The shift came decades earlier than experts expected. Researchers had predicted colorectal cancer would take the top spot by 2040, but the disease reached that point much sooner, signaling a serious public health warning.
Between 1990 and 2023, nearly 1.3 million people in the U.S. died from cancer before age 50. During that time, overall cancer death rates in this age group dropped sharply by 44%, thanks to better treatments, early detection, and declining smoking rates.
Most major cancers followed that downward path. Death rates fell steadily for brain, breast, leukemia, and lung cancers. Lung cancer, once the deadliest of all, saw the sharpest decline.
Colon cancer told a different story. Instead of falling, its death rate rose by about 1% each year from 2005 to 2023, making it the only major cancer moving in the wrong direction.
Doctors say part of the problem is timing. Many younger patients are diagnosed only after the disease has already spread, when treatment becomes harder and outcomes worse. Researchers stress the importance of paying attention to warning signs such as bright red blood in stool, ongoing abdominal pain, or unexplained changes in bowel habits.
Health experts continue to urge routine colorectal screening starting at age 45, a step that could save lives if widely adopted.
In a separate health finding, scientists are raising alarms about the hidden dangers of wildfire smoke during pregnancy. A large study from Southern California found that babies born to mothers exposed to wildfire smoke during the third trimester were more likely to be diagnosed with autism by age five.
The research tracked over 200,000 births and found that even a few days of smoke exposure late in pregnancy was linked to a higher risk. The strongest effect appeared in mothers exposed to more than 10 days of wildfire smoke, whose children had a 23% higher chance of an autism diagnosis.
Wildfire smoke carries a toxic mix of fine particles, heavy metals, and chemical pollutants, which can enter the bloodstream and potentially interfere with fetal brain development.
The study does not prove cause and effect, but it adds to growing evidence that air pollution can shape early brain growth. Researchers also noted higher autism risk among children born to older mothers, first-time mothers, and those with diabetes or obesity before pregnancy.
As climate change fuels longer and more intense wildfire seasons, scientists warn that protecting pregnant women from smoke exposure is becoming not just a health issue, but a policy priority.
