Cancer: It’s a diagnosis you never want hear, and yet it’s certainly possible. According to the National Cancer Institute, approximately 40.8 percent of men and women will be diagnosed with cancer at some point of their life. Today, there are more than 14 million people living with cancer in the United States.

One of the most common questions asked after a patient learns they have cancer is how fast will it spread. It’s important to know that there are many factors to consider when determining how quickly cancer cells will replicate and metastasize to other parts of the body. Some cancers, including pancreatic and ovarian cancers, can spread quickly. While others, including some skin cancers can spread slower.

Certain influencers can help determine how fast cancer may spread, including the size (bulk) of the tumor, microscopic appearance of the cells (they are graded and classified by the pathololgist), location of the tumor, and how the tumor responds to treatment – often various combinations of radiation, surgery, and chemotherapy. In the case of breast cancer, normally healthy chemicals including estrogen, progesterone, and the HER2/nue gene can also accelerate the tumor’s growth, making it difficult to gauge how quickly breast cancer can spread.