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'lizbeth · 05-18-2014, 01:39 PM

A study of the anatomic distribution of brain metastases in HER2+ breast cancer: Implications for hippocampal avoidance PCI.

Abstract No:
e11578
Publication-only abstracts (abstract number preceded by an "e"), published in conjunction with the 2014 ASCO Annual Meeting but not presented at the Meeting, can be found online only.

Author(s): Jacob Witt, Timothy J. Pluard, Daniel John Ferraro, Jerry Jeff Jaboin, Maria Anne Thomas, Imran Zoberi, Cliff Grant Robinson; Washington University in St. Louis, St. Louis, MO; Siteman Cancer Center, Washington University School of Medicine, St. Louis, MO; Washington University School of Medicine in St. Louis, St. Louis, MO
Abstract Disclosures

Abstract:

Background: While only 20% of all breast cancer is HER2+, it represents a disproportionate majority of breast cancer brain metastases, and up to half of these patients will die of CNS disease. Prophylactic cranial irradiation (PCI) reduces the risk of brain metastases and improves survival in small cell lung cancer, but at the cost of neurocognitive decline in 30-40%. RTOG 0933 demonstrated a reduction in neurocognitive decline with hippocampal-avoidance (HA) whole brain radiation compared with historic controls. HA-PCI may represent an approach to reduce the risk of symptomatic HER2+ brain metastases while simultaneously reducing the risk of neurotoxicity, presuming the incidence of metastases within the HA zone is low. Methods: Patients with HER2+ breast cancer and brain metastases treated with whole brain radiation (WBRT) or stereotactic radiosurgery (SRS) from 1/2004-2/2012 were identified from registries in the Department of Radiation Oncology. Pretreatment T1-weighted, postcontrast axial MRI images were reviewed, and metastases were scored as being within a 5 mm HA zone (as done in RTOG 0933), and further subdivided by whether (1) any portion was within the avoidance zone or (2) the nidus (assuming concentric growth of the metastasis) was within the HA zone. Results: Seventy-three patients with 513 metastases were identified. The median age was 52.2. The median number of brain metastases per patient was 7.03 (range, 1-157). 40 of the patients were treated with WBRT and 21 were treated with SRS, with the remainder undergoing unknown or no radiation therapy. Eleven patients (15.1%) and 14 metastases (2.7%) had any portion of the metastasis within the HA zone while only 5 patients (6.85%) and 5 metastases (0.97%) had the tumor nidus within the HA zone. Conclusions: Metastases within the HA zone are uncommon. Use of a 5 mm expansion from the hippocampus to create a HA zone for HA-PCI would be projected to result in a 1-3% excess risk of failure. Such a low risk of failure would be acceptable, particularly with the ability to salvage such patients with techniques such as SRS. A pilot study of HA-PCI for HER2+ metastatic breast cancer is in development.

05-18-2014, 01:39 PM	#4
'lizbeth Senior Member Join Date: Apr 2008 Location: Sunny San Diego Posts: 2,214	Re: Upcoming Abstracts for Her2 Breast Cancer ASCO 2014 A study of the anatomic distribution of brain metastases in HER2+ breast cancer: Implications for hippocampal avoidance PCI. Abstract No: e11578 Publication-only abstracts (abstract number preceded by an "e"), published in conjunction with the 2014 ASCO Annual Meeting but not presented at the Meeting, can be found online only. Author(s): Jacob Witt, Timothy J. Pluard, Daniel John Ferraro, Jerry Jeff Jaboin, Maria Anne Thomas, Imran Zoberi, Cliff Grant Robinson; Washington University in St. Louis, St. Louis, MO; Siteman Cancer Center, Washington University School of Medicine, St. Louis, MO; Washington University School of Medicine in St. Louis, St. Louis, MO Abstract Disclosures Abstract: Background: While only 20% of all breast cancer is HER2+, it represents a disproportionate majority of breast cancer brain metastases, and up to half of these patients will die of CNS disease. Prophylactic cranial irradiation (PCI) reduces the risk of brain metastases and improves survival in small cell lung cancer, but at the cost of neurocognitive decline in 30-40%. RTOG 0933 demonstrated a reduction in neurocognitive decline with hippocampal-avoidance (HA) whole brain radiation compared with historic controls. HA-PCI may represent an approach to reduce the risk of symptomatic HER2+ brain metastases while simultaneously reducing the risk of neurotoxicity, presuming the incidence of metastases within the HA zone is low. Methods: Patients with HER2+ breast cancer and brain metastases treated with whole brain radiation (WBRT) or stereotactic radiosurgery (SRS) from 1/2004-2/2012 were identified from registries in the Department of Radiation Oncology. Pretreatment T1-weighted, postcontrast axial MRI images were reviewed, and metastases were scored as being within a 5 mm HA zone (as done in RTOG 0933), and further subdivided by whether (1) any portion was within the avoidance zone or (2) the nidus (assuming concentric growth of the metastasis) was within the HA zone. Results: Seventy-three patients with 513 metastases were identified. The median age was 52.2. The median number of brain metastases per patient was 7.03 (range, 1-157). 40 of the patients were treated with WBRT and 21 were treated with SRS, with the remainder undergoing unknown or no radiation therapy. Eleven patients (15.1%) and 14 metastases (2.7%) had any portion of the metastasis within the HA zone while only 5 patients (6.85%) and 5 metastases (0.97%) had the tumor nidus within the HA zone. Conclusions: Metastases within the HA zone are uncommon. Use of a 5 mm expansion from the hippocampus to create a HA zone for HA-PCI would be projected to result in a 1-3% excess risk of failure. Such a low risk of failure would be acceptable, particularly with the ability to salvage such patients with techniques such as SRS. A pilot study of HA-PCI for HER2+ metastatic breast cancer is in development.