Abstract
PurposeIn-field prostate cancer (PCa) oligo-recurrence after pelvic radiotherapy is a challenging situation for which metastasis-directed treatments may be beneficial, but options for focal therapies are scarce.MethodsWe retrospectively reviewed data for patients with three or less in-field oligo-recurrent nodal, bone and/or locally recurrent (prostate, seminal vesicles, or prostatic bed) PCa lesions after radiation therapy, identified with molecular imaging (PET and/or MRI) and treated by focal ablative therapy (cryotherapy or radiofrequency) at the Institut Bergonié between 2012 and 2020. Chosen endpoints were the post-procedure PSA response (partially defined as a >50% reduction, complete as a PSA <0.05 ng/ml), progression-free survival (PFS) defined as either a biochemical relapse (defined as a rise >25% of the Nadir and above 2 ng/ml), radiological relapse (on any imaging technique), decision of treatment modification (hormonotherapy initiation or line change) or death, and tolerance.ResultsForty-three patients were included. Diagnostic imaging was mostly 18F-Choline positron emission tomography/computerized tomography (PET/CT) (75.0%), prostate specific membrane antigen (PSMA) PET/CT (9.1%) or a combination of pelvic magnetic resonance imaging (MRI), CT, and 99 mTc-bone scintigraphy (11.4%). PSA response was observed in 41.9% patients (partial in 30.3%, complete in 11.6%). In the hormone-sensitive exclusive focal ablation group (n = 31), partial and complete PSA responses were 32.3 and 12.9% respectively. Early local control (absence of visible residual active target) on the post-procedure imaging was achieved with 87.5% success. After a median follow-up of 30 months (IQR 13.3–56.8), the median PFS was 9 months overall (95% CI, 6–17), and 17 months (95% CI, 11–NA) for PSA responders. Complications occurred in 11.4% patients, with only one grade IIIb Dindo–Clavien event (uretral stenosis requiring endoscopic uretrotomy).ConclusionIn PCa patients showing in-field oligo-recurrence after pelvic radiotherapy, focal ablative treatment is a feasible option, possibly delaying a systemic treatment initiation or modification. These invasive strategies should preferably be performed in expert centers and discussed along other available focal strategies in multi-disciplinary meetings.
Highlights
Prostate cancer (PCa) ranks among the leading diagnosed cancers and causes of male cancer deaths worldwide, with an estimated 1,276,000 new cancer cases and 359,000 deaths in 2018, a number expected to grow in the upcoming years due to the growth and aging of the population [1]
Nine other patients were excluded for various reasons
To be noted is that one patient had three nodal lesions, one in the pelvis treated by cryotherapy and two others outside the previous radiation fields treated by radiation therapy (RT)
Summary
Prostate cancer (PCa) ranks among the leading diagnosed cancers and causes of male cancer deaths worldwide, with an estimated 1,276,000 new cancer cases and 359,000 deaths in 2018, a number expected to grow in the upcoming years due to the growth and aging of the population [1]. The role of local therapies, once restricted to localized disease with curative intent or palliative purposes, is gaining importance and has even shown overall survival benefits when treating newly diagnosed low metastatic burden prostate cancer with radiation therapy (RT) to the prostate in addition to the standard systemic treatment [2, 3]. The concept of oligo-metastatic disease, originating in Hellman and Weichselbaum theories over 20 years ago, showcases growing interest, notably with the development of more accurate imaging modalities, precise focal treatments like stereotactic body radiation therapy (SBRT), and more conservative surgery procedures [4, 5]. In PCa, led by advances in terms of imaging with the successive appearance of more sensitive radiotracers in 18F-sodium fluoride (NaF), 18F-Choline, and 68Ga-prostate-specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT), as well as emerging therapies offering prolonged survival, oligo-metastatic disease is increasingly diagnosed. A few phase II and III trials have shown the benefit of such strategies in terms of progression-free survival (PFS) and overall survival when used as consolidation or in addition to the systemic standard of care, for various neoplasms [7,8,9]
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