Retinoblastoma treatment carries increased risk of neutropenia

Neutropenia following intra-arterial chemotherapy (IAC) occurs more frequently than previously reported among children with retinoblastoma, with topotecan possibly linked to a risk increase, according to a study.

For the study, researchers looked at 49 children (mean age 1.7 years, 51.0 percent girls) with unilateral or bilateral retinoblastoma (64 eyes) who were treated with IAC. Multiple IAC cycles were administered, depending on treatment response.

Melphalan was the primary chemotherapy agent used, and topotecan or carboplatin could be used as an addition. Melphalan doses were kept to not more than 0.4 mg/kg per cycle. Following each IAC cycle, complete blood cell counts were obtained within 10 to 12 days and repeated until the absolute neutrophil count (ANC) was at least 1,000/μL.

The minimum ANC after each IAC cycle was the primary outcome, whereas the development of severe (grade 3 or 4) neutropenia (ANC <1000/μL) was designated as the secondary outcome.

In total, the participants received 171 cycles of IAC. The mean nadir ANC was 1,325.3/μL, which occurred a median of 10 days after IAC administration. The frequency of post-IAC neutropenia grades 0, 1, 2, 3, and 4 was 18.1 percent, 14.6 percent, 23.4 percent, 21.6 percent, and 15.2 percent of cycles, respectively.

Lower ANC showed a weak association with higher melphalan dose (β, −2,356; p=0.01) and higher topotecan dose (β, −4,056; p=0.006).

The findings suggest that limiting topotecan doses, especially in the setting of a high melphalan dose, may play a role in reducing the risk of neutropenia.