What Do Google PageRank, Viterbi Algorithm and Cancer Have in Common?

300px-Hmm-Viterbi-algorithm-med image credit: Good Search


Google PageRank algorithm. Viterbi Algorithm. Cancer. What can they possibly have in common?

Google PageRank was developed in 1996 by Larry Page, and Sergey Brin. PageRank predicts websites most likely to have pertinent information. It examines the destiny of links between websites. Thirty years earlier at Stanford University, Andrew Viterbi invented an algorithm that predicts the mostly likely path of digital wireless signals through a cellphone network.

Enter the twenty first century: Paul Newton of USC’s Viterbi School of Engineering collaborated with scientists at La Jolla-based Scripps Institute, one of 12 established by the National Cancer Institute. Several institutions took part in this study. The purpose was to understand behavior of cancer cells during metastasis (when cancer spreads from the primary tumor to other sites in the body.) The study specifically aimed to learn better ways of managing cancer. Andrew Viterbi was an advisor during this study.

The study was published in the journal of Cancer Research in March, 2013. It analyzed records of 3,827 deaths of untreated cancer patients between 1914 and 1943. One hundred sixty three were lung cancer patients. The years of these studies were before the use of radiation and chemotherapy for lung cancer. Sine the patients were untreated, their records showed the natural progression of cancer. According to American Lung Association, lung cancer is the leading cause of cancer death in the U.S.. About 160,000 Americans die each year from lung cancer. As of now—in general, once lung cancer becomes metastatic, few localized therapies are done. This study may change that. A follow-up study is looking to see if this is true for colon cancer as well.

The finding in the first study was that different areas in the body are “spreaders” or “sponges” of metastatic lung cancer cells. As their names suggest, some areas spread the cancer cells, and some areas receive the cancer cells, but don’t spread them as readily. So, some areas for metastasis are more dangerous than others. The study found that adrenal glands are “spreaders” and bones metastases are “sponges.”

When someone dies from metastatic lung cancer, they have metastases in multiple areas throughout their body. But, not everyone has the metastases in the same areas. The study is taking place in hopes of gaining an understanding of pathways cancer takes.

Viterbi said, “It’s very exciting to see mathematics being applied in all sorts of ways. For decades, it was mostly in physics or physical phenomena. Now it’s being used in software and even biology. It isn’t just this, it was much more effectively used in DNA sequence analysis where you’ve got lots and lots of bits.”

We can often get frustrated about the lack of progress on cancer research when we read findings that in moderation, eating dark chocolate and drinking red wine are good for our health—but further studies are needed. Of all the news I’ve read about studies being done, this “spreader/sponge” study is the most exciting to me. To think that it’s origin is from math and computer algorithms just amazes me.

Sources: Wikipedia; San Diego Union Tribune March 28, 2013; USC News.


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