(CNN) — The five-year lung cancer survival rate has increased 21%, from 21% in 2014 to 25% in 2018, making what experts call "remarkable progress" -- but it is still the leading cause of cancer death in the United States.

However, in communities of color, a person's odds of surviving five years after diagnosis are much lower, at only 20%, according to the 2022 State of Lung Cancer report, which was published by the American Lung Association on Tuesday.

The survival rate varies from state to state. Oklahoma has the lowest rate, at 19.7%, and Rhode Island has the highest, at 30.8%.

"A 21% increase in five-year survival is good. I don't think there are too many other groups that have seen that level of improvement," said Dr. Jeffrey Crawford, a medical oncologist with Duke Health who was not involved in the new report.

The generally low survival rate is in large part because people often find out that they have the cancer only in later stages of the disease.

The odds of surviving cancer increase significantly when it is diagnosed early. About 44% of cases of lung cancer aren't caught until a late stage, when the survival rate is only 7%, the report says.

More screening needed

In 2021, the US Preventive Services Task Force expanded its screening recommendations for lung cancer. It now urges screening for anyone ages 50 to 80 who has a "20 pack-year smoking history," meaning they smoked one pack a day for 20 years or two packs a day for 10 years, they currently smoke or they have quit in the past 15 years.

In 2021, only about 5.8% of the recommended population was screened, the new report says.

"When lung cancer screening is implemented, cancers are caught earlier, when they're more curable. There is a huge amount of progress to be made there," said Dr. John Heymach, chair of thoracic/head and neck medical oncology at MD Anderson Cancer Center, who was not involved in the new research. "And 5.8% is actually an improvement from before, but those numbers are still dismally low."

Some research suggests that as many as 60,000 lives could be saved each year if the 14.5 million Americans for whom it's recommended get lung cancer screening.

Almost all private insurance plans cover the cost of screening. Most are required to do so under Obamacare. The only plans that are not required to cover these tests are through state Medicaid programs, but most states do so.

"It's disappointing that the advances we are seeing are not due to massive success screening for lung cancer, which we should be doing. We're still only screening a minority of patients," Crawford said.

He said a part of the problem may lie at the primary care level.

"We've failed to get the primary care docs to change their attitudes about lung cancer because for decades, I think there's been a kind of pessimism about lung cancer. They say it's a smoker's disease, and the outcomes are poor, or they think patients won't be healthy enough to get surgery, so there's no need to screen," Crawford said. "There's all sorts of misconceptions that just really aren't true anymore, but I don't think we've really gotten that message through as opposed to mammography for breast cancer. No one's going to argue about that."

Lung cancer inequities

People of color are much less likely to be diagnosed with lung cancer at an early stage, the report says.

Members of Black and Latino communities were 15% less likely to be diagnosed with lung cancer early than White people. Asian Americans were 16% less likely to be diagnosed early.

Latinos with lung cancer were 28% more likely than Whites to not receive any treatment. For Black people, it was 10%.

American Indians with lung cancer were 13% less likely to be diagnosed early, 21% less likely to get surgical treatment and 23% less likely to survive five years than people who are White.

Nationally, the number of cases fell 11% from 2014 to 2018. Nearly 237,000 people will be diagnosed with lung cancer this year, the report says.

Cancer rates vary by state. Kentucky, for instance, has the worst lung cancer rate. It's almost 2.3 times the incidence rate of Utah, which has the best rate. This is because of differences in things like available treatments, insurance coverage and risk factors.

It's not only smokers who get lung cancer. Other risk factors include exposure to secondhand smoke, radon and air pollution.

About 137 million people live in parts of the US that have failing grades for unhealthy levels of air pollution, according to the 2022 American Lung Association State of the Air report

Why the state of lung cancer is improving

The new report does not explain why lung cancer numbers have declined over the years. One reason may be that fewer people smoke in the US than even 15 years ago, as the US Centers for Disease Control and Prevention has noted.

"Smoking cessation efforts in years and reductions in secondhand smoke due to policies in restaurants and other public places that restrict smoking have really been a fantastic success from a public health perspective and saved thousands of lives a year," Heymach said.

Treatments have also gotten "dramatically better," he said, with "dramatic strides" in survival.

Just a decade ago, for someone with cancer that has spread to other organs, the odds of surviving five years were less than 5%. The expected survival rate was about a year.

But with the discovery of targeted therapies known as EGFR inhibitors, pills that target specific mutations for lung cancer, the expected survival is now more than four years, Heymach said.

Those therapies apply only to the 40% to 50% of patients who have a mutation that can be targeted with a pill.

For others, immunotherapies like PD-1 inhibitors are used to stimulate the immune system to attack the cancer and improve the odds of five-year survival by more than 10%.

"That's not as high as we like, but it's still remarkable progress," Heymach said. "All of these therapies really have made dramatic differences."

He says there is a lot more to done to help people with lung cancer, but things are looking up.

"Of all the progress made in cancer survival in the last several years, a large percentage of that has been specifically in lung cancer. So lung cancer is the cancer type with the most dramatic advances in cancer therapies, and that's certainly a welcome change, because for a long time, there was no progress."

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