Cancer is far more commonly diagnosed today than it was 100 years ago, but that doesn’t mean your body is more likely to develop cancer than your great-grandparents’ bodies were. The biggest reason more people get cancer now is simple: more people live long enough to get it. When you account for age, cancer death rates have actually fallen significantly in recent decades. The real story is more nuanced than a yes-or-no answer, though, because some cancers have surged while others have nearly disappeared.
Why Age Changes Everything
Cancer is fundamentally a disease of aging. The longer cells divide, the more opportunities they have to accumulate the genetic errors that lead to tumors. In 1900, average life expectancy at birth was roughly 47 years in the United States, largely because so many children died in infancy. Today it’s about 77. That means tens of millions more people now reach the ages of 60, 70, and 80, when cancer risk climbs steeply.
It’s worth noting that people who survived childhood in earlier eras could live surprisingly long. Once you strip out infant mortality, life expectancy for men who reached age 5 in the mid-Victorian period was around 75. For women at age 15, life expectancy rose from about 62 years in 1901 to 79 by 1989 in England and Wales. So the shift isn’t that nobody used to reach old age. It’s that far fewer people did. A disease that mostly strikes after 60 will naturally produce more cases when the population over 60 doubles or triples in size.
What Age-Adjusted Numbers Actually Show
Epidemiologists use age-adjusted rates to answer the question you’re really asking: if you compare a 65-year-old today to a 65-year-old decades ago, is cancer more or less common? By that measure, the picture looks better than the raw numbers suggest. Between 2000 and 2021, the age-adjusted rate of new cancer diagnoses in the U.S. fell 5.7%, dropping from about 486 to 458 new cases per 100,000 people. The age-adjusted death rate fell even more dramatically, declining 27.5% over the same period, from roughly 199 to 144 deaths per 100,000.
Total cancer deaths still rose by about 10.6% during those two decades because the population grew and aged. That’s the tension at the heart of this question: cancer takes more lives in absolute terms, but your individual risk at any given age is lower than it was a generation ago.
Cancers That Have Disappeared and Cancers That Emerged
Not all cancers follow the same trend line, and looking at individual types reveals how dramatically the landscape has shifted over the past century.
Stomach cancer was the leading cause of cancer death in Western countries during the first half of the 1900s. By 1975 it had fallen to second place behind lung cancer, and between 1978 and 2008, U.S. stomach cancer rates dropped by 60%. The decline happened in every age group. The main reason was nothing glamorous: better food refrigeration, cleaner water, and improved sanitation reduced infection rates of H. pylori, the bacterium responsible for most stomach cancers. That single change in bacterial prevalence accounted for an estimated 43% of the decline.
Lung cancer moved in the opposite direction. Rare in 1900, it exploded through the mid-20th century as cigarette smoking became widespread, peaking in men around the 1980s before declining as smoking rates fell. Cervical cancer, once a major killer, dropped sharply after the Pap smear became widely used starting in the 1940s and 50s. Meanwhile, obesity-linked cancers are climbing. The prevalence of obesity in the U.S. has more than doubled since the 1960s, and excess weight is now connected to cancers of the colon, kidney, pancreas, and several other organs.
We Also Just Detect More Cancer Now
A century ago, many cancers were never diagnosed at all. There were no CT scans, no mammograms, no colonoscopies. The concept of routine cancer screening didn’t gain traction until the 1920s, when the American Medical Association first endorsed periodic health exams. Through the 1930s, 40s, and 50s, the American Cancer Society ran large public campaigns promoting the Pap smear and breast exams. Mammography wasn’t formally tested in randomized trials until the 1960s and 70s. Low-dose CT scanning for lung cancer came even later.
This matters because better detection inflates the apparent rate of cancer. A tumor that would have gone unnoticed in 1925, with the patient dying of something else first, now gets diagnosed, treated, and counted in cancer statistics. Prostate cancer is a classic example: widespread PSA testing starting in the late 1980s caused a massive spike in diagnoses without a proportional spike in deaths, because many of those tumors were slow-growing and would never have caused symptoms.
Early Records Were Unreliable
Comparing cancer rates across a full century is also complicated by the fact that death records from the early 1900s were often inaccurate. Death certificates frequently listed symptoms or complications rather than underlying causes. When more than one condition was present, the primary cause was inconsistently chosen. Studies comparing death certificates to clinical records and autopsy reports have found a varying lack of correspondence between the two. Cancers of easily examined sites (skin, breast) were generally reported more accurately than internal cancers, which often went unrecognized entirely. Changes in how causes of death were classified over the decades can also create the illusion of trends that aren’t real.
In practical terms, this means cancer was almost certainly more common in 1920 than the records of the time suggest. Some portion of the apparent rise in cancer over the 20th century reflects better record-keeping, not a true increase in disease.
How Lifestyle Shifts Changed the Risk Profile
The mix of cancer-causing exposures has changed enormously. Smoking rates in the U.S. have dropped by about 50% since 1964, which is the single biggest reason age-adjusted cancer death rates are falling. But other risks have grown. Obesity has more than doubled since the mid-1960s. Physical inactivity and alcohol use remain widespread. Research estimates that 40 to 60% of cancer deaths in the U.S. could be prevented by modifying these four factors alone: smoking, alcohol, excess weight, and inactivity.
Environmental chemical exposure adds another layer. The connection between pollutants and cancer has been recognized for centuries. As far back as the 1700s, the English physician Percivall Pott linked scrotal cancer in chimney sweeps to soot exposure. The carcinogenic compounds in coal tar weren’t identified until the 1920s. Today, industrial agriculture and manufacturing have introduced thousands of synthetic chemicals into daily life. Excluding tobacco, chemical exposure may account for roughly 10% of cancers. Certain herbicides, for instance, have been statistically associated with a 40% increased risk of non-Hodgkin lymphoma. The total burden of cancer driven or worsened by pollutant exposure appears to be growing.
The Bottom Line on Then vs. Now
More people are diagnosed with cancer today than at any point in history. But most of that increase is explained by population growth, longer lifespans, and far better detection. When you adjust for age, your risk of dying from cancer is meaningfully lower than it was even 25 years ago. The cancers that dominate today are different from those that dominated in 1925, shaped by shifts in diet, smoking, sanitation, and screening technology. A person alive in 1920 wasn’t protected from cancer so much as they were likely to die of something else first, and if they did develop cancer, it often went undiagnosed and uncounted.