Pediatric Solid Tumors: How Are They Different from Adult Cancers - Types and Features at a Glance

When parents hear that their child has been diagnosed with cancer, their mind goes blank. Yet as they listen to the doctor's explanation, the word "solid tumor" comes up often. You may wonder what on earth that means, but there is really nothing to overthink. Setting aside cancers like leukemia that arise in the body's blood or lymphatic system, any cancer that grows by forming a mass (tumor) somewhere is collectively called a solid tumor. Whether it forms in the kidney or in the brain, they share the common trait of being palpable or showing up as a mass on imaging.

It is easy to confuse them with adult cancers, but pediatric solid tumors are quite different in nature. In adults, cancer tends to arise from the epithelial cells of organs we commonly hear about, like the stomach, lung, and colon. In children, on the other hand, because the body is still very much in the middle of growing, cancer often starts from immature cells that have not finished developing. That is why the names are unfamiliar and why looking up information on adult cancers does not fit well. One reassuring point is that, depending on the type, childhood cancers tend to respond well to treatment, and cure rates have risen considerably compared with the past.

Looking at the types in a little more detail, it goes like this. Brain tumors are among the most common of the pediatric solid tumors, and since they form inside the head, the symptoms vary by location. Neuroblastoma arises in the sympathetic nervous system, is often found mostly inside the abdomen near the adrenal gland, and is commonly seen in very young infants and toddlers. Wilms tumor, which forms in the kidney, is often discovered by chance when the belly becomes distended, while osteosarcoma and Ewing sarcoma, which form in the bone, may begin with knee or arm pain in adolescence when children are growing fast. Besides these, there are rhabdomyosarcoma, which arises from muscle and soft tissue; retinoblastoma, which forms in the retina of the eye and makes the pupil appear white in photographs; hepatoblastoma; germ cell tumors; and others.

Because the symptoms are so varied, it is not easy for parents to notice them in advance. There are signals such as a belly that keeps swelling, limping on one leg, a child who is suddenly vomiting and complaining of headaches when they usually do not, and bruising strangely easily, but these overlap with common minor ailments and are easy to let slide. So if a symptom you put off thinking "it's probably nothing" fails to improve beyond two to three weeks or gradually worsens, that is when it is better to ask the hospital to take a proper look. There is no need to be too frightened, but the point is to check.

Diagnosis usually confirms the mass by imaging such as ultrasound, CT, or MRI, and a biopsy makes the final determination of which cells the cancer came from. Depending on the type and the degree of progression (stage), the tumor is removed by surgery, or chemotherapy and radiation therapy are used alone or in combination. These days, since each child's cancer has different characteristics, treatment has advanced considerably toward devising a strategy tailored to it. The treatment process is long and wears parents down alongside the child, but it is worth keeping in mind that pediatric solid tumors often respond to treatment better than adult cancers.

This piece is put together to help you understand pediatric solid tumors in broad strokes, so it is not enough to use as a standard for judging your own child's condition. If you have worrying symptoms, please consult a pediatrician or a pediatric hematology-oncology specialist directly.