14 June 2024

Generation X was found to be more susceptible to cancer

American epidemiologists, having studied the data of 3.8 million patients with cancer pathologies, have found out whether the incidence of cancer in general and different types of cancer in particular is growing or slowing down from generation to generation.

WHO estimates that about one in five people will develop some form of cancer in their lifetime, and one in nine men and one in 12 women will die from it. While the prevalence of some cancers is now declining, others are beginning to affect younger and younger age groups.

Despite the progress humanity has made in early cancer detection, treatment and patient care, a fundamental question remains: do we, as a whole, experience lower cancer susceptibility than our ancestors? This was asked by epidemiologists from the National Cancer Institute in Rockville, Maryland, USA, whose paper was published in the journal Jama Network.

Tracking the history of cancer, according to scientists, a difficult task, because it develops throughout life, and the period of observation in modern cancer registries covers at most a few decades. Therefore, the aim of the authors of the new study was to fill the gaps in knowledge, using data on different demographic groups, and to reconstruct the "trajectory" of the spread of cancer in the United States of America - from the "great" (those born between 1908 and 1927) and "silent" generations (1928-1945) to the baby boomers (1946-1964) and Generation X (1965-1980).

Epidemiologists collected data on 3.8 million cancer cases from the 13-registry SEER database. A total of 152 matrix charts covering 50 one-year ages (35-84 years) and 27 calendar years (1992-2018), as well as 76 one-year cohorts (1908-1983) for 21 types of invasive cancer - malignant neoplasms that develop from epithelial cells - were obtained.

The sample included men (51.0%) and women (49.0%). There were several ethnic groups: white non-Hispanic (71.5%), black non-Hispanic (10.4%), Hispanic (9.5%), and Asian or Pacific Islander (8.6%).

After analysing all the data, the authors concluded that the incidence of many cancers increased significantly in Generation X compared to baby boomers. For example, over time, women were more susceptible to thyroid cancer (2.76 times higher risk), kidney (1.99), colon (1.84), colorectal (1.56), pancreatic (1.39), as well as non-Hodgkin's lymphoma (1.40) and leukaemia (1.27).

Men born between 1965 and 1980 were more likely than the previous generation to experience thyroid cancer (2.16 times higher risk), kidney (2.14), rectal (1.80), colorectal (1.60), prostate (1.25) and leukaemia (1.34). At the same time, the prevalence of other types of cancers declined, with lung (0.60) and cervical (0.71) cancers in women, and lung (0.51), liver (0.76), gallbladder (0.85) and non-Hodgkin's lymphoma (0.75) in men.

When the researchers compared the "silent" and "great" generations, they found that those born between 1928 and 1945 had significantly lower incidence of the disease - for both sexes, but stronger in males, and across all ethnic groups. When comparing data from the baby boomers and the "silent" ones, the overall incidence was mixed. That is, it decreased in some groups (for example, by 5.4% and 10.6% in non-Hispanic white women and men, respectively) but increased in others (by 13.0% in Hispanic women).

"Comparing Generation X to baby boomers, we found that overall incidence increased in all groups except Asian or Pacific Islander men. The rise ranged from 5.5% for non-Hispanic black women to 28.0% for Hispanic women. For men, the rise in incidence ranged from 10.4% for Hispanics to 13.7% for non-Hispanic whites. The rate for non-Hispanic black males increased 13.7% but dropped 8.2% for Asians and Pacific Islanders. With the exception of Asian or Pacific Islander men, this increase was larger than any observed in previous generations," the epidemiologists added.

However, they emphasised that, in absolute terms, the highest incidence rate was found in non-Hispanic black males of generation X: 1,561 cases per 100,000 person-years. The lowest cumulative rate was found in Asian and Pacific Islander males: 519 cases per 100,000 person-years.

In general, while baby boomers, especially men, were less likely to get cancer than their parents born between 1917 and 1944, people from Generation X (excluding Asian and Pacific Islander men) were significantly more likely to experience cancer - compared to their predecessors.

"The significant increase we found in Generation X compared to baby boomers and their parents surprised us. During this time, humanity has found many preventable causes of cancer. Cancer control initiatives have led to significant reductions in tobacco use. Screening is widely used to diagnose precancerous lesions of the colon, rectum, cervix, uterus and breast. However, other carcinogenic exposures are on the rise. Unfortunately, as a detailed comparative analysis of generation X and the baby boomers has shown, the increase in cancer incidence has numerically outpaced its decline," the authors of the research paper stated.

They called for reflection: what could the cancer rates be for the 72 million Millennials born between 1981 and 1996, when they will be (or have been) in their 40s, 50s and 60s? While there are opportunities to reduce the future burden of disease, the new data are troubling: cancer prevalence in the U.S. may remain unacceptably high for decades to come. All the more reason to consider modern lifestyles, such as sedentary work and the overweight epidemic, as well as other factors that increase the risk of cancer.

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