Cancer has always been thought of as something that happens later in life, but that perception is rapidly changing. Millennials and Gen Z are facing a worrying trend, cancers that were once seen mostly in people over 50 are now appearing in people in their 20s, 30s, and early 40s. The most common cancers among young adults today include colorectal, breast, thyroid, skin, and cervical cancers. Sadly, early warning signs often get ignored because cancer isn’t “supposed” to affect young people.We at TOI spoke to Dr. Rakesh Kumar Agarwal, Senior Consultant & Head of Radiation Oncology, Andromeda Cancer Hospital, Sonepat and Dr.(Brig) Anil Kumar Dhar – Director and Head Medical Oncology, Marengo Asia Hospitals, Gurugram on why colon cancer cases are increasing among youngsters and what risk factors are triggering this surge. The experts point out that today’s lifestyle plays a huge role: processed foods, sugary drinks, sedentary habits, stress, poor sleep, and even vaping are all quietly raising cancer risk from a young age.We’ve always associated cancer with older age—why are we now seeing such a rise among Millennials and Gen Z?Dr. Rakesh Kumar Agarwal: Cancer incidence rates have risen nearly 80% around the world in people under 50 years of age since 1990. Millennials and Gen Z have been raised in an environment much different from those before them, where children are exposed to processed foods and plastics, pollution, and sedentary activities from a very young age. Because these kids have encountered risk factors so much earlier, adult onset of cancer is happening much earlier. In general, events that ordinarily took years to build up and become an illness are now taking place much sooner, and therefore, cancers are being diagnosed in younger people.Dr.(Brig) Anil Kumar Dhar: In the past, cancer was mainly thought of as an aging disease, because mutations build up over time. Now, Millennials and Gen Z are exposed to a multitude of risk factors at a younger age, such as poor diet, inactivity, pollution, stress, and sleep disturbances, all leading to earlier cellular damage. In addition, improved screening results in earlier detection of cancers. Therefore, due to all of these factors, cancers that typically present in the 50s and 60s are now happening in those in their 20s, 30s and early 40s.Which cancers are most common among younger adults today, and why might they be hitting these age groups earlier?According to Dr. Rakesh Kumar Agarwal, breast cancer is the most common cancer among young adults, especially women. Colorectal cancer is also on the rise, with one in five cases now occurring in people under 55. Thyroid cancer is becoming particularly common in the 20-39 age group. Other cancers that are popping up more often include those of the pancreas, kidney, stomach, gallbladder, and even testicular cancer. A lot of this has to do with lifestyle—poor diets, lack of exercise, and exposure to harmful chemicals are hitting the body earlier than ever, causing cancers to show up in younger people.Dr. (Brig) Anil Kumar Dhar points out that colon, breast, cervix, thyroid, and skin cancers are now the most prevalent among young adults. Colorectal cancer, which used to be rare under 50, is climbing rapidly, mainly due to low fiber intake, unhealthy eating, obesity, and sedentary habits. Hormonal changes and lifestyle choices play a role too, and delayed screenings mean some cancers get detected late.Both doctors agree that while better awareness and screenings are helping catch cancers earlier, lifestyle factors remain the biggest drivers. Basically, what we eat, how much we move, and the habits we pick up in our 20s and 30s are having a huge impact on our cancer risk—so paying attention now can make a big difference down the line.Are modern lifestyle habits like fast food, vaping, and sitting for hours online really fueling this increase?Both Dr. Rakesh Kumar Agarwal and Dr. (Brig) Anil Kumar Dhar agree that lifestyle choices are a huge factor when it comes to cancer risk in young adults. Eating lots of processed foods and sugary drinks, being overweight, and sitting for long hours all create chronic inflammation in the body, which can damage cells and raise the chance of developing cancer earlier in life.Vaping and smoking make matters worse by introducing harmful chemicals that can directly damage DNA, increasing the risk of several types of cancer. Spending hours online or on screens often means less physical activity, poor sleep, and disrupted body rhythms, which weaken the immune system even more.Add stress, irregular sleep, and generally unhealthy habits into the mix, and you’ve got the “perfect storm” for cancer to develop at a younger age. Basically, the lifestyle choices we make today especially in our 20s and 30s can have a huge impact on long-term health, and small changes now can make a big difference down the road.How do symptoms in young adults often get overlooked or misdiagnosed and what red flags should they never ignore?Dr. Rakesh Kumar Agarwal: Cancer is still thought of as being an illness of older age groups, so both patients and doctors may overlook early signs of this disease in young adults. Symptoms such as chronic digestion issues, unexplained weight loss, a general feeling of malaise, or abnormal bleeding will often be attributed to stress or some other minor illness. This results in many people being diagnosed with cancer later in the disease process when it is often more serious. Young adults should never ignore symptoms lasting longer than 2-3 weeks, regardless of their severity.Dr.(Brig) Anil Kumar Dhar: In young adults, presentations often get overlooked as insignificant or young for cancer, allowing for late diagnoses. Any persistent change such as unexplained weight loss, unexplained fatigue, unexplained rectal bleeding, new lumps, persistent coughing, and stool habit changes should never be taken lightly. If the symptoms persist for longer than 2 weeks, or simply feel unusual for your body, get an evaluation as soon as possible; because when it comes to cancer, the earlier you know the better your outcome, even in significantly aggressive cancers that affect younger people too.If you could give one piece of advice to young adults worried about cancer, what would it be?Both experts emphasize that the key to staying ahead of cancer is prevention and early detection. Around 40% of cancers can actually be prevented by making simple lifestyle changes—think eating more whole foods, exercising regularly, cutting down on alcohol, and avoiding tobacco. Small adjustments like these can make a huge difference over time.Equally important is listening to your body. If something feels off for more than a couple of weeks, unexplained fatigue, unusual lumps, or other persistent changes, don’t brush it aside. Getting checked early can dramatically improve survival rates, sometimes from as low as 14% to as high as 90%.Dr. Dhar adds that young adults, even in their 20s and 30s, should take charge of their health proactively. Schedule preventive screenings, maintain a balanced diet, stay active, and avoid harmful habits like smoking or vaping. Catching cancer early makes it far more treatable, and simple, consistent care now can protect you for years to come.