The American Cancer Society’s 2022 statistical report shows that the 30-year trend is continuing.
Cancer is a major killer. In its annual report on cancer incidence and deaths released earlier this year, the American Cancer Society projects that 609,360 people in the United States will die from cancer this year — an average of about 1,700 deaths per day — and close to 2 million cases of cancer will be diagnosed, which works out to about 5,250 cases per day. As has been true for many years, the greatest number of deaths stems from cancers of the lung, prostate, and the colon and rectum in men and of the lung, breast, and the colon and rectum in women.
But as sobering as those statistics may be, they are, in another way, heartening because they show the continuing decline in cancer mortality in the US, which peaked in 1991 and has been on a steady, downward trajectory ever since. Incidence (the detection of new cases) also peaked in the early ’90s, although there are more ups and downs to cancer incidence because it is affected by screening and changes in screening guidelines. Prostate cancer is a prime example.
As explained by the paper elucidating the cancer society’s statistics that was published in the January/February 2022 issue of CA: A Cancer Journal for Clinicians, incidence dropped from 2007 through 2014 following changes to guidelines from the US Preventive Services Task Force that curbed the use of PSA screening tests. Recently, though, the incidence of regional- and distant-stage prostate cancer has been increasing, noted lead author Rebecca Siegel, MPH, senior scientific director of surveillance research at the American Cancer Society, and her co-authors.
One important proviso to this year’s report is that it is based on incidence and mortality data from 2018 and 2019 and therefore doesn’t reflect the effect of the COVID-19 pandemic, which resulted in fewer screenings and some delays in care.
Credit goes to less smoking
Cancer mortality in the US has been declining for the past three decades for many reasons. Adjuvant chemotherapy — chemotherapy after surgery or radiation — for colon and breast cancers and combination therapies for other cancers deserve some credit, noted Siegel and her colleagues. They also mention advances in early detection, surgical techniques and making treatments more targeted. But they say the decline is largely because of reductions in smoking.
Cigarette smoking remains the main cause of lung cancer deaths. About 80% of the projected number of lung cancer deaths this year (105,840 out of 130,180) will be caused by cigarette smoking, according to calculations by Siegel and her team. The researchers estimate that another 3,650 lung cancer deaths will be caused by secondhand smoke. But the toll from lung cancer that is not caused by smoking is considerable. According to the cancer society’s estimates, those 21,700 deaths make lung cancer not associated with smoking the eighth-leading cause of cancer mortality in the US
Lung cancer incidence has also been decreasing as fewer people smoke. Among men the decrease started in the mid-1980s and among women, in the mid-2000s. “Declins in mortality began shortly thereafter but have accelerated in recent years because of earlier-stage diagnosis and improved treatment, which is reflected in longer survival,” notes Siegel. About 2 in 10 people who received diagnoses of lung cancer in 2004 were alive three years later. Now it is 3 in 10. Moreover, because lung cancer accounts for about 20% of cancer deaths in the US each year, reducing lung cancer mortality has a major effect on cancer mortality overall. “We’re talking about large numbers of people,” Siegel says. More people die from lung cancer every year than from prostate, breast and pancreatic cancers combined.
The report notes the rising incidence of breast cancer and of prostate cancer discovered at a later stage. Even more concerning, says Siegel, are the persistent racial, socioeconomic and geographic disparities for highly preventable cancers that may be worsened by uneven access to interventions such as HPV vaccination and expanded health care. The researchers trace cancer disparities by race and ethnicity to wealth disparities that are the result of structural racism and point to redlining — discriminatory home financing practices — as a manifestation of structural racism.
Gerold Bepler, MD, Ph.D., thoracic oncologist and president and CEO at the Barbara Ann Karmanos Cancer Institute in Detroit, notes that it is perhaps surprising that overall cancer incidence rates are declining in the US because of the shift in the country’s demographic profile to an older population as the baby boomers age into their 60s and 70s.
“However,” notes Bepler, “given that lung cancer is among the most frequently diagnosed cancers and much has been done over the past several decades to reduce risk factors associated with this disease, most notably cigarette smoking, this is the most likely explanation for the overall trend,” he says. “We should be proud as healthcare providers in this country that lung cancer is significantly on the decline.” Bepler says bans on cigarette advertising, increases in cigarette taxes and restrictions on indoor smoking
Following are other noteworthy developments mentioned by Siegel and her colleagues.
Liver cancer deaths are leveling off. Liver cancer mortality was increasing faster than mortality from any other type of cancer for decades. But the rate has leveled in the past five years. The big surge reflected steep increases in hepatitis C infections as a result of injection drug use during the 1960s and 1970s, Siegel says. Hepatitis C infection is the strongest risk factor for liver cancer and accounts for about a quarter of cases in the US. Effective antiviral treatment for hepatitis C infection may also be contributing to liver cancer declines in recent years, she adds.
Cervical cancer deaths, largely preventable, continue to happen. Cervical cancer is almost completely preventable, Siegel and her colleagues say, yet every year it’s the second-leading cause of cancer death among women in their 20s and 30s. “This is so frustrating because these are needless deaths; most of these women have either never been screened or haven’t been screened in decades,” Siegel says. “Pap tests detect precancers that can be easily removed before they progress to cancer, and also detect disease at an early stage when it can be treated successfully. And now we have HPV tests, which are even better, and HPV vaccination, which is better still. This is one cancer that really could be 100% eradicated, but even in one of the wealthiest countries in the world, we have a long way to go.”
People diagnosed with cancer are living longer. The survival gains have been especially large for people with the hematopoietic and lymphoid malignancies, according to Siegel and her colleagues. They cited the five-year survival rate for people diagnosed with chronic myeloid leukemia as an example. In the mid-1970s, the five-year survival rate was 22%. Now people treated with tyrosine kinase inhibitors — Gleevec (imatinib) was the first one developed — have a near-normal life expectancy, they said.
Keith Loria is a freelance writer in the Washington, DC, area.