Side effects of RT and any cancer therapy should always be thought of in terms of early and late effects.
For RT, early side effects occur at the time of treatment and for the first month after therapy is completed.
Early side effects associated with flank RT, whole abdominal RT and chemotherapy for Wilms tumor:
- Anorexia, nausea and vomiting (usually minimal)
- Avoided by giving Zofran (Ondansetron) half an hour to an hour before RT
- Diarrhea and small bowel irritation is extremely rare
- Bone marrow depression may occur with low counts (especially if whole abdomen or right flank is treated)
- RT is usually held if the absolute neutrophil count is less than 1000/mm3 or the platelets are less than 75000/mm3
- More profound with regimens with 3 or 4 chemotherapy agents, and following chemotherapy courses administered immediately after the completion of RT
- RT to right flank (not left flank) is associated with thrombocytopenia following administration of AMD (related to hepatic irradiation)
- Severity of effects are related to age. The use of lower drug doses did not increase the frequency of relapse among patients younger than 12 months and has led to the recommendation that all infants receive only 50% of the usual childhood dose of any chemotherapy agent
- Skin reactions are very rare as the dose of RT is very low, but might occur with Actinomycin (AMD) treatment
- Asymptomatic elevation of function tests or clinical hepatitis in 8% of patients after right sided flank RT
- Whole abdominal RT is more commonly causes hepatic dysfunction and thrombocytopenia
- Hepatic toxicity causes transient hepatomegaly, liver enzyme elevations, and thrombocytopenia
- Radiation hepatitis rare in patients who received <38 Gy to the liver, occurs in 42% of patients who receive >38 Gy
- Occasional transient nephropathy
- Chemotherapy and RT have adverse effects on the accelerated phase of renal hypertrophy after nephrectomy
Early side effects associated with whole lung RT and chemotherapy for Wilms tumor:
- Transient dysphagia secondary to mucosal irritation
- Clinically apparent acute pneumonitis after RT is very rare, but 13% of patients have radiological evidence of pneumonitis.
- Dactinomycin and doxorubicin modify tissue response to RT. The acute onset of tachypnea following administration of these drugs after whole lung RT may represent radiation pneumonitis.
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