Abstract 87P
Background
High precision radiotherapy techniques, as stereotactic body radiotherapy (SBRT), are increasingly used in the management of non-resectable early-stage lung cancer and also in oligometastatic disease, usually with curative intent. However, there is a need for personalized prognosis biomarkers to stratify patients, adapt treatments and assess their performance. Although, nowadays, more than 50% of cancer patients require radiotherapy, Genomics has not yet been integrated into the clinical practice of radiation oncology.
Methods
We performed germline, tissue- and liquid-biopsy NGS panels on 46 early-stage/oligometastatic cancer patients undergoing radiotherapy to identify personalized genomic biomarkers to be monitored in circulating tumor DNA (ctDNA) from serial liquid biopsies collected during radiotherapy and follow-up. ctDNA signal was compared to patient clinical response, assessed according to RECIST criteria.
Results
The integration of the different genomic tests enabled to determine the origin of the variants identified, essential for successful biomarker selection, only 1/3 of the genomic variants identified by the liquid biopsy panel were real tumor variants. This comprehensive genomic approach revealed variants associated with approved therapies (19.6% of cases) and with investigational therapies/access to clinical trials (60.9%), potential ctDNA biomarkers (100%) and hereditary predispositions to cancer (6.5%). The pre-treatment ctDNA signal was significatively associated with progression-free survival in early-stage and oligometastatic patients (p-value = 0.001). Also, longitudinal ctDNA analysis could be used as a follow-up biomarker, even anticipating other diagnostic tests.
Conclusions
In patients with early stage or oligometastatic disease treated with RT, comprehensive genomic testing showed a wide range of benefits. Moreover, in this cohort of patients ctDNA detection during the treatment and the follow-up has the potential to guide prognosis and to identify the patients who may benefit from further therapeutic interventions.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
Instituto de Medicina Oncológica y Molecular de Asturias (IMOMA), S.A.
Funding
Instituto de Medicina Oncológica y Molecular de Asturias (IMOMA), S.A.
Disclosure
All authors have declared no conflicts of interest.