Mar 18, 2011 - 4:36 am
Wootz I found this article earlier and I found a very small incidence rate of dementia after WBRT... 11% only a very small percentage.
LATE SIDE EFFECTS OF RADIATION THERAPY TO THE BRAIN
A review of the role of radiation in treating brain metastases would not be complete without a discussion of the late sequelae of therapy. There is a generalized fear that WBRT will result in horrendous late side effects. Much of the supporting data, though, come from the pediatric radiation literature and are not necessarily applicable to adult brains. There have also been many neurocognitive studies of glioma patients treated with radiation. It is probably not fair to compare this primary, infiltrate brain lesion with brain metastases because radiation doses, treatment fields, and the extent of surgery are all different.
In an often cited article on the late effect of palliative WBRT, DeAngelis at Memorial Sloan-Kettering27 reported on 47 patients alive without brain recurrence 12 months following WBRT. Five patients (11%) had dementia, but they all received non conventional radiation treatment. Four of the five had daily treatment fractions of 5 Gy to 6 Gy, or roughly twice what is considered the standard dose. The fifth patient received the conventional 3 Gy daily fraction size, but with a concurrent radiosensitizer. Daily radiation fraction size clearly affects late side effects in some tissues, including brain. Zero of 15 patients who received less that 3 Gy per fraction of WBRT had dementia. These data would argue that large daily radiation fraction size, and not WBRT itself, may lead to dementia or other severe late side effects. Even if one accepted the 11% dementia rate, only 15% of patients treated with WBRT are alive at one year. 8,9,10 That means that, at most, only 1.5% of patients alive at one year WBRT would develop dementia. Most patients treated with conventional WBRT are never going to develop severe late effects from their treatment. Long-term survivors may develop subtle neurocognitive changes not easily detected by bedside testing, but this must be weighted against the effects of not treating the patients with WBRT.
Radiosurgery is often advocated as a treatment option to avoid or delay WBRT: 37-63% of patients treated with SRS as monotherapy will require salvage brain treatment.7 In these retreated patients there is 5% radiation necrosis incidence requiring craniotomy. 7 The neurocognitive impact of retreatment plus or minus additional surgery are not well studied, but probably more worrisome than that of WBRT alone.