The researchers also found that the rise in death rates from colorectal cancer was confined to White individuals. "We looked at adults from ages 20 to 54 and following several decades of pretty rapid declines in death rates, over the past decade deaths in this age group have been increasing", lead investigator Rebecca Siegel, strategic director of surveillance information services at the American Cancer Society, told CBS News.
The study, spearheaded by lead researcher Rebecca Siegel of the American Cancer Society, analyzed the colorectal cancer mortality rates among US adults between the ages of 20 and 54 from 1970 to 2014. Screening prevalence has increased for all age groups over 50, but is lower in people 50 to 54 than in those 55 and older: 44 percent versus 62 percent, respectively, in 2013, according to the National Health Interview Survey.
Japan's National Cancer Center for the first time on August 9 released data showing the relative five-year survival rate of cancer patients at 188 hospitals around Japan - roughly half the number of institutions serving as bases for cancer treatment.
During that time, overall death rates from colon cancer dropped from about 6 to about 4 per 100,000 population.
Another interesting find was that the growing trend is being driven by colorectal cancer deaths in white men and women.
Death rates from colon cancer are on the rise among younger, white Americans and doctors are desperately trying to figure out why. After 2004, death rates began to increase slightly each year, reaching 4.3 per 100,000 in 2014. Among black individuals, mortality declined throughout the study period at a rate of 0.4 percent to 1.1 percent annually (from 8.1 in 1970 to 6.1 in 2014).
Studies are needed to understand if other environmental factors affect colon cancer rates and survival differently for whites compared with blacks, he added. The authors note that these disparate racial patterns are inconsistent with trends in major risk factors for colorectal cancer like obesity, which is universally increasing.
So what's going on?
Why this is so is unclear, Siegel said.
Researchers are looking into the matter, but many experts believe that the answer may lie partly in the microbiome, or the bacteria that normally live in the human body. "The answer is that no one really knows why this is happening", Siegel said.
"What's disturbing is that colon cancer is detectable and curable when detected early", said Dr. Darrell Gray, of the Ohio State University Comprehensive Cancer Center.
"Although the risk of colorectal cancer remains low for young and middle-aged adults, rising mortality strongly suggests that the increase in incidence is not only earlier detection of prevalent cancer, but a true and perplexing escalation in disease occurrence". Doctors say people should be aware of the symptoms, including changes in bowel habits, pain, cramps, or unexplained weight loss.