BRCA1 expression level as prognostic factor for recurrence in resected NSCLC with adjuvant chemotherapy: SCAT Trial

Background Post-operative platinum-based chemotherapy is the standard of care for resected NSCLC with nodal involvement. Expression of genes involved in DNA repair may have a prognostic role for the outcome. BRCA1 plays an important role in DNA repair pathways and could have a prognostic impact in this setting. The SCAT trial results found that for low BRCA1 levels subgroup Cis-Gem was superior to Cis-Doc and in high BRCA1 subgroup docetaxel single agent without platinum achieved similar survival to Cis-Doc. Risk of recurrence analysis according BRCA-1 levels has been performed. Methods From Jun/2007 to May/2013 591 patients were screened and 500 were included, 108 in the control arm treated with Cis-Docetaxel and 392 in the experimental arms treated with Cis-Gem, Cis-Doc or docetaxel alone according to terciles of BRCA1 expression level. With a cut-off September 30th 2018 and a median follow-up of 60 months, recurrence patterns were analysed for the whole group according BRCA1 levels in tumor tissue and comparison were made for risk of recurrence, single/multiple recurrence, thoracic/extrathoracic and metastatic sites (liver, bone, brain). Results Cumulative recurrence was evaluable in 232/456 patients (50.8%), 182/354 patients treated in the experimental arm and in 50/102 patients treated in the control arm (RR 1.04; 0.83-1.30) (p = 0.672). The majority of recurrences 159/232 (68.5%) were single site intrathoracic recurrences in 121/232 (52%) while 111/232 were extrathoracic (47.8%). Overall recurrence was 56.5% (113/200 p) for low tercile BRCA1 vs 48.8% (63/129) for intermediate tercile vs 44% (56/127) for high tercile (p = 0.025). No differences were seen between tercile groups for single site (p = 0.35), multiple site (p = 0.26), intrathoracic (p = 0.36), or extrathoracic (p = 0.38). More frequent distant metastatic sites were: bone (42 patients), brain (38 patients) and liver (11 patients). RIsk reduction was seen for brain metastases in patients with higher tercile BRCA1 (p = 0.003). Conclusions For NSCLC resected patients with lymph node involvement risk of recurrence remains high with a cumulative rate > 50%. Relative risk of recurrence was lower for tumors with higher BRCA1 levels. Distant metastases were seen in 47.8% of patients. Brain metastases risk was significant lower for patients with low BRCA1 expression. BRCA1 levels acts as a prognostic factor in early stages NSCLC. Clinical trial identification EudraCT: 2007-000067-15; NCT 00478699. Legal entity responsible for the study Spanish Lung Cancer Group - Grupo Espanol Cancer de Pulmon. Funding Sanofi Aventis. Disclosure All authors have declared no conflicts of interest.