I'm curious; what do you mean by database of cancers? If you mean actual tissue-banks with specific cancerous samples isolated and identified for testing, then

I'm curious; what do you mean by database of cancers? If you mean actual tissue-banks with specific cancerous samples isolated and identified for testing, then they exist. If you mean just databases of genomic data related to cancers, those exist too, but sadly you can't just BLAST away every problem you find. Tissue is extremely limited. The volume required to do testing shreds through the volume of tissue removed during biopsy very quickly, leaving limited amounts left over for study. As a result, access to cancerous tissue samples is actually a tremendous limiter on this type of research. In a company I worked on prior which was developing analogous technology, our ability to access a number of university affiliated tissue banks was a key differentiation between us and the competition.