The title of this post is similar to my post from one year ago – because the death rate from cancer is, in fact, continuing to decline, as it was a year ago. This is good news, reflecting several trends. It also is in direct contradiction to the typical alternative medicine, pseudoscience, everything-is-killing-you narrative spread by promoters of dubious treatments.
Here is an overview of the results:
Over the past decade of data, the cancer incidence rate (2006‐2015) was stable in women and declined by approximately 2% per year in men, whereas the cancer death rate (2007‐2016) declined annually by 1.4% and 1.8%, respectively. The overall cancer death rate dropped continuously from 1991 to 2016 by a total of 27%, translating into approximately 2,629,200 fewer cancer deaths than would have been expected if death rates had remained at their peak.
This represents an almost exact continuation of the trends from last year. Cancer deaths peaked in 1991, attributed to an aging population and greater detection. Since then cancer deaths have steadily decreased, as you can see by the graph. The downward lines are now fairly consistent. But let’s look a little bit deeper into the data.
First, we have to separate cancer incidence (the number of new cases of cancer) from cancer deaths (the number of people who die from cancer) and cancer survival rates (how long people live once they have been diagnosed with cancer). Cancer incidence is a result of several factors affecting risk and detection. The risk of cancer increases with age, and our aging population therefore will tend to increase the overall incidence. Other specific cancers have specific risk factors, and they will have a significant effect on the incidence. The biggest one here is smoking and lung cancer.
As we get better at detection this will also increase the numbers, but this is an artifact, not the detection of a real increase in new cases of cancer. There is generally better and earlier detection over time, but the biggest blip here is still prostate cancer. The use of PSA screening, a blood test for prostate cancer, dramatically increased the numbers. This practice was stopped because of overdiagnosis, however, and the number of detected cases dropped just as dramatically. Again – this is completely an artifact of medical practice, not reflecting real disease rates.
Overall cancer incidence, as indicated above, has been stable. There is a small decrease in men, due to the prostate issue, but if we take this out, cancer incidence has been pretty flat. Again – this breaks the “cancer epidemic” narrative that is dredged up to stoke false fears about vaccines, cell phones, GMOs, or whatever boogeyman you want to attack. Some specific cancers have been declining, however. The biggest one here is lung cancer in men, reflecting decreased smoking rates. Lung cancer is declining more slowly in women, reflecting the fact that women overall are slower to quit smoking.
This is a good example of how a public health campaign can have a real and dramatic effect on health. Smoking is a clear risk factor for lung cancer, which is the number one cancer killer for men and women (it is number two in incidence for both, behind prostate in men and breast in women). Lung cancer should be rare – it is only smoking that makes it as common as it is. In a sense, smoking is the number one cause of cancer deaths, and it is completely avoidable. We need to keep this message prominent, and keep up pressure to reduce smoking rates and prevent young people from taking up smoking.
Colorectal cancer is also on the decline. This is partly due to screening (get your scheduled colonoscopies), but screening cannot completely explain the decline.
Three cancer types, though small as a percentage of all cancers, are increasing a bit. Liver cancer is increasing, and this is thought to be primarily due to increased incidence of hepatitis C, which is a major risk factor. Alcoholism is also a risk factor, and that may be playing a role as well. Melanoma is also increasing, the major risk factor for which is sun exposure.
Thyroid cancer is also on the rise. This primarily due to increased detection of smaller cancers (many of which would never have posed a problem), but there is debate as to whether increased detection can explain all of the rise in incidence.
So overall what the incidence data tells us is – quit smoking, use sunscreen, and get your colonoscopy. It does not, however, contain any signal of increased risk for cancer due to some unknown environmental agent.
Let’s turn now to cancer death rate, which is a combination of the cancer incidence and survival. Overall incidence is stable, so this does not explain the steady decline in deaths. What does is mostly increased cancer survival. If you look at people who have cancer, at all ages and for most types of cancer, survival is increasing. This reflects improved treatment. It also reflects improved detection. If we are better at detecting cancer, we will find it earlier, which creates increased “lead time”. Survival will seem to increase simply because we knew about the cancer earlier. However, this is easy to control for in the statistics.
If we control for increased lead time, survival is still improving, reflecting better treatment. Treatment is also more effective if you start it earlier, so improved detection and treatment are related in this way. Improved treatment reflects continuing research in cancer. There are new treatments coming on line all the time. Recently we have moved into an era of immunotherapy for cancer, for example. Each time a new potential treatment is discovered it is overhyped as a potential “cure” but in reality each discovery contributes incrementally to overall progress.
The cumulative effect of all of these small but substantial advances is a steady increase in cancer survival. This is similar to other technologies dealing with complex multifactorial challenges. Battery and solar technology come to mind. In the exact same way, the press talks constantly of “breakthroughs” but in reality we are making steady incremental improvements that lead to a slow but steady (about 1% per year) increase in battery life and solar efficiency. Over the decades, these incremental improvements add up.
In a similar way, there will never be a “cure for cancer”. Cancer is many diseases, and it is complex. But each advance moves the needle a little bit, and over the last 25 years we have decreased cancer deaths by 27% – again, about 1% per year on average. The tortoise definitely wins this race.
Meanwhile, alternative cancer treatments have made no progress. They have nothing to show for all their conspiracy theories and overhyped claims – except an increase in the risk of death. People who use alternative cancer treatments, either in addition to or instead of mainstream treatments, die more quickly from their cancer. This effect will only get greater as survival with mainstream treatments steadily improves.
While this data are a bit complicated to unpack, there are some clear signals. Cancer detection and treatment are overall steadily improving. Public health campaigns to reduce risk factors and improve screening are also effective.
