An overwhelming number of cancer deaths are caused when the tumor cells spread the disease throughout the body. In a new study, researchers identified a specific process that causes the cell-spreading behavior, known as metastasis, to occur. They also found that two existing drugs utilized together may help disrupt the process.

In the study, published online in Nature Communications, researchers were studying what events promote metastasis and found that it may be attributed to a new biochemical signaling process.

Read: Metastasis: The 3 Most Common Ways Cancer Spreads Through The Body

“We found that it was not the overall size of a primary tumor that caused cancer cells to spread, but how tightly those cells are jammed together when they break away from the tumor," lead study author Hasini Jayatilaka said in a statement. "At a fundamental level, we found that cell density is very important in triggering metastasis.”

The researchers found that a combination of medications may help to slow metastasis. But, the authors caution their treatment has only been conducted on animal models thus far. However, they believe their discovery can play a key role in cancer research.

The two drugs they applied to the cells were Tocilizumab and Reparixin. Tocilizumab is an immunosuppressive drug used to treat moderate to severe rheumatoid arthritis and is currently undergoing trials for treating ovarian cancer. Reparixin has not yet been approved and is currently being evaluated on breast cancer cells.

"In our eight-week experiment, when we used these two drugs together, the growth of the primary tumor itself was not stopped, but the spread of the cancer cells was significantly decreased," Jayatilaka said. "We discovered a new signaling pathway that, when blocked, could potentially curb cancer's ability to metastasize."

Read: Breast Cancer Treatment 2017: Drug May Halt Metastasis In Triple-Negative Tumors

Cancer often spreads to other healthy parts of the body, which contributes to about 90 percent of cancer deaths, the study authors note. But despite this, commercial drugs target the primary site rather than inhibiting metastasis.

"The pharmaceutical companies view metastasis as a by-product of tumor growth," study author David Wirtz said. "Our study looked more closely at the steps that actually initiate metastasis. By doing this, we were able to develop a unique therapeutic that directly targets metastasis, not the growth of the primary tumor.”

Cancer cells attack other parts of the body through a series of steps. After growing into or invading nearby tissue, they travel via lymph nodes or the bloodstream to other parts of the body. When they move into the surrounding tissue, the cells grow until small tumors are formed. This causes new blood vessels to form, giving the cells a blood supply allowing them to continue to grow, the National Cancer Institute explains on their website.

See also: Survival Rate For Patients With Prostate Cancer Metastasis Higher When The Liver Is Not Involved

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