Factors predictive of recurrence of retinal tumors, vitreous seeds, and subretinal seeds following chemoreduction for retinoblastoma.

OBJECTIVE: To identify the clinical features of eyes with retinoblastomas that predict the recurrence of retinal tumors, vitreous seeds, and subretinal seeds following treatment with chemoreduction.
DESIGN: Prospective nonrandomized single-center clinical trial.
SETTING: Ocular oncology service at Wills Eye Hospital of Thomas Jefferson University (Philadelphia, Pa) in conjunction with the division of oncology at Children's Hospital of Philadelphia. PARTICIPANTS: There were 158 eyes with 364 tumors in 103 consecutive patients with retinoblastoma managed with chemoreduction between June 1994 and August 1999. INTERVENTION: All patients received treatment for retinoblastoma with 6 cycles of chemoreduction using vincristine, etoposide, and carboplatin combined with focal treatment (cryotherapy, thermotherapy, or plaque radiotherapy) for each retinal tumor. MAIN OUTCOME MEASURES: The 3 main outcome measures included recurrence of retinal tumors, recurrence of vitreous seeds, and recurrence of subretinal seeds. The clinical features at the initial examination were analyzed for their association with the main outcome measures using a series of Cox proportional hazards regressions.
RESULTS: All retinal tumors, vitreous seeds, and subretinal seeds showed an initial favorable response of regression during this treatment regimen. Using Kaplan-Meier estimates, at least 1 retinal tumor recurrence per eye was found in 37% of eyes at 1 year, 51% at 3 years, and no further increase at 5 years. By multivariate analysis, the only factor predictive of retinal tumor recurrence was the presence of tumor-associated subretinal seeds at the initial examination. Of the 54 eyes that had vitreous seeds at the initial examination, vitreous seed recurrence was found in 26% of eyes at 1 year, 46% at 3 years, and 50% at 5 years. By univariate analysis, the only factor predictive of vitreous seed recurrence was the presence of tumor-associated subretinal seeds at the initial examination. Of the 71 eyes that had subretinal seeds at the initial examination, subretinal seed recurrence was detected in 53% of eyes at 1 year, 62% at 3 years, and no further increase at 5 years. By multivariate analysis, factors predictive of subretinal seed recurrence included a tumor base greater than 15 mm and a patient age of 12 months or younger at diagnosis. There were no patients who developed retinoblastoma metastasis, pinealoblastoma, or second malignant neoplasms.
CONCLUSIONS: Chemoreduction combined with focal therapy is effective for selected eyes with retinoblastomas. Eyes with subretinal seeds at initial examination are at particular risk for recurrence of retinal tumor and vitreous seeds. Younger patients with large tumors are at risk for recurrence of subretinal seeds. Retinal tumor and subretinal seed recurrence seems to manifest within 3 years of follow-up. Close follow-up of all patients treated with chemoreduction is warranted.