The Age of Molecular Biomarkers: Cancer in the Era of Personalized Medicine. What Do Pathologists in Developing Countries Need to Know and Understand?

The complexity of cancer care is continuously increasing in the era of personalized medicine and there is a paradigm shift in the diagnosis and management of cancer. This is the era of precision oncology whose main objective is to identify cancer patients who are candidates for specific targeted therapies. This advanced approach to cancer care formulates treatment strategies for cancer patients based on the specific molecular characteristics of a malignant tumor which are identified through advanced molecular testing. This is the age of advanced prognostic and predictive biomarkers. Targeted therapies represent a groundbreaking shift in cancer therapy and are the cornerstone of precision oncology. Termed "tumor agnostic therapy", these drugs can treat different cancer types across multiple organs which demonstrate the same molecular alterations. A targeted drug in a specific cancer may be effective in another non-related cancer if the same genomic alteration is present. Pathologists need to appreciate these radical and exciting changes and adapt their practices as they will be required to be collaborative clinicians in the new era with a role in diagnosis, prognostication, and treatment of cancer. Pathologists need to become familiar with the ever-expanding number of new biomarkers and their crucial role in cancer care. They need to understand and adapt to new technologies such as Next Generation Sequencing and Comprehensive Genomic Profiling, liquid biopsies, DNA and transcriptome studies etc. They also need to familiarize themselves with tumor agnostic therapies, and concepts such as tumor heterogeneity and resistance to therapy. They can no longer be just morphologists but assume a central role in cancer care. Pathologists in developing countries and resource limited settings who may not currently have access to advanced molecular techniques need to be aware of and understand these fundamental shifts in cancer care and especially their role in the new era. The major changes in cancer care in the era of personalized medicine are discussed in this review mainly for the benefit of pathologists working in LMICs.