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ORAL 23 - Prevention and Cancer Risk (ID 121)
- Event: WCLC 2015
- Type: Oral Session
- Track: Prevention and Tobacco Control
- Presentations: 1
ORAL23.05 - Increased Proportion of Female and Young Mesothelioma Cases Are Indicators of Environmental Exposure to Carcinogenic Mineral Fibers in Nevada (ID 959)
10:45 - 12:15 | Author(s): F. Baumann
Inhalation of asbestos and other carcinogenic mineral fibers cause malignant mesothelioma (MM) and lung cancer. Occupational exposure leads to a MM male to female (M:F) sex-ratio of 4-8:1, with a mean age of diagnosis of 74 years old because of the 30-50 years latency between initial exposure and MM development. In places where people are only environmentally exposed to carcinogenic fibers, the M:F sex-ratio is about 1:1 and the mean age of diagnosis is 50-60 years. In places where both types of exposure exist, the M:F sex ratio decreases and the proportion of young (<55 years old) cases increases, compared to places with occupational exposure only. Therefore, incidence rates cannot distinguish between occupationally- and environmentally-caused mesotheliomas.
In order to detect areas with possible environmental exposure to carcinogenic fibers, we studied the geology of Nevada. We compiled and integrated known presence of fibrous minerals in Nevada from published sources. We used the CDC 2006-2010 cancer data to study MM incidence and death rates by state and by gender. We also analyzed MM mortality data from the CDC in different Nevada Counties, per sex and age group, for the 1999-2010 period.
Several fibrous minerals were identified in Nevada, including actinolite asbestos, other amphiboles such as magnesioriebeckite, winchite and richterite that caused an epidemic of asbestos-related disease in Libby, Montana, and the highly carcinogenic erionite. For the 2006-2010 period, Nevada has a global MM age-standardized incidence rate of 10 cases per million inhabitants-year (95% confidence interval (CI): 8-12), similar to the average MM rate in the US (10 per million; 95% CI: 10-10). We discovered that Clark and Nye counties in southern Nevada had higher proportion of young (<55 years) MM cases (11.28%) and lower M:F sex-ratio (2.69:1), compared with other Nevada counties (M:F sex-ratio=6.33:1, p=0.04; proportion of young MMs=9.09%, p=0.80) and with the US (M:F sex-ratio=4.97:1, p=0.04; proportion of young MMs=6.21%, p=0.02).
The significant decrease of MM M:F sex-ratio and increase of young cases are indicators of possible environmental exposure to carcinogenic fibers in southern Nevada. In this arid region, naturally occurring asbestos minerals are present in urban and rural areas where people use to enjoy outdoor activities including horseback riding, running, hiking, bicycling, and off-road vehicle (ORV) recreation. Airborne dust is common due to wind erosion. Asbestos fibers have been found in air and dust samples in Clark County. Further research should be conducted in this area to help identify sources of environmental exposure to these mineral fibers, activities that lead to the release of these carcinogenic fibers into the air, and measures to reduce the consequent risk of MM and other cancers.
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P2.08 - Poster Session/ Thymoma, Mesothelioma and Other Thoracic Malignancies (ID 225)
- Event: WCLC 2015
- Type: Poster
- Track: Thymoma, Mesothelioma and Other Thoracic Malignancies
- Presentations: 1
- Coordinates: 9/08/2015, 09:30 - 17:00, Exhibit Hall (Hall B+C)
P2.08-002 - Germline BAP1 Mutation Is Associated with a Significant Increased Survival and Multiple Cancer in Mesothelioma Patients (ID 961)
09:30 - 17:00 | Author(s): F. Baumann
Because the diagnosis is often made at a late stage, malignant mesothelioma (MM) prognosis is very poor, with a median survival of 6-12 months and a five-year survival of less than 5%. We found that germline BAP1 mutation is associated with a new cancer syndrome, including rare malignancies such as MM and uveal carcinoma (UV), and other cancers. We noted that some MM cases that we followed from BAP1 mutated families had prolonged survival. We carried out a pooled analysis of BAP1 mutated MM patients to test the hypothesis that they had a better survival compared to sporadic MM.
: We included all published BAP1 germline mutated MMs with available data on BAP1 status, site of MM, age at diagnosis, gender, and age at death or status at end of follow-up, in addition to the BAP1 mutated MM cases from families that we are following. Twenty-three BAP1 MM patients were included. Using the Kaplan-Meier method and Wilcoxon test, we compared survival among BAP1 mutated MM patients with that of all MMs (N = 10 556) recorded in the US SEER data from 1973 to 2010.
In our BAP1 cohort, ten patients had peritoneal MM, ten pleural MM, and three MM in both locations. Thirteen patients had one or more malignancies in addition to MM. Actuarial median survival for the MM patients with germline BAP1 mutations was five years, as compared with less than one year in the SEER MM control group. Five-year survival was 47%, 95%CI [24-67%], as compared with 6.7% [6.2-7.3%] in the SEER MM control group. The small size of our BAP1 cohort did not allow for significant statistical comparisons. However, patients with peritoneal MM (median survival of 10 years, P=0.0571), or with a second malignancy in addition to MM (median survival of 10 years, P=0.0716), survived for a longer time compared to patients who only had pleural MM, or MM patients without a second malignancy, respectively. Figure 1
MM patients with germline BAP1 mutations have an overall seven-fold increased survival, independently of sex and age. This better prognosis was associated with multiple cancer and/or peritoneal MM. Appropriate genetic counseling and clinical management should be considered for MM patients who are also BAP1 mutation carriers.