Why Treating Cancer is So Difficult, Part 5: Is This Thing On?

Cancer as a “disease” is incredibly complex, and patient care for a cancer diagnosis is complex as a result. I’m starting to explore some of these difficulties in a series of articles: “Why Treating Cancer is So Difficult.” Previously published in this series:

Previously published in this series: Part 1, Your Tumor is Not a Clone. Part 2, Cancer Cells are Still Cells. Part 3, Resistance is Not Futile. Part 4, There is No Google Translate for Science.

Part 5 // Is This Thing On?

A majority of cancer deaths come not from the “primary” tumor (where a patient first gets a tumor), but rather as the result of metastatic cancer, an aggressive form of cancer that has spread out from the primary tumor and into other parts of the body. Typically this happens when the tumor is at a more advanced stage, meaning that the tumor has been growing, possibly for a long period of time. This means that the earlier a cancer can be detected, it could help to improve a patient’s outcome by possibly decreasing the risk of developing a metastasis.

How can a cancer become metastatic? It can circulate through the blood or through the lymphatic system to other organs, sometimes far from the site of the primary tumor. Image via National Cancer Institute.

But detecting a primary tumor isn’t always so easyWhy not?

The National Cancer Institute (NCI) has a great website with information on cancer, from diagnosis and treatment to statistics and information on current cancer research being done. According to the NCI website, here are some of the most common symptoms for the cancer types that cause the most deaths in the US annually (lung, breast, prostate, and colorectal cancer):

  • Hoarseness or cough that does not go away
  • Changes in bowel habits
  • Problems with eating
  • Weight gain or loss with no known reason
  • Abdominal pain
  • Unexplained night sweats
  • Unusual bleeding or discharge
  • Feeling weak or very tired

These are non-specific symptoms, meaning that they don’t necessarily indicate cancer and could instead be a number of other diagnoses. It is also possible that, at early stages of tumor development, a patient might not have any symptoms at all.

Medical imaging techniques, like CT scans, can help doctors to detect tumors. Image via National Cancer Institute.

Cells are also really small. So at the early stage of cancer, when the tumor is only a mass of a small number of cells, it is really difficult to detect them. They wouldn’t always show up in an X-ray, or an MRI, or using some other medical test. There are some blood exams that are good at detecting some cancers at an early stage, but these types of tests don’t exist for all cancers, and even these tests have their limits of detection. Tumors can sometimes shed some cells from the surface, and these cells can circulate in your blood. These circulating cancer cells are difficult to detect, because it’s possible that you have small numbers of these cells (tens to hundreds of cells) in the 4-5 liters of blood you have in your body, so when a doctor draws a blood sample, there might not be a circulating cancer cell in that small vial of blood.

What are researchers doing about detecting cancer better?

Using information from places like The Cancer Genome Atlas (read more about what that is and what it’s done for cancer research in Part 4 of this series), scientists are learning more and more about the features of various cancers. It is also allowing researchers in places without big technologies to still join in furthering research, because all of the data is available online (free!). With this information, researchers are trying to develop not only new cancer therapies that are more effective for various cancers, but also new tests for cancer diagnosis.

// Wanna learn more?

More information about the cancer diagnosis research going on at the National Cancer Institute

Press release from the University of Bath: “Developing biosensor devices for better cancer diagnosis”

Podcast: Science podcast on how TCGA data could be translated to patient care (9:22)