colorectal cancer in younger people

colorectal cancer is increasingly being diagnosed in adults <50 yo (ie, prior to the time of recommended screening by USPSTF), with projections that by the year 2030, 1 in 10 colon cancers and 1 in 4 rectal cancers will be diagnosed in this younger group.  A recent population-based cohort study, looked at the disease stage at presentation, treatment patterns by stage, and cancer-specific survival (see colon ca in younger pts cancer2015 in dropbox, or DOI: 10.1002/cncr.29716)​. the study was supported by the Agency for Healthcare Research and Quality. details:

--the researchers accessed the large SEER database (Surveillance, Epidemiology, and End Results), a source for cancer incidence, survival and prevalence, which captures 28% of the US population and is geographically, racially and ethnically diverse. They looked at all patients 20-79yo diagnosed with histologically confirmed colon or rectal cancer between 1998-2012

--results:

    --258,024 individuals with documented colorectal cancer were in the database, of which 37,847 (14.7%) were too young for routine screening (mean age 42.5 +/- 6 years, 53.5% male)

    --in comparison to the group >50 yo (where mean age was 65.3 +/- 8.5, 54% male)

        --14.8 vs 12% were African American (p<0.001), and also more likely to be American Indian/Alaska Native or Asian/Pacific Islander (10.6% vs 8.5%, p<0.001)

        --right-sided cancer in 20% vs 31.1% (p<0.001)

        --rectal cancer in 31.2 vs 22.4% (p<0.001)

        --stage of disease (all with p<0.001):

            --localized in 35% vs 42.6%

            --regional in 39.3% vs 36.4%

            ​--distant in 25.7% vs 21.1%

        --younger patients were 37%  more likely to have regional vs localized disease (RR 1.37, p<0.001)

        --younger patients were 58%  more likely to have distant vs localized disease (RR 1.58, p<0.001)   

        --5-year cancer-specific survival, however, was better for younger patients (localized: 95.1 vs 91.9%; regional: 76 vs 70.3%; distant 21.3 vs 14.1%)

so,

--pretty striking that 1 in 7 patients have colorectal cancer at <50 yo, and there seems to be an increasing shift to younger people

--the younger ones tend to present with more advanced disease (perhaps a tribute to our screening the older ones).

--their survival curves are somewhat better than the older folks', perhaps related to a few issues: they tended to receive more aggressive cancer therapy (not shown above), and perhaps in part related to that, tend to have younger bodies which handle the assault of the disease and the therapy better than older patients.

--although it may be reasonable to consider screening at a younger age (in the assessment above, the mean age was 42.5, so this would mean huge numbers of more screenings), we really would need to study the real risks and benefits (and, it may be that the colorectal cancers that afflict younger patients are actually different: behave differently, perhaps are less aggressive,  respond differently to therapy, etc -- so the risk/benefit analysis may be very different from those with average age 65.3 as above)

--but, bottom line, we should really consider colorectal cancer in the differential for younger patients with rectal bleeding, iron-deficiency anemia, or change in bowel habits.