Google-like model shows how lung cancer metastasizes

A mathematical model similar to Google PageRank has challenged the traditional medical view that metastatic lung cancer progresses in a single direction from primary tumor site to distant locations. Instead, researchers found that cancer cell movement around the body likely occurs in more than one direction at a time, according to a study published in Cancer Research.

Paul Newton, PhD, from the University of Southern California School of Engineering in Los Angeles, and colleagues used an algorithm similar to the Google PageRank and to the Viterbi Algorithm for digital communication to analyze the spread patterns of lung cancer.

"This research demonstrates how similar the internet is to a living organism," Newton said in a press release. "The same types of tools that help us understand the spread of information through the web can help us understand the spread of cancer through the human body."

The researchers applied a Markov chain model to determine that cancer cell movement likely occurs in multiple directions. They also learned that the first site to which the cells spread plays a key role in the progression of the disease. The study showed that some parts of the body serve as "sponges" that are relatively unlikely to further spread lung cancer cells to other areas of the body. The study identified other areas as "spreaders" for lung cancer cells.

The study revealed that for lung cancer, the main spreaders are the adrenal gland and kidney, whereas the main sponges are the regional lymph nodes, liver and bone.

The study applied the advanced math model to data from human autopsy reports of 163 lung cancer patients in the New England area, from 1914 to 1943. This time period was targeted because it predates the use of radiation and chemotherapy, providing researchers a clear view of how cancer progresses if left untreated. Among the 163 patients, researchers charted the advancement patterns of 619 different metastases to 27 distinct body sites.

The findings could potentially impact clinical care by helping guide physicians to targeted treatment options. For example, if the cancer has moved to a known spreader location, imaging and interventions can be considered for focused treatment before the cells may more widely disperse. Further study is needed, according to the researchers.

The study was published online Feb. 27.