Pattern of Relapse after Metastases Directed Therapy in Patients with Oligorecurrent Prostate Cancer Detected with Choline PET-CT


      A better knowledge of the pattern of recurrence after metastases directed therapy (MDT) in patients with oligometastatic disease might be useful to select the most appropriate candidates. The aim of this study is to report in a prospective cohort of oligorecurrent prostate cancer patients factors associated with the pattern of relapse and disease control after MDT.


      From 2012 to 2017, 104 lesions diagnosed with Ch-PET in 53 consecutive oligometastatic-recurrence prostate cancer patients have been treated. Biochemical failure was defined using the nadir+2 ng/mL definition; a DFS event was defined as evidence of disease by any clinical, pathological, or radiological method. Reassessment with Ch-PET imaging was performed in case of biochemical failure or if clinically indicated to rule out local or distant metastatic progression. Patterns of first progression following MDT were recorded. In case of an oligometastatic recurrence outside the previous PTV field, a retreatment with SBRT or IMRT was offered. Descriptive analyses were done. Chi-square and Fisher-exact tests were performed to evaluate the influence of patient, tumor, and treatment characteristics on the pattern of relapse. A p<0.05 considered statistically significant.


      The different subsites of metastatic involvement before first MDT were lymph nodes in 67.9% and bone in 32.1% of patients. The treatments administered to the initial oligo-recurrence sites were IMRT (49%) and SABR (51%) +/- short course ADT. After a median follow-up of 28 months (6-54 months), 89% of the patients remain alive and only 3 deaths were related to prostate cancer. At last follow-up 34% of the patients were free from disease progression. Twenty-five patients with biochemical failure after first MDT presented distant recurrence on re-staging Ch-PET and 64% (16/25) were again oligometastatic relapses allowing for a second MDT in 12 patients. In terms of relapse site, 7/7 (100%) patients with initial bone disease presented a subsequent bone relapse, 10/18 (56%) patients with initial nodal disease presented a nodal relapse and 8/18 (44%) a bone relapse. At diagnosis, a PSA pre-PET<4.5ng/mL was associated with higher probability of presenting with nodal oligometastases (p=0.049). The variables with significant association with nodal relapse after MDT were a pre-MDT PSA<10ng/mL (p=0.049) and initial nodal oligometastatic site (p=0.02). A PSADT>12 months before MDT was the only factor statistically associated with higher disease control (p=0.011).


      Long-term disease control is still possible in oligometastatic patients who receive MDT. At relapse, most patients are again oligometastatic allowing for repeated MDT. The pre-MDT PSA and initial nodal oligometastatic site are associated with a further nodal relapse. Patients presenting with a PSADT>12 months and a PSApre-PET<4.5ng/mL may have a better prognosis.


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