By Layla Katiraee and Alison Bernstein
We often hear that “we’re sicker than we’ve ever been before”. This statement is often seen in memes and articles against vaccines, GMOs, medications, pesticides, etc as a reason why these tools are shunned. But is this true? Are we actually sicker now than in the past? Since there are many different ways that we can be sick, we need to break this claim down a bit. For example, we certainly do not die from smallpox anymore. So, in this article, we’re going to focus on cancer: are there more cases of cancer today?
It’s understandable to think that cancer is on the rise: we all know someone who has cancer. The news leaves us with the impression that there’s a growing number of carcinogens all around us. It doesn’t help that trust in our regulatory agencies is waning on both sides of the political spectrum. Funding and support for the agencies (like EPA) tasked with testing and protecting us from carcinogens is falling victim to political ideology. So let’s dig into the numbers and find out if our assumptions about the rising number of cancer cases are correct.
Understanding Cancer Statistics
The National Cancer Institute has an overwhelming amount of data on the incidence, prevalence, and mortality of cancer in the United States. It is important to understand the difference between these terms because the numbers and trends differ:
- Prevalence is defined as “the proportion of a population who have a specific characteristic in a given time period”. It includes people who have been recently diagnosed, as well as individuals who have been diagnosed in the past. It is reported as (for example) the number of people living with a diagnosis of breast cancer for every 100,000 people in the US.
- The incidence is the number of new cases that are diagnosed each year.
- The incidence rate is defined as the number of new cases that are diagnosed each year in a population. It is reported with a time/year and a population size: number of new cases of breast cancer for every 100,000 people in 2017. The statistic can be adjusted for the age of the population so that it’s more accurate.
- Mortality is the total number of deaths that are caused by a disease (such as breast cancer) in a given population.
With these definitions in mind, here are some of the most recent statistics from 2018:
- Incidence: An estimated 1.7 million cases of cancer were diagnosed in 2018 in the US.
- Mortality: Approximately 610 thousand individuals died from cancer in 2018 in the US.
- Incidence rate: 439 per 100,000 people per year are diagnosed with cancer in the US.
- Mortality rate: 163 per 100,000 people per year die from cancer. (This is on average – mortality is higher in men, particularly African-American men.)
- It is estimated that 38% of individuals will be diagnosed with cancer at some point in their lives
What are the most common types of cancer?
Cancer is not a single disease. Each type of cancer has unique genetic and environmental factors that drive the disease. Despite the detailed statistics, combining all these different types of cancer together may not give us an accurate picture of what’s happening. So understanding trends for specific types of cancer is also important.
With this in mind, the first question you may ask yourself is “What’s the most common type of cancer?” The most common type of cancer is skin cancer. According to the American Academy of Dermatology, approximately 9500 people are diagnosed with skin cancer each day. After skin cancer, the most common types of cancer are breast cancer, lung cancer, and prostate cancer.
Is the incidence of cancer increasing?
Looking at the incidence or number of new cases of cancer, we see that there is an increase year after year. But our population is also growing and we’re living longer. So, it’s more meaningful if we look at the incidence rate. Luckily, the CDC has all this data. If we look at the incidence rate across all different types of cancer together, we see that the incidence rate is actually decreasing from 481 in 100,000 in 1999 to 435 in 100,000 in 2016.
Why is the incidence rate of certain cancers declining?
The overall incidence rate of cancer is declining for most types of cancer. This includes lung cancer, breast cancer, cervical cancer, and prostate cancer, among others. There are various factors that are attributed to this, particularly efforts around curbing smoking. But the fact that there are social disparities in the incidence rate and mortality of cancer highlights socio-economic factors such as nutrition and environmental factors that are at play. It will be interesting to see how the HPV vaccine impacts the rate of cancer in the coming years.
Which cancers are being diagnosed more frequently?
The incidence of liver cancer is rising more quickly than other types of cancer. This is thought to be due to Hepatitis C, particularly among baby boomers (interestingly, 75% of individuals with Hepatitis C are baby boomers). Additionally, alcohol and obesity contribute towards this disease.
Additional types of cancer whose incidence rates are increasing include:
- Skin cancer (or melanomas): thought to be due to the lack of sunscreen use as well as indoor tanning.
- Throat cancer: incidence of HPV-related throat cancer is increasing, but could be prevented with the HPV vaccine.
Is cancer mortality increasing?
The National Cancer Institute estimates that cancer mortality has also decreased in the last decade. Cancer mortality decreased by 1.8% and 1.4% for men and women, respectively, between 2006 and 2015. A decrease in childhood cancer mortality was also observed. In fact, the mortality rate for cancer has been declining for the past 25 years. The decline in cancer mortality is thought to be due to improvements in cancer detection, particularly early detection, improvements in treatment, and lower smoking rates.
New data released in January 2020 by the American Cancer Society, shows that “the death rate from cancer in the United States declined by 29% from 1991 to 2017, including a 2.2% drop from 2016 to 2017, the largest single-year drop ever recorded.” But this decline in mortality is not even across all cancers. Due to the decline in smoking, lung cancer deaths dropped the most: a staggering 50% among men in the past 25 years. This decline in overall cancer deaths is due to drops in mortality rates for the 4 most common cancer types: lung, colorectal, breast and prostate. However, “obesity-related cancer deaths” are rising, such as cancer of the pancreas and liver.
In the United States, there are also many racial and socioeconomic discrepancies in cancer mortality rates. According to the National Cancer Institute:
- “African Americans have higher death rates than all other groups for many, although not all, cancer types.
- African American women are much more likely than white women to die of breast cancer. The mortality gap is widening as the incidence rate in African American women, which in the past had been lower than that in white women, has caught up to that in white women.
- African Americans are more than twice as likely as whites to die of prostate cancer and nearly twice as likely to die of stomach cancer.
- Rates of colorectal cancer deaths among those younger than 65 (“premature” deaths) are higher in states with the lowest education levels than in those with higher levels. People with more education are less likely to die prematurely of colorectal cancer than those with less education, regardless of race or ethnicity.”
These disparities have many underlying causes, ranging from access to care, implicit biases among clinicians that lead to black people not being treated equally to white people, to environmental factors, to biases in clinical trials where minorities have low participation.
Is the prevalence of cancer increasing?
This overall decrease in cancer mortality due to better diagnoses and treatments has lead to an increase in the number of people living with cancer. In other words, the prevalence of cancer has increased. If the incidence of cancer (proportion of people who are diagnosed each year) stays the same, but fewer people die from cancer, the prevalence (proportion of people alive with cancer) goes up.
As of January 2019, an estimated 16.9 million people in the United States are living with cancer. Since our population is aging, the National Cancer Institute estimates that this number will rise to 22.1 million people by 2030. Most of these individuals were diagnosed with cancer over 5 years ago. Nearly two-thirds of these individuals are older than 65.
There are many discrepancies in the prevalence data based on cancer type, but also based on socioeconomic factors. The prevalence of cancer is greater in individuals with insurance. Those who are insured go to the doctor more often so the likelihood of having their illness diagnosed is greater. At the same time, the likelihood of getting diagnosed earlier is also greater. The American Cancer Society states: “optimal cancer care is not universally available, resulting in disparities in stage at diagnosis, treatment, and outcomes for medically underserved populations, such as racial and ethnic minority groups, the uninsured or underinsured, rural populations, and the elderly.”
Why do so many believe that cancer is happening more often?
So, why is it that we believe so readily that the incidence rate of cancer is increasing? Well, it probably has to do with the fact that the prevalence of cancer, or the number of people living with cancer, is increasing. 38% of individuals will have cancer at some point in their lives. Given that we live longer than in decades past, this represents a lot of living people. We now all know someone who has had cancer. With social media and the relative breakdown of stigmas surrounding cancer, people are more aware of those in their lives who are affected by the disease. Consequently, it feels like the incidence rate is increasing.
What can we do to prevent cancer?
We tend to focus on activities and objects that give us very little protection against cancer, like trace pesticides or chemical cleaners. We tend to ignore large risks while focusing on small risks. Much of the risk of cancer is genetic, which we cannot change, and cancer often develops by chance. Even so, the hazards that pose the greatest risk for cancer are smoking, a sedentary lifestyle, obesity, lack of sunscreen, and insufficient vegetable and fruits in our diets. These are all modifiable risk factors that affect cancer risk across the population.
Learn more about risk in our series “Risk in Perspective”.
Cases of cancer: concluding thoughts
It looks like cancer is on the rise because the overall incidence rate of all cancers is staying the same and cancer mortality is decreasing. This has lead to an increase in prevalence and visibility. Although this is overall good news, this statistic provides little solace to people diagnosed with cancer and their families and friends. In addition, there are specific types of cancer that are not declining.
It is critical that research continues so the survival trends keep moving in the right direction for all cancers. It is also important to reduce health disparities so that these improvements can be shared across demographic groups. As mentioned throughout this piece, many populations within our communities are impacted more harshly by cancer. Cancer disproportionately impacts African Americans and other racial minorities, as well as individuals with limited access to health care. The National Cancer Institute highlights that work is being done to address these health disparities.
To address these issues, as individuals, we should vote for legislators and politicians that have concrete plans to improve access to care. We should voice our concerns to our elected officials when the strength and funding of our research agencies is compromised.
This post was edited on February 5, 2020 in response to comments by an astute reader. In the concluding section, we have corrected references to the incidence rate, rather than overall incidence. We also added references to the new US cancer statistics released in January 2020.