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Image source: National Cancer Institute. 

There's arguably no diagnosis patients can receive from their doctors that's scarier than cancer. The fear inspired by a cancer diagnosis is twofold. First, from the perspective of the patient, there's the concern that the cancer they've been diagnosed with isn't among those with a high long-term treatment success rate.

For example, more than 99% of all prostate cancer patients live five years or longer with the disease based on data from the American Cancer Society. On the flipside, a pancreatic cancer diagnosis has a very low long-term survival rate because it's rarely diagnosed in the localized stage. Just 7% of all pancreatic cancer patients will survive five years following their diagnoses, including the 26% whose cancer is discovered early.

The other aspect of cancer that's worrisome is that there's little consensus on how it develops and activates. Researchers don't dispute that there are certain risk factors associated with cancer development, such as smoking tobacco, and that the buildup of mutations over time in our DNA is what leads to cancer development. What researchers aren't certain of is why one person gets cancer and another, who may have a similar lifestyle and family history, does not.

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Image source: National Cancer Institute.

The surprising cause behind most cases of cancer
Early in 2015, researchers at Johns Hopkins School of Medicine published a report in the journal Science implying that "bad luck" played a substantial role in determining who developed cancer and who didn't. Although the report implied that two-thirds of cancer cases were due to bad luck, Johns Hopkins was quick to note that cancer is caused by a confluence of factors in combination with bad luck. Researchers simply don't know what these factors are in advance, thus making it nearly impossible to predict who will get cancer and who won't.

However, a new report published in online journal Nature in mid-December suggests that "bad luck" is a bad answer as to why certain people get cancer and others don't.

Researchers at Stony Brook University in New York found, through four different approaches, that external risk factors from the environment and via our behaviors are responsible for somewhere between 70% and 90% of all cancer development. Interestingly enough, the Stony Brook researchers used the same set of data that researchers at Johns Hopkins analyzed.

First, Stony Brook researchers examined tissue cell turnover, analyzing lifetime cancer risk for major cancer types, such as lung, pancreatic, and colorectal cancer. What they found was that intrinsic factors (i.e., non-external) played a major role in cancer incidence only about 10% of the time. Researchers further confirmed this point by noting that immigrants traveling from a country with a low cancer incidence rate had a higher propensity to develop cancer in a high-incidence-rate country.

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Image source: Stony Brook University.

Secondly, Stony Brook researchers analyzed data from the Surveillance, Epidemiologic and End Results Program. The data, which should come as no surprise, shows that numerous cancer types are increasing in incidence rate and mortality rate. This would appear to suggest that external factors are playing a growing role in cancer incidence.

Third, researchers analyzed approximately 30 mutagenic signatures of specific types of cancer. Although researchers did discover that some forms of cancer relied on a 50-50 mix of external and internal factors for development, a vast majority of mutagenic signatures (such as lung, bladder, and colorectal cancer) were likely caused predominantly by external factors.

Finally, researchers examined the likelihood of cancer formation from intrinsic factors using a computational model. Using the assumption that three or more intrinsic mutations are required for cancer onset, researchers note that in only a few instances were there a sufficient number of mutations to trigger cancer development.

Prevention takes on an important role
The primary takeaway from Stony Brook's study is that external factors, such as the environment and our personal behaviors, will have a major effect on whether or not we develop cancer. If this study is, in fact, correct, it implies that preventative steps and diagnostic/screening tools may be the smartest way to fight cancer. Even if cancer can't be predicted with high levels of accuracy, simply identifying certain biomarkers and risk factors could go a long way in improving your odds to beat cancer.

One good example would be Myriad Genetics (NASDAQ:MYGN), whose BRACAnalysis test is being used by women to determine whether or not they're a carrier of the mutant BRCA1 or BRCA2 gene. Mutations in these genes can cause a higher risk of breast and ovarian cancer in women.

Myriad's BRACAnalysis gene test really gained notoriety when Hollywood superstar Angelina Jolie tested positive for the BRCA gene mutations and subsequently underwent a preventative mastectomy. Relatively soon thereafter Jolie also had her ovaries and fallopian tubes removed after early signs of cancer were detected. This is a perfect example of prevention in action.

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Image source: Exact Sciences. 

Another promising advancement was the Food and Drug Administration approval of Exact Sciences' (NASDAQ:EXAS) Cologuard, a diagnostic used to detect colorectal cancer or advanced adenomas. Patients using Cologuard send a stool sample in packaging provided by the company to Exact Sciences labs. The company's technology then examines the sample for abnormal DNA, which is shed from the walls of the colon.

If abnormal DNA is detected, the patient will then be referred to a physician for a colonoscopy. Exact Sciences' Cologuard wasn't perfect -- it correctly identified 92% of colorectal cancer patients and 42% of advanced adenomas -- but it's a major step up from the previous noninvasive colorectal cancer disagnosis kit.

Numerous other diagnostics that have recently hit the market are designed to personalize the treatment process should a patient already be diagnosed with cancer. Biomarker tests for the KRAS mutation, PDL1 expression, and EGFR mutation, are just some of the tools physicians are using to ensure that patients get the best possible treatment for their particular cancer type.

Clearly, we'd like to see more studies on what leads to cancer development so drug and diagnostic developers can do their best to get one step ahead of cancer development. We're not there yet, as evidenced by the rising rate of cancer incidence. However, the improvement in overall survival that we've witnessed across most cancer types during the last three-plus decades suggests that educating the public, providing cutting-edge diagnostic tools, and personalizing the treatment process, is having a positive impact on survival rates for a majority of cancer patients.

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Sean Williams has no material interest in any companies mentioned in this article. You can follow him on CAPS under the screen name TMFUltraLong, track every pick he makes under the screen name TrackUltraLong, and check him out on Twitter, where he goes by the handle @TMFUltraLong.

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