Reccurrence Pattern After Adjuvant Customized Chemotherapy Based on BRCA Expression Level (SCAT Trial)

Abstract

Background Postop platinum-based CT improves outcomes in completely resected NSCLC with nodal involvement, (St II-IIIA). Customization is feasible in adjuvant setting (tissue availability) . Analysis of expressionin genes involved in DNA repair could be use to select CT regiment. •BRCA1 plays an important role in DNA repair pathways and functions as a differential regulator of response to cisplatin and antimicrotubuleagents. SCAT trial results found that for low BRCA1 levels subgroup Cis-Gemcitabine was superior to Cis-Docetaxel and in high BRCA1 levels subgroup Docetaxel single agent without platinum achieved similar survival to Cis-Doc. Analysis of recurrence pattern in different subgroups of the trials has been performed.

Method From Jun/2007 to May/2013 591 patients were screened and 500 p were included (108 in Control arm treated with Cisplatin-Docetaxel and 392 in Experimental arm treated with Cisplatin-Gemcitabine, Cisplatin-Docetaxel or Docetaxel alone according terciles BRCA1 expression level). With a cut-off September 30th 2018 and a median follow-up of 60 months, recurrence pattern are analysed in each arm and subgroup treatment and comparison are made for incidence of risk of recurrence, single/multiple recurrence, thoracic/extrathoracic and site of metastases (liver, bone, brain).

Result Cumulative recurrence 232/456 evaluable patients (p) (50.8%). Recurrence were seen in 182/354 patients treated in experimental arm and in 50/102 p treated in the control arm (RR 1.04; 0.83-1.30) (p=0.672). Majority of recurrences 159/232 (68.5%) were single site recurrence. Intrathoracic recurrences in 121/232 (52%) while extrathoracic metastatic disease 111/232 (47.8%). No significant differences were seen for single/multiple, intra/extrathoracic recurrences between experimental and control arm. More frequent distant metastatic sites were: bone (42 p), brain (38 p) and liver (11 p) In the experimental group between different treatments no significant differences were found for the overall metastatic rate or for the single/multiple, intrathoracic/extrathoracic recurrences. For specific metastatic sites related to experimental treatment a significant reduction of risk of brain metastases were found in the experimental group with high level BRCA1 treated with Docetaxel single agent (p=0.0016).

Conclusion For NSCLC resected patients with lymph node involvement (Stages II-IIIA) risk of recurrence remains high with cumulative rate >50%. There were no differences in the Relative Risk (1.04) of recurrence when control and experimental arm are compared. Majority of recurrences were single site (68.5%) and intrathoracic (52%) but distant metastases developed in 47.8% os p. More frequent metastatic site was bone, followed by brain and liver. Brain metastases risk were significant lower for patients with low BRCA1 expression treated with single agent Docetaxel.