External beam radiation therapy and retinoblastoma: long-term results in the comparison of two techniques.

PURPOSE

This study compares the long-term actuarial local control, eye conservation rate, survival, and ocular complications in children with retinoblastoma treated with two different external beam treatment techniques.

METHODS AND MATERIALS

From 1979-1991, 182 eyes in 123 children (104 bilateral) received primary external beam radiation therapy. An anterior lens-sparing electron beam technique delivering 38 to 50 Gy in 2.5 Gy fractions was used in 67 eyes from 1979-1984 and a modified lateral beam technique, delivering 42 to 46 Gy in 2 Gy fractions, was used in 113 eyes from 1984-1991. These groups were balanced with respect to known prognostic variables.

RESULTS

For Group I-III eyes, the 5- and 8-year local control was significantly improved using the modified lateral beam technique (84%) compared to (38%) using the anterior lens sparing technique (p < or = 0.0001). For Group IV-V eyes, the 5- and 8-year local control rates were not statistically different, despite a trend favoring the modified lateral beam technique. Survival endpoints including eye survival (no enucleation), cause-specific survival, and overall survival comparing the two treatment techniques were not significantly different. Overall, 22% of eyes developed cataracts. There was no difference between the two treatment groups in terms of cataract development. No eyes required enucleation for ocular complications.

CONCLUSION

There is a significant improvement in local control using the modified lateral beam technique compared to an anterior lens-sparing approach for Group I-III eyes. However, there was no difference in survival end points between the two treatment techniques. The incidence of ocular complications using these two external beam techniques is acceptable.