Cancer is a large group of diseases that can start in almost any organ or tissue of the body when abnormal cells grow uncontrollably, and go beyond their usual boundaries to invade adjoining parts of the body. According to the World Health Organization (WHO), it is the second most common cause of death globally, accounting for millions of deaths every year. Lung, prostate, colorectal, stomach and liver cancer are the most common types of cancer in men, while breast, colorectal, lung, cervical and thyroid cancer are the most common among women. However, these are not necessarily the deadliest forms of cancer.

What makes cancer the deadliest depends upon how many people have it and what percentage of those people actually survive. Cancer researchers determine this on the basis of five-year relative survival. This is the percentage of people who are expected to survive the effects of a given cancer, excluding their risk of other possible causes of death, for five years past a diagnosis. It is also important to note that what makes cancer really deadly is that practically no cure for it. A cure for cancer would imply that there are no cancerous cells remaining in the body.

Here are the 5 deadliest cancers in the U.S., according to SEER five-year relative survival data for cases diagnosed between 2014 and 2020.

1. Pancreatic cancer occurs when cells in your pancreas, a gland in your abdomen that aids digestion, mutate and multiply out of control, forming a tumour. Major risk factors include smoking, obesity, diabetes, chronic pancreatitis, certain genetic mutations and environmental chemical exposure.

2. Esophageal cancer develops in the oesophagus, which is the tube that connects your throat to your stomach.

3. Liver cancer and intrahepatic bile duct cancer originate in the liver or bile ducts, often linked to hepatitis infections, heavy alcohol use, obesity, and aflatoxin exposure.

4. Lung and bronchus cancer primarily caused by smoking, secondhand smoke, and environmental pollutants, affects the lungs and airways, making it the leading cause of cancer death in the US.

5. Acute myeloid leukaemia (AML) is an aggressive blood and bone marrow cancer that progresses rapidly, often linked to genetic mutations, radiation exposure, and certain chemicals.

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Even as Delhi’s H1N1 cases crossed 2,300, Director General of the Indian Council of Medical Research (ICMR) Dr. Rajiv Bahl today said there was “absolutely no cause for panic” and that seasonal influenza remains largely self-limiting.

Speaking to the media, Dr. Bahl said no new or unusual virus strain has been detected and that the rise in cases reflects expected seasonal changes.

The virus currently circulating in the country is the familiar H1N1 pdm09 strain that emerged during the 2009 pandemic and has since become a seasonal influenza virus.

The circulating Influenza A (H1N1) viruses have been identified as A/Missouri/11/2025 (H1N1) pdm09-like viruses. Hemagglutinin (HA) gene analysis places the isolates in clade 6B.1A.5a2a, subclade D.3.1.1.

Dr. Bahl said this lineage has been in continuous circulation in India since 2025. The genetic changes observed are consistent with the normal antigenic drift seen in seasonal influenza viruses.

Such minor genetic changes occur routinely as influenza viruses circulate and, by themselves, do not indicate the emergence of a new or dangerous strain.

No Urgent Need for Flu Vaccine

Dr. Bahl, who is also Secretary of the Department of Health Research (DHR), said there is no urgent need for everyone to take the flu vaccine.

He added that individuals above 65 and those who are immunocompromised may discuss vaccination with their doctors. He said that vaccination is currently only a recommendation from the WHO and is not part of the National Immunization Program.

Who Is at Higher Risk?

Seasonal influenza, including Influenza A (H1N1), is predominantly a mild and self-limiting respiratory illness in otherwise healthy individuals.

Common symptoms include:

• Fever
• Cough
• Sore throat
• Headache
• Body ache
• Fatigue and weakness

In most people, symptoms improve with supportive care, adequate rest and hydration. The presence of H1N1 does not, by itself, mean that a person will develop severe disease or require hospitalization.

However, certain groups have a higher risk of developing complications. These include:

• Elderly persons
• Young children
• Individuals with underlying medical conditions or co-morbidities
• People with compromised immunity

Dr. Bahl advised these individuals to exercise greater caution and seek timely medical advice if they develop influenza-like symptoms.

How to Prevent the Spread of Flu

Dr. Bahl advised the public to follow routine respiratory hygiene and infection-prevention measures.

Do's:

• Cover the mouth and nose while coughing or sneezing.
• Wash hands frequently with soap and water or use an appropriate hand sanitiser.
• Stay at home when unwell and avoid close contact with others.
• Maintain adequate hydration and get sufficient rest.
• Consume a healthy and balanced diet.
• Seek medical advice if symptoms are severe, persistent or worsening.
• Follow medical advice regarding testing or treatment.

Don’t:

• Do not panic because of the detection of H1N1.
• Do not take antivirals or antibiotics without medical advice.
• Avoid close contact with others while symptomatic.
• Avoid touching the eyes, nose and mouth with unwashed hands.

Stay Informed, Not Alarmed

The Ministry of Health said the public should remain “informed and vigilant, but not alarmed.”

Seasonal influenza is a familiar and routinely monitored respiratory infection. Following simple preventive measures, seeking timely medical consultation when required and avoiding unnecessary medication can help protect individuals and communities.

A massive analysis involving more than 100 million people has found strong links between recreational drug use and stroke, including among younger adults.

Stroke remains one of the world's biggest health problems and ranks as the third leading cause of death and disability combined.

The researchers found that cannabis use disorders were associated with stroke overall and were particularly linked to large artery stroke.

The study "provides compelling evidence that drugs like cocaine, amphetamines, and cannabis are causal risk factors for stroke. These findings give us stronger evidence to guide future research and public health strategies," said Dr. Megan Ritson from the Stroke Research Group at the University of Cambridge.

What Did the Study Find?

The team conducted a meta-analysis covering studies with more than 100 million participants. Their results, published in the International Journal of Stroke, showed substantial differences in stroke risk associated with several drugs.

Cocaine and amphetamine use were each linked to roughly twice the risk of stroke.

• Cocaine increased stroke risk by 96%.
• Amphetamine use was associated with a 122% increase.
• Cannabis use was associated with an increase of about 37%.
• Opioid use showed no statistically significant association with stroke risk.

Stroke Risk Was Especially High in Younger Users

The researchers separately examined people under age 55. Within this younger group, amphetamine use was associated with nearly three times the risk of stroke, an increase of 174%.

Cocaine use was associated with a 97% increase in stroke risk, while cannabis was linked to a smaller 14% increase.

Cocaine Linked to Brain Hemorrhage and Cardioembolic Stroke

Further genetic analysis revealed that cocaine use disorders were especially associated with brain hemorrhage and cardioembolic stroke.

In cardioembolic stroke, a blood clot forms in the heart and travels to the brain, blocking blood flow and causing damage to brain tissue.

According to the researchers, these genetic findings support the possibility of a causal relationship rather than an association alone.

Problematic alcohol use was also associated with an increased risk of cardioembolic stroke and large artery stroke. Alcohol addiction, meanwhile, was linked to a greater overall risk of stroke.

How Could Recreational Drugs Increase Stroke Risk?

The researchers noted several biological mechanisms that could help explain why these substances are associated with stroke. These include:

• Sudden increases in blood pressure
• Spasms and narrowing of blood vessels
• Abnormal heart rhythms
• Greater blood clotting, especially with cannabis
• Inflammation or vasculitis, particularly with amphetamines

All of these processes are already known to contribute to stroke. They can play a role in ischemic strokes, which occur when blood clots interrupt blood flow, as well as hemorrhagic strokes.

"Our analysis suggests that it is these drugs themselves that increase the risk of stroke, not just other lifestyle factors among users. Taken together, our findings emphasize the importance of public health measures to reduce substance abuse as a way of helping also reduce stroke risk," said Dr. Eric Harshfield, Alzheimer's Society Research Fellow at the Department of Clinical Neurosciences.

We often believe that depression may just result in changes in mood and behaviour. But a new study has found that major depressive disorder could disrupt production of new brain cells in the hippocampus, a region involved in memory and processing of emotions.

The study, published in Nature Medicine, analysed almost 500,000 individual brain cells from people with depression and people without the mental health condition. Researchers found changes not only in the formation of new neurons but also across the wider hippocampal circuit.

Depression May Disturb Brain’s Ability To Produce New Neurons

In the human brain, most neurons are produced before birth, but the hippocampus is one of the few regions where new neurons continue to develop even during adulthood. The researchers found that this process, known as adult hippocampal neurogenesis, stops in people with major depressive disorder.

Depression is viewed largely as a problem involving neurotransmitters such as serotonin. The new findings suggest a much more complex picture involving the brain's ability to adapt to stress and changing environments.

Maura Dupont, professor of psychiatry at Columbia University and the study's lead researcher, said, “Without the ability to create new neurons, people with depression may not have the resilience to effectively adapt to the environment."

Also read: Sugar Rationing In First 1,000 Days Linked To Lower Depression, Cancer Risk In Adulthood

The Hippocampus Links Memory With Emotional Responses

The hippocampus plays an important role in episodic memory, helping people distinguish between different experiences and connect memories with their emotional context.

Researchers say impaired neurogenesis may affect a process called pattern separation, which helps the brain keep similar experiences distinct. For instance, a friend being quiet in your company does not necessarily mean they are upset with you.

When the brain has a healthy pattern-separation system, it recognises that as an individual event rather than automatically misconstruing it and linking it to previous experiences of rejection.

Dupont said that when this ability is impaired, memories and their emotional associations can become blurred, potentially building the tendency to interpret new experiences negatively.

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Other Changes In Brain Changes That Extend Beyond Neuron Formation

The researchers found molecular changes across the hippocampal circuit, including genes involved in forming connections between neurons, communication between brain cells, energy production and movement of material inside cells.

The hippocampus's circuit also showed signs of inflammation and cellular stress in people with depression. This indicates that depression may involve widespread changes in how brain cells communicate and function.

What The Findings Could Mean For Depression Treatment?

The researchers say the findings could eventually help recognise different physiological effects of depression, helping develop specific treatments according to patients with different molecular structures.

Dupont said the team hopes depression could eventually be classified according to its molecular characteristics, similar to how some cancers are classified. However, the findings do not mean that depression can currently be treated by simply increasing the production of new neurons. The complete mechanism of the mental health condition is still not completely understood.