1. Refining the definition of biochemical failure in the era of stereotactic body radiation therapy for prostate cancer: The Phoenix definition and beyond
- Author
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Alan W. Katz, Alexandra Napieralska, Donald B. Fuller, Abigail Pepin, Xue Wu, D. Andrew Loblaw, Leszek Miszczyk, Sean P. Collins, Jeremie Calais, R. Philipson, Shrinivasa K. Upadhyaya, Rachel Glicksman, Matthew Rettig, Mark K. Buyyounouski, Amar U. Kishan, Paul C. Boutros, Constantine Mantz, Nicholas G. Nickols, Ming Wang, Hilary P. Bagshaw, Agnieska Namysł-Kaletka, Simeng Suy, Soumyajit Roy, Michael L. Steinberg, Nima Aghdam, N.G. Zaorsky, and Ting Martin Ma
- Subjects
Male ,Psa kinetics ,medicine.medical_specialty ,Fractionated radiotherapy ,business.industry ,Stereotactic body radiation therapy ,medicine.medical_treatment ,Biochemical failure ,Brachytherapy ,Prostatic Neoplasms ,Hematology ,Prostate-Specific Antigen ,False positivity ,Radiosurgery ,medicine.disease ,Radiation therapy ,Prostate cancer ,Oncology ,medicine ,Humans ,Radiology, Nuclear Medicine and imaging ,Radiology ,business ,Stereotactic body radiotherapy ,Retrospective Studies - Abstract
The Phoenix definition for biochemical failure (BCF) after radiotherapy uses nadir PSA (nPSA) + 2 ng/mL to classify a BCF and was derived from conventionally fractionated radiotherapy, which produces significantly higher nPSAs than stereotactic body radiotherapy (SBRT). We investigated whether an alternative nPSA-based threshold could be used to define post-SBRT BCFs.PSA kinetics data on 2038 patients from 9 institutions were retrospectively analyzed for low- and intermediate-risk PCa patients treated with SBRT without ADT. We evaluated the performance of various nPSA-based definitions. We also investigated the relationship of relative PSA decline (rPSA, PSAMedian follow-up was 71.9 months. BCF occurred in 6.9% of patients. Median nPSA was 0.16 ng/mL. False positivity of nPSA + 2 was 30.2%, compared to 40.9%, 57.8%, and 71.0% for nPSA + 1.5, nPSA + 1.0, and nPSA + 0.5, respectively. Among patients with BCF, the median lead time gained from an earlier nPSA + threshold definition over the Phoenix definition was minimal. Patients with BCF had significantly lower rates of early PSA decline (mean rPSA 1.19 vs. 0.39, p 0.0001) and were significantly more likely to reach nPSA + 2 ≥ 18 months (83.3% vs. 21.1%, p 0.0001). The proposed criterion (rPSA ≥ 2.6 or nPSA + 2 ≥ 18 months) had a sensitivity and specificity of 92.4% and 81.5%, respectively, for predicting BCF in patients meeting the Phoenix definition and decreased its false positivity to 6.4%.The Phoenix definition remains an excellent definition for BCF post-SBRT. Its high false positivity can be mitigated by applying additional criteria (rPSA ≥ 2.6 or time to nPSA + 2 ≥ 18 months).
- Published
- 2022
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