A mathematical model indicates that lung cancer probably metastasizes in more than one direction at a time, contradicting the traditional medical view that cancer progression is part of a unidirectional process initiated at the primary tumor site, with the disease spreading to variably distant sites in a fairly predictable fashion.
A system of mathematical equations known as the Markov chain model revealed that cancer cell movement around the body is likely multidirectional, and that the first site to which the cells metastasize plays a key role in disease progression.
“The model shows that the combined characteristics of the primary [tumor] and first metastatic site to which it spreads largely determine the future pathways and timescales of systemic disease,” affirmed lead author Paul K. Newton, PhD, of the Viterbi School of Engineering at the University of Southern California, Los Angeles, and fellow investigators in their report for Cancer Research.
The team learned that some parts of the body serve as “spreaders” for lung cancer cells, and other parts serve as “sponges.” The cells are relatively unlikely to metastasize beyond a “sponge” region. Newton’s group determined that for lung cancer, the main spreaders of systemic disease are the adrenal gland and kidney; the main sponges are regional lymph nodes, liver, and bone.
Very few patients die from their first metastasis, but the characterization of the first metastatic site as a spreader or a sponge yields important insights into metastatic pathway selection and the determination of progression timescales for patients, explained the authors. “The model may have implications for decisions surrounding surgical resection of oligometastatic diseases as one might predict different outcomes for patients whose solitary site of disease is a sponge or spreader,” they wrote.