CyberKnife Dose Escalation Prostate Cancer Trial
CyberKnife Dose Escalation Prostate Cancer Trial
Stereotactic body radiation therapy (SBRT) has been employed in the treatment of prostate
 cancer. Multiple single institution experiences suggest high biochemical control rates with
 acceptable toxicity in low risk prostate cancer but efficacy data in unfavorable type
 prostate cancer is less convincing. CyberKnife-SBRT (CK-SBRT) can be used to escalate
 radiation dose delivery to the prostate while sparing normal tissue.
The optimal radiation schedule for the curative treatment of prostate cancer remains unknown.
 Prostate cancer patients receiving radiation therapy are typically treated 5 days per week
 for 8-9 weeks. Recent data suggest that large radiation fraction sizes are radio-biologically
 favorable over lower fraction sizes in prostate cancer radiotherapy. The sensitivity of a
 tumor or normal tissue to fraction size of radiation can be approximated by the alpha-beta
 ratio. It has been suggested that the alpha/beta ratio for prostate cancer is actually as low
 as 1.5 implying that the current radiation therapy paradigm for prostate cancer treatment
 might be fundamentally flawed, as high fraction sizes would be expected to damage tumor more
 readily.

 Typical prostate SBRT doses do not appear to have similar efficacy in higher risk prostate
 cancer suggesting even higher doses are required. Many techniques including dose escalated
 external beam radiation therapy (EBRT), proton therapy (PT) and brachytherapy have been
 employed to increase dose to the prostate. Data from the ASCEND-RT trial utilizing low dose
 rate brachytherapy boost showed a dramatic 21% improvement in biochemical control at 9 years
 favoring brachytherapy boost compared to conventional dose escalated EBRT radiation therapy.
 However, no corresponding benefit was identified in overall survival, incidence of bone
 metastases or prostate cancer specific mortality while a 3 fold increase in late urinary
 toxicity was noted.

 SBRT is well tolerated with minimal acute and late side effects. In this protocol, CK-SBRT
 will be used to target the microscopic and gross disease in the prostate, seminal vesicles.
 An escalated dose of 40 Gy in 5 fractions will be delivered to the entire target volume while
 any nodules visible within the prostate gland on endorectal MRI will receive 50 Gy in 5
 fractions.
Inclusion Criteria:

 -  Histologically confirmed adenocarcinoma of the prostate diagnosed within 360 days of
 enrollment.

 -  Prostate Specific Antigen (PSA) documented within 90 days prior to registration.

 -  Clinical staging completed within 90 days of registration.

 -  No Nodal or Distant Metastases documented on CT or MRI of the pelvis and bone scan.

 -  Unfavorable Risk Prostate Carcinoma as Described is documented.

 -  No prior pelvic radiotherapy.

 -  No prior Trans-urethral resection of the prostate (TURP).

 -  Prostate volume < 100 cc

 -  American Urologic Association (AUA) score < 20

 -  No recent (within 5 years) or concurrent cancers other than non-melanoma skin cancers.

 -  Patient must have no medical or psychiatric illnesses that would interfere with
 treatment or follow-up.

 -  No implanted hardware adjacent to the prostate that would prohibit appropriate
 treatment planning and treatment delivery is allowed.

 -  Candidate for rectal spacer placement

 Exclusion Criteria:

 -  Other cancer diagnosis other than non-melanoma skin cancer with 5 years

 -  Prostate size greater than 100cc

 -  AUA greater than 20

 -  Implanted hardware impacting imaging

 -  Metastatic prostate cancer

 -  Contraindication to hormone therapy