In the past, cancer was seen as a death sentence. These days, it’s increasingly a survivable or chronic disease. But that’s especially true if you’re rich.

That’s the takeaway from the latest big reports on cancer deaths in the US and globally. On the one hand, screening to detect the disease early has become more widespread, and better treatments are helping people live longer with cancer than ever before.

Yet these successes aren’t being evenly distributed across populations. Cancer is increasingly a microcosm of the inequality that defines our time. As the gap between the haves and have-nots widens, the income gap in cancer deaths will continue to grow, too.

The cancer death rate in the US has dropped by 27 percent since 1991

First, the good news for the United States. Over the past decade, the US has made incredible gains in reducing cancer deaths, according to the American Cancer Society’s latest cancer statistics report.

The cancer death rate has declined by about 1.5 percent each year for both men and women — which you can see by 2016 translated to about 2.6 million fewer cancer deaths than the peak of the cancer death rate in the early 1990s:

Put another way, the cancer death rate has dropped by 27 percent from 215 deaths per 100,000 people in 1991 to 156 deaths per 100,000 in 2016.

Let’s pause to consider how remarkable this is. This consistent drop in the cancer death rate has continued at a time when other major causes of death in this country have flattened. So the cancer story really is one of progress.

That raises the question: How did we make these gains?

One big part of the story is that there have been huge advances in early detection and treatment of four major cancers — lung, breast, prostate, and colorectal — as you can see in the charts below:

And that’s helped make these cancers more survivable.

But the other big story has to do with smoking. Much of the increase in cancer deaths over the last century was driven by increases in smoking — which is still the leading cause of preventable disease and death in the US. So when smoking rates declined, a drop in the cancer death rate followed.

“Because of lower smoking rates, you have rapid declines in lung cancer in men, and a 45 percent drop in lung cancer death rates, which is great progress, and then an almost a 20 percent drop in women,” Rebecca Siegel, a researcher with the American Cancer Society, told Vox in 2018. (The decline in smoking-related lung cancer in women is lower than it is in men because women took up smoking later and were slower to quit.)

“These stories reflect the increasing and still increasing awareness about the health hazards of smoking,” she added, “as well as public health policies against smoking that have reduced smoking in public places.”

While the progress against the four major cancers is cause for celebration, in other cancers, the gains haven’t been as dramatic — or there have been reversals. The rate of liver cancer incidence is rising faster than that for any other cancer — a trend the American Cancer Society attributes to the high rate of undiagnosed hepatitis C among baby boomers. So there’s clearly a lot of work to be done.

The gains are not being equally shared in the US and globally

The progress against cancer is not unique to the US. The largest study of cancer survival trends, published in 2018 in the Lancet, pulled data from cancer registries in 71 countries covering 67 percent of the world’s population from 2000 to 2014. They too found cancer survival is increasing in many countries, even for some of the most deadly cancers, such as liver and lung.

But the paper highlighted another important story that emerges from the data: There are persistent disparities between the rich and the poor when it comes to your chances of beating cancer. And that’s as true within countries like the US as it is among high- and low-income countries.

In the Lancet paper, for example, cancer survival rates were the most consistently high in the world’s wealthiest countries, including the US, Canada, Australia, New Zealand, Finland, Norway, Iceland, and Sweden. Meanwhile, poorer countries did not see the same gains. When it comes to childhood brain cancer, for instance, the five-year survival rate was less than 40 percent in Brazil and Mexico, and about 80 percent in Sweden and Denmark.

Gaps related to income show up within the US, too. In one of the most recent papers on socioeconomic and racial disparities in cancer mortality, published in the Journal of Environmental and Public Health in 2017, researchers found that areas of the US that are wealthier, along with groups with higher levels of education and income, have lower cancer mortality than their poorer, less educated counterparts.

The American Cancer Society’s 2019 report states the starkest survival disparities are showing up for the most preventable cancers: “For example, compared with the most affluent counties, mortality rates in the poorest counties were 2-fold higher for cervical cancer and 40 percent higher for male lung and liver cancers during 2012-2016.”

Americans in high-education and high-income brackets also have a two- to three-fold lower rate of lung or colorectal cancer mortality than lower-income Americans, said Gopal Singh, a researcher at the Health Resources and Services Administration. “And we see these disparities changing over time — they are widening,” he added.

Stage of disease at diagnosis is the No. 1 factor in determining cancer survival, Singh said, and people of a lower socioeconomic status tend to have worse access to health care. That means their cancers aren’t being detected as early, which diminishes their chances of surviving the disease.

Some people also face real barriers accessing treatment. Some of the latest cancer treatments can cost as much as half a million dollars in the US, and even if your insurance covers them, living outside of certain US cities could make getting the treatments almost impossible.

Lifestyle factors are also driving the gap. Singh noted he found differences in the health behaviors that are associated with cancer — such as smoking, diet, alcohol use, and physical activity — between richer and poorer Americans. While the rich are getting better at adopting the lifestyle behaviors that lower their cancer risk, the poor lag behind.

Part of the solution to America’s widening cancer gap may lie with cities

Eliminating these disparities would avert one-third of all cancer deaths in this country, according to the American Cancer Society. Yet, as the Trump administration and Republicans in Congress work to cut health care for the poor, the cancer mortality gap may only continue to widen.

But if we think about preventing cancer, instead of just treating it, another study on health inequality points to a solution. And it suggests cities and local governments have a big role to play in closing the cancer gap.

For a 2016 study, published in JAMA, a group of researchers led by Stanford University economist Raj Chetty analyzed income data for the US population from 1.4 billion tax records between 1999 and 2014. They then compared it with mortality data from Social Security Administration death records. And they found a gaping divide in longevity between America’s richest and poorest.

Men who were among the top 1 percent of income earners lived 15 years longer than men at the bottom 1 percent. For women at the extremes of the income distribution, life expectancy differed by 10 years.

But they also found that low-income individuals lived the longest (and had more healthy behaviors) in places with well-educated, high-income populations, as well as generous government spending. And that the geographic differences in life expectancy for the poorest individuals were “significantly correlated” with behaviors like smoking.

Smoking bans, cigarette taxes, and anti-obesity efforts (such as the ban on trans fats or calorie labeling requirements) in cities such as New York may have had a net positive effect on the health of the local population — including the lowest-income people.

So if you consider that about a third of cancers can be avoided by adopting healthy behaviors — such as increasing levels of physical activity or cutting smoking — policy creativity at the level of cities and local governments could help close the cancer gap.