Final answer:
During the promotion stage of cancer, uncontrolled cell growth and division occurs. This leads to an increase in the number of mutated cells and tumor formation, although the cells have not yet gained the invasive properties associated with advanced cancer stages.
Step-by-step explanation:
The stage of cancer known as promotion involves uncontrolled cell growth and division. This stage follows the initiation stage where the DNA damage occurs, setting the foundation for tumor formation. During promotion, the mutated cells proliferate and expand, increasing the number of affected cells. Although the formation of a mass of abnormal cells, or a tumor, is evident, it is the progression stage that typically involves the cells gaining invasive properties and leading to malignancy.
Option 3: Uncontrolled cell growth and division describes what occurs during the promotion stage of cancer development. This is the step where cells begin to replicate more rapidly than normal due to mutations in proto-oncogenes and tumor-suppressor genes. These altered cells then accumulate to form a tumor. It is important to note that metastasis, described in option 2, is a process that occurs in the later stages of cancer, known as progression, where cancerous cells spread to other parts of the body.