Colorectal cancer (CRC) is the third most common cancer worldwide and is perhaps the best understood of all cancers. Despite this, our understanding of sporadic early-onset rectal cancer (EORC), the predominant CRC subtype in India, is limited. We have performed the first comprehensive genomic, molecular and clinico-pathological characterization of CRC from India. Surprisingly, a significantly high proportion of EORC do not appear to be driven by either of the two canonical tumorigenesis pathways namely Wnt activation and mismatch repair inactivation, that drive a majority of CRC worldwide. We further identified Ca2+/NFAT signalling as one possible driver of EORC in the absence of Wnt activation. We have now performed next generation sequencing based RNA and exome sequencing of a well characterised set of EORC samples. The results reveal ARID2, a component of the SWI/SNF chromatin remodelling complex, to be a novel tumor suppressor in EORC.