting an opinion from radiologist that does this.
Youth is wasted on the Young-(W.C. Fields)
Post Edited (zufus) : 7/20/2010 7:24:34 AM (GMT-6)