Is local invasion of a cancer more likely than metastasis (spread of cancer cells)?

From the Guidelines

Invasion of a cancer is not necessarily more likely than metastasis, as recent evidence suggests that metastasis can occur at a very early stage in disease development, even before invasion is clinically apparent. This is highlighted in a 2022 study published in the British Journal of Cancer, which notes that in breast cancer, for example, there is growing evidence that metastasis can occur at a very early stage in disease development, and micro-metastases may be present in patients at the time of diagnosis, which do not become clinically apparent until much later 1.

Key Points to Consider

• The process of metastasis is complex and requires cancer cells to overcome multiple biological barriers, but it can occur early in disease development 1.
• The ability to invade locally is a fundamental characteristic of malignant tumors, but metastasis represents a more advanced stage of disease progression that some cancers may achieve early on 1.
• Early diagnosis is crucial for improving patient outcomes, and the application of new and more sensitive approaches to early detection could be more important for patient survival in some specific cancer types 1.

Clinical Implications

• The distinction between invasion and metastasis is important clinically because invasive cancers that have not yet metastasized generally have better treatment outcomes and prognosis than those that have spread to distant sites.
• However, the fact that metastasis can occur early in disease development highlights the need for early and sensitive detection methods, such as those utilizing extracellular vesicles, to improve patient outcomes 1.

From the Research

Cancer Invasion and Metastasis

• Invasion of a cancer is a complex process that involves the migration of cancer cells from the primary site to surrounding tissues 2.
• Metastasis, on the other hand, is the transfer of malignant tumors from one organ to a distant organ, and is the most common cause of death in cancer patients 2.
• The process of metastasis involves several steps, including invasion, intravasation, circulation, extravasation, and colonization 3.

Comparison of Invasion and Metastasis

• While invasion is a necessary step for metastasis to occur, not all invasive cancers will metastasize 2.
• In fact, only 1% of micrometastases progress into macrometastases 2.
• This suggests that metastasis is a more complex and less likely process than invasion.

Factors Influencing Metastasis

• The microenvironment in the organ influences the formation of metastasis 2.
• Gene expression profiles of metastatic cells in various organs are different, and not every tumor cell has the capacity to metastasize 2.
• Lifestyle factors, such as obesity and circadian rhythm, have also been correlated with cancer metastasis 3.

Clinical Evidence

• Metastatic cells from a primary tumor can occur before the primary cancer is detected, and can remain dormant for many years after removal of the primary tumor 4.
• Late recurrences of cancer can occur decades after the primary treatment, due to the awakening of dormant malignant cells 4.