Results
Of 550 patients with retinoblastoma encountered in this practice during
the study period, our series used the 15 patients who developed a SPMN
(2.7%), 2 of whom (patient 4 and 7) developed 2 distinct SPMNs. The
median age at retinoblastoma diagnosis was 9.7 months (extremes 1.6 and
33.6 months). All 15 patients had a positive family history of
retinoblastoma. Twelve patients were male (80%) and three were female
(20%). Bilateral disease was present in 14 of the 15 (93.0%) patients,
and the genetic nature of the one unilateral case (case 7, TABLE 1) was
established by germline RB1 mutation on genetic analysis.
Demographics and characteristics of each patient’s retinoblastoma are
presented in TABLE 1. Eleven patients received treatment prior to
referral, including enucleation (11/30 eyes; 36.6%), and external beam
radiation therapy (EBRT) (12/30 eyes; 40.0%). Following completion of
their retinoblastoma treatment course, a total of 15/30 (50.0%) eyes
were enucleated, and 14/15 (93.3%) patients underwent EBRT. In 13
patients, retinoblastoma was diagnosed, and treatment was initiated
prior to the adoption of carboplatin-etoposide-vincristine (CEV) and
intravenous chemotherapy at our center (in 1995). All 15 patients were
diagnosed and underwent treatment for their retinoblastoma prior to the
availability of selective ophthalmic intra-arterial chemotherapy at our
institution (in 2008). The 2 patients diagnosed after the introduction
of primary systemic chemotherapy both received intravenous chemotherapy
during their treatment course. None of the patients developed metastasis
from retinoblastoma and no patient died of their retinoblastoma.
The characteristics of the SPMNs are reported in TABLE 2. Thirteen of
the 14 patients (92.9 %) who underwent EBRT developed their SPMN within
the field of prior radiation. The histopathologic type of SPMN was
osteosarcoma in 7, rhabdomyosarcoma in 3, malignant fibrous histiocytoma
in 3, and a malignant astrocytoma, liposarcoma, esthesioneuroblastoma
and a leiomyosarcoma in 1 case each. Treatment data for SPMN management
was available for 11 of the 15 patients and included a combination of
surgical resection in 11, intravenous chemotherapy in 6, and radiation
therapy in 4. The median time from initial retinoblastoma diagnosis to
development of SPMN was 19.0 years (extremes 3.4 and 39.4 years). The
median time from retinoblastoma diagnosis to death in the 6 patients who
died of their SPMN was 18.8 years (extremes 6.2 and 34.6 years), and the
median interval between SPMN diagnosis and death from the neoplasm in
these 6 patients was 1.2 years (extremes 0.25 and 4 years). In contrast,
the median duration of follow-up after retinoblastoma in the 9 surviving
patients was 32.0 years (extremes 12.5 and 39.3 years) and the median
follow-up interval after diagnosis of the SPMN in these patients was 8.9
years (extremes 1.6 and 27.6 years).