Israel Medical Association Journal

Background: Prophylactic cranial irradiation (PCI) exclusion in favor of brain magnetic resonance imaging (MRI) staging and surveillance in the management of small cell lung cancer (SCLC) is controversial yet accepted by some centers. The use of MRI suggests performing stereotactic radiosurgery (SRS) treatment for limited brain metastases. Data regarding SRS efficacy in this setting is limited.

Objectives: To assess intracranial objective response rate (iORR), progression-free survival (iPFS), intracranial failure patterns, overall survival (OS) and time-to-whole-brain radiation therapy (WBRT)/death, whichever occurred first (TTWD) with SRS in SCLC.

Methods: The study comprised 10 consecutive SCLC patients with brain metastases treated with SRS and followed-up at Davidoff Cancer center between Aug 2012 and March 2019. Brain MRI images were reviewed by a neuro-radiology specialist.

Results: iORR was 57% as assessed by response assessment in neuro-oncology brain metastases. Intracranial progression developed in 8 patients. Median iPFS was 4.0 months (95% confidence interval [95%CI] 1.7–7.2). In-site, off-site and combined pattern of intracranial failure was seen in 0, 5, and 3 patients, respectively; median number of new brain lesions following SRS was 4 (range, 1–12). SRS was performed 10 additional times in 6 patients (median number of lesions irradiated per round was 1, range 1–5). WBRT was administered in 3 patients. Median TTWD was 20.9 months (95% CI, 1.9–26.8). Median OS since SRS administration was 23.2 months (95% CI, 4.2–not reached).

Conclusions: MRI surveillance with multiple rounds of SRS may serve a reasonable alternative to PCI or therapeutic WBRT in SCLC. 

Background: The main acquired resistance mechanism to first- and second-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) in EGFR mutant non-small cell lung cancer (NSCLC) is the propagation of T790M clones, which can be detected in circulating tumor DNA (ctDNA).

Objectives: To analyze osimertinib outcomes according to T790M testing method.

Methods: The study comprised 33 consecutive patients with advanced EGFR mutant NSCLC who were diagnosed with a T790M mutation after progression on first- or second-generation EGFR TKIs and treated with osimertinib. The patients were divided into groups A (diagnosed by tumor testing) and B (by ctDNA testing). Osimertinib outcomes were compared between the groups.

Results: Objective response rate with osimertinib comprised 54% and 62% in groups A and B, respectively (P = 0.58). Median progression-free survival (PFS) with osimertinib was 8.9 months (95% confidence interval [95%CI] 1.8–17.5) and 9.1 months (95%Cl 5.3–12.6) in groups A and B, respectively (log-rank test 0.12, P = 0.73). Median overall survival (OS) was 13.8 months (95%CI 4.9–25.5) and 13.8 months (95%Cl 7.7–27.7) in groups A and B, respectively (log-rank test 0.09, P = 0.75). T790M testing technique did not affect PFS (hazard ratio [HR] 1.16, 95%CI 0.50–2.69, P = 0.73) or OS (HR = 1.16, 95%CI 0.45–3.01, P = 0.76). The proportion of patients diagnosed by ctDNA grew from 56% in 2015 to 67% in 2016–2017.

Conclusions: Our study provides a ctDNA validation for the purpose of T790M testing in EGFR mutant NSCLC.