Background Flashcards
Appx how many cases of malignant mesothelioma are diagnosed in the United States annually?
2,500–3,000 cases/yr of malignant mesothelioma in the United States.
In which body sites can mesothelioma arise?
Mesothelioma most commonly arises in the pleura surface but can also arise from the mesothelial surfaces of the peritoneum, pericardium, and tunica vaginalis testis.
What is the most common cause of malignant pleural mesothelioma (MPM)? What are some other etiologic factors?
The greatest risk factor for developing MPM is occupational asbestos exposure, with carcinogenicity greater for amphiboles [rodlike] than chrysotile [serpentine form]. Asbestos is commonly found in insulation material, brake pads, and shipyards, 95% of which are in the chrysotile form.
Other known causes include naturally occurring asbestos within soil (tremolite), therapeutic radiation exposure (i.e., supradiaphragmatic irradiation for childhood lymphoma or testicular germ cell tumors), and possibly genetics (familial clustering of cases), with loss of BAP1 being 1 of the implicated genes.
What is the median survival (MS) of pts with MPM?
The MS of pts with MPM is appx 12 mos (MS in most series is 4–20 mos).
What is the major difference b/t the incidence of MPM in the United States vs. the developing world?
B/c of early adoption of asbestos regulations, the incidence of MPM in the United States peaked in 2004 and has subsequently declined. The incidence has not yet peaked in the developing world and is not expected to for the next 10–20 yrs. However, the United States still has more cases than anywhere else in the world.
What is the estimated latency b/t asbestos exposure and MPM?
The estimated latency b/t asbestos exposure and MPM is 20–40 yrs. (Lanphear BP et al., J Occup Med 1992)
What % of MPM cases are related to asbestos exposure?
70%–80% of cases have documented asbestos exposure.
What is lifetime risk of MPM for someone with an occupational asbestos exposure Hx?
The lifetime risk of developing MPM with asbestos exposure is ∼10%.
Does smoking cause MPM?
No. Smoking alone is not associated with MPM, but smoking increases the risk associated with asbestos exposure.
Does asbestos increase the risk for developing other cancers besides MPM?
Yes, along with cigarette smoking asbestos exposure acts synergistically to increase the risk of lung cancer by 60-fold compared to nonsmoking, nonasbestos exposed persons. Other cancer includes nonmesothelioma GI cancers. An asbestos worker has a 50% chance of dying from cancers compared to nonexposed individuals (∼18%).
Is there a sex predilection for MPM?
Yes. Males are more commonly affected than females, likely related to occupational exposure differences.
At what age does the incidence of MPM peak?
The incidence does not peak. It continuously increases with age. The median age at Dx is 72 yrs.
What are the 3 most common histopathologic subtypes of MPM in decreasing order of frequency?
Histopathologic subtypes of MPM: epithelioid (favorable, 40%) > mixed or biphasic (35%) > sarcomatoid or mesenchymal (25%)
`What are some common genetic changes seen in MPM?
Loss of tumor suppressor genes p16, p14, and NF-2 are common genetic changes in MPM.
