Tumor as a Necessity
In an interview released in early June, researchers from Saint Petersburg Polytechnic University revisited a controversial idea about the role of tumors in evolution. Andrei Kozlov, who leads the laboratory for new functionalization of genes at the Institute of General Genetics of the Russian Academy of Sciences, revisited a theory he proposed decades ago. The idea suggests that tumors may play a fundamental part in the evolutionary history of multicellular life.
A frequent collaborator and co-author in this line of work is Nikolai Yankovsky, academician of the Russian Academy of Sciences and the scientific director of the Institute of General Genetics. He maintains that the theory offers the most coherent explanation for how complex organs arose in multicellular organisms. He asserts that tissue formation hinges on processes that resemble tumor growth in kind, if not in consequence, and that understanding these dynamics is key to grasping organ development.
Every day, the body encounters many instances of abnormal cell growth. Most of these cells are eliminated through a self-destruct mechanism known as apoptosis. When a cell detects that its behavior is inappropriate, it initiates its own destruction. This is a routine process, happening many times each day. In rare cases, cells fail to self-destruct, which can lead to the emergence of a tumor.
Researchers note that most tumors are not instantly fatal and that danger typically arises only when the body’s regulatory systems fail. An illustrative example cited is a goldfish that develops a protective cap on its head, effectively a tumor. Yet the fish continues to live with this condition for life. Such cases show that not all tumors lead to immediate harm, and some may persist without compromising basic vitality.
Kozlov has also mentioned that adipose tissue, or fat, can appear tumor-like under certain conditions. Yankovsky emphasizes the importance of clearly defined terms in such debates. He notes that standard criteria for classifying organs may not always align with Kozlov’s proposals, and that any agreement on terminology would shape how evidence is interpreted in the future. He even suggests that, if Kozlov’s criteria were adopted, it could pave the way to identifying a set of genes that, if edited, might prevent deadly tumors from forming. Such work would be of profound scientific significance.
The notion of a comprehensive framework that explains all aspects of development has drawn mixed reactions from other scientists. Some acknowledge the appeal of a theory that connects tumor biology with the emergence of tissues and organs, while remaining cautious about labeling it a universal model of development.
A researcher at Göttingen University, Konstantin Krutovsky, commented that it is plausible some tissues or organs arise initially within tumor-like structures and later integrate into normal ontogenetic progression. He regards the carcino-evo-devo concept as an intriguing and original contribution, but he warns against treating it as a single, all-encompassing theory of biological development. He suggests it may reflect an unusual instance of evolutionary tissue formation rather than a universal rule.
Krutovsky also underscores the evolutionary role of genetic elements such as oncogenes, oncoviruses, and other mobile genetic agents. These factors contribute to genetic variability, which drives selection for new tissues, organs, and traits. By their nature, these elements can trigger tumor formation as well, indicating a potential link between cancer processes and the evolution of novel biological features.
Several experts consider the relationship between tumor development and organogenesis to be a meaningful area of inquiry, though not yet fully understood. Pavel Volchkov, who heads a genome engineering laboratory at a leading research institution, points out that while there are connections between tumor-like processes and embryogenesis, the direct formation of fully developed organs through tumors in humans remains unproven. He emphasizes that developmental stages must occur within the context of embryogenesis for true organ formation to take place.
Volchkov also remarks that although some sebaceous or adipose tissues may exhibit tumor-like characteristics under certain circumstances, these conditions do not imply that adipose tissue is inherently pathological. In normal physiology, fat tissue is well-organized and highly functional, serving as a reservoir and energy store. Excessive intake can disrupt bodily systems and trigger abnormal changes, potentially resembling tumor-like processes, but this does not mean typical fatty tissue should be classified as tumors.
Despite ongoing debate, supporters of the tumor-centric view argue that many tissues could have originated through tumor-like events, which would justify referring to various organs as tumor-like in a broader evolutionary sense. Critics counter that tumors are generally abnormal, self-limiting or destructive phenomena in ordinary human biology, and that the term tumor may not be the most accurate descriptor for normal organ development. Both sides agree that further study is necessary to clarify what constitutes a tumor in an evolutionary context and to determine how such processes might have contributed to the emergence of diverse organ systems. The scientific community continues to explore these ideas, weighing evidence and refining terminology as research advances.