What is your approach to treating gliomatosis cerebri?

When would you recommend chemotherapy alone, radiation alone, and combined chemoradiotherapy? When treating with RT, what volumes and doses do you use?

1 Answer

Mednet Member

Radiation Oncology · St. Jude Children's Research Hospital

Answered on

I think a number of considerations have to be taken into account:

- Symptoms, KPS, patient age, prior therapy, and underlying morbidities...

At present, there are no clear biologic prognostic factors and so clarifying whether the cases represent true gliomatosis is essential. A recent consensus conference identified two types of GC: Type 1 being the diffusely infiltrative version with enlargement of all involved structures without a definitive enhancing solid component and Type 2 which may be a variant of type 1, plus an obvious mass.

Optimal timing is debatable and may depend on the extent of symptoms at the time of diagnosis. The symptomatic response rate has almost always been higher with radiotherapy, however, the long-term quality of life is impaired. The durability of response has almost always been better than any other form of systemic therapy.

In the absence of symptoms and younger age, I think most would prefer chemotherapy initially and reserve radiotherapy for salvage.

Salvage radiotherapy should generally be cranial radiotherapy to 54 Gy. If the patient has a suspected adult-type GC with a biopsy-proven low-grade component, there is no strong evidence for higher doses beyond 45-50.4 Gy. Any and all GC cases with high-grade histology should be treated to 54 Gy with care taken to minimize the volume going about 54 Gy. In order to get a more favorable plan, it is almost always necessary to use forward planning with segmented fields or IMRT to minimize hot spots and improve dose homogeneity.