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MINI 04 - Clinical Care of Lung Cancer (ID 102)
- Event: WCLC 2015
- Type: Mini Oral
- Track: Treatment of Advanced Diseases - NSCLC
- Presentations: 1
MINI04.08 - Malignant Pleural Effusions Are Predictive of Peritoneal Carcinomatosis in Patients with Advanced EGFR Positive Non-Small Cell Lung Cancer (ID 3191)
16:45 - 18:15 | Author(s): W.T. Purcell
Lung cancer is the most frequent cause of cancer death and metastatic disease at the time of initial diagnosis is common. Peritoneal carcinomatosis (PC) from lung cancer is a rare clinical event with a reported incidence of 1.2% (Satoh et al. 2001). However, there are limited data on what factors predict peritoneal progression in lung cancer. Over the last decade, molecular analysis of NSCLC has provided more detailed classification of patterns of metastatic spread. It has also been shown that oncogene-addicted subsets of NSCLC have different patterns of metastatic spread (Doebele et al. 2012). We investigated whether certain baseline patterns of metastatic spread in patients with advanced EGFR mutation positive (EGFR+) NSCLC can predict subsequent PC.
We identified 156 patients with EGFR+ (Exon 19 or L858R) mutations from 2009 - 2014, of which 139 had metastatic NSCLC. 11 patients developed PC. This was defined as the presence of biopsy-proven adenocarcinoma from peritoneal fluid or radiographic patterns consistent with omental metastases. We identified areas of metastatic disease in predefined sites (brain, liver, lung, adrenal, soft tissue and pleura) at the time of diagnosis or metastatic recurrence. We noted if patients developed T790M, a resistance mutation to targeted therapy, in EGFR+ patients. A Fisher-Exact test was used to determine statistical significance between metastatic site and subsequent PC.
Table 1 - Sites of metastasis and presence of T790M mutation in patients with PC and without PCThe presence of a pleural effusion was universal in all 11 EGFR+ patients who subsequently developed PC and this finding was statistically significant (P = 0.0001). 9 out of 11 patients with PC were identified to have a T790M mutation, a finding that was statistically significant (P = 0.0001). Except one patient, all EGFR+ patients developed PC following targeted tyrosine kinase therapy.
Metastatic site / mutation PC No PC P value Lung 9.1% 38.6% P = 0.06 Liver 18.2% 15.8% P = 0.689 Bone 36.4% 46.8% P = 0.549 Brain 0% 23.7% P = 0.3570 Adrenal 0% 6.4% P = 0.123 Soft tissue 9.1% 2.2% P = 0.265 Pleural effusion 100% 26.6% P = 0.0001 T790M mutation 81.1% 34.5% P = 0.0001
The presence of a malignant effusion is highly predictive of developing PC in patients with EGFR+ NSCLC. Although the underlying mechanism of PC is not entirely clear, it may be related to serosal communication with subsequent micrometastatic seeding of the peritoneal cavity. The T790M mutation, the most common acquired resistance mechanism to EGFR kinase inhibitors, was significantly more prevalent in the group that developed PC, although it remains unclear whether this mutation has any causative effect on spread to the peritoneum.
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