Experts define metastatic cancer as cancer that spreads from the anatomical location where it started to a distant part of the body. Regarding most types of cancer, oncologists classify metastatic cases as Stage IV disease. Cancer can spread, or metastasize, to just about any part of the body. In general, the most common sites of distant disease are the bone, lung, and liver, but different cancer types tend to associate with specific secondary areas. Metastatic cancer patients can first experience early-stage cancer, which develops into metastatic cancer, or they can receive a metastatic diagnosis when first learning they have cancer. When the first cancer diagnosis includes metastatic disease, doctors refer to the case as “de novo metastatic cancer.”
Discussing metastatic cancers can seem confusing because it refers to cancer in a different part of the body than the primary cancer. For example, we refer to breast cancer that metastasizes to the brain (as reviewed on Labroots) as breast cancer, not brain cancer. We base this classification on the primary cancer site, not the distant metastatic site, because the metastatic cancer cells retain the functions and characteristics of the primary cancer. So, to return to our example, metastatic cancer cells originating in the breast and migrating to the brain will look and act like breast cancer cells, not brain cancer cells. These classifications become important not just for characterization but also for treatment planning and prognostic evaluation.
According to the National Cancer Institute (NCI), most metastatic cancers have treatment options that aim to stop or slow the metastatic growth. What may surprise you is that when the treatment can control the cancer, some people can live with metastatic cancer for years. Indeed, with advances in therapeutics and drug development, we’d expect the number of people living with metastatic cancer to increase.
As expected, The Journal of the National Cancer Institute recently reported that the number of Americans living with is increasing. The study investigated the prevalence of individuals in the United States living with metastatic prostate, lung, colorectal, and bladder cancer or metastatic melanoma, as well as women in the United States living with metastatic breast cancer. The researchers utilized data entered into the Surveillance, Epidemiology, and End Results (SEER) registries, federally-curated systems which collect, store, and manage data on patients with cancer through 2018.
The analysis estimated that in 2018, over 623,405 individuals living in the United States had metastatic breast, prostate, lung, colorectal, or bladder cancer or metastatic melanoma. Using the US Census Bureau July 1, 2016, population projections from the 2010 Census, the researchers estimated that in 2025, the number of individuals in the United States living with these metastatic cancers would rise to 693,452.
The study also showed that, in 2018, the percentage of de novo metastatic cancer diagnoses differed significantly between cancer types. De Novo metastatic cancer occurred in about 28% (bladder cancer), 30% (melanoma), 38% (breast cancer), 45% (prostate cancer), 56% (colorectal cancer), and 70% (lung cancer). Notably, the one- and five-year survival estimates for most de novo metastatic cancer have increased.
The authors conclude that the study provides valuable information to guide the next era of cancer research. Additionally, these findings can inform how healthcare infrastructure can evolve to address the needs of this unique and growing population of cancer survivors.
Sources: J Natl Cancer Inst