Cancer mortality rates – mostly great news in war on cancer

Despite the cancer tropes that seem to afflict Facebook and Twitter these days, which includes the laughable “Big Pharma is hiding a secret cancer cure” myth, recently published evidence shows that cancer mortality rates in the USA are dropping. This is great news if you’re wondering if cancer is an end-of-life diagnosis – science-based medicine is attacking and beating cancer with numerous strategies for each cancer. And yes, instead of hiding cancer cures, Big Pharma is providing a lot of the successful medications in treating the disease.

The report, published in the journal Cancer by researchers at the American Cancer Society, the Centers for Disease Control and Prevention, the National Cancer Institute, and the North American Association of Central Cancer Registries, provides us with the mostly good news. Cancer mortality rates, which describes the number of cancer deaths per 100,000 people per year, have dropped significantly in the USA. This drop includes most of the common cancers, such as lung, colorectal, breast, and prostate.

Unfortunately, the news isn’t all good – some cancer mortality rates have increased, and I will try to explain why. Let’s take a look at cancer and this new paper.

A quick, oversimplified cancer primer

Cancer is a group of diseases characterized by abnormal cell growth which can invade or metastasize to other tissues and organs. Although people use tumor and cancer interchangeably, not all tumors are cancer. There are benign tumors that do not metastasize and are not cancers.

Cancer usually requires numerous, up to 10, independent genetic mutations in a population of cells before it can become a growing, metastatic cancer. Each mutation is selected, as in natural selection, because it provides some benefit to the cancer cell, such as causing blood vessels to supply the cells for nutrition and oxygen, or the ability to divide rapidly, whatever the feature is.

These mutations aren’t “naturally” a part of the cell’s physiology. Moreover, these mutations can have a lot of different causes – environmental (like smoking or UV radiation), viral (hepatitis B and human papillomavirus are the most famous), heredity, and maybe other things.

There is a controversial hypothesis that these mutations are more or less random, just bad luck. In this 2017 study, the authors analyzed data for 32 cancer types and found that approximately two-thirds of the mutations found in these cancers resulted from random or spontaneous errors in the DNA. This data came from 69 countries on six continents, in which the researchers found a statistically significant correlation between the incidence of cancer and the total number of stem cell divisions. Moreover, this correlation held up globally, irrespective of the environment encountered.

The original 2015 study, authored by Cristian Tomasetti, a biostatistician interested in cancer evolution, genomics, and stem cell dynamics, and Bert Vogelstein, who is one of the preeminent leaders in cancer research, first proposed the hypothesis that cancer was mostly “bad luck.” That article generated dozens of published comments (no, not like what you find on Facebook, but actually published by the journal Science in subsequent issues).

Dr. David Gorski, a surgical oncologist, wrote about this study back in 2015 in Science-Based Medicine. Although Dr. Gorski does criticize some parts of the paper by Tomasetti and Vogelstein, overall he does indicate that random mutations are responsible for a large majority of cancers:

Given the level of uncertainty inherent in such estimates, even if you interpret Vogelstein and Tomasetti’s conclusion that two thirds of cancers are due to “bad luck,” their estimate of the percentage of cancers that are probably not preventable is definitely in the ballpark of commonly-accepted estimates, albeit at the lower end. Does that mean they’re on to something in concluding that stem cell replication over one’s lifetime primarily determines the “stochastic” component of cancer risk for each organ? That remains to be seen, but their preliminary finding makes sense, both from the perspective of producing a result that’s in the ballpark of what we already know based on epidemiology and being biologically plausible based on basic cancer biology.

There are a few things one can do to prevent cancer, such as quitting smoking, staying out of the sun, getting your hepatitis B and HPV vaccinations, not drinking alcohol, keeping a low, healthy body weight, and eating a balanced diet. But even if you are a paragon of “healthy” living, a random mutation in some cell in your body can lead to cancer. Apparently, you have little control over two-thirds of the cancers that might arise.

One last thing, the basis of the secret cancer cure myths always seems to rely upon a belief that there is (or will be) one cure to cure them all. This relies upon a complete misunderstanding of cancer as a disease.

Basically, cancer is not one disease. The National Cancer Institute claims that there are over 100 types of cancer.  Cancer Research UK states that there are over 200 types of cancer.  The American Cancer Society lists over 70 types of cancer (although some are more classes of cancer rather than a single type).  Wikipedia lists over 180 different cancers.

Why such a variance in the number? There are several reasons mostly surrounding the lack of precise definitions for some cancers. So researchers may group several different cancers into one heading. But clearly, there are up to 200 or more different cancers.

Furthermore, each of these cancers has different etiologies (causes), pathophysiologies (development), treatments and prognoses. When someone is called a “cancer researcher,” they are rarely studying all cancers, but they’re studying one small part of the story of one or a few of the 200 or so cancers. There isn’t one overarching research direction to “cure” all cancers – there are literally thousands of research and treatment strategies.

One last thing. A lot of our ideas about what may or may not cure cancer are based on preclinical research, that is very rarely brought forward into clinical trials or is successful in clinical trials. In fact, there seems to be a lot of evidence that it is difficult, if not impossible, to repeat the preclinical studies, so it makes it difficult, if not impossible, to accept the results of them. Simply, a lot of research that is publicly touted often ends up meaning nothing.

Cancer mortality rates paper

Let’s get right to the highlights – cancer mortality rates have dropped in men, women, children, and most (but not all) racial and ethnic groups. From 1999 through 2015, the last year included in the study, the rate has declined 1.8% annually for men and 1.4% annually for women. Furthermore, cancer mortality rates have dropped for 11 of 18 cancer types in men, and 14 of 20 cancer types in women between 2011 and 2015. We are seeing both long-term and short-term declines in cancer mortality rates.

As I mentioned above, there are some bits of bad news, including rising liver, pancreatic, and brain cancer mortality rates. And there appears to be a continuing disparity in cancer mortality rates across different ethnicities. Let’s take a look at this massive report and focus on the key points.

Furthermore, the incidence of new cases of cancer per 100,000 people has increased slightly in children, remained steady for women, and dropped for men. However, men are still more likely to be diagnosed and die of cancer than women.

Cancer also published a second report that specifically examined prostate cancer – it concluded that the overall incidence of prostate cancer has declined. On the other hand, advanced cases have gone up. The authors were not sure what created that seemingly conflicting data. It may be related to the fact that fewer men are getting tested for prostate-specific antigen – apparently, the blood test sometimes lead to aggressive treatment for slow-growing prostate cancer (see Note 1).

The authors proposed that cancer mortality rates are declining for a number of reasons:

  • Lower tobacco smoking, which has fallen from 20.5% in 2005 to around 15.5% of adults in the USA in 2016. Of course, smoking is closely linked to lung cancer (which is very rare in the absence of smoking) and many other cancers. Smoking causes more than 25% of all cancer deaths in the USA.
  • Better early detection of most cancers.
  • Better treatment modalities.

One of the fastest growing cancer mortality rates is for liver cancer. The mortality rate is increasing for both women and men, probably as a result of hepatitis B and C infections. However, we can prevent hepatitis B with a vaccine, and we have powerful medications for treatment of hepatitis B and C infections. Theoretically, we should see lower cancer incidence and mortality rates from liver cancer in the future as more people are treated for these infections.

Just because I am an advocate of HPV (human papillomavirus) vaccines, let me note that the report stated that the cancer mortality rates for the oral cavity, pharynx, and soft tissue (often called oropharyngeal cancers) have increased significantly. About 70% of these cancers are causally linked to HPV infections. These cancers can be largely prevented by not smoking and getting the HPV vaccine.

Now this study has some bad news. Black men and black women had the highest cancer mortality rates for many cancer sites. This group had the highest mortality rate in the US population for lung, prostate, female breast, colorectal, and pancreatic cancer. It is possible that this rate results from the USA’s healthcare system that where people of color often have more barriers to access to proper care. Interestingly, Hispanic men and women had a lower cancer incidence and mortality rate than non-Hispanics (see Note 2).

Overall, the cancer incidence for all cancers combines is highest in black men and white women. For the overall US population, the largest increases in cancer incidence were for liver cancer, multiple myeloma, melanoma (skin cancer), thyroid cancer, and leukemia, with smaller increases in kidney and breast cancer. Let’s remember that incidence could increase because of an actual rise in the rate of that cancer or from increased diagnoses as a result of better screening.

The researchers point to obesity as a causal factor of the increase in the incidence of some cancers. They estimated that 25% of pancreatic cancer and 68% of uterine cancer deaths are linked to obesity in the USA. I have pointed out, over and over, that lowering body weight to “normal” levels is one of the best ways to reduce risks of all cancers.

One last bit of troubling data from this study. The authors wrote:

Among children, overall cancer incidence rates increased by 0.8% per year from 2010 to 2014, and overall cancer death rates decreased by 1.5% per year from 2011 to 2015.

They speculated that most of the increased incidence of cancer incidence is as a result of better early detection, but the increase in cancer mortality rates in children is troubling. No, vaccines do not cause cancer (because I can never ignore vaccines), so let’s not create a false correlation (let alone causation) between increased vaccinations and increased cancers in children.

Conclusions about lower cancer mortality rates

The authors concluded that:

For all cancer sites combined, cancer incidence rates decreased among men but were stable among women. Overall, there continue to be significant declines in cancer death rates among both men and women. Differences in rates and trends by race and ethnic group remain. Progress in reducing cancer mortality has not occurred for all sites.

For all the people who think that modern medicine is useless against cancer, you’re wrong. For all the people who think that Big Pharma is useless against cancer, think again. Cancer mortality rates have dropped substantially over the last few decades, thanks to modern medical care and modern medications

We are doing a relatively good job at mostly lowering cancer incidence through reduced smoking and other choices that can reduce cancer risks and mortality. We can do more. We need to end the obesity epidemic in the USA. We need to increase HPV and hepatitis B vaccinations, which can prevent a large number of cancers. And we need to further reduce tobacco smoking in this country.

But it’s mostly good news. We are winning much of the war on cancer.

Notes

  1. There appears to be a wholesale change in prostate cancer screening over the past few years. Many healthcare plans in the USA no longer screen for it, because the benefits for positive long-term health outcomes seem to be limited. First, finding prostate cancer may (or even probably not) improve health short-term or help one live longer. Second, the results from the PSA test can give false positives. Finally, follow-up testing, like biopsies, may have significant complications.
  2. Take that Comrade Donald Trump!

Citations



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The Original Skeptical Raptor
Chief Executive Officer at SkepticalRaptor
Lifetime lover of science, especially biomedical research. Spent years in academics, business development, research, and traveling the world shilling for Big Pharma. I love sports, mostly college basketball and football, hockey, and baseball. I enjoy great food and intelligent conversation. And a delicious morning coffee!