Incidence of retinoblastoma in Dutch children conceived by IVF: an expanded study.

BACKGROUND: In 2003, we reported an increased risk of retinoblastoma in children conceived by IVF between 1995 and 2002. However, population-based studies among children conceived by IVF did not find an elevated risk of retinoblastoma. METHODS: From nationwide estimates of numbers of live births conceived by IVF (n = 40 330), we estimated the expected numbers of patients with retinoblastoma conceived by IVF in the period 1995-2007. The observed number of retinoblastoma diagnoses in children conceived by IVF was obtained by questionnaires sent to the parents of children with retinoblastoma diagnosed between 1995 and 2005. For non-responders and patients diagnosed after 2005, information was available through the medical files, in which information on fertility treatment has been routinely recorded since 2000. The relative risk (RR) of retinoblastoma among children conceived by IVF was calculated for the total study period (1995-2007) and for the expanded study period (2002-2007). RESULTS: Of all eligible patients with retinoblastoma (n = 162) diagnosed in the period 1995-2007, seven were conceived by IVF. In the total study period (1995-2007) the risk was significantly elevated [RR = 2.54, 95% confidence interval (CI) = 1.02-5.23]. In the expanded study period (2002-2007), no significantly elevated risk (RR = 1.29, 95% CI = 0.16-4.66) was found. CONCLUSIONS: We found a significantly increased risk of retinoblastoma in children conceived by IVF in the total study period 1995-2007. However, this increased risk was mostly based on the much stronger risk increase observed previously, for 1995-2002. Caution and awareness on the one hand and avoiding unnecessary worries on the other hand are important at this stage of our knowledge.

Risk of third malignancies and death after a second malignancy in retinoblastoma survivors.

Retinoblastoma patients have a strongly increased risk of second malignancies, and survivors with a third or subsequent malignancy are increasingly observed. However, it has not been examined whether survivors who developed a second malignancy have a greater risk of a subsequent malignancy. On the basis of the Dutch retinoblastoma registry, the risk of a third malignancy was compared with cancer risk in the Dutch population. Cox model analysis with a time-dependent covariate was used to compare the subsequent malignancy risk and survival among patients with and without a second malignancy. Risk of a third malignancy was increased 8-fold compared with the general population. The hazard ratio (HR) of a third malignancy after a second malignancy was more than 7-fold increased compared to the risk of a second malignancy after retinoblastoma. Radiotherapy increased the risk 3-fold. A third malignancy was associated with worse survival compared with survival of patients only diagnosed with a second malignancy (HR=5.0). Survivors of retinoblastoma who already developed a second primary malignancy have an even higher risk of subsequent primary malignancies than retinoblastoma survivors without a second malignancy. Treating physicians and patients should be aware of this higher risk.

Cancer mortality in long-term survivors of retinoblastoma.

This study examined long-term cause-specific mortality among 998 Dutch retinoblastoma survivors, diagnosed from 1862 to 2005, according to follow-up time, treatment and heredity. After a median follow-up of 30.8 years, only cause-specific mortality for second malignancies among hereditary retinoblastoma survivors was statistically significantly increased with 12.8-fold. Risk of death from second malignancies among non-hereditary survivors was not increased. Mortality rates of second malignancy among hereditary patients were non-significantly elevated with 1.6-fold for treated with radiotherapy, compared to those treated otherwise. Standardised mortality ratios (SMRs) for second malignancy among hereditary patients increased during the first three decades after retinoblastoma diagnosis. Whereas these risks decreased after three decades, the absolute excess risk (AER) increased significantly, up to 23.2 excess cases per 1000 patients/year after five decades of follow-up. Fifty years after retinoblastoma diagnosis the cumulative mortality from any second malignancy was 17.3% for hereditary patients. Very long-term follow-up of retinoblastoma patients revealed an emerging excess risk of mortality in hereditary retinoblastoma survivors. This implies that lifelong follow-up is needed, whereas at the same time, patients and their physicians must be alerted to the increased second malignancy risks.