Intratumor heterogeneity (ITH) describes the diversity of cancer cells within a single tumor. This heterogeneity includes differences in the cells' phenotypes, genotypes, and functions. As a result, cancer cells can vary in their morphology, gene expression and protein profiles, metabolic behavior, and their ability to proliferate and invade surrounding tissues. As a hallmark of cancer, ITH presents major obstacles to the effective treatment of solid tumors by contributing to therapeutic resistance, increased metastatic potential, and higher relapse rates. ITH arises from multiple factors, including genetic instability, epigenetic modifications, selective pressures from the tumor microenvironment, and therapy-induced selection. Individually or collectively, these factors alter the transcriptomic and proteomic landscapes of cancer cells, driving heterogeneity and enabling them to adapt, survive, and evolve under hostile growth conditions. Despite its clinical relevance, the holistic understanding of ITH is still a challenge. Various biophysical techniques are being employed to gain a deeper insight of ITH. Importantly, the intricate nature of ITH implies that existing therapies primarily eliminate dominant clones, unintentionally permitting minor subclones to survive and contribute to disease relapse and therapeutic resistance. Thus, developing strategies that combine adaptive multi-agent therapies with functional analysis of subclonal dynamics is anticipated to drive substantial improvements in precision oncology, paving the way toward personalized and durable cancer care. The present study discusses ITH in-depth, describes the genetic, epigenetic, microenvironmental, and therapy-induced factors that contribute to its definition, assesses current analytical techniques, and considers ways to mitigate its impact on cancer treatment.
Kumar et al. (Wed,) studied this question.