BOSTON—Patients diagnosed with orbital lymphoma should have a complete staging workup before radiation therapy, according to a Rare Cancer Network presentation at the American Society for Therapeutic Radiology and Oncology (ASTRO) annual meeting.

Radiation therapy was shown to be an effective treatment in a retrospective study of 88 consecutive patients with orbital lymphoma treated at 11 European institutions between 1980 and 1999, as analyzed by Dr. Sylvie Martinet, the principal investigator. In multivariate analysis, neither technique nor dose influenced disease-free survival, but complete staging did, along with age less than 65 and conjunctival localization.

Fewer Recurrences

Rene O. Mirimanoff, MD, professor of radiation oncology, University of Lausanne and Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland, and Dr. Martinet reported that the disease recurred in one third of patients who did not have complete staging but in only one eighth of those who did.

A full staging workup consists of chest x-ray, abdominal ultrasound and/or thoracoabdominal CT scan, bone marrow assessment, CBC, and LDH. Dr. Mirimanoff told ONI that a complete workup is important because “some of those patients may have lymphoma elsewhere in the body.”

All of the patients reviewed had Ann Arbor stage I or II primary orbital lymphoma. The median age was 64. Complete remission was achieved in 98% (86 patients) immediately after radiation therapy. Five-year disease-free survival was 65%; 5-year overall survival was 76%. The median follow-up was 58 months.

Most of the patients had a single orbital localization: conjunctiva (25), orbit (25), or eyelid (15). Surgical excision was performed in 29 patients, and 11 had chemotherapy in addition to radiation therapy. Eighteen patients had a systemic relapse, and seven developed metachron-ous contralateral eye involvement.

The most prominent late toxicities were cataracts and xerophthalmia. There was no correlation between the development of cataracts and lens shielding.

The study was conducted to find the most appropriate treatment for the disease, which occurs too infrequently for a prospective clinical trial to be performed.

“Chemotherapy is not needed in the majority of cases,” he said, pointing to the research group’s conclusion that moderately low dose radiation therapy—less than 34 Gy— is usually sufficient.

About 35 centers participate in the Rare Cancer Network, which was started in 1993. Dr. Mirimanoff said its purpose is to help researchers collect, analyze, and publish data on any “type of cancer so uncommon that there is no large series in the literature, no more than 10 to 20

cases in any study.” Unusual presentations of common cancers are also eligible for investigation. Orbital lymphoma, for example, accounts for only 10% to 15% of all orbital tumors and 1% of all lymphomas, Dr. Mirimanoff said.

Any researcher at a member institution can initiate a study by sending out an invitation asking other members whether they have cases of a rare cancer and want to participate. In this manner, the group hopes to collect enough cases to do meaningful retrospective studies when a prospective trial is not possible.

No US institutions currently are members of the network, but Dr. Mirimanoff welcomes new members and can be contacted at rmiriman@chuv.hospvd.ch.