What feature makes cancer cells "immortal" in nature?

The characteristic that makes cancer cells "immortal" is their unlimited lifespan. Unlike normal somatic cells, which undergo a limited number of divisions due to mechanisms such as telomere shortening, cancer cells can maintain or lengthen their telomeres. This allows them to bypass the normal limits on cell division and continue to proliferate indefinitely. This immortality is a hallmark of cancer, contributing to the uncontrolled growth and spread of tumors.

In contrast, features like detachment from neighboring cells, enhanced intercellular communication, and strong adhesion properties do not directly contribute to the "immortal" nature of cancer cells. While detachment can facilitate metastasis, enhanced communication often relates to signaling pathways that drive proliferation, and strong adhesion properties are generally more associated with normal cells or specific types of tumors. These attributes do not inherently provide the capacity for indefinite replication, which is truly what defines the immortality of cancer cells.