As the country plunged into recession between 2008 and 2012, something unexpected happened: An earlier small decline in the number of new cancer cases became a much bigger one.

The authors of a study published last month by the Cancer Prevention Institute of California believe they have a plausible explanation for the trend: People who lost their incomes or health insurance during that time were less likely to get routine screenings or visit the doctor.

The researchers’ analysis of data from the California Cancer Registry, published in the journal Cancer Causes & Control, shows that in the state’s 30 largest counties, cancer diagnosis rates during the recession and subsequent recovery dropped by 3.3 percent annually for males and 1.4 percent for females — much faster than the average decline of 0.7 percent for males and 0.5 percent for females documented over the previous decade.

A 2015 analysis in the Journal of Cancer covering the years from 1973 to 2008 found that the incidence and treatment of cancer in the United States dropped during recessions and with increased unemployment rates. During such periods, patients were perhaps more likely to forgo tests for early detection or ignore symptoms due to financial consideration, the researchers suggested.

The recent study from California buttresses that earlier finding. The largest drops were seen in the rates for prostate, lung and colorectal cancers. The declining rates of most cancers were especially noteworthy given the growing population of aging Baby Boomers, since cancer is more common later in life.

If people did delay getting screened for early-stage cancers during the recession, “might we then start seeing an uptick of late-stage cancers?” wondered Scarlett Lin Gomez, the study’s lead author and a researcher with the Cancer Prevention Institute of California.

Dr. Jennifer Hastings, who was not involved with the study, expects that to be the case. She is director of the transgender health care program for Planned Parenthood Mar Monte, which serves 29 counties in California and 13 in Nevada. The clinics screen for breast, cervical and colon cancer.

Hastings said doctors at her clinics started seeing more patients with advanced cancers and other serious illnesses starting in 2014, as previously uninsured people obtained coverage under the Affordable Care Act and began seeking care.

“There was great surprise about how sick people were,” she said. With the fate of the ACA now in limbo, Hastings said she’s very concerned about those people losing coverage.

Michelle Quiogue, a family doctor with Kaiser Permanente in Bakersfield and president-elect of the California Academy of Family Physicians, said she frequently sees patients make medical decisions based on the cost of care.

“Even when people have insurance, they will delay care if the cost share is too high,” Quiogue said.

During the recession, a number of her patients lost their job-based health insurance and stopped coming in for regular check-ups, she said. They didn’t return until they gained insurance under the ACA.

Lisa Schlager, vice president of community affairs and public policy for Facing Our Risk of Cancer Empowered, a Tampa, Fla.-based nonprofit advocacy group focusing on hereditary ovarian and breast cancers, said it’s common for people to wait to seek treatment because they don’t have insurance or don’t have the money to pay medical bills or high deductibles.

Schlager recalled a woman who was between jobs when she felt a lump in her breast. The woman decided to wait until she found a new job — then waited a few more months before her employer-sponsored insurance kicked in. By the time she went in for an exam, her cancer had advanced. She died of it.

“It’s sad, but it’s a reality in our country that money a lot of times drives the medical services that people receive or seek out,” Schlager said.

However, the state of the economy is not the only factor that can explain the drop in cancer diagnoses during the recession.

Dennis Deapen, director of the Los Angeles County Cancer Surveillance Program and a professor at the University of Southern California’s Keck School of Medicine, offered some alternative explanations for the declines in diagnoses of certain cancers, including prostate, lung and colorectal.

“It struck me that there’s good reason that those particular cancers would have been declining over that period, regardless of economic factors,” he said, noting that prostate cancer diagnosis rates, which dropped 6.3 percent annually during the study period, “have been plunging for years.”

That’s largely attributable to evolving guidelines for prostate cancer screening.

In 2008, the U.S. Preventive Services Task Force recommended against routine screening for prostate cancer among men over 75; in 2011, it recommended against the routine use of prostate-specific antigen screening in healthy men. Prior to that, Deapen said, prostate cancer was actually over-diagnosed.

Lung cancer diagnosis rates also have been dropping in recent years, at least partly due to a decrease in smoking, especially in California, he added. And colorectal cancer has declined because improved screening techniques have allowed for the removal of precancerous polyps.

Deapen said the diagnosis of some other cancers, including melanoma, is more likely to be influenced by economic factors. Melanoma often is discovered because a patient asks a doctor to check a mole, or the doctor independently notices it during a medical visit.

“If you’ve lost access, that doesn’t happen,” Deapen said. The incidence of melanoma flattened or showed slight declines during the recession years, compared with annual increases in the previous decade.

Deapen said he is interested to find out whether increased access to health care under the Affordable Care Act will have the opposite effect of the findings described in the study, allowing more people to get diagnosed — and treated — earlier.

He cited evidence that the ACA led to earlier diagnosis and saved lives. Without solid details about a replacement plan, he said he wasn’t ready to comment on whether that trend might be reversed if the law is repealed.

This story was produced by Kaiser Health News, which publishes California Healthline, an editorially independent service of the California Health Care Foundation.