Childhood Cancer Warning Signs Parents Should Know

Possible childhood cancer warning signs are worth knowing, but the first fact matters most: childhood cancer is rare. The National Cancer Institute estimated 14,910 cancer diagnoses among U.S. children and teens ages 0 to 19 in 2024. Nearly every lump, bruise, and headache a parent will ever see has an ordinary cause. This page explains the small set of lasting signs that doctors take seriously. The goal is to know what deserves a visit, not to add worry.

There is no routine screening test for most childhood cancers. MedlinePlus notes childhood cancers may happen suddenly, without early symptoms. So diagnosis usually starts when a parent or doctor notices something that does not go away or does not fit.

Two facts sit together here. Cancer is the leading cause of death by disease after infancy among U.S. children. Yet outcomes have improved greatly. NCI reports the childhood cancer death rate fell by more than 50 percent from 1975 to 2022. Roughly 83 to 88 percent of children diagnosed in 2013 to 2019 lived at least 5 years, depending on age at diagnosis. Noticing persistent changes early gets a child to answers, whatever those answers turn out to be.

The pattern to watch is not any single symptom. It is persistence without a clear cause.

Leukemia, a cancer of the blood-forming cells, is the most common childhood cancer. For childhood acute lymphoblastic leukemia, NCI lists signs that include:

• Fever.
• Easy bruising or bleeding.
• Flat, pinpoint, dark-red spots under the skin caused by bleeding. These are called petechiae.
• Weakness, fatigue, or pale skin.
• Bone or joint pain.
• Painless lumps in the neck, underarm, stomach, or groin. These are swollen lymph nodes.
• Pain or a feeling of fullness below the ribs.
• Loss of appetite and weight loss.
• Frequent infections, or infections that do not go away.

NCI adds the sentence that belongs beside every list on this page: these symptoms may be caused by problems other than ALL. The only way to know is for your child to see a doctor.

Brain and spinal cord tumors are the second most common group of childhood cancers. For medulloblastoma and related tumors, NCI lists:

• A headache, especially in the morning. Also a headache that goes away after vomiting.
• Nausea and vomiting.
• Loss of balance, trouble walking, lack of coordination, or slow speech.
• Double vision or other eye problems.
• Weakness on one side of the face, or general weakness.
• Unusual sleepiness or a change in energy level.
• Seizures.

In infants and young children, the signs can be quieter. NCI lists irritability, slow growth, poor appetite, and delays in development. Again, NCI is direct that something other than a tumor is usually the cause. A pattern that repeats is what should prompt a visit. Morning headache with vomiting is the classic example.

Retinoblastoma is a cancer of the eye that occurs most often in children younger than 2 years. NCI lists these signs:

• A pupil that appears white instead of red when light shines into it. This may show up in flash photographs.
• Eyes that appear to look in different directions, called crossed eyes.
• Pain or redness in the eye, or infection around it.
• An eyeball larger than normal, or a cloudy look to the colored part of the eye.

A white glow in photos is easy to dismiss as a camera quirk. It deserves a prompt eye exam.

Wilms tumor is a childhood kidney cancer. About 650 children are diagnosed with it each year, most between ages 2 and 5. NCI's list of possible signs includes a lump, swelling, or pain in the abdomen. It also lists blood in the urine, high blood pressure, fever for no known reason, loss of appetite, and unexplained weight loss. As with every list here, other problems are far more often the cause.

Most of the changes above can wait for a regular appointment. A few should move faster.

• Make an appointment promptly, within days, if your child has a pupil that glows white in photos, or an eye that has newly turned. Do the same for a painless lump that is not going away. New bruising or petechiae without an injury count too. So do bone pain that persists and repeated morning headaches, especially with vomiting. Each of these is on an NCI list of signs a doctor should check.
• Call the doctor's office now, or seek urgent care, if a fever has no known cause and is not going away. Do the same if your child is unusually pale, weak, or hard to wake, or if a swollen belly hurts.
• Use emergency care for trouble breathing, a first seizure, or a child who cannot be woken. These need immediate care whatever the cause.

If the visit leaves your question unanswered and the sign persists, go back. Saying "this is still here and it is not explained" is exactly how these diagnoses get made, and far more often it is how parents get reassurance.

The pediatrician starts with an exam and simple tests. NCI's guidance repeats the same line across cancer types: the only way to know is for your child to see a doctor. If cancer is ever found, children are usually referred to specialized children's cancer centers. NCI notes these centers have teams of pediatric oncologists, surgical specialists, nurses, social workers, and psychologists. Many belong to the NCI-supported Children's Oncology Group.

• Cancer in Children and Adolescents — National Cancer Institute
• Childhood Cancers — National Cancer Institute
• Childhood Acute Lymphoblastic Leukemia Treatment (PDQ) — National Cancer Institute
• Childhood Medulloblastoma and Other CNS Embryonal Tumors Treatment (PDQ) — National Cancer Institute
• Retinoblastoma Treatment (PDQ) — National Cancer Institute
• Wilms Tumor and Other Childhood Kidney Tumors Treatment (PDQ) — National Cancer Institute
• Cancer in Children — MedlinePlus