Survival of the fittest! Sadly this also applies to cancer cells. In the early phase of cancer, (epi)genetic mutations in initiated cells may be selected for their ability to exploit cell competition to eliminate neighboring less competent cells, thereby facilitating tumor expansion.

These tumor cells' competitive skills include but are not limited to the ability to live under hypoxia and acidic microenvironment, clonal expansion of cancer stem cells that contributes to tumor heterogeneity, as well as evading host immune cell surveillance. Interestingly, it has been recently shown that cell competition can also occur in later phases of cancer.

More importantly, cancer risk factors (such as unhealthy diet and chronic inflammation) could also produce variations of niche supplying the tumor and might dictate the outcome of cell competition in tumorigenesis.

It is anticipated that strategies pinpointing competitive cell interactions in various phases and microenvironments of cancers might help to suppress cancer initiation, expansion, and progression. In this collection, we welcome original articles focusing on tumor cell competition research.

With the advancement of sequencing technologies, whole genome sequence information can be obtained robustly in a fairly short time and at low cost. Yet, currently there is often a lack of connection of genomic data to proteomic data, probably due to the fact that standard proteomics workflows rely on databases of only known wild-type/canonical proteins, but these databases generally do not integrate the data of cancer-associated proteins with countless amino acid sequence alterations due to gene mutations, post-translational modifications, and aberrant chromosome rearrangement. Therefore, in the next phase, it becomes extremely important to integrate experimentally-generated Mass Spectrometric data accordingly with the genomic information to identify tumor-specific proteins and isoforms.

Onco-proteogenomics has great promise and holds the key in improving our understanding of cancer biology and it is anticipated that the routine utilization of this integrated omics approach would become one of the gold standards of precision oncology. In this collection, we welcome original articles focusing on cancer proteogenomics research.