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ORAL 22 - Moving Beyond a Smoking Related-Cancer to the Young, Never-smokers and Inherited Disease (ID 117)
- Event: WCLC 2015
- Type: Oral Session
- Track: Biology, Pathology, and Molecular Testing
- Presentations: 1
ORAL22.02 - Spectrum of Cancer Types in Kindreds with NSCLC and EGFR T790M Mutations: Results from INHERIT EGFR (ID 3180)
10:45 - 12:15 | Author(s): J.C. Heng
EGFR T790M is most commonly seen as a somatic mutation in non-small cell lung cancer (NSCLC) following resistance to EGFR targeted therapies. Rarely EGFR T790M can be seen as a germline mutation where, in case reports, it has been associated with inherited lung cancer risk. However, the penetrance of the T790M germline mutation for NSCLC is not known, nor is it known whether germline carriers are also at risk for other cancers. The INHERIT study (INvestigating HEreditary RIsk from T790M, NCT01754025) is designed to prospectively identify and study individuals and family members with this rare germline mutation.
Eligible subjects had EGFR T790M identified on routine cancer genotyping (excluding acquired T790M after therapy), or if they or a relative had already been found to carry a germline EGFR mutation. Confirmatory testing of saliva or blood was done to identify germline T790M carriers. Detailed 3-4 generation pedigrees of probands were constructed and analyzed for type of cancer, age at diagnosis, and relationship to proband with T790M mutation.
23 eligible kindreds were enrolled between 12/12 and 4/15, with 17 probands identified to have germline T790M and 6 probands shown to have acquired T790M. Average age at diagnosis for probands with germline T790M mutation was 55.8 (range 29 to 76) compared to 62 years (range 47 to 74) for non-germline probands. Pedigrees from confirmed T790M probands had an average kindred size of 28 members (range 3 to 40). Among the 325 1[st] and 2[nd] relatives, there were a total of 61 (18.7%) cancer diagnoses; 25 (39.7%) in lung, 4 (6.3 %) breast, 3 (4.8 %) colon, 4 (6.3) esophagus, 4 (6.3 %) leukemia/lymphoma, 3 (4.8 %) prostate, 3 (6.8%) bladder, 2 (3.2%) testes with about 1% or less with pancreatic, renal, brain, cervical cancer. Further, 7 of these 17 kindreds (41%) had multi-generational lung cancers consistent with autosomal dominant inheritance. In contrast, the cancer profile from the non-germline T790M kindreds showed high prevelance of breast cancer (61%; 13 of 21 relatives with cancer) and low prevalence of lung cancer (9%; 2 of 21). None of these 6 kindreds showed an autosomal dominant pattern of inheritance.
A wide variety of tumor types were reported in this unique set of kindreds identified by tumor typing of probands for EGFR T790M mutations, with lung cancer as the most frequently reported cancer in close relatives. A high proportion of germline T790M kindreds also had a strong family history consistent with dominant inheritance. Future research will be needed to clarify the cancer risks in relatives of patients with EGFR T790M germline mutations and to develop guidelines and standards for prevention and early detection.
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