The number of cancer cases has increased by almost 80% in three decades among those under 50, according to a study

The number of people under the age of 50 diagnosed with cancer has increased worldwide over the past three decades, according to a large study published Wednesday, and the causes of this increase are not fully known.

Cancer cases among people aged 14 to 49 increased by almost 80%, from 1.82 million to 3.26 million, between 1990 and 2019, according to the study published in the British journal. BMJ Oncology.

While experts caution that part of this increase is due to population growth, previous research has found increasingly frequent cancer diagnoses among those under 50.

As the main underlying risk factors in this age group, the international team behind the new study pointed to poor diet, smoking and alcohol.

But the cause of early cancer growth “is not yet clear,” they added.

Breast cancer, the most diagnosed in recent decades

According to the study, just over a million people under the age of 50 died of cancer in 2019 (+28% compared to 1990). The most deadly cancers were those of the breast, trachea, lung, intestine and stomach.

Breast cancer has been the most frequently diagnosed cancer for three decades. But the fastest growing cancers are those of the nasopharynx – where the back of the nose meets the top of the throat – and prostate cancer. In contrast, liver cancer decreased by 2.9% per year.

The researchers used data from the 2019 Global Burden of Disease Study, looking at the rates of 29 different cancers in 204 countries. The more developed the country, the higher the cancer rate among those under 50, according to the study.

This could suggest that wealthier countries with better health systems detect cancer earlier. But only a few countries screen people under 50 for certain types of cancer, the researchers say.

An increase in the number of cases that will continue

According to the study, in addition to a poor diet, smoking and alcohol consumption, genetic factors, physical inactivity and obesity could also contribute to this trend.

And the number of global cancer cases among people under 50 is expected to rise another 31% through 2030, mostly among people ages 40 to 49, according to a model developed by the researchers.

However, they note that cancer data from different countries varies widely, with developing countries potentially underreporting cases and deaths.