The same research team had previously identified an increase in eight cancer types in a 2019 study. This new analysis was designed to close a significant gap in the data by accounting for both how many people are developing cancer and how many are dying from it, broken down by generation.
The central finding: Gen X and Millennials have cancer incidence rates 2 to 3 times higher than those born in 1955. Researchers also noted that as these younger cohorts age, the overall cancer burden in the population is expected to grow further.
A growing body of research on generational cancer risk
The same research team had already identified rising cancer rates in younger generations in a 2019 study, but that earlier work covered only eight cancer types and did not account for mortality data. The new Lancet analysis fills that gap by tracking both diagnosis and death rates by birth cohort across 34 cancers. Researchers have previously established that exposure to carcinogenic factors early in life can affect cancer incidence in people aged 50 or younger.
The 17 cancers rising in Gen X and Millennials — pancreas and kidneys most affected
Of the 34 cancer types examined, 17 showed increased incidence in Gen X and Millennials. The list includes colorectal, endometrial, pancreatic, kidney and renal pelvis, gallbladder and other biliary, myeloma, leukemia, ovarian, and estrogen receptor-positive breast cancer, among others. Several cancers showed increases specific to one sex: liver and intrahepatic bile duct cancer and non-HPV-associated oral and pharynx cancer rose in females, while Kaposi sarcoma and anal cancer increased in males.
The incidence rise was especially pronounced in cancers of the pancreas, kidneys, renal pelvis, thyroid, and small intestine. Beyond new diagnoses, mortality rates also climbed for five cancer types: liver, endometrial, gallbladder, testicular, and colorectal cancers.
Researchers emphasized that the surge in new cases is not simply a byproduct of better detection. The number of new diagnoses is growing fast enough to outpace improvements in treatment, pointing to a genuine rise in risk at the population level.
Obesity linked to 10 of the 17 cancers, alongside diet and environmental factors
Obesity stands out as one of the most significant contributing factors, associated with 10 of the 17 cancers identified in the study. While obesity rates have risen across all age groups since the 1970s, the most rapid increase has occurred in individuals aged between 2 and 19 years — the very window during which Gen X and Millennials grew up.
Other factors cited by the researchers include environmental pollutants, altered sleep patterns, and a sedentary lifestyle. The study also points to the modern Western diet — typically high in processed foods, sugar, saturated fats, and refined grains — as directly linked to increased risk of colorectal and breast cancers.
