Study examines tumor diagnosis in children

      (U-WIRE) DURHAM, N.C. -- Sometimes, a late diagnosis of childhood brain cancer may not be the fault of inadequate detection mechanisms.

      Earlier this month at the annual meeting of the American Society for Therapeutic Radiology and Oncology, Duke University Comprehensive Cancer Center researchers presented this and other intriguing and counter-intuitive results of a study they conducted this year.

      The scientists analyzed data collected from 122 patients with medulloblastoma, a common childhood brain tumor, and found that faster-growing tumors in children are generally diagnosed earlier than slow tumors.

      Additionally, the study found that girls are diagnosed earlier than boys, and it also detected a small but statistically significant tendency for those with birthdays in autumn to have medulloblastoma.

      "These [results] are particularly interesting because people are taught to believe that a delayed diagnosis means a higher level of cancer," said Dr. Edward Halperin, professor of radiation oncology and the study''s lead author.

      He also noted that this particular finding will have important impacts on lawsuits filed against physicians for not detecting a cancer early enough.

      Halperin attributed the difference in diagnosis time to brain plasticity, or the ability to adjust.

      "A common question is ''How did the tumor [in the brain] get so big?''" said Halperin. "But if it grew slowly enough, the brain adapted and there were few symptoms."

      However, if the tumor is fast-growing, it is usually identified in six to eight weeks because the symptoms surface quickly and are frequent and obvious.

      Medulloblastoma is characterized by a tumor in the posterior portion of the brain, the cerebellum, and has a tendency to grow locally and spread across the spinal fluid and to the cerebrum. Its common symptoms include vomiting, nausea and a staggered walk. There are approximately 8,000 new cases of the disease reported each year.

      The study also found a correlation between the duration of symptoms prior to diagnosis and the patient''s gender. Halperin speculated that this finding may be due to specific hormonal processes or even social biases. He pointed out that boys'' clumsiness may be attributed to the child''s gender, rather than a disease, and shrugged off by the parents.

      The study also found that out of 122 children with medulloblastoma analyzed at the Medical Center, 44 were born in the fall.

      Halperin explained that previous studies have confirmed a disproportionate amount of babies in the United States are born in the fall. However, statistically speaking, only 31 of the 122 patients should have had fall birthdays.

      Stephen George, a professor of biometry who aided Halperin with the study''s design and data analysis, said that although a small sample size may appear to skew the results, the observed differences in the data were still large enough to rule out random chance with more than 95 percent certainty.

      "The statistics test takes small sample sizes into account and [in these cases] won''t detect a small probability," George said.

      Dorothy Watson, a Cancer Center statistician working on the study, added that the she was surprised by the result, especially because the differences were detected in such a small sample.

      The observed birthday trends are further supported by larger sample sizes used in national studies conducted in Norway and Japan. These studies found a greater incidence of winter birthdays in people with the disease. Winter is the most common time of births in Europe.

      Halperin speculated that these trends may be a result of varying seasonal factors like environmental pollutants or drugs taken for allergies or other seasonal conditions.

      He said the findings call for a more involved study to determine the causes of these trends; however, he also cautioned that his study only reported on the observed trends and was not intended to prescribe the best time of the year to have a baby.

(C) 1999