Advanced, precise radiation may boost limb-sparing therapy for sarcoma

USC study shows brachytherapy holds promise as treatment for once-debilitating cancers

Brachytherapy, the administration of radiation therapy locally through radioactive seeds, holds promise as part of a limb-sparing treatment program for patients with soft-tissue sarcomas, according to researchers at the Keck School of Medicine of the University of Southern California. After five years, 83 percent of patients in a trial incorporating brachytherapy into the treatment plan had survived, according to a team of Keck School radiation oncologists, orthopaedists and preventive medicine researchers, who announced the results recently at the 46th Annual Meeting of the American Society for Therapeutic Radiology and Oncology in Atlanta. The results equal that of a similar trial done at Memorial Sloan-Kettering Cancer Center.

Oscar E. Streeter Jr., M.D., associate professor of radiation oncology at the Keck School and USC/Norris Comprehensive Cancer Center, shared results of the team’s study with colleagues on October 5 at the Georgia World Congress Center. Sarcomas are cancers that grow in the connective tissues of the body, commonly within muscle and bone. Surgery and radiation have been an important part of successful treatment for these sarcomas.

In the past-and even in some cases, today-surgeons have had to amputate a limb to treat soft-tissue sarcomas. But limb-sparing procedures and new technological breakthroughs are helping make modern treatment less drastic. Physicians want to take advances even further, trying to keep radiation from harming skin that is healing from cancer surgery, for example, and focusing radiation on where it is most desired. Brachytherapy may increasingly be part of that effort.

In brachytherapy, after a surgeon removes the tumor from the patient, the radiation oncologist then inserts several catheters through the skin and into the cavity left by the tumor. After at least five days, when the patient has recovered from surgery, a radiation oncologist uses a computer-controlled machine to thread tiny radiation sources through the catheters and into the cavity. This radiation treatment can often be done over just a few days, and then the catheters are removed.

The idea is to deliver high-energy X-rays right to where they are most needed-where cancer cells might still linger, in the tissue near the tumor site. Brachytherapy also means less chance of radiation burning the skin or hurting surrounding healthy tissues in the body.

In the USC study, researchers looked at 12 patients with soft-tissue sarcomas in the arms or legs (or both) between 1994 and 1995. Sarcomas were removed by USC orthopaedic surgeon Lawrence Menendez, M.D. Eight of the patients had chemotherapy before the surgery, while 10 received traditional external beam radiation therapy before the surgery and one received the external beam radiation therapy after the surgery. All 12 patients received high-dose-rate brachytherapy after surgery.

The researchers followed up to see how patients were doing five years later. In one patient, cancer had returned locally at the tumor site about three years after treatment. In another, cancer had returned both locally and away from the tumor site after about two years. Another two patients developed distant metastases early (at five and 12 months, respectively), and both patients died. Other patients remained disease-free. Overall, sarcomas recurred in a third of the patients.

The Keck School physicians’ experiences indicate that high-dose-rate brachytherapy, combined with other therapies, can reduce the risk that sarcoma will recur at the original tumor site, Streeter said. In addition, they believe that chemotherapy before surgery may be important to preventing cancer’s return locally, as well helping improve overall and disease-free survival.

“Dr. Lawrence Menendez, director of orthopedic oncology, and Dr. Sant Chawla, medical oncologist specializing in sarcomas, are excited about writing a protocol giving neoadjuvant chemotherapy, surgery and brachytherapy alone in a prospective trial to see if our preliminary study holds up,” Streeter said.