Cancer Rates Are Rising in Young Adults and Adolescents!

According to a study covering approximately half a million cases, cancer rates among adolescents and young adults in the United States (people aged 15-39) from 1973 to 2015 increased by 30%.

In 1973, there were 57.2 new cancer diagnoses annually per 100,000 people; this rose to 74.2 in 2015. This corresponds to an annual increase of 0.537 people per 100 thousand.

The highest rate of increase was in kidney cancer. There were also marked increases in thyroid and colorectal cancer, germ cell and trophoblastic cancers and melanoma, among others.

This noteworthy study was published on December 1 in JAMA Network Open.

The increasing incidence of cancer in adolescents and young adults needs investigation

Now that the common and increasing cancer types in this age group are better understood, prevention, screening for early detection, diagnosis, and treatment protocols specifically targeting this population should be developed.

The reasons for these increases are unclear, but environmental and particularly dietary factors, rising obesity, and more widespread cancer screening appear to be possible causes. Cancer screening and overdiagnosis are also thought responsible for much of the increase in thyroid and kidney cancer rates, among others.

The American Cancer Society (ACS) recently found increases in thyroid, kidney, colorectal, and uterine cancers among adolescents and young adults. The rise in colorectal cancer is particularly striking and directly associated with an unhealthy diet, inactivity, and obesity (see our article Why is colorectal cancer targeting young people?).

Increasing thyroid cancer incidence can be explained by widespread ultrasound use and overdiagnosis. However, alongside rising colorectal and uterine cancer incidence in young people, it is extremely important to consider cancer mortality trends in this age group. The increase in both incidence and mortality for these two cancers indicates a real rise in disease burden and certainly requires greater attention and research.

Historically, treating cancers in adolescents and young adults has fallen somewhere between pediatric and adult oncology, neither of which meets the distinct biological, social, and economic needs of adolescent and young adult cancers.

These new findings are valuable in guiding more targeted research and interventions specifically for cancers in adolescents and young adults.

Among female patients, who made up 59.1% of the study group, the incidence of 15 cancers increased: kidney cancer (annual percentage increase 3.632), thyroid cancer (3.456), and myeloma, mast cell, and various lymphoreticular cancers (2.805). Rates decreased for 5 cancers, including the brain tumor astrocytoma (annual percentage decrease 3.369) and gonadal carcinoma (–1.743).

Among male patients, the incidence of 14 cancers increased: kidney cancer (annual percentage increase 3.572), soft-tissue sarcoma (2.543), and thyroid cancer (2.273). Incidence decreased for 7 cancer types, including astrocytoma (–3.759) and lung cancer (–2.635).

Rising testicular cancer rates (annual percentage increase 1.246) may be associated with greater prenatal exposure to estrogen and progesterone or dairy consumption. Treatments used to improve premature babies' survival and greater exposure to marijuana, among other possibilities, are also cited as potential causes.

Increases in colorectal cancer may be associated with fewer vegetables and more fat and processed meat in the diet; lack of exercise; and increasing obesity. Human papillomavirus (HPV) infection has also been implicated.

Higher melanoma rates may be related to tanning-bed use and tanning trends.

Declines in some cancers may be associated with increased use of oral contraceptives (birth-control medications). Other factors include laws reducing exposure to benzene and other chemical carcinogens, and fewer people smoking.

Although kidney cancer increased at the highest rate, it remains relatively rare. Obesity is also one of its most important risk factors. The researchers stated that colorectal and thyroid cancer, melanoma, non-Hodgkin lymphoma, and gonadal germ cell and trophoblastic cancers contributed more to the overall cancer increase among adolescents and young adults.

In conclusion, an unhealthy lifestyle in particular (low fiber, inactivity, obesity) increases the incidence of certain cancers in adolescents and young adults. This trend requires cancer screening to be reassessed with these changes in mind. Tumor biology in adolescent and young adult patients also emerges as a new area of oncology requiring urgent research.