I was just wondering why Mesothelioma specifically is one of the the hottest keyword that has a higher bid rate...

and why not other cancers!!!
Here are some facts that I found interesting...
In short it is
estimated that the total costs of asbestos litigation in the USA alone is expected to reach $200 billion... this makes it really hot for claimants, defendants and the
attorneys.
What is MesotheliomaMesothelioma is a form of cancer that is almost always caused by previous exposure to asbestos. In this disease, malignant cells develop in the mesothelium, a protective lining that covers most of the body's internal organs. Its most common site is the pleura (outer lining of the lungs and chest cavity), but it may also occur in the peritoneum (the lining of the abdominal cavity) or the pericardium (a sac that surrounds the heart).
Most people who develop mesothelioma have worked on jobs where they inhaled asbestos particles, or have been exposed to asbestos dust and fibre in other ways, such as by washing the clothes of a family member who worked with asbestos, or by home renovation using asbestos cement products. Unlike lung cancer, there is no association between mesothelioma and smoking.
(source:wiki)