Final answer:
Cancer staging is used to classify cancer by its size and the spread, with Stage I being localized and Stage IV involving metastasis to distant sites. Early stages may be cured by surgery, and staging informs treatment choices. The activation of tumor-suppressor genes does not cause cancer.
Step-by-step explanation:
The spread of cancer is often described using a staging system, and the lower the stage, the less advanced the cancer is. Cancer staging is a method of classifying cancer based on factors such as tumor size and the extent of the cancer's spread. The general cancer staging includes:
- Stage I: Localized cancer that is limited to the place where it started, with no sign of spreading beyond local tissue.
- Stage II & III: Regional cancer implies that the cancer has spread to nearby lymph nodes, tissues, or organs.
- Stage IV: This stage indicates metastasis, where cancer cells have spread through the blood to distant sites, typically resulting in a worse prognosis.
The goal of cancer staging is to assess the severity of cancer and guide treatment decisions. Surgery might fully cure cancer mainly in its early stages, particularly stage I or sometimes stage II, before it has metastasized. Knowing the stage of cervical cancer, for example, is crucial because symptoms often do not start to occur until the cancer is at a more advanced stage, when treatment is less successful. The activation of tumor-suppressor genes is actually a protection against cancer, not a cause, making statement 13 false.