Results of two radiation therapy randomizations in the third National Wilms' Tumor Study.

In the third National Wilms' Tumor Study (NWTS-3), patients with Stage II favorable histologic type (FH) or Stage III FH Wilms' tumor were randomized according to a factorial design for both radiation therapy (RT) and chemotherapy to be given after nephrectomy. Patients with Stage II FH disease were randomized between 2000 cGy and no postoperative RT; patients with Stage III FH disease were randomized between 2000 and 1000 cGy. No significant differences in survival were noticed. Although there were no significant differences in the rate of intraabdominal relapses, those patients with Stage III disease who received 1000 cGy and dactinomycin and vincristine (seven patients) experienced a relapse in the abdomen more frequently than those who received 2000 cGy and dactinomycin and vincristine (three patients), 1000 cGy and dactinomycin, vincristine, and doxorubicin (three patients), or 2000 cGy and dactinomycin, vincristine, and doxorubicin (two patients). This would suggest that doxorubicin might be a good substitute for the second 1000 cGy of RT. Boost doses of RT, although allowed, were rarely given and no assessment of the value of supplemental RT can be made. The dismal prognosis of abdominal relapse after RT is confirmed and delay of initiation of treatment beyond 10 days after surgery was a significant adverse factor as in NWTS-1 and NWTS-2.

Adjustable portal film cassette holder for radiation therapy.

An adjustable portal film cassette holder has been designed and constructed. The holder provides for: holding portal film perpendicular to and centered with the central axis of the beam film-to-patient distance to minimize magnification; angling (swivel) film to match collimator angle; and ease of correct repositioning of arrangement when frequent filming is required. This device has now been in use for several months with good results.

Solid malignancies in children and adolescents.

The cure rate in childhood cancer has improved markedly during the past 20 years. In the 1960s the cure rate was about 20 to 30 per cent, but today more than 50 per cent of children and adolescents with cancer are being cured. This improvement is principally due to multidisciplinary teamwork in diagnosing, staging, and treating children with cancer; newer and more chemotherapeutic agents; and a recognition that combination therapy consisting of surgery, radiotherapy, and chemotherapy is frequently indicated.

Generation of iso-TDF maps: considerations for radiation therapy planning.

The NSD (nominal standard dose) concept has been useful in therapy for comparing various radiation treatment schedules. More recently, TDF (time, dose, and fractionation) factors were introduced. By incorporating treatment schedules (time and fractionation) with isodose summations, TDFs can be determined throughout the patient contour, including tissue in and outside the tumor volume. For this purpose an isodose summation program was modified to generate iso-TDF maps based on the treatment schedule. For schedules in which all fields are not treated every day, recovery is not inhibited throughout the total treatment volume. It was necessary to reevaluate the concept of "recovery time" for tissues outside the tumor volume and to introduce a "threshold to inhibit recovery" model. Clinical examples assuming this recovery model are presented.