Cancer is the second most cause of the death worldwide. According to World Health Organization (WHO) around 10 million deaths were caused by cancer globally. There are more than 120 types of cancers. The most common types of cancers are: bladder, breast, colon and rectal, kidney, leukemia, lung, pancrease, prostate, skin and thyroid. Many of the cancers are genetically inherited from one generation to the next. Therefore, sequencing and comparing of genomes will help to predict the probability of occurrence of cancer. If cancer responsible genes are detected, this will help patient to be alert in advance and take preventive measures.
With the rapid advancement in next generation sequencing technology, genome sequencing is getting more accessible and cheaper every year. As the more genomic data are available, our understanding of genetic make- up of human body is getting better day by day. Scientists have already sequenced more than 50,000 cancer genomes worldwide, and it is expected to increase the number of sequenced cancer genomes in hundreds of millions within a decade. Recently, genetic testing panels for genetically inherited cancers based on next generation sequencing are available. Although several cancer panels are available for genetic testing, sometimes they miss to detect cancer causing mutations. Therefore, whole genome sequencing is needed for extensive exploration of cancer related genes. For example, in the UK, three sisters developed breast cancer within 13 months of each other, but the common breast cancer associated genes BRCA1 and BRCA2 were not conclusive in all three sisters. However, when the genomes of two sisters were sequenced, scientists were able to detect a pathogenic DNA mutation in the PALB2 gene. The gene was predicted to hinder its function and increase the risk of breast cancer.