decreasing cancer, but increasing social disparities

the American Cancer Society published their 2019 report on cancer statistics, finding an overall major decrease in cancer deaths but that increasing socioeconomic disparities in cancer are widening, especially in the most preventable cancers (see cancer statistics CA2019 in dropbox, or doi: 10.3322/caac.21551, or https://onlinelibrary.wiley.com/doi/epdf/10.3322/caac.21551 )

Details:
--cancer incidence data through 2015, compiled from:
    --SEER program (Surveillance, Epidemiology, and End Results)
    --National Program of Cancer Registries
    --North American Association of Central Cancer Registries
--mortality data through 2016  from:
    --National Center for Health Statistics

Results, with my embedded commentary:
--2019 (projected results): 1,762,450 new cancer cases and 606,880 cancer deaths
    --most common: colon 101K cases/51K deaths, lung 228K cases/143K deaths, breast 271K cases/42K deaths, melanoma 96K cases/7K deaths, prostate 175K cases/32K deaths, bladder 80K cases/18K deaths, kidney 74K cases/15K deaths, non-Hodgkins 74K cases/20K deaths
    --states with highest estimated new cancer cases (>100K): CA 187K, FL 131K, NY 112K, TX 125K
    --states with highest estimated deaths (>25K): CA 61K, FL 45K, NY 35K, OH 25K, PA 28K, TX 41K
--cancer incidence (from 2006-2015) was stable in women but declined 2%/yr in men
--cancer death rate (from 2007-2016) decreased annually 1.4% for women and 1.8% for men
--overall cancer death rate dropped continuously from 1991-2016 by 27% (2,629,200 fewer deaths vs expected if there had been no change in death rate)
--racial gap is slowly narrowing
--BUT, socioeconomic inequalities are widening, esp in the most preventable cancers. eg from 2012-2016:
    --cervical cancer: 2-fold mortality difference in poorest counties than most affluent
    --male lung cancer: 40% higher in poorest counties
    --male liver cancer: 40% higher in poorest counties
--and, not so surpringly, some states have both the wealthiest and poorest counties in their borders
--cancer survival, comparing black individuals to white:
    --the increased cancer death rates in black patients is particularly high for:
        --melanoma, 26%
        --cancers of uterine corpus, 21%
        --oral cavity and pharyneal ca, 18%
        --the above differences are largely explained by later stage at diagnosis for black patients (though, adjusting for age, sex, and stage of cancer at diagnosis, black patients have a residual higher risk of death after a cancer diagnosis, suggesting that other factors come into play)
--the above disparities are worse for American Indians/Alaska Natives (51% more likely to die from cancer)
--prostate cancer mortality decreased  by 4%/year for 2 decades, attributed to earlier stage of diagnosis after PSA testing. from 2013-2016, there has been a leveling off, perhaps associated with less PSA testing and more distant stage disease
    --[it is not surprising that the more PSAs done, the more treatments done, and the lower the development of advanced prostate cancer. but at what cost? huge numbers of men who would never have died from prostate cancer running around in diapers and unable to have sex? it is pretty clear that PSA is not a great test: some high-grade cancer can be found with PSA <0.5, and really high PSA can happen in the setting of prostatitis: see https://gmodestmedblogs.blogspot.com/2018/05/psa-screening-recs-from-uspstf.html for elaboration]
--cancer survival by socioeconomic status (SES):
    --a study found that 34% of cancer deaths in the those 25-74 yo "could be averted with the elimination of socioeconomic disparities"
    --overall cancer death rates were 20% higher among residents of the poorest vs the most affluent counties in the 1970s, but now are 35% higher, attributable to "changes in dietary and smoking patterns that influence colorectal cancer risk, as well as the slower dissemination of screening and treatment advances among disadvantaged populations."
        --there has been a shift in cancer-associated behaviors since the 1970s: back then smoking (and lung cancer) was more in people of higher SES. Now, "the prevalence of behaviors that increase cancer incidence and mortality are vastly higher among residents of the poorest countries, including double the prevalence of smoking and obesity compared to residents of the wealthiest counties", as well as lower prevalence of cancer screenings in the poorer communities
        --increasing access to care weakens this association between SES and health outcomes
    --the SES-related differences in cancer mortality are "small or absent for malignancies that are less amenable to prevention or treatment".
        --eg there is basically no disparity for pancreatic or ovarian cancers (which have no early detection, and therefore no difference related to access to care)!!!
--geographical variation:
    --some is related to differences in risk factors: from 2011-15  kentucky had 3.5 times the incidence of lung cancer vs utah (kentucky has the highest and utah the lowest smoking prevalence: in 2016, 1 in 4 in kentucky smoked, vs 1 in 10 in utah) [overall lung cancer death have dropped about 50% in men since 1991, undoubtedly related to overall decreases in smoking]
    --we can anticipate large differences in HPV-related cancers in the future, given large differences in HPV vaccination rates (in 2017, 78% of kids 13-17 were vaccinated in Rhode Island and DC, vs 29% in Mississippi)
        --see http://gmodestmedblogs.blogspot.com/search?q=hpv for an array of blogs on HPV, including a recent FDA recommendation to extend the age to 45.

so, this report does confirm decreasing cancer mortality overall. some from lifestyle changes (eg smoking), some from earlier detection, some probably from better treatment.  but it is quite striking that in the richest country in the world, there are such dramatic differences related to socioeconomic disparities, even in some of the same states. and this seems to be getting worse (no big surprise, since income inequality is galloping forward)....

geoff

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