Fewer Americans are dying of cancer, part of a decades-long trend that began in the 1990s as more people quit smoking and doctors screened earlier for certain cancers.
However, the American Cancer Society warned that those gains are threatened by an increase in cancers among people younger than 55, in particular cervical and colorectal cancer, and by the continued disparities between white Americans and people of color.
“The continuous sharp increase in colorectal cancer in younger Americans is alarming,” said Dr Ahmedin Jemal, senior vice-president for surveillance and health equity science at the American Cancer Society and senior author of the study published on Wednesday in CA: A Cancer Journal for Clinicians. His comments came in a press release accompanying the findings.
Cancer is the second leading cause of death in the United States behind heart disease, with smoking a major contributor to both causes of death. As more Americans have quit smoking, rates of and deaths from smoking-related cancers have experienced a long decline.
Problematically, younger people have seen a steady increase in cancer diagnoses through the same period, with colorectal cancer of particular concern to researchers. The rate of people younger than 55 diagnosed with colorectal cancer has increased 1%-2% annually since the 1990s, and is now the first leading cause of cancer death for men and second for women (behind breast cancer).
“We need to halt and reverse this trend by increasing uptake of screening, including awareness of non-invasive stool tests with follow-up care, in people 45-49 years, [old]” said Jemal.
Although cancer remains primarily a disease of the elderly, the increase in cancers in younger people is part of a global medical mystery. The trend is particularly pronounced in developed regions, such as North America, Australia and western Europe.
“On the whole, the more developed the country and region, the higher the incidence of early-onset cancer,” authors of a recent article in BMJ Oncology said. Although the increase may be partially attributable to earlier screening, there may also be links to “potential risk factors” particular to developed nations.
Writing in Nature, a group of specialist doctors summarized the risk factors that researchers are now examining, including “a Western-style diet, obesity, physical inactivity and antibiotic use, especially during the early prenatal to adolescent periods of life”, that changes the gut microbiome.
In addition to the physical impact of a cancer diagnosis on younger people, researchers worried about how this group of diseases affects people in middle age, often seen as the prime of life.
“People younger than 65 are less likely to have health insurance and more likely to be juggling family and careers,” said Dr William Dahut, chief scientific officer at the American Cancer Society, said in a statement. “Also, men and women diagnosed younger have a longer life expectancy in which to suffer treatment-related side effects, such as second cancers.”
Another concern for doctors is widening racial disparities and increases in uterine (endometrial) cancer deaths. Black Americans are now twice as likely to die from uterine cancer (9.1 deaths per 100,000 people) than white Americans (4.6 deaths per 100,000 people), with incidence increasing steadily at 2% a year.
Stomach and prostate cancers have also seen widening disparities between white and Black Americans. Similarly, mortality rates for Native Americans are twice that of their white counterparts for liver, stomach and kidney cancers.
