Clinical Outcomes of Dose-Escalated Hypofractionated External Beam Radiation Therapy (5 Gy × 5 Fractions) for Spine Metastasis.

Purpose: The objective of this study was to determine the toxicities and outcomes of patients with spinal metastasis treated with external beam radiation therapy (EBRT) to 25 Gy in 5 fractions. Methods and Materials: Data were extracted from an institutional tumor registry for patients with spinal metastasis who were treated with EBRT to 25 Gy in 5 fractions to their spinal lesion(s). Cox regression and Kaplan-Meier analyses to determine local control and overall survival (OS) were employed. Results: Seventy-five patients with 86 total treated spinal metastatic tumors were identified. The median follow-up was 7 months. The median age was 66 years. Fifty-six patients (75.7%) experienced partial or complete pain relief for a median duration of 6 months (range, 1-33). Fifty-one (59.3%) cases were planned using intensity modulated radiation therapy while 19 (22.1%) employed 3-dimensional conformal radiation therapy and 16 (18.6%) cases used nonconformal radiation technique. Greater than 90% of cases had a point dose maximum to the spinal cord/cauda equina <27.5 Gy. No patient experienced treatment-related myelopathy. The most common toxicities were fatigue (23.3%), pain flare (14.0%), and nausea (8.1%). There were no grade 3 toxicities. One-year local control was 80.6%, and 1-year OS was 38.4%. Higher Karnofsky performance status (P = .001) and radiosensitive tumor histology (P = .014) were significant predictors for better OS. Conclusions: Our single-institutional retrospective analysis of patients with spinal metastasis suggested that palliative EBRT to 25 Gy in 5 fractions is safe, with a low toxicity profile and minimal risk for myelopathy with an achievable dose maximum to the spinal cord and cauda equina ≤27 Gy (equivalent total dose in 2-Gy fractions ≤50 Gy), and it may provide durable palliation and local control in cases where stereotactic body radiation therapy may not be indicated.

A polycomb-mediated epigenetic field defect precedes invasive cervical carcinoma.

Human papillomavirus (HPV)-associated cervical carcinoma is preceded by stages of cervical intra-epithelial neoplasia (CIN) that can variably progress to malignancy. Understanding the different molecular processes involved in the progression of pre-malignant CIN is critical to the development of improved predictive and interventional capabilities. We tested the role of regulators of transcription in both the development and the progression of HPV-associated CIN, performing the most comprehensive genomic survey to date of DNA methylation in HPV-associated cervical neoplasia, testing ~2 million loci throughout the human genome in biopsies from 78 HPV+ women, identifying changes starting in early CIN and maintained through carcinogenesis. We identified loci at which DNA methylation is consistently altered, beginning early in the course of neoplastic disease and progressing with disease advancement. While the loss of DNA methylation occurs mostly at intergenic regions, acquisition of DNA methylation is at sites involved in transcriptional regulation, with strong enrichment for targets of polycomb repression. Using an independent cohort from The Cancer Genome Atlas, we validated the loci with increased DNA methylation and found that these regulatory changes were associated with locally decreased gene expression. Secondary validation using immunohistochemistry showed that the progression of neoplasia was associated with increasing polycomb protein expression specifically in the cervical epithelium. We find that perturbations of genomic regulatory processes occur early and persist in cervical carcinoma. The results indicate a polycomb-mediated epigenetic field defect in cervical neoplasia that may represent a target for early, topical interventions using polycomb inhibitors.

DNA demethylation by 5-aza-2'-deoxycytidine is imprinted, targeted to euchromatin, and has limited transcriptional consequences.

BACKGROUND: DNA methylation can be abnormally regulated in human disease and associated with effects on gene transcription that appear to be causally related to pathogenesis. The potential to use pharmacological agents that reverse this dysregulation is therefore an attractive possibility. To test how 5-aza-2'-deoxycytidine (5-aza-CdR) influences the genome therapeutically, we exposed non-malignant cells in culture to the agent and used genome-wide assays to assess the cellular response. RESULTS: We found that cells allowed to recover from 5-aza-CdR treatment only partially recover DNA methylation levels, retaining an epigenetic 'imprint' of drug exposure. We show very limited transcriptional responses to demethylation of not only protein-coding genes but also loci-encoding non-coding RNAs, with a limited proportion of the induced genes acquiring new promoter activation within gene bodies. The data revealed an uncoupling of DNA methylation effects at promoters, with demethylation mostly unaccompanied by transcriptional changes. The limited panel of genes induced by 5-aza-CdR resembles those activated in other human cell types exposed to the drug and represents loci targeted for Polycomb-mediated silencing in stem cells, suggesting a model for the therapeutic effects of the drug. CONCLUSIONS: Our results do not support the hypothesis of DNA methylation having a predominant role to regulate transcriptional noise in the genome and indicate that DNA methylation acts only as part of a larger complex system of transcriptional regulation. The targeting of 5-aza-CdR effects with its clastogenic consequences to euchromatin raises concerns that the use of 5-aza-CdR has innate tumorigenic consequences, requiring its cautious use in diseases involving epigenetic dysregulation.