Development of new retinoblastomas after 6 cycles of chemoreduction for retinoblastoma in 162 eyes of 106 consecutive patients.

Objective: To evaluate the occurrence of new retinoblastomas in patients treated with 6 cycles of chemoreduction.
Design: Prospective nonrandomized single-center case series.
Setting: Ocular Oncology Service at Wills Eye Hospital of Thomas Jefferson University, Philadelphia, Pa, in conjunction with the Division of Oncology at The Children's Hospital of Philadelphia.
Participants: A total of 162 eyes of 106 patients with retinoblastoma treated with 6 cycles of chemoreduction between January 1, 1995, and May 31, 2002.
Intervention: All patients received intravenous chemoreduction with vincristine sulfate, etoposide, and carboplatin, combined with focal treatment (cryotherapy or thermotherapy) to each retinal tumor.
Main Outcome Measure: Development of new intraretinal retinoblastoma during or after treatment with chemoreduction. Recurrent subretinal tumor seeds or vitreous seeds were excluded from this analysis, and only primary new intraretinal tumors were included.
Results: Of 28 patients with unilateral retinoblastoma, new intraretinal tumor development was found during or after chemoreduction in 2 (9%) of the 23 patients with sporadic disease and 4 (80%) of the 5 patients with familial disease. The new tumor was located in the macula in none, between the macula and equator in 7 (54%), and between the equator and ora serrata in 6 (46%). Of the 78 patients with bilateral retinoblastoma, new tumor development was found during or after chemoreduction in 11 (19%) of the 57 patients with sporadic disease and 8 (38%) of the 21 patients with familial disease. The new tumor was macula in 2 (4%), between the macula and equator in 30 (55%), and between the equator and ora serrata in 23 (42%). Overall, according to Kaplan-Meier analysis, new tumor development occurred in 23% of patients by 1-year follow-up and 24% by 5-year follow-up. By multivariate analysis, the most important risk factors for the development of new tumors was younger age at presentation (median age, 2 months with new tumor vs 9 months without new tumor) and family history of retinoblastoma (12 [48%] of patients with new tumor vs 14 [17%] without new tumor).
Conclusions: Children with retinoblastoma treated with chemoreduction should be followed for new intraretinal tumor development, as it peaks at a mean interval of 5 months after initiation of chemoreduction and affects 24% of patients by 5 years of follow-up. New tumors are most commonly found in those who develop disease as young infants and those with a family history of retinoblastoma.