Radiation treatment of retinoblastoma

Incidence and Mortality of Second Primary Cancers in Danish Patients With Retinoblastoma, 1943-2013

IMPORTANCE

In heritable retinoblastoma, there is a significantly increased risk of second primary cancers (SPCs). Improved knowledge about the incidence and influence of heritability and treatment is important during therapy for patients with retinoblastoma.

OBJECTIVE

To assess the incidence of SPC in patients diagnosed with retinoblastoma in Denmark from 1943 to 2013 with a focus on heritability and the association of external radiotherapy with mortality.

DESIGN, SETTING, AND PARTICIPANTS

In this retrospective cohort study, data were extracted from the Danish Ocular Oncology Group Database containing complete data on all patients diagnosed with retinoblastoma , and obtained from the Danish Cancer Registry, which includes information on all patients with cancer from 1943 to December 31, 2013. Data analysis was conducted from December 1, 2017, to October 1, 2019. Data on 323 patients were included.

EXPOSURES

Heritability and retinoblastoma treatment.

MAIN OUTCOMES AND MEASURES

Standardized incidence rate, excess absolute risk, cumulative incidence of SPC, and mortality from SPC. Association of heritability and treatment with outcomes was estimated.

RESULTS

Of the 323 patients included in the analysis, 181 were men (56%), 133 had heritable retinoblastoma (41%), and 190 had nonheritable retinoblastoma (59%). The median age at diagnosis of SPC was 32.4 (interquartile range, 15.4-43.9) years in patients with heritable retinoblastoma and 38.6 (interquartile range, 20.5-49.4) years in those with nonheritable retinoblastoma. Twenty-five SPCs were identified in patients with heritable retinoblastoma vs 14 in patients with nonheritable retinoblastoma. Standardized incidence rate (SIR) of SPC in patients with heritable retinoblastoma was 11.39 (95% CI, 7.37-16.81) with an excess absolute risk of 70 cases per 10 000 person-years; the highest SIRs were for sarcoma (181.13; 95% CI, 98.94-303.92) and malignant melanoma (26.78; 95% CI, 9.78-58.30). The SIR for SPC in patients with nonheritable retinoblastoma was 1.52 (95% CI, 0.81-2.60). The cumulative incidence of SPCs at age 60 years was significantly higher in patients with heritable retinoblastoma (51%) compared with those with nonheritable retinoblastoma (13%) (P < .001) (hazard ratio, 5.0; 95% CI, 2.5-10.3). No significant differences were identified in overall risk of SPC in patients with heritable retinoblastoma treated with 3 different modalities: external radiotherapy, plaque (but no external) radiotherapy, and enucleation only, but an increased proportion of sarcomas was noted in the irradiated field. Mortality due to SPC was also higher in survivors of heritable retinoblastoma compared with those with nonheritable retinoblastoma (cumulative mortality, 34% vs 12% at age 60 years; P = .03).

CONCLUSIONS AND RELEVANCE

The findings of this study suggest that the incidence and mortality associated with SPC were significantly higher in patients with heritable retinoblastoma vs patients with nonheritable retinoblastoma. The largest increases in risk were noted for sarcoma and malignant melanoma. External radiotherapy did not appear to increase the risk. These findings are relevant when treating patients with retinoblastoma to manage the risk for SPC.

Danish retinoblastoma patients 1943-2013 - genetic testing and clinical implications

BACKGROUND

In heritable retinoblastoma there is a 50% risk of transmitting the RB1 mutation, and offspring carriers have more than 90% risk of developing retinoblastoma. Today, all newly diagnosed retinoblastoma patients in Denmark are screened for mutations in RB1, as opposed to only a minority of patients diagnosed before DNA testing was offered. Knowledge of heredity increases the chance of early diagnosis in offspring, leading to improved prognosis. We present data from the Danish retinoblastoma patients that emphasize the need for genetic counseling and RB1 screening in all untested retinoblastoma survivors.

MATERIAL AND METHODS

Data are extracted from The Danish Ocular Oncology Group Database, a national population database containing data on all Danish retinoblastoma patients since 1943.

RESULTS

In total 323 retinoblastoma patients have been diagnosed between 1943 and 2013. Since 1963, the rate has been stable around 1 per 14 000 live births with 95% of the patients surviving their retinoblastoma. Stratifying data on the time of diagnosis and status of genetic testing, the number of screened patients gradually increased from 5% in the beginning of the period to 96% in the last five-year period. A cohort of 181 retinoblastoma survivors with sporadic disease (15% heritable) did not receive genetic testing. Since the introduction of routine testing, one of 14 sporadic unilateral patients tested (7%) has been identified with a germline mutation. Before routine testing, five additional sporadic unilateral patients have been identified as heritable.

CONCLUSION

Only a minority of Danish retinoblastoma patients diagnosed before routine genetic testing was offered have been RB1 screened. To counsel the remaining untested patients and their families sufficiently regarding the risk to offspring and elevated risk of second primary cancers, we recommend information and access to genetic counseling and RB1 screening. This has ethical, psychological and possible economic consequences, and should be handled with caution.

Sightsaving therapy in retinoblastoma. Experience with external megavoltage radiotherapy

In Norway, sightsaving therapy in retinoblastoma has only been given to least affected eyes in bilaterally affected children. The results in 8 eyes given external high energy radiotherapy are reported. Additional focal therapy was given to 3 eyes for residual tumours and to one eye with new tumour at the ora serrata. Cataract was treated in 2 of the 3 eyes in which it developed. Vitrectomy was performed in 2 eyes with vitreous haemorrhage and persisting vitreous haze. Secondary enucleation has been avoided in all eyes 3-9 years after irradiation. One patient developed metastases in the temporal region at the enucleated side. Visual acuity is 6/12-6/6 if the macula has not been destroyed by tumour or focal therapy. Sightsaving therapy is presently also offered to unilateral cases and worst affected eyes in bilateral cases if the eyes belong to Reese-Ellsworth groups I-IV.

The combined effect of haematoporphyrin derivative and light on the normal mouse retina

Combined treatment with haematoporphyrin derivative (Hpd) and light irradiation has been reported to be an effective method of killing cancer cells. This would be a very suitable treatment of intraocular tumours because the light can be controlled by the refractive media of the eye. Light and electron microscopy of Hpd and light treated normal mouse retina showed that only the irradiated area was damaged. Tissue destruction increased with greater concentrations of Hpd and longer light exposure. The outer layers of the retina were most sensitive. Hpd was retained in the tissue for 6 days.

Importance of age in management of retinoblastoma of the first eye

The possible treatments of retinoblastoma are briefly discussed, and the different situations when one or two eyes are affected is stressed. The age at onset is an important factor in distinguishing between uni and bilateral cases. By an analysis of 59 cases it is shown that below the age of 12 months, the risk of bilaterality is above 90 per cent whereas above the age of 18 months the risk is almost zero. It is recommended that in retinoblastoma, uni- as well as bilateral cases, the possibility of a conservative treatment is seriously considered. Radiation is today the basic modality of treatment. The acute management by the mutilating enucleation is a procedure of the past.

Retinoblastoma treated with a 60CO applicator

The 60Co applicator for treatment of retinoblastoma, described in 1963, has the advantage of exact local positioning. It is suitable in cases with solitary small tumours. The complications and the results of treatment in 20 patients followed up for at least 2 years are reported and discussed.