In an update of a Norwegian trial reported in the Journal of Clinical Oncology, Ekanger et al found that long term, salvage reirradiation for locally recurrent prostate cancer was feasible and associated with good outcomes.
Study Details
The study included 38 patients with locally recurrent disease at > 2 years after primary curative radiation therapy and no grade 2 or 3 toxicity from the primary radiotherapy. Reirradiation consisted of external-beam radiation therapy (EBRT) at 35 Gy in five fractions to magnetic resonance imaging–based targets; 6 months of androgen-deprivation therapy was administered starting 3 months before radiotherapy.
Key Findings
Median follow-up was 7.2 years. Biochemical recurrence–free survival rates at 2 and 5 years after reirradiation were 81% (95% confidence interval [CI] = 69%–94%) and 58% (95% CI = 49%–74%). At 5 years after reirradiation, local recurrence–free survival was 93% (95% CI = 82%–100%), metastasis-free survival was 82% (95% CI = 69%–95%), and overall survival was 87% (95% CI = 76%–98%).
Factors associated with poorer biochemical recurrence–free survival included prostate-specific antigen (PSA) doubling time of ≤ 6 months at reirradiation (hazard ratio [HR] = 11.9, 95% CI = 3.4–42.1, vs doubling time > 12 months), a Gleason score of > 7 (HR = 2.97, 95% CI = 1.17–7.58, vs score ≤ 7), and PSA nadir of ≥ 0.1 ng/mL (HR = 0.26, 95% CI = 0.10–0.70, for nadir < 0.1 vs ≥ 0.1).
Acute and chronic grade 3 genitourinary (GU) toxicity was observed in 5% and 16% of patients, respectively; acute and chronic gastrointestinal (GI) toxicity was observed in 0% and 3%. Durable grade 3 GU toxicity was observed in two patients, one with grade 3 GI toxicity. No grade 4 or 5 GU or GI toxicity was observed.
The investigators concluded, “Reirradiation with EBRT for locally recurrent prostate cancer after primary curative radiation therapy is clinically feasible and demonstrated a favorable outcome with acceptable toxicity in this prospective study with long-term follow-up.”
Christian Ekanger, MD, of the Department of Oncology and Medical Physics, Haukeland University Hospital, Bergen, Norway, is the corresponding author for the Journal of Clinical Oncology article.
Disclosure: The study was supported by a grant from the Trond Mohn Foundation. For full disclosures of the study authors, visit ascopubs.org.
