(P136) Quantitative Measurement of Contrast Enhancement in Myxoid Liposarcomas: Response to Neoadjuvant Therapy With Volumetric and Pathologic Correlates

OncologyOncology Vol 29 No 4_Suppl_1
Volume 29
Issue 4_Suppl_1

MLs exhibit favorable clinical responses to NeAT by size criteria; however, this may not account for biological tumor changes. We present a technique for quantifying changes in contrast enhancement that may better predict biological tumor response.

Tobias R. Chapman, MD, MPharmacol, George Jour, MD, Darrin J. Davidson, MD, MHSc, FRCSC, Robin L. Jones, MD, MRCP, Ben Hoch, MD, Gabrielle Kane, MD, Edward Y. Kim, MD; University of Washington

PURPOSE: Clinical assessment of response to neoadjuvant therapy (NeAT) in soft tissue sarcoma (STS) is often based on Response Evaluation Criteria in Solid Tumors (RECIST) criteria, which may not reflect changes in tumor biology. Myxoid liposarcomas (MLs) have favorable responses to NeAT by RECIST and exhibit contrast enhancement on T1-weighted, postcontrast magnetic resonance imaging (MRI) (T1+). Tumor response may also manifest as changes in contrast enhancement. We present a quantitative assessment of contrast enhancement and correlate these findings with volumetric and pathologic data.

MATERIALS AND METHODS: After institutional review board (IRB) approval, 67 patients from 1999–2013 were identified with ML. Five patients received neoadjuvant radiation therapy (RT) with MRI prior to each NeAT and surgery. Tumor volumes (TVs) were contoured on the relevant T1+ MRI. Mean contrast enhancement (MCE) was calculated by subtracting the T1 precontrast MRI signal from the T1+ MRI after normalization to normal muscle. Percent change was calculated using MIM software. Specimen analysis was performed by an STS pathologist.

RESULTS: The majority of patients was male, and most tumors were of the limb, low-grade, large (> 5 cm), and deep (T2b). Three patients received neoadjuvant chemotherapy. Pre- and postchemotherapy mean MCE values were 71% (range: 54%–82%) and 24% (range: 2%–47%), respectively. The mean postchemotherapy change in TV was −0.2%. All patients received neoadjuvant RT, with pre- and post-RT mean MCE of 50% and 47%, respectively. Mean post-RT change in TV was −64%. Two patients received neoadjuvant RT alone, with pre- and post-RT mean MCE of 95% and 23%, respectively. The mean post-RT-alone change in TV was −72%. All patients had significant pathological responses to NeAT, with > 80% treatment effect. With median follow-up of 23.5 months, there were no local or distant recurrences.

CONCLUSION: Patients with ML treated with neoadjuvant chemotherapy exhibit decreased MCE, with no associated change in TV. Subsequent RT postchemotherapy causes no additional change in MCE but does cause tumor shrinkage. Treatment with RT alone causes changes in both. These data from ML patients with excellent pathologic responses to NeAT suggest that differential tumor responses may not be captured using size criteria alone and that responses to chemotherapy may be better evaluated using MCE.

CLINICAL RELEVANCE/APPLICATION: MLs exhibit favorable clinical responses to NeAT by size criteria; however, this may not account for biological tumor changes. We present a technique for quantifying changes in contrast enhancement that may better predict biological tumor response.

Proceedings of the 97th Annual Meeting of the American Radium Society - americanradiumsociety.org

Articles in this issue

(P005) Ultrasensitive PSA Identifies Patients With Organ-Confined Prostate Cancer Requiring Postop Radiotherapy
(P001) Disparities in the Local Management of Breast Cancer in the United States According to Health Insurance Status
(P002) Predictors of CNS Disease in Metastatic Melanoma: Desmoplastic Subtype Associated With Higher Risk
(P003) Identification of Somatic Mutations Using Fine Needle Aspiration: Correlation With Clinical Outcomes in Patients With Locally Advanced Pancreatic Cancer
(P004) A Retrospective Study to Assess Disparities in the Utilization of Intensity-Modulated Radiotherapy (IMRT) and Proton Therapy (PT) in the Treatment of Prostate Cancer (PCa)
(S001) Tumor Control and Toxicity Outcomes for Head and Neck Cancer Patients Re-Treated With Intensity-Modulated Radiation Therapy (IMRT)-A Fifteen-Year Experience
(S003) Weekly IGRT Volumetric Response Analysis as a Predictive Tool for Locoregional Control in Head and Neck Cancer Radiotherapy 
(S004) Combination of Radiotherapy and Cetuximab for Aggressive, High-Risk Cutaneous Squamous Cell Cancer of the Head and Neck: A Propensity Score Analysis
(S005) Radiotherapy for Carcinoma of the Hypopharynx Over Five Decades: Experience at a Single Institution
(S002) Prognostic Value of Intraradiation Treatment FDG-PET Parameters in Locally Advanced Oropharyngeal Cancer
(P006) The Role of Sequential Imaging in Cervical Cancer Management
(P008) Pretreatment FDG Uptake of Nontarget Lung Tissue Correlates With Symptomatic Pneumonitis Following Stereotactic Ablative Radiotherapy (SABR)
(P009) Monte Carlo Dosimetry Evaluation of Lung Stereotactic Body Radiosurgery
(P010) Stereotactic Body Radiotherapy for Treatment of Adrenal Gland Metastasis: Toxicity, Outcomes, and Patterns of Failure
(P011) Stereotactic Radiosurgery and BRAF Inhibitor Therapy for Melanoma Brain Metastases Is Associated With Increased Risk for Radiation Necrosis
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