Role of radiotherapy and chemotherapy in the risk of leukemia after childhood cancer: An international pooled analysis.

Childhood cancer survivors are at increased risk for second primary leukemia (SPL), but there is little consensus on the magnitude of some risk factors because of the small size of previous studies. We performed a pooled analysis of all published studies with detailed treatment data, including estimated active bone marrow (ABM) dose received during radiation therapy and doses of specific chemotherapeutic agents for childhood cancer diagnosed from 1930 through 2000, in order to more thoroughly investigate treatment-related risks of SPL. A total of 147 SPL cases (of which 69% were acute myeloid leukemia [AML]) were individually matched to 522 controls, all from four case-control studies including patients from six countries (France, United Kingdom, United States, Canada, Italy and Netherlands). Odds ratios (OR) and corresponding 95% confidence intervals (CIs) were calculated using conditional logistic regression, and the excess OR per Gray (EOR/Gy) was also calculated. After accounting for the other therapies received, topoisomerase II inhibitor was associated with an increased SPL risk (highest tertile vs none: OR = 10.0, 95% CI: 3.7-27.3). Radiation dose to the ABM was also associated with increased SPL risk among those not receiving chemotherapy (EOR/Gy = 1.6, 95% CI: 0.1-14.3), but not among those who received chemotherapy (CT). SPL were most likely to occur in the first decade following cancer treatment. Results were similar when analyses were restricted to AML. The evidence of interaction between radiation and CT has implications for leukemogenic mechanism. The results for topoisomerase II inhibitors are particularly important given their increasing use to treat childhood cancer.

Second malignant neoplasms in digestive organs after childhood cancer: a cohort-nested case-control study.

PURPOSE: Cancers of the digestive system constitute a major risk for childhood cancer survivors treated with radiotherapy once they reach adulthood. The aim of this study was to determine therapy-related risk factors for the development of a second malignancy in the digestive organs (SMDO) after a childhood cancer. METHODS AND MATERIALS: Among 4,568 2-year survivors of a childhood solid cancer diagnosed before 17 years of age at eight French and British centers, and among 25,120 patients diagnosed as having a malignant neoplasm before the age of 20 years, whose data were extracted from the Nordic Cancer Registries, we matched 58 case patients (41 men and 17 women) of SMDO and 167 controls, in their respective cohort, for sex, age at first cancer, calendar year of occurrence of the first cancer, and duration of follow-up. The radiation dose received at the site of each second malignancy and at the corresponding site of its matched control was estimated. RESULTS: The risk of developing a SMDO was 9.7-fold higher in relation to the general populations in France and the United Kingdom. In the case-control study, a strong dose-response relationship was estimated, compared with that in survivors who had not received radiotherapy; the odds ratio was 5.2 (95% CI, 1.7-16.0) for local radiation doses between 10 and 29 Gy and 9.6 (95% CI, 2.6-35.2) for doses equal to or greater than 30 Gy. Chemotherapy was also found to increase the risk of developing SMDO. CONCLUSIONS: This study confirms that childhood cancer treatments strongly increase the risk of SMDO, which occur only after a very long latency period.

Relationship between the brain radiation dose for the treatment of childhood cancer and the risk of long-term cerebrovascular mortality.

To date, very little is known about the long-term risk of death from cerebrovascular sequelae following childhood cancer treatment. The purpose of this study was to assess the role of treatment in very long-term cerebrovascular mortality following childhood cancer. We studied 4227 5-year survivors of a childhood cancer. Information on chemotherapy was collected and the radiation dose delivered to 11 anatomical sites in the brain was estimated. The main outcome that was considered was death due to cerebrovascular disease occurring before 1 January 2008. After a median follow-up of 29 years, 23 deaths due to cerebrovascular diseases had occurred. In the brain, the radiation dose delivered to the prepontine cistern seemed to play a greater role than the average radiation dose received throughout the brain or the dose to any other specific anatomical site in the brain. The risk of death from cerebrovascular disease increased linearly with the local radiation dose to the prepontine cistern. Each unit of absorbed radiation (Gray) delivered to this area increased the risk by 22% (95% confidence interval: 1-44%). Compared with patients who had not received radiotherapy or who had received <0.1 Gray in the prepontine cistern area, those who had received >50 Gray had a 17.8-fold (4.4-73.0) higher hazard ratio of death from cerebrovascular disease. In conclusion, among 5-year survivors of childhood cancer, the radiation dose to the brain during radiotherapy was significantly associated with long-term cerebrovascular mortality.

Role of cancer treatment in long-term overall and cardiovascular mortality after childhood cancer.

PURPOSE: The purpose of this study was to assess the role of treatment in long-term overall and cardiovascular mortality after childhood cancer. PATIENTS AND METHODS: We studied 4,122 5-year survivors of a childhood cancer diagnosed before 1986 in France and the United Kingdom. Information on chemotherapy was collected, and the radiation dose delivered to the heart was estimated for 2,870 patients who had received radiotherapy. RESULTS: After 86,453 person-years of follow-up (average, 27 years), 603 deaths had occurred. The overall standardized mortality ratio (SMR) was 8.3-fold higher (95% CI, 7.6-fold to 9.0-fold higher) in relation to the general populations in France and the United Kingdom. Thirty-two patients had died as a result of cardiovascular diseases (ie, 5.0-fold [95% CI, 3.3-fold to 6.7-fold] more than expected). The risk of dying as a result of cardiac diseases (n = 21) was significantly higher in individuals who had received a cumulative anthracycline dose greater than 360 mg/m(2) (relative risk [RR], 4.4; 95% CI, 1.3 to 15.3) and in individuals who received an average radiation dose that exceeded 5 Gy (RR, 12.5 and 25.1 for 5 to 14.9 Gy and > 15 Gy, respectively) to the heart. A linear relationship was found between the average dose of radiation to the heart and the risk of cardiac mortality (estimated excess [corrected] RR at 1 Gy, 60%). CONCLUSION: This study is the first, to our knowledge, to establish a relationship between the radiation dose received by the heart during radiotherapy for a childhood cancer and long-term cardiac mortality. This study also confirms a significant excess risk of cardiac mortality associated with a high cumulative dose of anthracyclines.

Pregnancy outcomes among adult survivors of childhood cancer in the British Childhood Cancer Survivor Study.

PURPOSE: We used data from the first large-scale overwhelmingly population-based study (a) to quantify the risk of adverse pregnancy outcomes in survivors of childhood cancer in relation to cancer type and treatment and (b) to assess live birth rates relative to the general population. METHODS: A questionnaire, including questions inquiring about pregnancy outcomes, was completed by 10,483 survivors. A total of 7,300 pregnancies were reported. Odds ratios (OR) for live birth, miscarriage, termination, stillbirth, premature birth, and low birth weight were calculated for different types of childhood cancer and by whether initial treatment involved chemotherapy and abdominal or brain irradiation. For females, the observed number of live births was compared with that expected based on the general population of England and Wales. RESULTS: Female survivors exposed to abdominal irradiation had a significantly increased OR of delivering preterm [OR, 3.2; 95% confidence interval (95% CI), 2.1-4.7] and producing offspring with a low birth weight (OR, 1.9; 95% CI, 1.1-3.2). An increased OR of miscarriage was also associated with abdominal radiotherapy (OR, 1.4; 95% CI, 1.0-1.9). The number of live births observed from all female survivors was two thirds of that expected (O/E, 0.64; 95% CI, 0.62-0.66) and lowest among survivors treated with brain (O/E, 0.52; 95% CI, 0.48-0.56) and abdominal radiotherapy (O/E, 0.55; 95% CI, 0.50-0.61). CONCLUSION: Female survivors of childhood cancer treated with abdominal radiotherapy are at 3-fold increased risk of delivering preterm, 2-fold increased risk of low birth weight, and a small increased risk of miscarriage. Overall, female survivors produce considerably fewer offspring than expected, particularly those treated with abdominal or brain radiotherapy.