Faculty Bibliography

In parallel with the discovery of the taxanes, our understanding of the molecular underpinnings that comprise the classic biologic principles of fractionated radiotherapy has rapidly evolved over the past half century. Early studies have implicated DNA as the primary target for radiation-induced lethality. More recently, however, the molecular biology involved in radiosensitization of tumor cells has been unveiled. Specifically, factors associated with DNA damage and cell killing, collectively known as the 'four Rs' of radiobiology, including (r)eassortment of tumor cells into the radiosensitive phases of the cell cycle (G2/M), (r)eoxygenation of hypoxic areas within a tumor, (r)epair of sublethal DNA damage, and (r)epopulation of surviving tumor cells, have been elucidated, and upon manipulation of each factor or a combination of factors a significant impact on radiation-associated tumor control probabilities was found. Not only does spatial cooperation have a theoretical benefit in patients with undetectable micrometastatic disease at presentation, but the manipulation of either of the 'four Rs' using taxanes provokes further local radiation-associated tumor cell killing with an associated improvement in clinical responses. Numerous studies have shown that taxanes radiosensitize tumor cells directly and/or indirectly by perturbing the tumor microenvironment in a time-dependent and dose-dependent manner. Herein, the impact of taxanes on radiobiological tenets as a mode of radiosensitizing tumor cells and their clinical implications are reviewed.

A posteriori evidence suggests that radiotherapy to a targeted tumor can elicit an immune-mediated abscopal (ab-scopus, away from the target) effect in non-targeted tumors, when combined with an anti-cytotoxic T-lymphocyte antigen-4 monoclonal (CTLA-4) antibody. Concurrent radiotherapy and ipilimumab (a human monoclonal anti-CTLA-4 antibody) induced immune-mediated abscopal effects in poorly immunogenic pre-clinical tumor models and metastatic melanoma patients. However, no such reports exist for patients with metastatic lung adenocarcinoma. We report the first abscopal response in a treatment-refractory lung cancer patient treated with radiotherapy and ipilimumab. A post-treatment increase in tumor-infiltrating cytotoxic lymphocytes, tumor regression, and normalization of tumor markers was observed. One year after treatment with concurrent radiotherapy and ipilimumab the patient is without evidence of disease.

Breath testing could provide a rational tool for radiation biodosimetry because radiation causes distinct stress-producing molecular damage, notably an increased production of reactive oxygen species. The resulting oxidative stress accelerates lipid peroxidation of polyunsaturated fatty acids, liberating alkanes and alkane metabolites that are excreted in the breath as volatile organic compounds (VOCs). Breath tests were performed before and after radiation therapy over five days in 31 subjects receiving daily fractionated doses: 180-400 cGy d(-1) standard radiotherapy (n = 26), or 700-1200 cGy d(-1) high-dose stereotactic body radiotherapy (n = 5). Breath VOCs were assayed using comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry. Multiple Monte Carlo simulations identified approximately 50 VOCs as greater-than-chance biomarkers of radiation on all five days of the study. A consistent subset of 15 VOCs was observed at all time points. A radiation response function was built by combining these biomarkers and the resulting dose-effect curve was significantly elevated at all exposures 1.8 Gy. Cross-validated binary algorithms identified radiation exposures 1.8 Gy with 99% accuracy, and 5 Gy with 78% accuracy. In this proof of principal study of breath VOCs, we built a preliminary radiation response function based on 15 VOCs that appears to identify exposure to localized doses of 1.8 Gy and higher. VOC breath testing could provide a new tool for rapid and non-invasive radiation biodosimetry.

Objective: In early 1999, the National Cancer Institute (NCI) issued a clinical alert based on 5 randomized trials in locoregional cervical cancer showing better overall survival (OS) with concurrent chemoradiotherapy (CCRT) than with surgery or radiation alone. This study seeks to confirm whether OS did change significantly after the alert was issued. Methods: SEER 18-Registry data (2011 submission) were queried using SEER*Stat 7.1.0 software. Cases were selected using the following criteria: cervix uteri, FIGO stages IB2-IVA, diagnosis years 1995-2002, radiotherapy given, and no other malignancy. Kaplan- Meier (K-M) OS curves with diagnosis year as the independent variable were generated for the following 3 comparisons: 1995-1996 (Y95-96) vs. 1997-1998 (Y97-98), 1997-1998 vs. 1999-2000 (Y99- 00), and 1999-2000 vs. 2001-2002 (Y01-02). Log rank tests for significance and hazard ratios (HR) for death were calculated. Cox multivariate model was used to account for other risk factors for death. In the Cox model, treatment years were aggregated into 2 levels (95-98 vs. 99-02). All tests were 2-tailed, with alpha P < 0.05 and 95% CI reported. Data were analyzed with IBM SPSS Statistics v.20. Results: K-M OS improved significantly for Y99-00 compared to Y97- 98 (log rank P= 0.001, HR=0.828). OS was not significantly different for Y95-96 vs. Y97-98 (log rank P =0.799). Similarly, OS was not significantly different for Y99-00 vs. Y01-02 (log rank P =0.692). Cox multivariate model revealed the following significant variables: time period, age group, race, histology, grade, FIGO stage, tumor size, lymph node status, surgery extent, and radiation type. After adjusting for other variables, the multivariate HR for death for patients treated after vs. before the 1999 alert was 0.806 (CI 0.747-0.871). Conclusions: Adoption of CCRT within 2 years of the 1999 NCI alert resulted in higher OS for stage IB2-IVA cervical cancer patients (Table). While SEER data did not explicitly include information on chemotherapy!

Background: The Radiation Therapy Oncology Group (RTOG) protocol 0618 was a phase II trial utilizing SBRT to treat early stage non-small cell lung cancer in operable patients (pts). Methods: All pts were deemed operable by a thoracic surgeon utilizing specific criteria. Pts with biopsy proven peripheral T1-T3, N0, M0 tumors were eligible. The prescription dose was 18 Gy X 3 fractions delivered in 1-2 weeks. The primary endpoint was 2-year primary tumor control (PTC, avoidance of in-field (INF) and marginal failure (MF)) with overall and progression free survival (OS, PFS), adverse events (AE), local (LF), regional (RF), and distant failure (DF) as secondary endpoints. Early surgical salvage was directed as part of protocol design in the event of LF after SBRT. Results: The study opened December 2007 and closed May 2010 after accruing a total of 33 pts. Of 26 evaluable pts, 23 had T1, and 3 had T2 tumors. Median age was 72 years. Median FEV1, DLCO at enrollment were 72%, 68% predicted, respectively. 4 pts (16%) had SBRT related grade 3 AEs while 0 had grade 4-5 AEs. Median follow-up was 25 months. 2 pts have been scored with INF (11.7 and 12.4 months post SBRT) and 1 with MF (32.5 months post SBRT) giving an estimated 2-year primary tumor failure rate of 7.7% (95% CI: 0.0%, 18.1%). 2-year estimates of LF (primary tumor plus involved lobe failure), RF, and DF are 19.2% (95% CI: 3.7%, 34.7%), 11.7% (95% CI: 0.0%, 24.5%), and 15.4% (95% CI: 1.2%, 29.6%), respectively. Only one patient was eligible for attempted surgical salvage and underwent lobectomy 1.2 years post SBRT complicated by a grade 4 cardiac arrhythmia. 2-year estimates of PFS and OS are 65.4% (95% CI: 44.0%, 80.3%) and 84.4% (95% CI: 63.7%, 93.9%), respectively. Conclusions: SBRT given appears to be associated with a high rate of PTC, moderate treatment related morbidity, and infrequent need for surgical salvage in operable early stage lung cancer pts with peripheral lesions. These results support ongoing enrollment into the ACOSOG Z40!

Objectives: Some patients are medically unfit for or averse to undergoing a brachytherapy boost as part of cervical cancer radiotherapy. In order to be able to definitively treat these patients, we assessed whether we could achieve a boost plan that would mimic our brachytherapy plans using external beam radiotherapy.Methods: High dose rate brachytherapy plans of 20 patients with stage IIB cervical cancer treated with definitive chemoradiotherapy were included in this study. Patients had undergone computer tomography (CT) simulations with tandem and ovoids in place. Point "A" dose was 600-700 cGy. We attempted to replicate the boost dose distribution from brachytherapy plans using intensity-modulated radiotherapy (Varian Medical Systems, Palo Alto, CA, USA), volumetric modulated arc therapy (Rapid Arc, Varian Medical Systems, Palo Alto, CA, USA), or TomoTherapy (Accuray, Inc., Sunnyvale, CA, USA) with the brachytherapy 100% isodose line as our target. Target coverage, normal tissue dose, and brachytherapy point doses were compared with ANOVA. Two-sided p-values