Multi-Institutional Analysis of Metastasis Directed Therapy with or without Androgen Deprivation Therapy in Oligometastatic Castration Sensitive Prostate Cancer

PURPOSE/OBJECTIVE(S)

Several prospective trials in oligometastatic castration sensitive prostate cancer (omCSPC) have shown metastasis-directed therapy (MDT) can delay time to progression and initiation of androgen deprivation therapy (ADT) compared to observation. However, the optimal integration of ADT with MDT remains unclear. Here we report a multi-national, multi-institutional retrospective cohort of omCSPC treated with MDT to characterize the long-term outcomes of patients treated with MDT alone or in combination with ADT.

MATERIALS/METHODS

Patients with a controlled primary site and omCSPC (defined as ≤ 5 lesions on conventional imaging) treated with MDT with or without concurrent ADT and with at least 36 months follow-up were retrospectively screened across 13 institutions. The primary endpoints included biochemical progression free survival (bPFS) and radiographic progression free survival (rPFS) calculated using Kaplan-Meier method and stratified by treatment group (MDT alone vs MDT + ADT). Multivariable Cox regression was performed adjusted for variables found to be prognostic on univariate analysis.

RESULTS

Among 414 patients screened, a total of 263 patients treated between 2003 and 2018 met inclusion criteria and included. Of these, 105 received MDT alone and 158 received MDT+ADT, with median follow-up of 49.5 and 54.5 months, respectively. The majority were metachronous (90%) and had bone lesions (60%). Median ADT duration was 21.3 months (IQR 12.0- 31.9). Patients who received ADT vs. no ADT had poorer prognostic features including 23% vs. 1% synchronous (p<0.001), and 55% vs 40% Gleason 8-10 (p = 0.012). ADT use was associated with a better 5-year bPFS 24% vs 11% (p<0.0001) and rPFS 41% vs 29% (p<0.001). On multivariable Cox regression adjusting for post-MDT PSA nadir and salvage therapy, ADT use maintained significance for both bPFS (HR 0.51 (0.36, 0.71), p<0.001) and rPFS (HR 0.67, 95% CI 0.46-0.96, p = 0.03).

CONCLUSION

Long-term outcomes with MDT alone suggest a small proportion of patients experience sustained disease control. The addition of ADT appears to improve rPFS, however prospective studies are needed in order to allow for personalization of care in patients with omCSPC.

SEOR SBRT-SG survey on SRS/SBRT dose prescription criteria in Spain

AIM

Stereotactic body radiotherapy (SBRT) and stereotactic radiosurgery (SRS) are essential tools in radiation oncology. In Spain, the use of these techniques continues to grow as older linear accelerators (linacs) are replaced with modern equipment. However, little is known about inter-centre variability in prescription and dose heterogeneity limits. Consequently, the SBRT-Spanish Task Group (SBRT-SG) of the Spanish Society of Radiation Oncology (SEOR) has undertaken an initiative to assess prescription and homogeneity in SRS/SBRT treatment. In the present study, we surveyed radiation oncology (RO) departments to obtain a realistic overview of prescription methods used for SBRT and SRS treatment in Spain.

METHODS

A brief survey was developed and sent to 34 RO departments in Spain, mostly those who are members of the SEOR SBRT-SG. The survey contained seven questions about the specific prescription mode, dose distribution heterogeneity limits, prescription strategies according to SRS/SBRT type, and the use of IMRT-VMAT (Intensity Modulated Radiation Therapy-Volumetric Modulated Arc Therapy).

RESULTS

Responses were received from 29 centres. Most centres (59%) used the prescription criteria D_95% ≥ 100%. Accepted dose heterogeneity was wide, ranging from 107 to 200%. Most centres used IMRT-VMAT (93%).

CONCLUSIONS

This survey about SRS/SBRT prescription and dose heterogeneity has evidenced substantial inter-centre variability in prescription criteria, particularly for intended and accepted dose heterogeneity. These differences could potentially influence the mean planning target volume dose and its correlation with treatment outcomes. The findings presented here will be used by the SEOR SBRT-SG to develop recommendations for SRS/SBRT dose prescription and heterogeneity.

Recommended procedures and responsibilities for radiosurgery (SRS) and extracranial stereotactic body radiotherapy (SBRT): report of the SEOR in collaboration with the SEFM

Today, patient management generally requires a multidisciplinary approach. However, due to the growing knowledge base and increasing complexity of Medicine, clinical practice has become even more specialised. Radiation oncology is not immune to this trend towards subspecialisation, which is particularly evident in ablative radiotherapy techniques that require high dose fractions, such as stereotactic radiosurgery (SRS), and stereotactic body radiotherapy (SBRT). The aim of the present report is to establish the position of the Spanish Society of Radiation Oncology (SEOR), in collaboration with the Spanish Society of Medical Physics (SEFM), with regard to the roles and responsibilities of healthcare professionals involved in performing SRS and SBRT. The need for this white paper is motivated due to the recent changes in Spanish Legislation (Royal Decree [RD] 601/2019, October 18, 2019) governing the use and optimization of radiotherapy and radiological protection for medical exposure to ionizing radiation (article 11, points 4 and 5) [1 ], which states: "In radiotherapy treatment units, the specialist in Radiation Oncology will be responsible for determining the correct treatment indication, selecting target volumes, determining the clinical radiation parameters for each volume, directing and supervising treatment, preparing the final clinical report, reporting treatment outcomes, and monitoring the patient's clinical course." Consequently, the SEOR and SEFM have jointly prepared the present document to establish the roles and responsibilities for the specialists-radiation oncologists (RO), medical physicists (MP), and related staff -involved in treatments with ionizing radiation. We believe that it is important to clearly establish the responsibilities of each professional group and to clearly establish the professional competencies at each stage of the radiotherapy process.