MONTREAL -- Delayed diagnosis of childhood cancer continues to confound efforts to achieve the best possible clinical outcomes, a review of the pediatric oncology literature suggests.
MONTREAL, July 9 -- Delayed diagnosis of childhood cancer continues to confound efforts to achieve the best possible clinical outcomes, a review of the pediatric oncology literature suggests.
The review showed that the average duration of delay varied by cancer type, ranging from a low of 2.5 weeks for nephroblastoma to a high of 29.3 weeks for brain tumors, noted Tam Dang-Tan, M.Sc., and Eduardo L. Franco, DrPH, of McGill University here.
Multiple factors contributed to the delays, they found, including the child's age at diagnosis, cancer type, parents' education, symptoms at presentation, tumor site, cancer stage, and the first medical specialty consulted.
The impact of the delays on clinical courses was muddled, with overtones of a classic chicken-versus-egg conundrum: "Do delays in diagnosis worsen the extent of the disease, or does the extent of the disease influence diagnosis delays?" the authors asked.
The review, posted online in advance of the Aug. 15 issue of Cancer, encompassed 23 studies that evaluated any type of delay along the cancer-care continuum. The only study that calculated the average delay for all types of cancers found a mean delay of 15.8 weeks.
The authors grouped delays into three broad categories: patient- or parent-related factors, disease-related factors, and factors attributable to the healthcare delivery system.
In general, physician-related delays were more prolonged compared with delays attributable to patient or parent factors. Diagnosis and physician delay were reduced for patients who saw a pediatrician first, rather than a family physician or another type of specialist. Physician delay also was reduced when the first contact was with an emergency physician instead of a pediatrician. Studies that evaluated diagnostic delay as a function of access to care yielded inconsistent results.
Seven studies examined the impact of diagnostic delay on prognosis and produced inconsistent findings. Four of the studies showed a negative association between delays and prognosis, whereas the other three found no association
Patient age was a key influence on the likelihood of diagnostic delay, as most studies indicated that older children had a greater risk of delay compared with infants and younger children. A variety of parent-related factors emerged from different studies, but in a multivariate analysis, religion and father's ethnicity remained the only significant predictors of delay.
All studies showed that the type of cancer influences the timeliness of diagnosis. In particular, leukemia had a shorter diagnostic lag time compared with most other types of cancer. Rare or unusual symptoms tended to be associated with less delay in diagnosis compared with common or nonspecific symptoms.
Most studies that evaluated the tumor site found an effect on diagnostic delay. For example, a study of rhabdomyosarcoma showed that tumors of the pharynx and orbit were diagnosed more quickly than were tumors in the face or neck. Disease stage had a mixed effect, as some data showed that more advanced disease was associated with a shorter diagnostic lag, whereas other data found no such association.
The authors pointed several limitations of the study. "Most studies in this review have been retrospective cohort studies and are, therefore, subject to certain limitations inherent in their design. The use of pre-existing records makes it difficult to ascertain the reliability of information collected and to obtain information on potential confounding variables."