Incidence of new tumor formation in patients with hereditary retinoblastoma treated with primary systemic chemotherapy: is there a preventive effect?

ABSTRACT

PURPOSE: To report the incidence of new tumor formation in hereditary retinoblastoma patients treated with primary systemic chemotherapy. DESIGN: Noncomparative retrospective case series. PARTICIPANTS: Fifty-eight consecutive patients with hereditary retinoblastoma treated with primary systemic chemotherapy. METHODS: The charts of 58 consecutive patients with hereditary retinoblastoma treated between January 1996 and August 2005 were reviewed. Data extracted included gender, age at diagnosis, family history of retinoblastoma, laterality of disease, tumors per eye, Reese-Ellsworth grouping of affected eyes, starting and ending dates for chemotherapy, number of cycles of chemotherapy, chemotherapy regimen, need for external beam radiotherapy and/or enucleation, and development and location (macula, midzone, and periphery) of new tumors after the start of systemic chemotherapy. MAIN OUTCOME MEASURE: New tumor formation after treatment with primary systemic chemotherapy. RESULTS: Of the 58 patients, 48 had bilateral involvement at diagnosis. Median age at diagnosis was 6.6 months. Thirteen patients had a positive family history. Of the eyes with tumor (n = 106) at diagnosis, 52 (49%) were in Reese-Ellsworth groups I to III, whereas 54 (51%) were in group IV or V. Seven patients (12%) with a median age of 1.6 months at diagnosis formed 36 new tumors in 11 eyes after the start of chemotherapy. Median time from initiation of chemotherapy to detection of the first new tumor was 3 months (range, 1-15). Cumulative incidence of new tumor formation at 2 years was 10+/-3%. An age of <6 months at diagnosis, family history of retinoblastoma, and Reese-Ellsworth grouping of I to III were found to correlate significantly with an increased incidence of new tumor formation (P<0.001, P<0.001, and P = 0.021, respectively). Median follow-up for all patients was 5 years (range, 1-10.1). CONCLUSION: New tumors continue to form in patients with hereditary retinoblastoma despite treatment with primary systemic chemotherapy. Younger patients and those with a positive family history are more likely to have new tumors formed. However, chemotherapy may impact small previously undetected lesions by slowing their growth and facilitating later focal consolidation.