Black/White Gap Gone: 'The Only Cancer Where This Has Happened'

Pam Harrison

August 20, 2020

The historically higher incidence rates of lung cancer among Black men compared with White men in the United States have all but been eliminated, at least among most men in the younger age groups, a new analysis from the American Cancer Society (ACS) indicates.

Among women, the trend is even more impressive, as the Black/White gap in lung cancer incidence rates has actually reversed in younger women. Black women in certain age groups are now less likely to develop lung cancer than white women, the same study indicates.

These trends reflect the steeper declines in smoking rates among Blacks in the US compared with comparably-aged whites, say the authors.

"This is the only cancer where this has happened," lead author Ahmedin Jemal, DVM, PhD, senior vice president for Data Science at the American Cancer Society, told Medscape Medical News.

"If you look at cancers that are affected by access to screening and treatment, the disparity between the Blacks and the Whites has been increasing over the years because tests and treatment require access to insurance, so the Whites are getting more of them than the Blacks," Jemal explained.

"But for smoking, all you have to do for prevention is just don't smoke, so this is a success story that really should be highlighted," he emphasized.

The study was published online today in JNCI Cancer: Spectrum

Nationwide Incidence Data

For this study, Jemal and colleagues collected nationwide incidence data on individuals between ages 30 to 54 who had been diagnosed with lung cancer between 1997 and 2016.

"We categorized age at diagnosis by 5-year age intervals (from 30-34 to 50-54 years) and year of diagnosis by 5-year calendar period (from 1997-2001 to 2012-2016)," the investigators explain.

Analyses showed that lung cancer incidence rates generally decreased among both Black and White men during the study interval but the decline in incidence rates was steeper in Black men than than White men.

As a consequence, the Black-to-White incidence rate ratios (IRRs) became similar in men born between 1967 and 1972 and reversed in women born since about 1967.

For example, the Black-to-White IRRs in men between the ages of 40 and 44 who were born between 1957 and 1972 declined from 1.92 to 1.03.

Similarly, lung cancer incidence rates during the study interval declined among both Black and White women between the ages of 30 to 49 but, again, the decline was "considerably larger" among Black women.

As a consequence, the Black-to-White IRR in women age 45 to 49 dropped from 1.25 during the period 1997-2001 down to 0.83 during the period 2012-2016.

This is in stark contrast to historical trends in lung cancer incidence rates, which were over 30% higher among similarly-aged black women born in the late 1950s.

Now, lung cancer incidence rates are about 30% lower for similarly-aged Black women born in 1972 compared with white women.

For Black and White women between age 50 and 54, lung cancer incidence rates either declined only slightly or remained stable during the study interval, the investigators reported.

The one exception to the diminishing gap in lung cancer incidence rates between Black and White men was an observed increase in IRRs in men born around the period 1977-1982

Among this group of men, who were between age 30 to 39 in the years 2012-2016, lung cancer incidence rates were higher in Black men than in White men.

As the authors point out, this increase in lung cancer rates among young Black men likely reflects a rapid rise in smoking seen among Black youth in the 1990s.

This trend coincided with an R.J. Reynolds tobacco ad campaign in which African Americans were targeted; between 1991 and 1997, the prevalence of smoking among Black high school students doubled from 14.1% to 28.2%, the investigators point out, citing a 2008 CDC report on cigarette use among US high school students.

Smoking Prevalence Rates

Smoking prevalence rates were derived from National Health Interview Survey data from 1970 to 2016.

Mirroring findings in the racial patterns of lung cancer incidence rates, smoking prevalence rates declined in successive birth cohorts in both Black and White males and females, but the decline was again steeper in black men and women than it was in white men and women.

As a result, the historically higher sex-specific smoking prevalence rates seen historically in Blacks disappeared in men born around 1960, and reversed in women born at the same time, Jemal and colleagues point out.

As the authors explain, the more rapid decline in smoking prevalence after 1960 is likely a reflection of the "precipitous" drop in smoking initiation rates among Black teenagers starting about the late 1970s through to the early 1990s.

For example, among 12th graders, smoking prevalence rates between 1977 and 1992 dropped from 36.7% to 8.1% among Black teens. In stark contrast, they hardly changed at all among white teens, dropping only from 38.3% in 1977 to 31.8% in 1992.

Jemal suggested that steeper decline in smoking initiation rates seen between the late 1970s and early 90s reflects the fact that Black teenagers were deterred from smoking because the cost of cigarettes kept going up.

He also suggested that smoking is less acceptable in the Black community than it is in the white community, especially among churchgoers, where smoking is severely frowned upon and non-smoking is the community "norm."

Additionally, Black youth may simply be heeding government anti-smoking messages to a greater extent than white youth, Jemal suggested.  

He wondered if there are parallels now in the current pandemic. "When I go to a store here in Georgia, I would say almost all Blacks are wearing a mask (even though masks are not mandatory in Georgia) whereas it's amazing the number of Whites who don't wear a mask," he recounts.

"So it would seem that Whites feel that government is simply interfering with their lives, while Blacks have a better perspective of the harms of smoking so they are listening to the government's anti-smoking campaigns," he speculated.

Some Isolated Areas

Asked to comment on the study's findings, Otis Brawley, MD, Bloomberg distinguished professor of oncology and epidemiology at Johns Hopkins University in Baltimore, Maryland, said that while overall Black smoking rates are declining, there are some isolated areas where they are still very high.

For example, in his hometown of Baltimore, recent prevalence rates indicate that over 30% of Blacks are still smoking "so these areas with high usage are still areas to focus on," he told Medscape Medical News in an email.

On the other hand, the study also supports the benefits of local, state, and federal government efforts to promote anti-smoking messages and tobacco-control activities over the past number of years.

"It proves that tactics used to control tobacco use have had some effect [even though] the study also shows that the tobacco industry's advertising tactics such as the R.J. Reynolds targeted ads in the 90s can have deleterious effects," Brawley noted.

Lung cancer has traditionally been one of the biggest drivers in the Black/White cancer mortality gap, Brawley said, adding that steeper declines in smoking initiation rates among Blacks compared with Whites are the main reason why this disparity is decreasing.

The study was supported by the Intramural Research Department of the American Cancer Society. The study authors have disclosed no relevant financial relationships. Brawley declares he does some consulting work for pharmaceutical company Genentech.

JNCI Cancer Spectrum. Published online August 20, 2020. Full text

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