Mind & body, in brief

IARC, the World Health Organization's cancer research agency, estimates that infections caused about 2.3 million new cancers worldwide in 2024. [1][2]

That is about 12 in every 100 new cancers, or roughly one in eight. [2]

The study was published on 28 September in The Lancet Oncology, a cancer journal. [1] It counts 12 germs known to cause cancer in people. [1]

H. pylori, a bacterium that lives in the stomach, caused about 760,000 of the cancers. [1][3] HPV, a common virus passed on during sex, caused about 750,000. [1][4]

Hepatitis B and hepatitis C, two viruses that can lead to liver cancer, caused about 360,000 and 160,000. [1][5] The Epstein-Barr virus, known for cancers at the back of the nose and of the lymph system, caused about 260,000. [1] Together these five germs cause almost all the cancers that infections cause. [1]

A germ that stays in the body can cause cancer by damaging a cell's DNA or by keeping a tissue inflamed for years. [3] HIV works another way: it weakens the immune system, so other cancer-causing germs do more harm. [3]

H. pylori is usually caught in childhood and stays for life unless it is treated. [3] Its long inflammation of the stomach lining can end in stomach cancer. [3]

Almost everyone who has sex catches HPV at some point, and the body usually clears it. [4] Cancer of the cervix, the lower part of the womb, comes from infections that persist, usually over 15 to 20 years. [4]

Eastern Asia had 42% of these cancers, mostly from H. pylori and hepatitis B. [1] More than three in four were in low- and middle-income countries. [1]

Most could already be prevented with HPV and hepatitis B vaccines, and with testing and treatment for H. pylori and hepatitis. [1] IARC says these tools are underused because of money, politics and barriers in health systems. [1]

In 11 trials that compared treatment with a dummy pill, treating healthy people who carried H. pylori cut their later stomach cancers by 36%. [3]

The Epstein-Barr virus is now also counted as a cause of some stomach cancers. [1] There is no vaccine against it yet. [1]

Why it matters. Watch whether low- and middle-income countries, which carry more than three in four of these cancers, widen HPV and hepatitis B vaccination and H. pylori testing; IARC says cost and politics hold them back. [1]

The US Centers for Disease Control and Prevention (CDC) has surveyed US high school students every two years since 1991. [11] In 2025, 33% reported persistent feelings of sadness or hopelessness in the past year, down from a peak of 42% in 2021. [11][13] The share who seriously considered suicide fell from 22% to 14%, and the share who made a plan fell from 18% to 12%. [12] Girls reported this sadness far more often than boys, 43% against 24%. [13]

Why it matters. With the questions unchanged, the share of persistently sad or hopeless students since 2015 went 30%, 31%, 37%, 42%, 40% and 33%. [12][13] So the fall since 2021 is real, and 2025 is still above 2015. [13] A psychologist told the New York Times that suicidal thinking is now lower than in 2019. [11]

When the US Food and Drug Administration (FDA) proposed banning menthol cigarettes in 2022, it received 175,000 public comments in three months. [17] Researchers at Rutgers, a US university, found that 97% were form letters, copies of the same text, opposing the ban. [17] Only 2% were unique. [17] Nearly half used the wording of campaigns run by Altria and Reynolds American, the makers of Marlboro Menthol and Newport. [17] The Biden administration postponed the ban in April 2024, citing the response, and it was scrapped in 2025. [17]

Why it matters. About 80% of Black smokers in the US use menthols, and Black smokers die of smoking-linked illness at higher rates. [17] After Canada banned menthol cigarettes, daily menthol smokers were 8 percentage points more likely to quit than other daily smokers, a 2022 study found. [18]

On 23 September the WHO published new guidelines on contraception, including three methods not in its guidance before. [15][16] Combined contraceptive pills can now be taken for up to six months in a row, or continuously for a year, as an alternative to the usual cycles. [15] Implants can stay in for up to five years, and a pill called mifepristone, taken within five days of sex, is added as emergency contraception. [15] The WHO advised countries not to add contraceptive pills containing quinestrol to their programmes, citing limited evidence and reports of serious side effects. [15]

Why it matters. An estimated 164 million women who want to avoid pregnancy use no contraception, the WHO says. [15] It also set out, for the first time, what a future male contraceptive should offer. [15] More than 75% of couples in a WHO survey said they would be willing to use one. [15]

University of Hawaii researchers tested the urine of 1,400 adults on Maui. [9] The tests ran up to a year and a half after the August 2023 wildfires, which destroyed the town of Lahaina and killed more than 100 people. [9] Antimony was nearly 40 times higher than in US national data, manganese 3.8 times, barium 2.3 times and arsenic 2.2 times. [9] People with more metal in their bodies did worse on breathing tests. [9] The study was published on 28 September in PNAS, a US science journal. [9]

Why it matters. The researchers say the metals may have come from burned buildings, cars and electronics, rather than only burned plants. [9] They cannot say exactly how much came from the fire, because there is no comparable data from before it. [9] The study hopes to collect data for a decade after the fire. [10]

The same CDC report found that about one US high school student in four slept at least eight hours on a school night in 2025, fewer than in 2015. [14] About one in four was active for an hour a day, and that share also fell over the ten years. [14] More students ate fruit and vegetables daily than in 2023, and more played on a sports team. [14][12] About one in three used social media every hour or more. [14]

Why it matters. This year's report led with diet, sleep and screen time, priorities of US Health Secretary Robert F. Kennedy Jr. [12] It left out teen vaping, sex and violence, which past reports covered, although the survey still collected that data. [12]

A team including Jesse Poganik, who studies ageing at Harvard, grafted extra hearts between young, middle-aged and old mice, then read age-linked chemical tags on the hearts' DNA. [7] Young hearts in old mice aged faster, and old hearts in young mice looked biologically younger. [7][8] Tissue samples from the hearts of 11 people at a Boston hospital, whose donors were much older or younger than them, showed the same pattern. [7] The work is a preprint, not yet checked by other scientists. [7]

Why it matters. Doctors usually prefer donors under 45. [7] The US did 4,636 heart transplants in 2024, and hundreds of people around the world still die each year waiting for one. [7] Poganik says some ageing is probably irreversible, and an outside expert says these measures of age are still experimental. [7][8]

In the early 1960s a US drug company, William S. Merrell, handed out thousands of unlabelled doses of thalidomide, a sedative, without FDA approval. [20] An FDA reviewer, Frances Oldham Kelsey, kept it off general sale, but some pregnant women were given it for morning sickness. [20] Some of their babies were born with shortened limbs, and many doctors did not tell the mothers or write it down. [20] The FDA recognises 17 US survivors. [20] One author estimates about 100. [20]

Why it matters. Survivors are asking the US Congress to recognise them and pay each $150,000. [20] Many were told by doctors they could not be survivors, because the United States had supposedly escaped the drug. [20] They say their health is getting worse as they age. [20]

Some TikTok videos, with hundreds of thousands of likes, promote garlic fermented in honey as a natural antibiotic for flu season. [19] Health Canada, the country's national health body, warned that fermenting garlic in raw honey at room temperature can carry a risk of botulism. [19] Honey alone is too dry for germs to grow, but bacteria in the honey can draw water from the garlic and begin to multiply. [19] They grow best with little oxygen, and their toxin can stop the diaphragm, the muscle that drives breathing. [19]

Why it matters. Botulism is rare: the CDC recorded 243 confirmed and 30 probable US cases in 2021, and 181 of them were babies. [19] Raw honey is not given to babies under one year old because of the botulism risk. [19]

IARC and the American Cancer Society estimated in July that 20.6 million people were diagnosed with cancer in 2024, and 9.8 million died of it. [21] The count covers 34 cancer types in 186 countries. [21] Lung cancer was the most common, with about 2.6 million new cases, followed by breast, bowel, prostate and stomach cancer. [21] Lung cancer also caused the most deaths, about 1.9 million. [21]

Why it matters. The figures mean about one person in five develops cancer in their lifetime. [21] New cases are expected to reach 34.4 million a year by 2050, 67% more than in 2024. [21]

Reynolds American, owned by British American Tobacco, is selling Vuse Pro vapes in peach, berry, watermelon and fresh mint in Ohio and other states, STAT reported on 8 September. [22] The FDA has not authorised them. [22] In May the agency said it would not act against unauthorised fruit-flavoured vapes whose makers had applications pending and had sent data on the risk to young people. [22] Only 48 e-cigarettes have ever been authorised. [22]

Why it matters. The FDA's new policy came about a week after Reynolds American gave $5 million to a super PAC, a political fundraising group, backing President Trump, STAT reported. [22] Reynolds says the sales follow state rules and come with ID checks and purchase limits. [22]

In November 2025 the WHO launched the sixth edition of its Medical Eligibility Criteria, the guide that tells health workers which contraceptive is safe for which person. [24] A fourth edition of its guide on how to use each method came with it. [24] Under the new editions, progestogen-only hormone injections can be offered straight after childbirth, and emergency contraception can be repeated within one cycle. [24] Hormonal methods can also be used safely by women taking PrEP, medicine that prevents HIV infection. [24]

Why it matters. Countries in all six WHO regions use these guides to write their own rules. [23] New evidence on progestogen-only methods, including injections, found no harm to breastfeeding or to babies, even when started within six weeks of birth. [23]

A May 2026 analysis by KFF, a US health policy research group, found 15% of Americans aged 12 to 17 had a major depressive episode in 2024. [25] That means at least two weeks of low mood or lost interest, with several other symptoms. [25] The share was 21% in 2021. [25] About 19% reported moderate to severe anxiety, and 7.8% had a drug or alcohol use disorder, down from 9.2% in 2021. [25]

Why it matters. This is a different national survey from the CDC's, and it also shows a fall since 2021. [25][13] KFF notes that federal money for school mental health services was disrupted under the second Trump administration. [25]

Researchers estimated the biological age of 11 organs in 11,757 people from a US community heart study, using proteins in their blood. [26] Older organ ages went with the diseases of that organ, even after allowing for a person's real age. [26] For every five years a person's heart looked older, their risk of heart disease was about 16% higher. [26] The study was published in December 2025 in JCI Insight, a medical journal. [26]

Why it matters. The group whose organs all looked older had higher risks of cancer, heart failure, kidney failure and death. [26] Today's transplant study found a heart's biological age can shift in a new body. [7]

A study in Nature Communications in December 2025 built an inventory of pollution from buildings burned in wildfires across the lower 48 US states from 2000 to 2020. [27] National pollution records do not count these emissions. [27] The 20 most destructive fires produced 68% of all the carbon monoxide from burned buildings. [27] In several states, burning buildings released more of some toxic gases, such as hydrochloric acid, than all human-made sources combined. [27]

Why it matters. Destructive building fires were more likely in fire weather and in forested, built-up areas. [27] The study names the 2023 Lahaina fire, which destroyed more than 2,000 buildings, as a recent fire of this kind. [27]

After the Palisades and Eaton fires in Los Angeles in January 2025, researchers tested the air and surfaces in 19 homes before people moved back. [28] Metals in the air were below health limits. [28] But wipe samples found metals on surfaces in many homes, and lead on window sills and entry floors went above US Environmental Protection Agency dust limits in several. [28] The study was published in December 2025. [28]

Why it matters. Homes near the fire, without air purifiers, cleaned with ordinary vacuums, or with windows open during the fire had more dust in the air. [28] The authors say surfaces can hold fire pollution even two months after the fire. [28]

A study of US convenience-store sales, published in January 2026, found cigarette sales fell from 9.23 billion packs in 2016 to 5.61 billion in 2024. [29] Menthol cigarettes fell slowly until 2021, then by about 15% a year from 2021 to 2024. [29] The cheapest, deep-discount brands were the only group to grow, and their prices fell. [29]

Why it matters. Menthol sales were falling fast even though the US ban proposed in 2022 never took effect. [29][17] The authors call for research on whether the growing cheap brands change who smokes. [29]

Since November 2023, US school staff have uploaded photos of nicotine products taken from pupils to a Rutgers University project. [30] By the end of September 2025 they had sent 1,535 images showing 9,589 products, its 2025 report says. [30] Of those, 99.1% were e-cigarettes, mostly disposable, and over 99% of flavoured products were not tobacco-flavoured, most often fruit. [30] Nicotine pouches were 0.4%. [30]

Why it matters. The most common brand was Geek Bar, at about a quarter of products. [30] The project says school confiscations give an early view of which brands young people are getting. [30]

People who receive a donated organ or stem cells get cancer more often, which is usually put down to drugs that weaken the immune system and let cancer-causing viruses in. [31] A team including researchers at Brigham and Women's Hospital in Boston studied the DNA of 41,874 cancers. [31] In tumours from 13 transplant patients they found a new pattern of DNA changes, unlike those caused by tobacco or faulty DNA repair. [31] It was published in January 2026. [31]

Why it matters. The team names a strong candidate: ganciclovir, an antiviral drug many transplant patients take against cytomegalovirus, a common virus, though the exact mechanism is not settled. [31] Their estimate that about 10% of tumours after transplant carry it is uncertain, they say. [31]

A UCLA study, published in 2025, followed 221,712 US veterans with cirrhosis, a badly scarred liver, from 2000 to 2021. [32] About 80% had hepatitis C, and 61% had a mental health condition, most often alcohol or drug use disorders. [32] Veterans with mental health conditions had a higher risk of liver cancer, even after allowing for age and hepatitis C treatment. [32]

Why it matters. The authors think these conditions may stop people getting their hepatitis C cured. [32] The senior author, Jihane Benhammou, says curing hepatitis C alone is not enough to protect them. [32]

The WHO has updated its 2011 guideline on preventing early pregnancy among adolescents in low- and middle-income countries, its authors wrote in November 2025. [33] Girls aged 15 to 19 in those countries have about 21 million pregnancies a year, half of them unintended. [33] The update focuses on two aims: preventing child marriage and helping married girls, and getting more adolescents to start and keep using contraception. [33]

Why it matters. Worldwide, births to 15- to 19-year-olds fell from 64.5 per 1,000 in 2000 to 42.5 in 2021. [33] Rates are highest among girls with less schooling or less money, and the update puts more weight on groups left out of that progress. [33]

PFAS are human-made chemicals found in the blood of nearly all US residents, and some are linked to certain cancers. [34] A study published in June 2026 measured 12 of them in the blood of 550 volunteer firefighters in nine US states. [34] Volunteers make up 65% of the US fire service. [34] Firefighters can meet PFAS in firefighting foam, in smoke and in their protective gear. [34]

Why it matters. Levels tracked people's age, sex, region and health more strongly than their firefighting work. [34] The authors say that points to exposure from their wider communities, not only from the job. [34]

Researchers at the California National Primate Research Center, part of the University of California, Davis, exposed airway lining cells from laboratory primates to wood smoke again and again. [35] The smoke changed which genes the cells switched on, including genes for inflammation and cell death. [35] Many of the changes were still there a week after the smoke stopped. [35] The study was published in November 2025. [35]

Why it matters. Under the microscope, the tissue looked normal. [35] So the smoke changed the cells in ways a microscope did not show. [35]

A study published in November 2025 compared CDC survey results for US high school students from 2013 to 2023. [36] In the survey years when teens slept less on average, more of them reported symptoms of depression, and the link was strong. [36] The authors say this does not show that short sleep causes depression. [36] Sleep loss affects over 70% of US adolescents, they write. [36]

Why it matters. The CDC's 2025 results broke the pattern for now: sadness fell while the share of students sleeping eight hours did not change. [13][14]