The Emperor of All Maladies - Part Five Summary

In part five of an Emperor of all Maladies, we learn about the discoveries that elucidated the mechanisms underlying the biology of cancer. Mukherjee starts the section with a reflection on his time as a medical oncology fellow, reminding the reader of the human costs of cancer as he and the other fellows reflect on the patients they have lost. We also get an update on his leukemia patient Carla, who is now in remission and through the worst of her treatments. The anecdotes about his patients serve as a reminder of the struggles of treating cancer as we shift into a discussion of the research that finally led scientists to understand the molecular mechanisms of cancer. 

The observation that cancer cells proliferate at an abnormal rate compared to normal cells was made by multiple scientists including Dr. Flemming and Dr. Boveri. From their observations, they concluded that chromosomal changes were driving cancer. However, the underlying mechanism for how chromosomal changes would lead to cell proliferation remained unclear. The discovery that a virus, Rous sarcoma virus, could induce cancer in chickens caused the majority of cancer researchers to believe that viruses were the root cause of all cancers. The hard work of many dedicated virologists would lead to important breakthroughs in the field. Dr. Temin made the groundbreaking discovery of retroviruses, which are able to convert RNA back into DNA. This discovery upended the central dogma of biology and is the underpinning of many molecular biology techniques today. Research by many scientists finally showed that genetic changes, rather than viruses themselves, were the root cause of cancer. Oncogenes, genes that when improperly expressed can lead to cancer, explained how cancer could be both inherited and have multiple causes. Radiation and mutagens, whether in the form of UV light or cigarette smoke, lead to genetic changes in oncogenes that promote abnormal cell proliferation leading to cancer. Although initially only a few oncogenes were described, soon a whole litany of cancer genes were discovered. Based on the genetic evidence, Doctors Weinberg and Hanahan wrote out their famous list of six essential alterations that must occur in a cell to lead to cancer. We end section five after learning about the leaps and bounds made in the mechanistic understanding of cancer, which will eventually give rise to a new generation of cancer treatments. 

Andi DeRogatis is a graduate student at UC Davis in the animal biology graduate group. She is currently studying how the avian immune system is influenced by the process of molt. She loves all things birds and is passionate about getting others excited about birds as well! You can follow her on Twitter @andiderogatis.

Lindsey Mooney is a graduate student in the UC Davis Psychology Department. You can follow her on Twitter @Linz_Mooney.

For more content from the UC Davis science communication group "Science Says", follow us on Twitter @SciSays.