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Stereotactic Ablative Body Radiotherapy in Patients With Oligometastatic Cancers
TAKE-HOME MESSAGE
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The authors of this prospective National Health Service registry–based observational study evaluated the outcomes of 1422 patients with solid cancer extracranial oligometastatic disease treated with stereotactic ablative body radiotherapy. The 1- and 2-year overall survival rates were 92% and 79%, respectively. Grade 3/4 toxicity was rare.
- These real-world findings support both earlier trial data and this therapeutic approach in the selected patient population.
abstract
This abstract is available on the publisher's site.
Access this abstract nowBACKGROUND
Stereotactic ablative body radiotherapy (SABR) is increasingly being used to treat oligometastatic cancers, but high-level evidence to provide a basis for policy making is scarce. Additional evidence from a real-world setting is required. We present the results of a national study of patients with extracranial oligometastases undergoing SABR, representing the largest dataset, to our knowledge, on outcomes in this population so far.
METHODS
In 2015, National Health Service (NHS) England launched a Commissioning through Evaluation scheme that funded a prospective, registry-based, single-arm, observational, evaluation study of patients with solid cancer and extracranial oligometastases treated with SABR. Prescribed doses ranged from 24-60 Gy administered in three to eight fractions. The study was done at 17 NHS radiotherapy centres in England. Patients were eligible for the scheme if aged 18 years or older with confirmed primary carcinoma (excluding haematological malignancies), one to three extracranial metastatic lesions, a disease-free interval from primary tumour development to metastases of longer than 6 months (with the exception of synchronous colorectal liver metastases), a WHO performance status of 2 or lower, and a life expectancy of at least 6 months. The primary outcome was overall survival at 1 year and 2 years from the start of SABR treatment. The study is now completed.
FINDINGS
Between June 15, 2015, and Jan 30, 2019, 1422 patients were recruited from 17 hospitals in England. The median age of the patients was 69 years (IQR 62-76), and the most common primary tumour was prostate cancer (406 [28·6%] patients). Median follow-up was 13 months (IQR 6-23). Overall survival was 92·3% (95% CI 90·5-93·9) at 1 year and 79·2% (76·0-82·1) at 2 years. The most common grade 3 adverse event was fatigue (28 [2·0%] of 1422 patients) and the most common serious (grade 4) event was increased liver enzymes (nine [0·6%]). Notreatment-related deaths were reported.
INTERPRETATION
In patients with extracranial oligometastatic cancer, use of SABR was associated with high overall survival and low toxicity. 'The study findings complement existing evidence from a randomised, phase 2 trial, and represent high-level, real-world evidence supporting the use of SABR in this patient cohort, with a phase 3 randomised, controlled trial to confirm these findings underway. Based on the selection criteria in this study, SABR was commissioned by NHS England in March, 2020, as a treatment option for patients with oligometastatic disease.
Additional Info
Disclosure statements are available on the authors' profiles:
Stereotactic Ablative Body Radiotherapy in Patients With Oligometastatic Cancers: A Prospective, Registry-Based, Single-Arm, Observational, Evaluation Study
Lancet Oncol 2021 Jan 01;22(1)98-106, A Chalkidou, T Macmillan, MT Grzeda, J Peacock, J Summers, S Eddy, B Coker, H Patrick, H Powell, L Berry, G Webster, P Ostler, PD Dickinson, MQ Hatton, A Henry, S Keevil, MA Hawkins, N Slevin, N van AsFrom MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
Oncology
This “real-world,” prospective, single-arm, observational study recruited over 1400 patients from the United Kingdom with one to three extracranial oligometastases to receive stereotactic ablative body radiotherapy (SABR). Although I would not consider this study to be practice-changing, some very interesting concepts should be considered.
First, the excellent 1- and 2-year survival rates are encouraging; but, without a comparative arm, cannot be definitely attributed to SABR. The results are likely also due to the selection of patients with a high likelihood of 1- to 2-year survival (prostate, colorectal).
Second, the real-world nature of this study is important as it allowed the recruitment of >1400 patients. This is by far the largest prospective study on the use of SABR for oligmetastatic disease. Previous phase II studies (which are changing practice) had fewer than 100 patients. Additionally, the patients in this study appear to be at least older than in previous SABR studies as well (median age of 69 years, and >80% aged 60 years and older). This is likely a lot more consistent with the ages of most patients seen in oncology clinics, which allows the results of this study to be generalizable to the patients I am most likely to treat.
Finally, as per the plan of NHS England, the study results led to the approval/availability of SABR as a treatment option for patients in England. Although I mentioned that I did not believe this was a practice-changing study, I do very much welcome the approval of SABR for a select patient population in England. These “real-world” results, combined with the survival benefit results seen in several phase II studies, still need to be confirmed in phase III studies. But, in the meantime, the data are compelling enough to allow patients to receive these treatments, which have been shown to cost less than many systemic agents and to have very few adverse side effects. I am very encouraged that NHS England was willing to approve SABR after these results and did not require patients to wait on the results of larger phase III studies, which may take years to conclude.