Case Studies from WellSpring Cancer Center
CyberKnife Radiosurgery Case Study
- Published: 08 June 2012
CyberKnife Body Radiosurgery Case, Recurrent Uterine Cancer
A 72 year-old, Caucasian female has a history of Endometrial Carcinoma presenting in 2006 with a grade 2 moderately differentiated adenocarcinoma, involving 50% of the myometrial thickness and involving the lower uterine segment, treated with TAH-BSO (FIGO Stage IB, Gr2). She did not require any additional treatment at that time.
In January of 2007, she developed a recurrence in the vaginal cuff and underwent radical upper vaginectomy. She received postop radiation therapy to the pelvis, with a boost to the cuff, total dose: 59.4GY. She was well until November 2007 when she developed a left pelvic sidewall recurrence with a 3.1 cm mass in the proximal iliac chain. She was initially treated with chemotherapy, followed by a second course of chemo-radiation delivering an additional 30.6Gy completed in April 2008.
Follow-up PET-CT in September 2008 revealed persistent disease in the left sidewall mass associated with left lower extremity pain and edema. It was determined that she would not be a suitable candidate for any additional chemotherapy or conventional radiation therapy. She declined radical surgery as this would have required sacrificing the left femoral nerve resulting in chronic leg weakness and edema.
She opted to proceed with Stereotatic Body Radiosurgery using the CyberKnife system. She initially underwent Gold Seed Fiducial placement required for 6D tracking and then PET-CT for mapping and planning. Her prior radiation records were reviewed and great efforts were made to avoid any additional dose to the small bowel adjacent to the mass since this had reached tolerance dose from her prior two courses.
The CyberKnife is ideally suited for this application given its ability to chose from a library of 1200 non isocentric beamlets to accurately “dose-paint” the target, and monitor internal organ and respiratory movement with its real time imaging system and compensate accordingly with its robotic arm.
A hypofractionated course delivering 30Gy in 6Gy fractions over five treatments in 10 elapsed days (January 6 to 16, 2009) was chosen to maximize tumor effect and minimize the possibility of long term radiation effects. She tolerated the treatment well without appreciable side effects other than fatigue. Her left leg pain completely resolved within a week of completing treatment. Follow-up PET-CT three months after treatment in March 2009 showed complete resolution of disease. A second PET-CT in June at six months post treatment was also negative and she remains asymptomatic.