Retinoblastoma Survivors: Sarcomas and Surveillance

Orbital sarcomas in retinoblastoma patients: recommendations for screening and treatment guidelines

PURPOSE OF REVIEW

Retinoblastoma is the most common primary ocular malignancy in children. Although currently retinoblastoma has an excellent survival rate in developed countries, hereditary retinoblastoma survivors as well as those with a history of radiation therapy as children are at an increased risk for second primary tumors (SPTs), and specifically, for orbital sarcomas. Despite the known increased risk for SPTs in retinoblastoma survivors and the associated morbidity and mortality, no screening or treatment guidelines exist.

RECENT FINDINGS

Understanding of retinoblastoma tumorigenesis and genomic expression has expanded significantly, and treatment has evolved with a shift away from radiotherapy. Until the last two decades, however, radiation was the therapy of choice for patients with bilateral disease. Because both hereditary retinoblastoma and radiation are independent risk factors for the development of SPTs such as sarcomas and these SPTs are often fatal, appropriate surveillance for retinoblastoma survivors is crucial.

SUMMARY

As a result of the excellent survival rates for retinoblastoma patients, it is important to: recognize the risk of sarcoma, particularly in patients with hereditary retinoblastoma and/or prior radiation therapy; establish a screening protocol, such as the one proposed, to maximize early detection; and discuss and develop treatment guidelines for high-risk patients. Future directions of research for these patients will involve the development of molecularly targeted agents and the use of proton radiotherapy.

Efficacy of vincristine and carboplatin as chemo-reduction for advanced bilateral retinoblastoma, the Saudi experience

PURPOSE

To evaluate the efficacy of a 2-drug chemotherapy regimen without external-beam radiotherapy (EBRT) and/or without enucleation in bilateral retinoblastoma.

METHODS

From 1996 to 2010, 79 patients were diagnosed with bilateral RB and were eligible for chemotherapy. Chemotherapy was administered prior to and/or following local therapy to the eye. All patients received 3 cycles of chemo-reduction with carboplatin and vincristine, additional cycles of the same or other chemotherapy, local therapy, EBRT and enucleation were determined according to re-evaluation by the ophthalmologist.

RESULTS

Advanced disease was seen in 115 (79%) eyes (group IV and V: 96, Group D and E: 19) out of 146 affected eyes. Tumor response after chemotherapy was observed in 78 patients (98.7%); complete response in 25 (32.1%), partial response in 49 (62.8%) Four (5.1%) had progressive disease. A total of 50 (63.3%) patients required EBRT; 38 for persistent disease, 4 for progressive disease, 2 for new lesions, 2 for re-activation and 4 for disease control. Enucleation was required in 15 (19%). Secondary malignancies occurred in two patients who underwent EBRT; one osteogenic sarcoma and one rhabdomyosarcoma then later osteogenic sarcoma. The 10 year overall survival was 96.3% with a median follow-up time of 3.124 ± 0.536 years (95%CI: 2.074-4.174).

CONCLUSIONS

The 2-drug chemotherapy regimen combined with local therapy appears to be adequate therapy for low stage disease but not in patients with advanced disease. The occurrence of secondary cancers in this group of patients is worrisome further highlighting the deleterious effects of EBRT.

Sarcomas in hereditary retinoblastoma

Children diagnosed with the hereditary form of retinoblastoma (Rb), a rare eye cancer caused by a germline mutation in the RB1 tumor suppressor gene, have excellent survival, but face an increased risk of bone and soft tissue sarcomas. This predisposition to sarcomas has been attributed to genetic susceptibility due to inactivation of the RB1 gene as well as past radiotherapy for Rb. The majority of bone and soft tissue sarcomas among hereditary Rb survivors occur in the head, within the radiation field, but they also occur outside the radiation field. Sarcomas account for almost half of the second primary cancers in hereditary Rb survivors, but they are very rare following non-hereditary Rb. Sarcomas among hereditary Rb survivors arise at ages similar to the pattern of occurrence in the general population. There has been a trend over the past two decades to replace radiotherapy with chemotherapy and other focal therapies (laser or cryosurgery), and most recently, chemosurgery in order to reduce the incidence of sarcomas and other second cancers in Rb survivors. Given the excellent survival of most Rb patients treated in the past, it is important for survivors, their families and health care providers to be aware of the heightened risk for sarcomas in hereditary patients.