Final answer:
Invasion refers to the local spread of a tumor into nearby tissues, while metastasis is the formation of secondary tumors at distant sites in the body. Invasion is a feature of invasive carcinoma, whereas metastasis is associated with malignant tumors that can transport cells through the bloodstream to form new tumors elsewhere.
Step-by-step explanation:
Difference Between Invasion and Metastasis
The terms invasion and metastasis are critical in the study of cancer biology and describe two different aspects of cancer progression. Invasion refers to the ability of a tumor to spread into neighboring normal tissues. This is a defining property of invasive carcinoma. In contrast, metastasis is the process by which cancer cells break away from the original (primary) tumor and establish new tumors in distant organs. This ability is characteristic of malignant tumors.
Pre-malignancy or non-invasive tumors (such as atypia, dysplasia, and carcinoma in situ) are not yet invasive, but they can potentially progress to invasive cancer if left untreated. In the context of a malignant tumor, cells that gain the ability to metastasize can travel through the bloodstream and form new metastases or secondary cancers at distant sites.
The process of cancer spread via blood to distant locations results in these secondary tumors, which continue to proliferate and acquire additional mutations, potentially enhancing their ability to invade and spread further.
To summarize, invasion is the local spread of a tumor into adjacent tissues, while metastasis refers to the formation of new tumors in distant parts of the body, illustrating an advanced and often more dangerous stage of cancer. Both aspects significantly impact treatment and prognosis.