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Treatment of Oligoresistant and Oligoprogressive Disease in Metastatic Prostate Cancer Patients with Radiation Therapy

A Roth1*, G Cooley1, J Smilowitz1, P Ferjancic1, G Liu1, R Jeraj1,2, (1) University of Wisconsin, Madison, WI, (2) University of Ljubljana, SI


(Sunday, 7/12/2020)   [Eastern Time (GMT-4)]

Room: AAPM ePoster Library

Purpose: To supplement systemic therapy that is effectively controlling the majority of the disease with a local radiation therapy (RT) to non-responding disease in metastatic prostate cancer (mPC) patients.

Methods: Bone-mPC patients received ¹8F-NaF PET/CT scans before starting systemic therapy (enzalutamide, baseline), after 12 weeks (to determine oligo-resistant disease), and at progression or two years (to determine oligo-progressive disease). Lesions were semi-automatically identified, segmented, matched between scans, and classified by response category. The five progressing or new lesions with the highest total uptake (iSUVtotal) were selected for RT and confirmed as achievable targets by a radiation oncologist. Expected change in whole-body disease burden (SUVtotal) was calculated assuming that RT-treated lesions would completely respond. Patients with modeled significant decrease in total disease burden (?SUVtotal=-25%) were considered well-suited for RT of oligo-resistant or oligo-progressive disease.

Results: Twenty-one patients received the NaF PET/CT at week 12 to determine oligo-resistant disease. Eight patients received all three scans to determine oligo-progressive disease. Patients had a median of 13.9% (0.0-70.4%) of lesions that were progressing or new at week 12. Of these patients, 29% (6/21) were deemed eligible for oligo-resistant RT with anticipated change of ?SUVtotal=-25%. At progression or year two, 13.4% (6.5-30.0%) of lesions were progressing or new. 75% (6/8) of patients were deemed eligible for oligo-progressive RT with anticipated change of ?SUVtotal=-25%.

Conclusions: This proposed approach to oligo-resistant and oligo-progressive radiation therapy selects eligible patients based on quantitative NaF PET/CT response. The results suggest that roughly a third of bone-mPC patients receiving enzalutamide may benefit from added oligo-resistant RT and three quarters of patients from oligo-progressive RT.

Funding Support, Disclosures, and Conflict of Interest: Data was acquired through funding from the Prostate Cancer Foundation and Pfizer. This work was additionally supported by the University of Wisconsin Carbone Cancer Center Support Grant P30 CA014520. Author GL is a co-founder and CMO of AIQ Solutions. Author RJ is a co-founder and CSO of AIQ Solutions.


Functional Imaging, Image Guidance, PET


IM/TH- Image Analysis (Single Modality or Multi-Modality): Computer-aided decision support systems (detection, diagnosis, risk prediction, staging, treatment response assessment/monitoring, prognosis prediction)

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