Local control treatment of children aged 3 years and younger

Very young children (aged ≤36 months) diagnosed with rhabdomyosarcoma pose a therapeutic challenge because of their increased risk of treatment-related morbidity.[9] Reduced radiation doses have been used when delayed surgery can provide negative margins. However, for most patients and those in whom surgical resection is not appropriate, higher doses of RT are given.[52] Radiation techniques are designed to maximize normal tissue sparing and should include conformal approaches, often with intensity-modulation or protons. When radiation is omitted, even in those with Stage 1 disease, there is a high risk of recurrence, with local recurrence being the most common, confirming the need for RT.[53-55]

Delayed primary excision may allow for a radiation dose reduction and has been studied in select patients.[8] However, the youngest patients frequently do not get appropriate RT because of concerns about normal tissue toxicity, and these are the best patients for whom surgical resection by delayed primary excision is a particularly important consideration. Local control can be achieved by both RT and surgery. Both treatments are optimal, but at least one approach is necessary in addition to chemotherapy. Local control rates from delayed primary excision and reduced-dose RT are equivalent to that from RT alone.[8]

In studies of infants younger than 1 or 2 years, 77 patients with nonmetastatic rhabdomyosarcoma were included. These studies showed 5-year failure-free survival (FFS) rates of 57% to 68% and OS rates of 76% to 82%.[56] Most failures were local, often because RT was withheld in violation of protocol guidelines. In contrast, for infants treated according to guidelines, both FFS and OS were clearly superior.[57] This experience has been confirmed for children up to age 2 years.[56] Consequently, the COG recommends treating children aged 2 years or younger with the same guidelines as recommended for children older than 2 years.