Cancers among under-50s rose by 79% in last 30 years: BMJ study

New Delhi: There has been a striking 79 per cent increase in new cases of cancer among the under 50s around the world over the last 30 years, according to a study published in the journal BMJ Oncology.

The research found that the fastest rise was in windpipe and prostate cancers while the heaviest death toll was seen for cancers of breast, windpipe, lung, bowel, and stomach.

The team led by researchers at the University of Edinburgh in Scotland found that breast cancer accounted for the highest number of 'early onset' cases in this age group in 2019. Cancers of the windpipe and prostate have risen the fastest since 1990.

They estimate that the global number of new early onset cancer cases and associated deaths will rise by a further 31 per cent and 21 per cent, respectively, in 2030, with those in their 40s the most at risk.

The findings upend received wisdom about the types of cancers typically affecting the under 50s, researchers said.

While cancer tends to be more common in older people, the evidence suggests that cases among the under 50s have been rising in many parts of the world since the 1990s.

The researchers drew on data from the Global Burden of Disease 2019 Study for 29 cancers in 204 countries and regions. They looked at the incidence, deaths, health consequences (disability-adjusted life years or DALYs) and contributory risk factors for all those aged 14 to 49 to estimate annual percentage change between 1990 and 2019.

In 2019, new cancer diagnoses among the under 50s totalled 1.82 million, an increase of 79 per cent on the 1990 figure, the researchers said.

Overall, breast cancer accounted for the largest number of these cases and associated deaths at 13.7 and 3.5 per 100,000 of the global population, respectively, they said.

However, new cases of early onset windpipe and prostate cancers rose the fastest between 1990 and 2019, with estimated annual percentage changes of 2.28 per cent and 2.23 per cent, respectively, according to the study.

At the other end of the spectrum, early onset liver cancer fell by an estimated 2.88 per cent every year, the researchers found. More than 1 million (1.06) under 50s died of cancer in 2019, an increase of just under 28 per cent on the 1990 figure, they said.

After cancer of the breast, cancers exacting the highest death toll and subsequent poor health were those of the windpipe, lung, stomach, and bowel, with the steepest increases in deaths among people with kidney or ovarian cancer.

The highest rates of early onset cancers in 2019 were in North America, Australasia, and Western Europe.

However, low to middle income countries were also affected, with the highest death rates among the under 50s in Oceania, Eastern Europe, and Central Asia, according to the study.

In low to middle income countries, early onset cancer had a much greater impact on women than on men, in terms of both deaths and subsequent poor health, the researchers said.

The researchers noted that genetic factors are likely to have a role.

However, diets high in red meat and salt, and low in fruit and milk, alcohol consumption and tobacco use are the main risk factors underlying the most common cancers among the under 50s, with physical inactivity, excess weight, and high blood sugar contributory factors, the data indicate.

The researchers acknowledge various limitations to their findings: the variable quality of cancer registry data in different countries may have led to under-reporting and under-diagnosis.

It is still not clear to what extent screening and early life exposure to environmental factors may be influencing the observed trends, they added.