Early onset cancer refers to cancers diagnosed in adults younger than 50 years old, which is younger than typically noted for most cancers.

In the United States and other developed nations, the incidence of early onset cancer has increased in recent years. The most common early onset cancers include breast, colorectal, and thyroid cancers, but early onset cancer can be seen across a spectrum of cancers such as pancreatic, ovarian, lung, and brain cancers, sarcomas, and blood cancers.

With timely diagnosis and appropriate treatment, people who are diagnosed with early onset cancer often achieve good outcomes. In addition to comprehensive cancer care, support from family and friends can help people navigate early onset cancer and its treatment.

Early onset cancer is cancer that is diagnosed in adults under age 50. While cancer is often thought of as a disease of older adults, some cancers are increasingly being diagnosed in younger adults.

Normally, the body’s cells grow, divide, and die in a controlled manner. Cancer occurs when cells begin to grow and divide uncontrollably, forming a mass or tumor or affecting the blood or immune system. In early onset cancer, this process starts at a younger age than is typical.

Early onset cancer is being diagnosed more often, especially in adults in their 40s. In the United States, national cancer registries show a small overall rise in cancers diagnosed before age 50 from 2010 to 2019. Most early onset cases occur between ages 40 and 49, followed by cases in people between ages 30 and 39. Women accounted for nearly two-thirds (about 63%) of early onset cancer cases in the U.S. between 2010 and 2019. Similar trends have been observed globally, with early onset cancer rates rising in many countries, especially in high-income regions.

However, while the number of cancer cases has increased in young adults, the death rates for most early onset cancers have not risen at the same pace. For many cancer types, mortality rates have remained stable or even decreased, likely due to better detection and treatment.

The most common early onset cancers include:

• Breast cancer: This is the most frequently diagnosed early onset cancer, especially in women (though it can also occur in men).
• Colorectal cancer: Cancer that begins in the colon or rectum, which are parts of the large intestine.
• Thyroid cancer: Often found in younger women, this cancer affects the thyroid gland in the neck.
• Melanoma: This form of skin cancer starts in the pigment-producing cells and is more common in younger adults than other types of skin cancer.
• Kidney cancer: Cancer that starts in one or both kidneys.
• Uterine cancer: Cancer of the uterus is rising in women under age 50.
• Pancreatic cancer: Less common than other cancers, this type of cancer starts in the pancreas, which helps digestion and regulates blood sugar levels.
• Stomach cancer: Cancer of the stomach lining has increased in younger women.
• Testicular cancer: This is the most common cancer in young men, especially those aged 18–39.
• Cervical cancer: This cancer starts in the cervix, the lower part of the uterus.
• Some blood cancers: These include cancers such as leukemias.

Among these, colorectal cancer has the fastest-growing incidence rates in younger adults. Cancers of the urinary tract and female reproductive system are also increasing, while rates of lung and prostate cancer in younger adults have decreased, though it is still possible for individuals to be diagnosed with these cancers at young ages.

Rates of different types of cancer differ between males and females. Among females, breast cancer, thyroid cancer, and melanoma are most common, while the most common early onset cancers among males are colorectal, testicular, and melanoma.

The exact causes of early onset cancer are not fully understood and may differ by type of cancer. However, researchers have several theories for why rates of some types of early onset cancer may be rising:

• Early-life exposures: Some scientists believe that exposures to certain risk factors in childhood, adolescence, or young adulthood may play a role. These could include infections, environmental factors, or other exposures.
• Lifestyle changes: Changes in diet, physical activity, and body weight over recent decades may contribute to the risk of early onset cancer. For example, more people are eating processed foods, exercising less, and generally being less physically active.
• Obesity: Obesity has been linked with risk for specific cancers, with some evidence of association to early onset cancer.
• Microbiome: The community of bacteria and other organisms in the gut (the microbiome) may influence cancer risk, especially for digestive system cancers.
• Genetic factors: Some people may inherit changes in certain genes that increase their risk of cancer at a younger age.

Overall, early onset cancer likely results from a combination of genetic, lifestyle, and environmental factors, but more research is needed to understand the exact causes.

Risk factors for early onset cancer may be similar to risk factors for cancer overall:

Family history and genetics:

• Family history of certain cancers (such as breast, colorectal, or prostate cancer)
• Inherited gene changes (such as BRCA1, BRCA2, or Lynch syndrome)

Infections:

• Infection with certain viruses or bacteria (such as human papillomavirus (HPV) for cervical cancer, or Helicobacter pylori for stomach cancer)
• Chronic hepatitis B or C infection (for liver cancer)

Lifestyle and behavioral factors:

• Diet high in red or processed meat
• Diet low in fruits, vegetables, whole grains, milk, or calcium
• Alcohol use
• Tobacco use (smoking or other forms)
• Physical inactivity or sedentary lifestyle
• Obesity or high body mass index (BMI)
• UV light exposure (tanning)

It is important to note that many people with these risk factors will not develop cancer, and some people with early onset cancer have no known risk factors.

Early detection of cancer often means more treatment options and better outcomes. However, given that routine screening for most cancers starts at older ages, average-risk younger adults may not be offered regular screening. Early onset cancers are often detected when a person seeks medical care for symptoms, such as unexplained pain, lumps, bleeding, or changes in bowel habits.

Early onset cancers can be detected and diagnosed in several ways:

• Screening tests:
• Colorectal cancer screening: Recommended to start at age 45 for average-risk adults. Tests include colonoscopy (a procedure to look inside the colon and rectum), stool-based tests (to check for blood or abnormal DNA), and flexible sigmoidoscopy (to look at the lower part of the colon). This screening can begin at younger ages if there is a close relative with colon cancer diagnosed under age 50. Therefore, knowing family history can be important to inform when to start screening.
• Cervical cancer screening: Recommended for women starting at age 21. Tests to screen for cervical cancer include Pap tests (to look for abnormal cells in the cervix) and, in some cases, HPV testing.
• Breast cancer screening: In some settings, women may be offered mammograms (breast X-rays) starting at age 40. This screening can begin at younger ages if there is a close relative with breast cancer diagnosed under age 50. Therefore, knowing family history can be important to inform when to start screening.

• Risk-based or enhanced screening:
• People with certain symptoms, a strong family history of cancer, or known hereditary syndromes (such as BRCA gene changes or Lynch syndrome) may be offered earlier or more frequent screening. This can include earlier mammograms, colonoscopies, PSA (prostate-specific antigen) screening for prostate cancer, or other tests based on their risk.
• Imaging tests:
• Computed tomography (CT) scans, magnetic resonance imaging (MRI), and ultrasound may be used to help diagnose cancer after symptoms appear or in those at high risk. Occasionally, cancer may be detected on imaging tests ordered for another condition.

Because current guidelines do not recommend screening for all types of early onset cancer for average-risk people under 50, it is important to pay attention to new or unusual symptoms and talk to a health care provider if you have a family history of cancer or if you have concerns about your risk of cancer.

Treatment for early onset cancer depends on the type or sub-type of cancer and the stage at which it is diagnosed. Treatment may involve surgery, chemotherapy, radiation, immunotherapy, hormone therapy or other regimens aimed at removing or eliminating the cancer cells while minimizing damage to healthy tissue. Treatment is tailored to the person and the type of cancer and can involve several different approaches to improve outcomes. Ongoing follow-up and monitoring are usually necessary even after treatment is concluded.

In addition to comprehensive medical care to treat the disease, people with early onset cancer also benefit from emotional and other types of support to help them navigate diagnosis and treatment and the range of ways cancer has impact on their life.

Cancer treatments can affect fertility and sexual health, which are important parts of young adult life planning. People with early onset cancer should receive information about fertility preservation options as early in the course of their care as possible. Open conversations with health care providers about fertility and family planning, as well as sexual health, are important not only for physical recovery but also for psychological well-being before, during, and after treatment.

People with early onset cancer can benefit from psychosocial support such as:

• Emotional support for anxiety, depression, or stress
• Help with addressing work or school-related challenges
• Support for family, children, and caregivers
• Guidance on financial or insurance concerns

People who have experienced early onset cancer will need regular follow-up visits to monitor for cancer recurrence or late effects of treatment. Ongoing health care should include support for healthy lifestyle changes, such as exercise and nutrition, and access to mental health services and counseling.

Experiencing cancer at a young age—while launching a career, building relationships, or starting a family—can be extremely disruptive. From receiving an unexpected diagnosis to undergoing sometimes difficult treatment regimens to dealing with the lingering physical, emotional, and logistical effects of treatment, people with early onset cancer can face unique physical and emotional challenges that can continue for years and even decades. Family and friends as well as support groups can play an important role in navigating early onset cancer and its aftermath.

For example, during and after treatment, people with early onset cancer may experience:

• Fatigue or low energy
• Changes in fertility
• Concerns about ability to have children or care for children
• Changes in sexual health or body image
• Memory or concentration problems
• Depression and anxiety
• After treatment ends, fear of cancer recurrence
• Ongoing pain or nerve problems
• Risk of other health problems, such as heart or bone issues, as side effects of treatment

The outlook for people with early onset cancer depends on several factors, including the type of cancer, how advanced it is at diagnosis, and the treatments available.

Survival rates for early onset cancers can vary by cancer type. Timely diagnosis, effective treatment, advances in clinical research, and supportive care all play a role in improving outcomes.

While early onset cancer can be life-changing, many people go on to live full and meaningful lives after treatment. Ongoing research and advances in care continue to improve the outlook for people diagnosed with cancer at a younger age.

“Yale Cancer Center and Smilow Cancer Hospital offer a comprehensive program dedicated to early onset cancer,” says Yale Medicine medical oncologist Veda Giri, MD, co-director of the Early Onset Cancer Program at Yale Cancer Center and Smilow Cancer Hospital. “The Early Onset Cancer Program at Yale addresses the clinical, research, psychosocial, and educational needs of patients with early onset cancer and their families in conjunction with their clinical teams. We have launched the Early Onset CONNECT initiative that provides assessment and navigation for patients newly diagnosed with an early onset cancer for personalized support throughout their cancer journey. We have multiple research studies which aim to uncover barriers to care for patients with early onset cancer, increase engagement in clinical trials, and understand factors associated with aggressive early onset cancers. Our Early Onset Cancer Program at Yale is a regional and national resource and our goal is to reduce the burden of early onset cancer through a patient-centered approach.”

“A cancer diagnosis and the complexity of treatment can be so overwhelming,” says Nancy Borstelmann, PhD, MPH, LCSW, co-director of the Early Onset Cancer Program. “Our goal is to ‘meet patients where they are,’ meaning that we dedicate time to learn about their specific needs and concerns as younger cancer patients early on, and hope to empower them with information and support that is tailored to their current priorities. Working closely with the oncology care team of physicians, nurses, social workers, and many others, we help ease the burden wherever we can.”