From the Research
Yes, a cancer tumor can remain the same size and still metastasize. Metastasis occurs when cancer cells break away from the primary tumor and travel through the bloodstream or lymphatic system to form new tumors in other parts of the body. This process is independent of the primary tumor's growth rate. Even small, stable tumors can shed cancer cells that have acquired the ability to invade surrounding tissues and travel to distant sites. The metastatic potential of a tumor depends on various factors including genetic mutations, tumor microenvironment, and the cancer type rather than simply its size or growth rate. Some cancers are particularly prone to early metastasis while still small, such as pancreatic cancer and certain types of lung cancer.
According to a study published in 2021 1, human cancer cell lines isolated from metastatic sites have higher potential to metastasize to another site in mice, compared to human cancer cell lines isolated from primary sites, for certain types of cancer including liver, lung and pancreas cancer. This suggests that the potential of metastases to further metastasize compared to that of primary tumors might be cancer type-dependent.
Another study published in 2017 2 found that a metastasis biomarker, MetaSite Score, is associated with distant recurrence in hormone receptor-positive, HER2-negative early-stage breast cancer, and is an independent predictor for 5-year relapse free interval. This study highlights the importance of considering factors beyond tumor size, including lymph node involvement and distant metastasis, in cancer staging.
Regular monitoring through imaging and other diagnostic tests remains important even when a tumor appears stable in size, as metastatic spread can occur silently before becoming clinically detectable. Key factors that influence the metastatic potential of a tumor include:
- Genetic mutations
- Tumor microenvironment
- Cancer type
- Lymph node involvement
- Distant metastasis
These factors are crucial in determining the metastatic potential of a tumor, rather than simply its size or growth rate. Therefore, it is essential to consider these factors in cancer staging and treatment decisions, rather than relying solely on tumor size.