Identification of Site-specific Recurrence Following Primary Radiation Therapy for Prostate Cancer Using C-11 Choline Positron Emission Tomography/Computed Tomography: A Nomogram for Predicting Extrapelvic Disease

Abstract

Background Management of recurrent prostate cancer (CaP) after radiotherapy (RT) is dependent on accurate localization of the site of recurrent disease. Objective To describe the anatomic patterns and clinical features associated with CaP recurrence following RT identified on advanced imaging. Design, setting, and participants Retrospective review of 184 patients with a rising prostate-specific antigen (PSA) after RT for CaP. Intervention C-11 choline positron emission tomography/computed tomography (CholPET). Outcome measurements and statistical analysis Recurrence patterns were classified as pelvic soft tissue only (as a surrogate for potentially salvageable disease) versus any extrapelvic disease, and clinical features were compared between patterns. Multivariable logistic regression was used to generate a predictive nomogram for extrapelvic recurrence. Discrimination was assessed with a c-index. Results and limitations Recurrence site was identified in 161 (87%) patients, with 95 (59%) sites histologically confirmed. Factors associated with the detection of recurrence included the difference between PSA nadir and PSA at CholPET (odds ratio: 1.30, p < 0.01) and National Comprehensive Cancer Network high-risk classification (odds ratio: 10.83, p = 0.03). One hundred (54.3%) patients recurred in the pelvic soft tissue only, while 61 (33%) had extrapelvic recurrence. Of 21 patients who underwent CholPET prior to meeting the Phoenix criteria of biochemical failure, 15 (71%) had recurrence identified on CholPET with 11 localized to the pelvis. On multivariable analysis, PSA at CholPET, time from RT, and National Comprehensive Cancer Network risk group were predictive of recurrence outside of the pelvis, and a nomogram was generated with a c-index of 0.79. Conclusions CholPET identified the site of recurrence in 87% of patients with a rising PSA after RT; most commonly within the pelvis in potentially salvageable locations. A predictive nomogram was generated, and pending external validation, this may aid in assessing the risk of disease beyond the pelvis. These findings underscore the importance of advanced imaging when considering management strategies for patients with a rising PSA following primary RT. Patient summary We identified anatomic patterns of recurrence in patients with a rising prostate-specific antigen after radiotherapy using C-11 choline positron emission tomography/computed tomography. Most recurrences were localized to the pelvis and we were able to generate a tool to aid in disease localization prior to evaluation with advanced imaging.

Prevalence and prognosis of low‐volume, oligorecurrent, hormone‐sensitive prostate cancer amenable to lesion ablative therapy

“…In the present study, we showed that three out of four relapses were low‐volume and potentially amenable to LAT. These results corroborate the findings of other series showing a similar pattern (Table ) . With regard to the location of recurrences, the dominant pattern is lymphotropic in all reported series (Table ), with bone metastases observed in approximately one in five patients.…”

“…Sobol et al 21 Parker et al 20 PET, positron-emission tomography. *In six patients, the primary treatment method was not registered and those patients are not shown in the frequently, even for patients not entered in the trial.…”

Patterns of Recurrence After Postprostatectomy Fossa Radiation Therapy Identified by C-11 Choline Positron Emission Tomography/Computed Tomography

“…Other institutions have shown a limited sensitivity of CholPET when the PSA is <2.0ng/mL (37), which may reflect the lower doses of C-11 choline used in other series relative to the protocol employed here. Indeed, reports from our institution where operative characteristics are available have shown a detection rate of 64% among patients with a PSA <2.0ng/mL (34), compared to 45% as reported in the aforementioned study of 4,000 restaging scans (27). …”

“…Previous investigations have established the role for CholPET in the evaluation of biochemical recurrence after either RP or RT (24, 27, 34). The National Comprehensive Cancer Network (NCCN) and the European Association of Urology (EAU) (35, 36) recognize the use of CholPET in the identification of sites of metastatic disease, but acknowledge that additional study is needed to define best practices.…”

Current Status of MRI and PET in the NCCN Guidelines for Prostate Cancer

“…In a study of 161 patients with PSA increasing after primary RT who underwent C-11 choline PET/CT, 87% were found to have sites of recurrence, 59% of which were histologically confirmed. 72 The median PSA level of the cohort was 7.8 ng/mL, but with PSA levels less than the Phoenix criteria threshold median of 1.9 ng/mL, 73 71% had confirmed sites of recurrence.…”