Source: Flickr user Erik Soderstrom.

Cancer is possibly the scariest diagnosis a patient can be given. Within the United States cancer is the second-leading cause of death behind only heart disease. It was responsible for nearly 577,000 deaths in 2011 -- essentially one out of every five deaths.

What's particularly scary about cancer is that researchers are still in the dark as to what causes cancer, how it triggers, and in many cases how to fight it. In spite of throwing billions upon billions of dollars at cancer research, we've only managed to marginally improve overall survival for some cancer types, including lung cancer and pancreatic cancer, over the past four decades.

Don't get me wrong, researchers do have a good idea as to what can increase a person's risk of getting cancer -- smoking or long-term sun exposure, for example -- but differentiating why some smokers live to be healthy well into their 90's while a person who eats right and exercises regularly gets cancer in their 40's has often stumped researchers and consumers alike.

In case you missed it, this is terrifying news
A new study out this past week from Johns Hopkins Medicine potentially answers this question, although the answer is downright terrifying.

Breast cancer cell. Source: Wikimedia Commons.

According to Johns Hopkins researchers roughly two-thirds of all cancer cases are the result of random mutations in genes that can lead to cancer growth. In plainer terms, two-thirds of all cancer cases are really nothing more than a result of bad luck. Researchers described these changes as minute alterations in the DNA of our stem cells that can lead to cancerous growth in certain genes. If the number of mutations accumulates, a person can potentially develop cancer.

The study did, however, uncover some exceptions (i.e., the remaining one-third of cancer cases). The two researchers leading the study discovered that smoking can increase a users' potential to get lung cancer, long-term exposure to the sun can potentially lead to skin cancer, and some forms of cancer are influenced by genetics and whether or not members in your family have had a certain type of cancer. Said cancer researcher Bert Vogelstein, "All cancers are caused by a combination of bad luck, the environment, and heredity."

What this study really means
To be clear, this study doesn't mean that now is the time to cancel your healthy diet, stop exercising, and take up smoking. Evidence is still plentiful that poor lifestyle habits can exacerbate your chance of getting cancer.

Source: National Cancer Institute, Wikimedia Commons.

However, it also means that simply living a healthy lifestyle and eating right may not be enough to keep a person from getting a cancer diagnosis during their lifetime. Per the Surveillance, Epidemiology, and End Results Program, a branch of the National Cancer Institute, approximately 40.4% of men and women will be diagnosed with cancer at some point during their lifetime, based on data between 2009 and 2011. This high diagnosis rate could certainly be explained by random gene mutations as described by Johns Hopkins' study.

If there was one message that really came out of Johns Hopkins study it's that we need more efficient diagnostic tests to detect cancer. The key to beating or successfully managing cancer over the long-term is to catch it early before it spreads into the lymph nodes or to other organs where treatment can become difficult.

To that end, the good news is we have seen a surge in the number of new cancer-detecting and assisting diagnostics that have hit the market.

Diagnostic tests that could save lives
One of the more exciting diagnostic tests approved by the Food and Drug Administration in recent memory is Cologuard, which was developed by Exact Sciences (NASDAQ:EXAS).

sDNA capture lab. Source: Exact Sciences. 

Cologuard is a non-invasive colorectal cancer screening test that analyzes a patients' stool sample (which is sent to Exact Sciences' lab). The diagnostic works by examining the DNA of cells shed on the sample sent to Exact Sciences' lab for analysis. Normal cells are regularly shed from the inner walls of the intestines, but Cologuard is designed to detect mutations in that DNA. If a test comes back as positive for colorectal cancer or an advanced adenoma, it would signal to the patient that he or she should undergo a more thorough diagnostic colonoscopy.

In clinical studies that led to Cologuard's approval, Cologuard positively identified 92% of all colorectal cancer and 42% of all advanced adenomas compared to the previous noninvasive standard of care which identified 74% of all colorectal cancer and 24% of advanced adenomas. While not perfect, Cologuard is a clear step forward in early diagnostic technology. 

Another exciting under-the-radar early diagnostic test that could work its way into the spotlight in coming years is EarlyCDT (short for Early Cancer Detection Test), a lung cancer detection test developed by privately held Oncimmune and partnered in a handful of U.S. markets with Enzo Biochem (NYSE:ENZ). EarlyCDT-Lung works by utilizing a panel of tumor antigens selected because of their involvement in cancer development and measuring the amount of autoantibodies that circulate throughout the body. The measurement can tell researchers whether or not there's a high probability of cancerous cells being present. 

Source: Myriad Genetics.

Perhaps the most prevalent example of an early diagnostic test geared at cancer detection or prevention is Myriad Genetics' (NASDAQ:MYGN) BRACAnalysis. This diagnostic tool, made famous by actress Angelina Jolie which used it to determine she was at a higher risk of developing breast and/or ovarian cancer, analyzes whether someone is a carrier of the BRCA1 or BRCA2 gene mutations. These mutations correlate with a higher risk of getting breast or ovarian cancer in women. The idea here would be that women who are positive for these mutations should be especially diligent about getting regular breast and/or ovarian exams.

Clearly the idea that cancer can occur at random isn't what people want to hear. Fortunately diagnostic developers are working toward the goal of creating more early detection kits and making a vast majority of them affordable enough for the average American. There's still plenty of work left to be done, but we're definitely on the right path.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.