PSMA-Directed Para-Aortic Radiation Therapy for Oligorecurrent Prostate Cancer

Progression-free survival (PFS) among participants will be assessed during treatment and clinical follow-up. PFS is defined as the time from start of treatment until any of the following: Biochemical failure, escalation of therapy, radiological evidence of disease progression or death of any cause. Radiological evidence of disease progression will be assessed by the treating physician using the Response Evaluation Criteria in prostate-specific membrane antigen (PSMA) PET/CT (RECIP) version 1.0.

Biochemical failure-free survival among participants will be assessed during treatment and clinical follow-up. Biochemical failure-free survival is defined as the time from study enrollment to time of biochemical failure. Biochemical failure, as adapted from the Prostate Cancer Working Group 2 (PCWG2), is defined as when prostate-specific antigen (PSA) level increases ≥ 25% and ≥ 2 ng/mL above the nadir, which is confirmed by a second value obtained three or more weeks later.

Metastasis-free survival among participants will be assessed during treatment and clinical follow-up. Metastasis-free survival is defined as the time from study enrollment to clinical or radiological evidence of metastatic disease or death.

Overall survival (OS) among participants will be assessed. OS is defined as the time from study enrollment to death of any cause.

Median case specific survival among participants will be assessed. Median cause specific survival is defined as the time from study enrollment to death secondary to prostate cancer.

The proportion of participants undergoing escalation of therapy will be reported. Escalation of therapy is defined as subsequent course of radiation therapy or change in systemic therapy (except for intolerable side effects).

The proportion of participants experience late grade ≥ 2 treatment related toxicity between 90 days and two years following para-aortic radiation therapy (PA-RT) will be reported. Late toxicity is defined as Grade ≥ 2 treatment-related toxicities occurring more than 90 days after completing para-aortic radiation therapy (PA-RT). The severity of the reactions to the treatment will be assessed according to using the NCI Common Terminology Criteria for Adverse Events (CTCAE) version 5.0.

Health-related Quality of Life (HRQOL) will be measured using the Expanded Prostate Cancer Index Composite 26 Short Form (EPIC-26) to evaluate patient function and satisfaction after prostate cancer treatment. EPIC-26 is a short form version of the Expanded Prostate Cancer Index Composite, and is a validated comprehensive instrument developed to measure the health-related quality of life among men with prostate cancer. EPIC-26 consists of 26 items under 5 domains of urinary incontinence, urinary irritative/obstructive, bowel, sexual, and hormonal. Response options for each item form a Likert scale, and multi-item scale scores are transformed linearly to a 0-100 scale, with higher scores representing better HRQOL.

Health-related Quality of Life (HRQOL) will be measured using the Hospital Anxiety and Depression Scale (HADS) questionnaire. The HADS is a validated instrument used to measure patient symptoms of anxiety and depression. The HADS questionnaire consists of six questions, three questions each in two domains, HADS-Anxiety and HADS-Depression. Scores in each domain range from 0-9, with higher scores representing greater levels of anxiety and depression.

Health-related quality of life (HRQOL) will be measured using the International Prostate Symptom Score (IPSS) to evaluate patient urinary function and quality of life. There are 7 questions related to urinary function. Responses are on a scale from 0 ("not at all") to 5 ("almost always"), with higher scores indicating higher levels of urinary dysfunction. There is one quality of life question related to urinary symptoms. Responses are on a scale from 0 ("delighted") to 6 ("terrible"). Responses will be tabulated for a composite score.

The Complete Early Response rate among participants will be reported. Complete Early Response is defined as seen as on the 3-month post-PA-RT PSMA PET/CT scan using the Response Evaluation Criteria in prostate-specific membrane antigen (PSMA) PET/CT (RECIP) version 1.0; or a PSA level ≤ 0.1 ng/mL. A composite of these two evaluations will be used to determine the complete early response rate.