Which characteristic differentiates benign tumors from malignant tumors?

The distinguishing characteristic between benign and malignant tumors is that benign tumors do not spread to other parts of the body. This is a key feature that defines benign tumors: they grow in a localized manner and typically do not invade surrounding tissues or metastasize to distant sites, which is a hallmark of malignant tumors.

Benign tumors often have well-defined borders and are generally considered non-threatening to health, although they can still cause problems due to their size or location, depending on where they are situated in the body. In contrast, malignant tumors are characterized by aggressive growth and the ability to invade nearby tissues and spread to other areas through the bloodstream or lymphatic system, which can lead to cancerous metastasis.

The alternative options present distinctions that do not accurately differentiate these two types of tumors. For instance, malignant tumors, by definition, are cancerous, contradicting the claim that they are non-cancerous. Similarly, the notion that malignant tumors do not increase cancer risk misrepresents their nature, as they inherently represent a form of cancer that is capable of further inducing cancer risks in the body. Thus, the correct characteristic that identifies benign tumors is that they do not spread, making the answer a reliable and clear indicator of their benign nature.