The number of cancer deaths worldwide is expected to nearly double by 2050, largely due to increases in low and middle-income countries.

Habtamu Bizuayehu at the University of Queensland in Australia and his team made the discovery by looking at recent figures for cases and death rates for 36 types of cancer in 185 countries from the Global Cancer Observatory database. They then projected future cases and deaths by applying these rates to the 2050 population predictions from the United Nations Development Programme.

They found that the total number of cancer cases worldwide is expected to grow by nearly 77 per cent between 2022 and 2050, which would mean an additional 15.3 million cases in 2050 on top of the 20 million in 2022. Global cancer deaths are also projected to rise by almost 90 per cent during this period, resulting in 8.8 million more in 2050 compared with 2022, in which 9.7 million people died from the disease.

The largest increases are expected in countries with low or middle rankings on the UN’s Human Development Index, which is based on average life expectancy, education level and income per person. Cancer cases and deaths are, on average, anticipated to nearly triple by 2050 in countries with a low score, such as Niger and Afghanistan. Meanwhile, countries with a very high score – such as Norway – are projected to see cases and deaths increase, on average, by more than 42 per cent and 56 per cent, respectively.

This reinforces other evidence that shows cancer cases are trending upwards, says Andrew Chan at Massachusetts General Hospital in Boston, who wasn’t involved with the study. Multiple factors are probably driving this, including people living longer, which raises the risk of cancer, he says. However, the work didn’t account for the advent of new or more effective treatments.

Less-developed countries will probably see the greatest increases due to the “so-called Westernisation of populations”, says Chan. “Some of the habits that we traditionally associate with higher risk of cancer, such as rising rates of obesity and poor diet, are becoming a trend in low and middle-income countries.”

A common sunscreen ingredient, zinc nanoparticles, may help protect rice from heat-related stress, an increasingly common problem under climate change.

Zinc is known to play an important role in plant metabolism. A salt form of the mineral is often added to soil or sprayed on leaves as a fertiliser, but this isn’t very efficient. Another approach is to deliver the zinc as particles smaller than 100 nanometres, which can fit through microscopic pores in leaves and accumulate in a plant.

Researchers have explored such nanoparticles as a way to deliver more nutrients to plants, helping maintain crop yields while reducing environmental damage from using too much fertiliser. Now Xiangang Hu at Nankai University in China and his colleagues have tested how zinc oxide nanoparticles affect crop performance under heatwave conditions.

They grew flowering rice plants in a greenhouse under normal conditions and under a simulated heatwave where temperatures broke 37°C (98.6°F) for six days in a row. Some plants were sprayed with nanoparticles and others weren’t treated at all.

When harvested, the average grain yield of the plants treated with zinc nanoparticles was 22.1 per cent greater than the plants that hadn’t been sprayed, and this rice also had higher levels of nutrients. The zinc was also beneficial without heatwave conditions – in fact, in these cases, the difference in yield between treated and untreated plants was even greater.

Based on detailed measurements of nutrients in the leaves, the researchers concluded that zinc boosted yields by enhancing enzymes involved in photosynthesis, as well as antioxidants that protect the plants against harmful molecules known as reactive oxygen species.

“Nanoscale micronutrients have tremendous potential to increase the climate resilience of crops by a number of unique mechanisms related to reactive oxygen species,” says Jason White at the Connecticut Agricultural Experiment Station.

The researchers also found that rice treated with zinc nanoparticles maintained more diversity among the microbes living on the leaves – called the phyllosphere – which may have contributed to the improved growth.

Tests of zinc oxide nanoparticles on plants like pumpkin and alfalfa have also shown yield increases. But Hu says more research is needed to verify this could benefit other crops, such as wheat.