Another new study has been released that supports the idea that mesothelioma patients who are missing the tumor suppressor called BAP1 are more likely to survive longer than those who have intact BAP1 genes.
The BRCA-1-associated protein 1 (BAP1) gene is located on the chromosome 3p21. Because the job of BAP1 is to help suppress cancer, a mutation that causes this gene to be inactive raises the risk that a person could get mesothelioma or another cancer. BAP1 loss has also been associated with increased risk of skin cancer, renal cell cancer and some lung and breast cancers.
But there appears to be an upside to BAP1 loss. Data published in the journal Pathology suggests that mesothelioma patients with BAP1 loss are more likely to be younger when they are diagnosed and to have the epithelioid variety of mesothelioma. Both of these factors have been associated with longer survival.
To conduct the new study, a team of Australian scientists analyzed the cases of 229 pleural mesothelioma patients diagnosed at Royal North Shore Hospital in St. Leonards, Australia between 1991 and 2014. All cases were independently reviewed to confirm the diagnosis and to classify them by subtype – epithelioid, sarcomatoid or biphasic.
Forty-six percent of the patients (106) had negative tests for the presence of BAP1. These patients were younger at diagnosis, typically had the epithelioid variety of mesothelioma, and had survival rates more than twice as long as the BAP1 positive group. In the BAP1 negative group, the median survival was 16.11 months versus just 6.34 months in those with no BAP1 loss.
What will the results mean for current and future mesothelioma patients? The study’s authors predict that, if their results are confirmed by further studies, more mesothelioma patients may undergo BAP1 testing after diagnosis as a way to predict survival and help make critical treatment and/or life decisions.
A multi-center study published in Carcinogenesis in 2014 found a seven-fold increase in mesothelioma survival rates in patients with the BAP1 mutation.
Farzin, M et al, “Loss of expression of CAP1 predicts longer survival in mesothelioma”, May 1, 2015, Pathology, Epub ahead of print
Baumann, F, et al, “Mesothelioma Patients with Germline BAP1 Mutations have Seven=Fold Improved Long-term Survival”, November 7, 2014, Carcinogenesis