Discussion
In the present study, there was a high incidence of metastatic disease
at presentation (50.70%). Pakos et al 30, in an
international OS compilation, where OS Brazilian Group was included,
showed 13% of the patients with metastatic disease, the same could be
seen in the OS Children Oncology Group (COG) (27%) and Cooperative
Ewing Sarcoma Study (CESS) group (30%) 30–34.
Patients arrived at INCA with advanced disease and this characteristic
probably influenced in their pain status in all follow-up moments.
At registration, pain was related as the most frequent symptom
(61.27%). Even if pain scales were not used, the majority of patients
self-assessed pain as moderate to severe and three children had
excruciating pain. At that moment, the most frequent drugs used for pain
control were mild analgesics (paracetamol or dipyrone) and treatment was
changed in 42.25% of patients. This data contrasts with the WHO
recommendation, that suggested the use of strong opioids at that level
of pain, specially morphine. This undertreatment could be attributed to
the fear of using opioids 16,35–38.
By contrast, end-of-life patients used strong opioids and morphine was
the most frequently used, followed by anticonvulsant and antidepressant
drugs, as well as other drugs and procedures, as a multimodal therapy.
This has been used in agreement with international references.27,28,35,39
Along the follow-up period, more patients had their pain classified.
Also, pain complaint decreased, and no excruciating pain was observed at
last evaluation. At registration, 34.21% had no pain and at last
evaluation 73.77% of all patients had no pain. These results suggest
the effectiveness of the management of pain control associated during
follow-up.
However, we observed association between pain at last evaluation and the
presence of disease progression. Those patients presented 3.5 times more
pain compared to the others. Comparing with previous international
cooperative pediatric bone cancer groups studies, the influence of this
variable followed the same direction, being associated to pain20–23,31–34,40–42.
At last evaluation we observed no difference in pain complaint between
end-of-life patients and the others. This suggests that pain management
was effective. Also, it was observed opioid use associated to pain
complaint at last evaluation, this is a reverse cause-effect
association, as those who have more pain use more opioids.
However,19.64% of end-of-life patients and 18.60% of those undergoing
treatment or in disease control still presented moderate and severe
pain, at last evaluation. We suggest that this might have occurred
because of family misconception for the use of pain control drugs.
Similar results were seen by Snaman et al., who revealed difficulty in
pain control, with the principal obstacle being lack of information and
misconceptions of opioid use. 5,29,27,43.