Exploring All Avenues for Radiotherapy in Oligorecurrent Prostate Cancer Disease Limited to Lymph Nodes: A Systematic Review of the Role of Stereotactic Body Radiotherapy

Abstract

Context: Stereotactic body radiotherapy (SBRT) is emerging as a treatment option in patients affected by oligorecurrent prostate cancer disease limited to lymph nodes, a subgroup of patients who would otherwise be treated only with androgen deprivation therapy (ADT).

Objective: To perform a systematic review of SBRT for oligorecurrent prostate cancer limited to lymph nodes.

Evidence acquisition: We performed a systematic review of PubMed/Medline in October 2016 according to the Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA). We searched for studies reporting on biochemical or clinical progression and/or toxicity or complications of SBRT. Reports were excluded if these end points could not be ascertained or separately analyzed, or if insufficient details were provided.

Evidence of synthesis: A total of 363 patients from nine studies were collected. Of these patients, 211 were treated with SBRT for a total of 270 lymph nodes. With an alpha-beta ratio of 3 Gy, the biologically effective dose in fractionated SBRT was >100 Gy in all studies (range, 88-216 Gy). With a median follow-up of 19.23 mo, local control was achieved in 98.1% of patients. Median progression-free survival (defined as biochemical and/or radiological progression) was 22.5 mo (range, 11-30 mo). Information about ADT during SBRT was available in 281 patients, of whom 114 (40.5%) were on ADT during SBRT, and the duration of hormone therapy ranged from 1 to 17.5 mo. Median ADT-free survival was 32.8 mo (range, 25-44 mo). About toxicity, Common Terminology Criteria for Adverse Events toxicity scale was most used. Acute and/or late grade ≥2 toxicity was reported in only 5.6% of patients, and no patient developed grade 4 toxicity.

Conclusions: SBRT seems to be promising in lymph node oligorecurrent prostate cancer, although there is a weak level of evidence to support such investigational treatment, which is currently based on retrospective studies of single-institution or pooled experiences. ADT-free survival is an interesting end point, which needs to be investigated.

Patient summary: We performed a systematic review to assess outcomes and toxicity of stereotactic body radiotherapy (SBRT) for patients affected by oligorecurrent prostate cancer limited to lymph nodes. We concluded that SBRT is a promising therapy in this setting, but it needs to be validated in randomized controlled trials.

Keywords: Androgen-deprivation free survival; Local control; Lymph node metastasis; Oligorecurrent prostate cancer; Progression-free survival; Stereotactic body radiotherapy.