Cancer Death Rates Continue to Fall in US -- Why?

Pam Harrison

January 05, 2018

Mortality from most cancers continues to decline across the United States, although there is still concern that liver cancer continues to "increase rapidly," according to new figures released by the American Cancer Society.

They come from the annual report, Cancer Statistics 2018, which was published online January 4 in CA: A Cancer Journal for Clinicians.

From a peak death rate in 1991, mortality from all cancers had declined by 26% by 2015.

This means that there are approximately 2.4 million fewer deaths from cancer now than what would have occurred had peak mortality rates remained at 1991 levels, the authors note.

"The decline in cancer mortality over the past 2 decades is primarily the result of steady reductions in smoking and advances in early detection and treatment," they comment.

The largest fall in cancer deaths was for lung cancer deaths in men, which decreased by 45% between 1990 to 2015.

The smoking connection was emphasized by Otis Brawley, MD, chief medical officer of the American Cancer Society. "A decline in consumption of cigarettes is credited with being the most important factor in the drop in cancer death rates," he said in a statement.

A decline in consumption of cigarettes is credited with being the most important factor in the drop in cancer death rates. Dr Otis Brawley

"Strikingly, though, tobacco remains by far the leading cause of cancer deaths today, responsible for nearly 3 in 10 cancer deaths," he adds.

Combing Through Statistics to See Trends

Under lead author Rebecca Siegel, MPH, strategic director, Surveillance Information Services, American Cancer Society, Atlanta, Georgia, the team estimated the number of new cancer diagnoses and death rates for 2018 on the basis of incidence data through 2014 and mortality data through 2015.

Incidence data were collected by the Surveillance, Epidemiology and End Results program, the National Program of Cancer Registries, and the North American Association of Central Cancer Registries. Cancer mortality rates were tracked by the National Center for Health Statistics.

The authors estimate that in 2018, there will be 1,735,350 new diagnoses of cancer across the nation, or more than 4700 new cancer diagnoses each day.

Cancers of the prostate, lung, and colorectum will account for 42% of all cancer diagnoses in men. Among women, cancer of the breast, lung, and colorectum will account for approximately 50% of all new cancer diagnoses in 2018, with breast cancer contributing about 30% of the diagnoses.

Furthermore, "an estimated 609,640 Americans will die from cancer in 2018, corresponding to almost 1700 deaths per day," the researchers add.

Not surprisingly, death from cancer of the lung, prostate, and colorectum in men and death from lung, breast, and colorectal cancer in women will be the most common causes of cancer-related mortality this year, accounting for 45% of all cancer-related deaths in men and women, one quarter of which will be due to lung cancer, study authors note.

Overall Cancer Incidence

The researchers also found that during the past decade, the overall incidence of cancer declined by about 2% a year in men. This reflects large, continuing declines in the rates of both lung and colorectal cancer as well as a decrease in the incidence of prostate cancer.

Indeed, the incidence of lung cancer in men is dropping about twice as rapidly in men as in women, the authors note, a reflection of the fact that men took up smoking earlier than women as well as the fact that more men are quitting smoking than women.

Rates of colorectal cancer are generally similar in men and women and have similarly declined by about 2% to 3% a year from 2005 through 2014. This reflects more widespread screening by colonoscopy among older adults throughout the United States, the authors suggest.

In contrast, "the overall cancer incidence rate in women has remained generally stable over the past few decades because declines in lung and colorectal cancers have been offset by increasing or stable rates for breast, uterine corpus and thyroid cancers and for melanoma," the researchers observe.

Liver Cancer Continues to "Increase Rapidly"

Trends in liver cancer seen between 2010 and 2014 are interesting because they vary by age and sex.

Overall, the incidence of liver cancer continues to "increase rapidly" in women, though not in men. However, rates are increasing in both sexes in those younger than 40 years, whereas rates remained stable or declined in men and women aged 40 to 59 years.

For individuals aged 60 to 69 years, the incidence of liver cancer increased by 8% each year between 2010 and 2014 and by 3% for those 70 years of age and older, the researchers note.

This pattern likely reflects detection rates of hepatitis C infection (HCV) as well as new antiviral therapies that reduce the risk for liver cancer, they observe.

On the other hand, there is a "worrisome 2-fold increase in HCV infections from 2010 to 2014...driven by individuals aged 20-39 years as a consequence of the opioid epidemic," investigators state.

As for melanoma, the rapid rise in the incidence of this skin malignancy that occurred between 2005 and 2014 appears to be slowing down, especially among younger individuals.

Reflecting changes in practice guidelines, thyroid cancer rates have also begun to stabilize in recent years.

Survival Rates

From a peak death rate in 1991, mortality from all cancers had declined by 26% by 2015, but the fall in cancer death rates was larger in men than in women (32% vs 23%), the authors report.

Large declines across the decades have been recorded for all four of the main cancer types in both men and women:

  • 39% decline in breast cancer in women from 1989 to 2015

  • 52% decline in prostate cancer from 1993 to 2015

  • 52% decline in colorectal cancer from 1970 to 2015

  • 19% decline in lung cancer in women from 2002 to 2015

"For all cancers combined, the 5-year relative survival rate is 68% in whites and 61% in blacks," researchers continue.

Prostate cancer is associated with the highest survival rates, at 99% at 5 years, followed by melanoma, at 92%, and breast cancer in women, at 90%.

The lowest survival rates are seen with pancreatic cancer, at 8% at 5 years, followed by lung and liver cancer, both at 18%.

"Survival is lower for black than for white patients for every cancer type...except cancers of the kidney and pancreas," the researchers note.

As has been widely reported elsewhere, black patients are more likely than white patients to present with more advanced cancer. After adjusting for all confounders, including stage of diagnosis, "the relative risk of death after a cancer diagnosis is 33% higher in black patients than in white patients," they observe.

Among all ages combined, death rates from cancer were 14% higher in non-Hispanic blacks than in non-Hispanic whites.

These rates are 33% lower relative to mortality rates in 1993, and the mortality gap between blacks and whites is now even lower, at 7%, in patients 65 years of age and older, likely because of better access to healthcare offered by Medicare.

In fact, mortality rates from cancer are lower among blacks in Massachusetts and New York than they are for white patients.

Massachusetts now offers almost universal healthcare coverage, which may have helped eliminate racial disparities in cancer mortality rates, the authors note.

Cancer is the second most common cause of death in children 14 years of age and younger. The researchers estimate that 10,590 children will be diagnosed with cancer in 2018 and that 1180 will die from it.

Leukemia is the most common childhood cancers, followed closely by brain tumors and other nervous system tumors.

Adolescents are most susceptible to brain tumors and other nervous system tumors, followed closely by lymphoma.

The authors have disclosed no relevant financial relationships.

CA Cancer J Clin. Published January 4, 2018. Full text

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