Cancer patients are getting younger

Cancer patients are getting younger: ©romaset - stock.adobe.com

The American Cancer Society published its annual statistical report today, both as an article in its journal CA: A Cancer Journal for Clinicians and as an 88-page, standalone report for a general audience, 2024 Cancer Facts and Figures.

The statistics paint an overall picture that is encouraging, with the decline in cancer deaths that started in the early 1990s continuing, due partly to declining smoking rates, and improving five-year survival rates, from 49% for diagnoses made in the 1970s to 69% for those made during 2013-2019. The cancer society's numbers also show a narrowing of the Black-White disparity in cancer mortality, from 33% in 1993 (279 deaths per 100,000 population among Black people vs. 210 deaths per population among White people) to a 13% difference from 2016-220 (175.8 deaths per 100,000 population vs. 155 per 100,000 population)

The cancer incidence (the number of new cases) trends are less clear cut, partly because incidence is partly a function of screening, and overall cancer incidence soared in the early 1990s as a result of widespread prostate-specific antigen (PSA) screening for prostate cancer.

Rebecca L. Siegel, M.P.H., the lead author of the CA article about the statistics, and her colleagues note that cancer incidence for men fell sharply for men as PSA screening decreased following changes in prevention guidelines but has leveled off since 2013. Cancer incidence has been edging up among women for 40 years, however, and Siegel and her colleagues noted that increased incidence of some cancers (breast, uterine corpus and melanoma) haven’t been offset by decreasing incidence in others (lung and colorectal).

Eddying beneath the overall trends are some cross currents that head in different direction.

It is axiomatic that cancer risk increases with age. Even so, today's tranche of cancer statistics show a tilt toward diagnosis at a younger age. The result is a population of cancer patients that is younger than it used be. More precisely, the proportion of new cancer diagnoses in the population ages 65 and older decreased from 61% in 1995 to 58% during 2019-2020, according to Siegel and her colleagues, even though that baby boomer-dominated demographic group grew as a proportion of the overall population from 13% to 17%.

Meanwhile, the proportion of cancer patients ages 50-64 grew from 25% to 30% which is roughly in keeping with that age group's growth as proportion of the general populationfrom 13% to 19%.

Seigel and her colleagues say obesity, a risk factor for several cancersm could be one reason for this shift to younger population but also mention exposures “yet to be elucidated.” They say the decrease in the older population can be traced to steep decreases in the incidence of prostate cancer and smoking-related cancer in older men.

Siegel and her colleagues note elsewhere in the CA article that the “best indicator of progress against cancer is patterns in young adults, which manifest more recent exposure.” If that is the yardstick, then it is notably good news that mortality rate for all cancers combined among those younger than 50 has decreased by almost 2% per year since 1975. But a closer look by anatomical site shows some unevenness; for example, Siegel and her colleagues note that while the death rates from lung cancer and leukemia have dropped substantially among men younger than 50, the death rate from colorectal cancer has climbed. Among younger women, breast cancer is the leading the cause of cancer death but colorectal cancer has surpassed lung cancer to become the second leading cause of death.

Another finding that goes agains the grain of the staistical report is the five-year survival rate for people diagnosed with uterine corpus cancer.

“The only cancer for which survival has decreased over the past four decades is uterine corpus cancer,” Siegel and her colleagues point out. In 1975-1977, the five-year survival rate was 87%. In 2013-2019, it had slipped to 81%. The researchers point out that the uterine corpus cancer is the fourth most commonly diagnosed cancer in women in the U.S., has an increasing mortality rate, and one of widest Black-White disparity gaps with respect to mortality. Yet, note Siegel and colleagues, uterine corpus cancer ranks 24th in National Cancer Institute research funding. The Black-White difference in five-year survival (63% vs. 84%) partly reflects that Black women tend to be diagnosed at a later stage of uterine corpus cancer, they say.