Using math to fight cancer

Friday, March 30, 2001

Engineers at the Georgia Institute of Technology are using integer programming and computational optimization techniques in the fight against prostate cancer. Mixed integer programming is a mathematical/optimization tool in which problems are modeled into a mathematical formulation. The formulation consists of variables that can be either continuous or integers.

Prostate brachytherapy requires implanting small radioactive "seeds" in cancerous prostate. Planning treatment and deciding where seeds should be placed is a manual and time-consuming procedure that takes hours of a doctor's valuable time. But Eva Lee, an assistant professor of industrial and systems engineering at the Georgia Institute of Technology and Emory University's school of medicine, found a way to reduce the pre-planning to only fifteen minutes.

Lee realized that the placement of the radioactive seeds is a binary problem-a matter of deciding which of 300 possible locations is best for seed implantation. Her use of mixed integer programming and optimization techniques allows doctors to effectively manipulate the large number of variables involved, such as shrinkage of the cancerous tumor over time and distortion of the needles used for delivering the seeds.

"In the prostate cancer case, we formulate the treatment planning into a mathematical model which includes all the clinical properties that we would like to see in the plan,' says Lee. "We solve the model and the solution tells us where to place the radioactive seeds inside the prostate."

Lee says her approach frees doctors from having to do the math behind the seed placement. "All they have to do is tell the system what they want in the plan," she says. She also indicates that the new approach should help cut the recurrence rate for prostrate cancer and reduce toxicity in adjacent healthy tissues.

The system is ready for commercialization, but has yet to receive FDA approval. In addition to prostate cancer applications, the system may also have applications for planning external beam radiation treatment for brain and other types of cancer.

"Every sector in industry can benefit from the use of mixed integer programming and optimization techniques," says Lee. Outside of medicine, applications include in-vehicle routing and scheduling, and integrated circuit design. For more information, contact Lee at [email protected] or call (404) 894-4962.