Radiation of gangliogliomas is potentially useful only when total resection can't be done

NEW YORK (Reuters Health), Dec 3 - In a large series of patients with very rare gangliogliomas, gross total resection (GTR) provided the best outcomes. When only subtotal resection (STR) was possible -- as was often the case -- postoperative radiotherapy improved local control but not survival.

The role of radiation for these tumors is controversial, in part because the patients are often young, the research team reports online ahead of print in the journal Cancer.

The researchers investigated the potential benefit of postoperative radiotherapy for local control and overall survival in 402 cases, which represent "the largest series of ganglioglioma patients to date," Dr. Dirk Rades, of the University of Lubeck, Germany, told Reuters Health.

Using all published reports of gangliogliomas published between 1978 and 2007, as well as data on their own patients, the authors compared four therapies: GTR (n = 188), GTR plus radiotherapy (n = 21), STR (n = 113), and STR plus radiotherapy (n = 80).

Overall, 45 patients (11%) died during follow-up. Ten-year overall survival rates were 95% after GTR, 95% after GTR plus radiotherapy, 62% after STR, and 74% after STR plus radiotherapy. Radiotherapy did not significantly improve survival after STR (p = 0.22).

Seventy-four patients (18%) developed local recurrence during follow-up. Ten-year local control rates were 89% and 90% after GTR and GTR plus radiotherapy, respectively, and 52% and 65% after STR and STR plus radiotherapy, respectively (p < 0.001). STR plus radiotherapy significantly improved local control compared to STR alone (p = 0.004).

On multivariate analyses, overall survival was significantly associated with tumor site (relative risk, 1.64; p = 0.007), pathologic grade (RR, 4.85; p < 0.001), and treatment regimen (RR, 0.36; p < 0.001), and local control was significantly associated with pathologic grade (RR, 6.70; p < 0.001) and treatment regimen (RR, 0.45; p < 0.001).

Local control (p = 0.23) and overall survival (p = 0.29) were similar with GTR and GTR plus radiotherapy.

The results were similar for both low-grade and high-grade tumors.

"Both survival and local control are important endpoints," Dr. Rades noted. "A local recurrence within the brain may cause severe neurologic symptoms such as seizures or intracerebral hemorrhage," he said. "Furthermore, recurrent gangliogliomas may have a malignant course including craniospinal dissemination."

The authors acknowledge the drawbacks of a review such as theirs, but they point out that because the disease is so rare, prospective studies are unlikely.

Despite the limitations of the data, Dr. Rades concludes, "Postoperative radiotherapy should be seriously considered if only STR of low-grade or high-grade tumors has been achieved. However, in children and young adults, one should be more reserved regarding the indication for postoperative radiotherapy, because radiotherapy may induce malignant tumors occurring several years or even decades later."

By Michelle Rizzo

Cancer 2009.

Last Updated: 2009-12-02 18:24:29 -0400 (Reuters Health)

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