Treatment Option Overview
Radiation therapy for patients with low- or intermediate-risk neuroblastoma in the current COG treatment plan (COG-ANBL0531) is reserved for symptomatic life-threatening or organ-threatening tumor bulk that does not respond rapidly enough to chemotherapy. The common situations where radiation is used in these patients include: 1) infants aged 60 days and younger with stage 4S and marked respiratory compromise from liver metastases that has not responded to chemotherapy, or 2) for symptomatic spinal cord compression that has not responded to initial chemotherapy and/or surgical decompression. In contrast, radiation therapy to the primary site is often recommended for high-risk patients even in cases of complete resection.
Immediate treatment should be given for symptomatic spinal cord compression. Neurologic recovery is more likely the less the severity of compromise and the shorter the duration of symptoms. Neurologic outcome appears to be similar whether cord compression is treated with chemotherapy, radiation therapy, or laminectomy. Laminectomy, however, may result in later scoliosis, and chemotherapy is often needed whether or not surgery or radiation is used.[10,11,12] The current COG neuroblastoma treatment plans recommend immediate chemotherapy for cord compression in patients classified as low or intermediate risk (COG-ANBL0531). Children with neuroblastoma whose spinal cord compression worsens on medical therapy may benefit from surgical intervention.
Description of International Neuroblastoma Response Criteria
In order to stop therapy after the initially planned number of cycles, certain response criteria, depending on treatment group, must be met. These criteria are defined below:[14,15]
- Complete Response (CR): Total disappearance of tumor, with no evidence of disease. VMA/HVA are normal.
- Very Good Partial Response (VGPR): Primary tumor has decreased by 90% to 99%, and no evidence of metastatic disease. Urine VMA/HVA are normal. Residual bone scan changes are allowed.
- Partial Response (PR): 50% to 90% decrease in the size of all measurable lesions; the number of bone scan positive sites is decreased by greater than 50% and no new lesions are present; no more than one positive bone marrow site allowed if this represents a reduction in the number of sites originally positive for tumor at diagnosis.
- Mixed Response (MR): No new lesions, 50% to 90% reduction of any measurable lesion (primary or metastatic) with less than 50% reduction in other lesions and less than 25% increase in any lesion.
- No Response (NR) or Stable Disease (SD): No new lesions; less than 50% reduction and less than 25% increase in any lesion.
- Progressive Disease (PD): Any new lesion; increase in any measurable lesion by greater than 25%; previous negative bone marrow now positive for tumor. Neither persistent elevation in urinary VMA/HVA with stable disease nor an increase in VMA/HVA without clinical or radiographic evidence of progression indicate progressive disease, but does warrant continued follow-up. Care should be taken in interpreting the development of metastatic disease in an infant who was initially considered to have stage 1 or 2 disease. If the pattern of metastases in such a patient is consistent with a 4S pattern of disease (skin, liver, bone marrow less than 10% involved) these patients should not be classified as progressive/metastatic disease, which would be a criteria for removal from protocol therapy. Instead, these patients should be managed as stage 4S.