The biological “red flags” and early physical symptoms of pediatric cancer have not changed in 2026. Because childhood cancers are typically the result of DNA changes that occur early in life rather than lifestyle or environmental factors, the way these diseases manifest in the body remains consistent with previous years.

However, how we identify these signs is evolving. In 2025 and 2026, there has been a significant shift toward earlier detection through “precision surveillance” and new diagnostic tools.

Consistent Early Warning Signs

The “classic” symptoms that parents and doctors look for remain the primary indicators:

• Unexplained Lumps or Swelling: Persistent, painless lumps in the neck, abdomen, or limbs.

• Vision Changes: A white “glow” in the pupil (leukocoria), a new squint, or sudden vision loss.

• Persistent Pain: Bone or joint pain that often worsens at night or causes a limp.

• Energy and Color: Unusual paleness (anemia) and extreme fatigue that doesn’t improve with rest.

• Unexplained Fevers: Recurrent or persistent fevers not linked to a typical viral infection.

• Easy Bruising: Unexplained bruising or small purple/red spots (petechiae) on the skin.

What is Different in 2026?

While the symptoms are the same, the medical approach to them has become more proactive:

• Genomic Surveillance: For children with known genetic predispositions (identified through family history or newer screening panels), doctors now use “pre-symptom” monitoring. This involves regular whole-body MRIs and blood tests to catch tumors before physical signs even appear.

• Updated Referral Guidelines: Major health organizations (such as the UK’s CCLG “Child Cancer Smart” campaign) have updated their 2025–2026 protocols. These provide GPs with “decision-support tools” to faster distinguish common childhood ailments from “red flag” cancer symptoms, specifically for bone and kidney cancers.

• AI-Enhanced Imaging: New AI tools are being integrated into radiology in 2026 to help identify subtle patterns in scans that might have been missed in the past, allowing for diagnosis at a much earlier stage.

• Blood-Based “Liquid Biopsies”: While still primarily used in clinical settings, there is an increase in the use of liquid biopsies to monitor for cancer markers in the blood, which can sometimes signal a problem before a physical mass is palpable.

The role of blood tests varies depending on the type of cancer:

1. Blood Cancers (Leukemia and Lymphoma)

For cancers that originate in the blood or bone marrow, blood tests like a Complete Blood Count (CBC) or a blood smear are often the first step. They can show abnormal levels of white blood cells, red blood cells, or platelets. However, even in these cases, a bone marrow biopsy is usually required to confirm the diagnosis and determine the specific subtype.

2. Solid Tumors (Brain, Bone, and Organ Tumors)

For solid tumors like brain cancer (the second most common childhood cancer), neuroblastoma, or Wilms tumor (kidney cancer), blood tests are often less effective for initial detection.

• Brain Tumors: These rarely release markers into the bloodstream that a standard blood test can find. Doctors rely on MRI or CT scans for detection.

• Tumor Markers: Some solid tumors release specific proteins or hormones (biomarkers) into the blood, but these are not present for all cancers and are sometimes elevated by non-cancerous conditions.

3. The “Normal Blood Work” Challenge

It is possible for a child to have cancer even if their blood work appears completely normal. In the early stages of many cancers, the disease may not yet have affected the blood cell counts or chemical balance enough to be detected by standard laboratory equipment.

4. The Future: Liquid Biopsies

Research is currently focused on liquid biopsies, which look for “circulating tumor DNA” ($ctDNA$)—tiny fragments of genetic material shed by tumors into the blood. While this technology is promising and could eventually allow for the detection of many more cancers via a simple blood draw, it is currently used mostly in research or for monitoring treatment rather than as a universal screening tool.

Summary of Diagnostic Tools

Since blood tests alone aren’t enough, doctors use a combination of methods:

• Imaging: X-rays, Ultrasounds, CT scans, and MRIs.

• Biopsies: Taking a physical sample of the tissue or bone marrow.

• Physical Exams: Checking for lumps, swelling, or neurological changes.

No, a persistent fever is not always a sign of cancer. In fact, it is much more commonly caused by other conditions.

In children, fevers are usually the body’s healthy way of fighting off an “intruder.” While a fever that won’t go away is something doctors take seriously, they look at it as one piece of a much larger puzzle.

1. Common Causes of Persistent Fever

Most fevers that last more than a few days are due to:

• Viral Infections: Viruses like Mononucleosis (Mono) or CMV can cause fevers that last for two weeks or more.

• Bacterial Infections: Hidden infections like a urinary tract infection (UTI), sinus infection, or even a bone infection (osteomyelitis) can cause a lingering fever.

• Autoimmune/Inflammatory Issues: Conditions like Juvenile Idiopathic Arthritis or Kawasaki Disease cause the immune system to overreact, leading to prolonged high temperatures.

• Periodic Fever Syndromes: Some children have rare genetic conditions that cause recurring fevers with no clear infection.

2. When Doctors Become Concerned

A fever is rarely the only symptom of childhood cancer. Doctors usually look for “red flags” that occur alongside the fever:

• Unexplained Weight Loss: Not just a lack of appetite, but noticeable weight loss.

• Night Sweats: Fevers that break at night, leaving the child’s pajamas or bedding drenched in sweat.

• Easy Bruising or Bleeding: Small red spots on the skin (petechiae) or bruises in unusual places (like the back or chest).

• Bone or Joint Pain: Pain that is deep, persistent, and often wakes the child up at night.

• Lumps or Swelling: Firm, painless lumps in the neck, armpit, or groin that don’t go away.

3. Defining “Persistent”

Medical professionals usually categorize fevers into two types:

• Prolonged Fever: Lasts more than 8 days.

• Fever of Unknown Origin (FUO): Lasts more than 3 weeks without a clear cause after initial tests.

Even in cases of FUO, cancer is statistically the least common cause. The majority of these cases turn out to be unusual presentations of common infections.

Summary: A fever alone is rarely enough to diagnose cancer. If a fever lasts more than a few days, or if your child seems unusually pale, tired, or has new aches and pains, a pediatrician can run simple tests (like a CBC) to help rule out serious issues.

A white glow in the eye—medically known as leukocoria—is a clinical sign where the pupil (the black center of the eye) reflects a white, yellow, or pale color instead of the typical “red-eye” seen in flash photography.

While it can be alarming, it is not always a sign of something dangerous. Here is a breakdown of what it can mean and what you should look for.

1. Common and Harmless Causes

The most frequent reason for a white glow, especially in photos, is actually harmless:

• The Optic Nerve Reflection: If a child (or adult) looks at the camera at a specific angle (usually about 15 degrees), the flash can bounce directly off the optic nerve, which is naturally white. This often appears in only one photo or from one specific angle.

• Camera Artifacts: Digital cameras and smartphones sometimes process light in a way that creates a “white eye” effect, especially if red-eye reduction is turned off.

2. Medical Conditions (Non-Cancerous)

If the glow is persistent or appears in multiple photos, it may indicate a treatable eye condition:

• Cataracts: A clouding of the lens. This is the most common medical cause of a white reflex in children.

• Coats’ Disease: A rare condition where the blood vessels in the retina develop abnormally and leak fluid, causing a yellowish-white reflection.

• Retinal Detachment: If the retina pulls away from the back of the eye, it can reflect light differently.

• Infections: Certain infections, such as those caused by parasites (like Toxocariasis), can cause inflammation that appears as a white glow.

3. Retinoblastoma (Childhood Eye Cancer)

In young children (usually under age 6), a persistent white glow is the most common early sign of retinoblastoma, a rare form of eye cancer.

• Why it glows: The tumor itself is a white mass growing on the retina at the back of the eye. When light hits it, it reflects back through the pupil like a “cat’s eye” caught in headlights.

• Urgency: Retinoblastoma is highly curable if caught early, which is why doctors take a “white glow” very seriously.

When to See a Doctor

You should have a child’s eyes checked by a professional (pediatrician or optometrist) if you notice any of the following:

• The white glow is present in multiple photos.

• The glow is visible to the naked eye in low-light settings (like a dim room).

• One eye looks white while the other has the normal red-eye reflection in a photo.

• The child has a “squint” (one eye turns in or out) or the eyes don’t seem to look in the same direction.

Simple Home Check: If you saw the glow in a photo, look through your older photos of the child. If you see the same white reflection in only one eye across several different pictures, it is important to schedule an eye exam as soon as possible.

In the context of childhood health, night pain is considered a “red flag” because it behaves differently than the typical aches and pains of childhood.

While most childhood pain (like growing pains or minor injuries) occurs during or after activity and gets better with rest, certain types of pain that wake a child from a deep sleep or worsen when the body is still can indicate an underlying medical issue that requires investigation.

1. Night Pain vs. “Growing Pains”

It is very common for parents to mistake persistent night pain for “growing pains.” However, there are distinct differences:

2. Why is it a “Red Flag” for Cancer?

In rare cases, night pain can be a symptom of bone cancers (like Osteosarcoma or Ewing Sarcoma) or blood cancers (like Leukemia).

• Bone Tumors: As a tumor grows, it stretches the “periosteum” (the sensitive outer lining of the bone), which can cause a deep, throbbing ache. This pain often feels worse at night when there are fewer distractions and the body is still.

• Leukemia: This cancer starts in the bone marrow. As the marrow becomes crowded with abnormal cells, it can create pressure inside the bones, leading to a “toothache-like” pain in the limbs that may keep a child awake.

3. Other Causes of Night Pain

Cancer is statistically rare. Night pain is more frequently caused by:

• Infections: Bone infections (osteomyelitis) can cause deep, persistent pain and fever.

• Inflammatory Conditions: Juvenile Arthritis can cause joints to stiffen and ache, especially after being still for a long time (like during sleep).

• Benign Tumors: Some non-cancerous bone growths, like an Osteoid Osteoma, are famous for causing pain that occurs specifically at night and is relieved almost instantly by ibuprofen.

4. When to See a Doctor

One night of leg cramps is usually nothing to worry about. However, you should consult a pediatrician if the night pain:

1. Wakes the child up repeatedly or makes it hard for them to fall asleep.

2. Is accompanied by swelling, redness, or a visible lump.

3. Is localized to one specific bone rather than a general muscle ache.

4. Occurs alongside other symptoms like unexplained fever, weight loss, or limping.