Intraoperative Radiation Therapy provides new options for treatment

Harry Reynolds , MD, FACS, FASCRS
Assistant Professor of Surgery
Division of Colon and Rectal Surgery

Presentation : A 69-year-old male underwent low anterior resection of a rectal cancer in 2003. He received no preop or postop chemo or radiation therapy. He developed progressive urgency and frequency of bowel movements associated with worsening pelvic pain and rectal bleeding.

Workup : Colonoscopic and proctoscopic evaluation revealed a recurrent rectal cancer at the previous anastomosis. This extended into the anal canal and was fixed in the pelvis on digital exam. CT scan demonstrated a mass in the distal rectum adjacent to the sacrum and a secondary mass of matted internal iliac nodes along the left pelvic sidewall (figure 1 & 2). MRI revealed no boney destruction of the sacrum. PET scanning revealed no extrapelvic disease.

Treatment : The patient received preoperative combined capecitebine chemotherapy and external beam radiation, resulting in considerable shrinkage of this aggressive recurrent tumor. This was followed by abdominoperineal and left pelvic sidewall resection with concomitant resection of the left obturator and internal iliac nodes, approximately eight weeks after completion of his preoperative radiation and chemotherapy. We performed IORT with 12 Gy to the left pelvic sidewall and 12 Gy to the sacrum with the use of the Mobetron intraoperative unit (pictured above). His postoperative course was largely unremarkable other than a urinary tract infection and brief readmit for a small bowel obstruction, managed medically.

Discussion : IORT offers new options for treatment of locally advanced primary and recurrent rectal cancers as well as other advanced pelvic and colonic malignancies. In patients who would previously have been deemed inoperable, combined resection and IORT can provide a curative option for patients with close or microscopically involved margins adjacent to unresectable structures. Vital structures such as the ureter and small intestine can be shielded from the radiation field and protected from injury. Likewise, morbid procedures such as sacrectomy, prostatectomy, or pelvic exenteration may be avoided in selected patients. We were able to avoid sacrectomy in this patient and provide IORT to a close margin along the pelvic sidewall. We have treated over 40 advanced malignancies with combined colorectal resections and IORT since the introduction of the Mobetron at University Hospitals, representing one of the largest series of patients treated with this type of unit. There are only four other Mobetrons in the United States and 18 in the world. University Hospitals Case Medical Center has the only unit in northeast Ohio.