Background Five-10% of retinoblastoma (RB) patients harbor deletion of chromosome 13q (13q-). Treatment related toxicities in this population have not been described. Methods Sixty-eight RB patients on a single institutional protocol (RET5) from 2005–2010 were reviewed. Genetic screening identified eleven patients (7 female) with 13q-. Patients with early (Reese-Ellsworth [R-E] group I–III) disease (6/23 with 13q-) received 8 courses of vincristine/carboplatin (VC). Patients with advanced (R-E group IV–V) bilateral disease (2/27 with 13q-) received 2 courses of vincristine/topotecan (VT) followed by 9 courses of alternating VT/VC. Patients undergoing upfront enucleation received histopathology-based chemotherapy: intermediate risk (2/8 with 13q-) or high risk (1/10 with 13q-). Dose reductions were mandated for >7 day delay in 2 consecutive courses following hematologic toxicity. Grade 3 and 4 hematologic, infectious, and gastrointestinal toxicities were compared between RET5 patients with and without 13q-. Results Demographics were similar between groups. When present, prolonged neutropenia (median 7 days, range 0–14 days) delayed chemotherapy and resulted in more frequent dose reductions among 13q- patients (5/11) than non-13q- patients (4/57) (p<0.01). GI toxicity was similar between groups (5/11 13q- vs. 13/57 non-13q-) (p=0.14), but halted chemotherapy in one 13q- patient. Infectious complications and disease outcomes were similar between groups. At follow-up, all patients are alive (median 6.1 years, range 7.6 months to 9.5 years). Conclusion 13q- RB patients had a higher incidence of neutropenia requiring chemotherapy dose reductions, but did not have increased treatment failure.

No abstract