Cancer survival in Indigenous and non-Indigenous Australian children: what is the difference?

PURPOSE: This study assessed variation in childhood cancer survival by Indigenous status in Australia, and explored the effect of place of residence and socio-economic disadvantage on survival. METHODS: All children diagnosed with cancer during 1997-2007 were identified through the Australian Pediatric Cancer Registry. Cox regression analysis was used to assess the adjusted differences in survival. RESULTS: Overall, 5-years survival was 75.0 % for Indigenous children (n = 196) and 82.3 % for non-Indigenous children (n = 6,376, p = 0.008). Compared to other children, Indigenous cases had 1.36 times the risk of dying within 5 years of diagnosis after adjustments for rurality of residence, socio-economic disadvantage, cancer diagnostic group, and year of diagnosis (95 % CI 1.01-1.82). No significant survival differential was found for leukemias or tumors of the central nervous system; Indigenous children were 1.83 times more likely (95 % CI 1.22-2.74) than other children to die within 5 years from 'other tumors' (e.g., lymphomas, neuroblastoma). Among children who lived in 'remote/very remote/outer regional' areas, and among children with a subgroup of 'other tumors' that were staged, being Indigenous significantly increased the likelihood of death (HR = 1.69, 95 % CI 1.10-2.59 and HR = 2.99, 95 % CI 1.35-6.62, respectively); no significant differences by Indigenous status were seen among children with stage data missing. CONCLUSIONS: Differences in place of residence, socio-economic disadvantage, and cancer diagnostic group only partially explain the survival disadvantage of Indigenous children. Other reasons underlying the disparities in childhood cancer outcomes by Indigenous status are yet to be determined, but may involve factors such as differences in treatment.

Cancer incidence and mortality in Indigenous Australian children, 1997-2008.

We report cancer incidence and mortality among Indigenous children in Australia and compare the results with corresponding data for non-Indigenous children. This information is important in understanding the overall burden of cancer in this population, and where disparities exist, to plan what action is required. Age-standardized rates, and indirectly standardized incidence and mortality ratios (SIRs and SMRs) were calculated for the years 1997-2008. There were 224 cancers identified among Indigenous children (99.5 per million per year) and 52 Indigenous children died from cancer during the study period (22.9 per million per year). The SIR for all cancers was 0.64 (95% CI = 0.56-0.73; P < 0.001) while the SMR was 0.81 (95% CI = 0.61-1.07). These results provide a baseline with which to monitor cancer among Indigenous children over time.

Area-based differentials in childhood cancer incidence in Australia, 1996-2006.

BACKGROUND: International studies examining the association between the incidence of childhood cancer and characteristics of the area in which the patient lives have generally reported inconsistent patterns. Area-based differentials in childhood cancer throughout Australia have not been previously published at a national level. PROCEDURE: Population-based information from the Australian Paediatric Cancer Registry was used to identify all children aged 0- to 14-years old diagnosed with invasive cancer or intracranial and intraspinal tumors of benign or uncertain behavior between 1996 and 2006. Age-standardized incidence rates per million children per year and the corresponding incidence rate ratios were calculated, categorized by remoteness of residence and an area-based index of socioeconomic disadvantage. Results were also stratified by the most common types of childhood cancer. RESULTS: There was a significant, decreasing gradient in the incidence of childhood cancer as remoteness of residence increased. Children living in remote or very remote areas were 21% less likely to be diagnosed with cancer compared to children in major cities, mainly due to differences in the incidence of leukemias and lymphomas. This differential was no longer significant when only non-Indigenous children were considered. No clear relationship was found between incidence and socioeconomic status (SES) in contrast to similar earlier studies. CONCLUSIONS: The findings by remoteness of residence are consistent with the lower incidence rates of cancer that are typically associated with Indigenous Australians. There is also a suggestion that the etiological factors associated with childhood leukemia and SES may have altered over time.

Assessing the feasibility and validity of the Toronto Childhood Cancer Stage Guidelines: a population-based registry study.

BACKGROUND: Cancer stage at diagnosis is crucial for assessing global efforts to increase awareness of childhood cancer and improve outcomes. However, consistent information on childhood cancer stage is absent from population cancer registries worldwide. The Toronto Childhood Cancer Stage Guidelines, compiled through an international consensus process, were designed to provide a standard framework for collection of information on stage at diagnosis of childhood cancers. We aimed to assess the feasibility of implementing the Toronto Guidelines within a national population cancer registry. METHODS: We did a population-based registry study using data from the Australian Childhood Cancer Registry and included data from children aged 0-14 years diagnosed between Jan 1, 2006, and Dec 31, 2010 with one of 16 childhood cancers listed in the Toronto Guidelines (acute lymphoblastic leukaemia, acute myeloid leukaemia, Hodgkin's lymphoma, non-Hodgkin lymphoma, neuroblastoma, Wilms' tumour, rhabdomyosarcoma, non-rhabdomyosarcoma soft tissue sarcoma, osteosarcoma, Ewing's sarcoma, retinoblastoma, hepatoblastoma, testicular cancer, ovarian cancer, medulloblastoma, and ependymoma). We extracted data from medical records, and assigned stage according to the Tier 1 criteria (basic) and Tier 2 criteria (more detailed, requiring data from cytology, imaging, and other diagnostic tests, where available) using computer algorithms derived from the Toronto Guidelines. Additionally, expert reviewers independently assigned Tier 2 stage to a random subsample of 160 cases (ten per malignancy type). Feasibility of the guidelines was assessed on the percentage of cases that could be staged, agreement between stage assigned by the algorithms and the expert reviewers, and the mean time (min) taken to collect the required data. FINDINGS: We obtained data for 1412 eligible children. Stage could be assigned according to Tier 2 criteria for 1318 (93%) cases, ranging from 48 (84%) of 57 cases of non-rhabdomyosarcoma soft tissue sarcoma to 46 (100%) cases of hepatoblastoma. According to Tier 1 criteria, stage could be assigned for 1329 (94%) cases, ranging from 131 (87%) of 151 cases of acute myeloid leukaemia to 46 (100%) cases of hepatoblastoma. By contrast, stage at diagnosis was recorded by the treating physician for 555 (39%) of the 1412 cases. The computer algorithm assigned the same stage as did one or more independent expert reviewers in 155 (97%) of the 160 cases assessed. The mean time taken to review medical records and extract the required data was 18·0 min (SD 9·5 per case). INTERPRETATION: The Toronto Guidelines provide a highly functional framework that can be used to assign cancer stage at diagnosis using data routinely available in medical records for most childhood cancers. Data on staging have the potential to inform interventions targeting improved diagnosis and survival. FUNDING: Cancer Australia.

Childhood cancer mortality in Australia.

AIM: To determine current rates of childhood cancer mortality at a national level for Australia and to evaluate recent trends. METHODS: Using population-based data from the Australian Paediatric Cancer Registry, we calculated cancer-related mortality counts and rates for the 3-year period 2006-2008 and trends between 1998 and 2008 by sex, age group, and cause of death (defined according to the International Classification of Childhood Cancers, third edition). Rates were directly age-standardised to the 2000 World Standard Population, and linear regression was used to determine the magnitude and significance of trends. The standardised mortality ratio for non-cancer deaths among children with cancer was also estimated. RESULTS: A total of 282 children (23 per million per year) died from cancer in Australia between 2006 and 2008. Large decreases were observed in cancer mortality rates over the study period, particularly for boys (-5.5% per year; p<0.001), children aged 10-14 years old (-5.5% per year; p=0.001), and leukaemia patients (-9.4% per year; p<0.001). However, there was no significant change in mortality due to tumours of the central nervous system. Children with cancer were twice as likely to die from non-cancer causes compared to other children (SMR=2.06; p=0.001). CONCLUSIONS: While ongoing improvements in childhood cancer mortality in Australia are generally encouraging, of concern is the lack of a corresponding decrease in mortality among children with certain types of tumours of the central nervous system during the past decade. The results also highlight the need for intensive monitoring of childhood cancer patients for other serious diseases that may subsequently arise.

Differentials in survival for childhood cancer in Australia by remoteness of residence and area disadvantage.

BACKGROUND: It is not known whether improvements in cancer survival over recent decades have benefited children from different geographic locations equally. This is the first study to produce national survival estimates for childhood cancer in Australia by remoteness of residence and area-based socioeconomic status. METHODS: The study utilized population-based data from the Australian Paediatric Cancer Registry for children diagnosed with cancer from 1996 onward who were at risk of mortality between January 2001 and December 2006 (n = 6,289). Remoteness was specified according to the Australian Standard Geographical Classification Remoteness Areas, whereas an index of area disadvantage was obtained from census information. Five-year relative survival estimates were produced by the period method for all cancers and the most common diagnostic groups, with corresponding age-sex adjusted mortality hazard ratios calculated using Poisson regression. RESULTS: Overall, children with cancer from remote/very remote areas had a significantly lower survival rate than their counterparts in major cities (HR = 1.55, 95% CI = 1.08-2.23). Survival was also lower for children with leukemia living in inner regional (HR = 1.52, 95% CI = 1.11-2.08) or outer regional areas (HR = 1.53, 95% CI = 1.03-2.28). There was weak evidence (P(grad) = 0.051) of a trend toward poorer survival by greater area disadvantage for all childhood cancers. CONCLUSIONS: Some variation in prognosis by place of residence was present for children with cancer in Australia, particularly among leukemia patients. IMPACT: Treatment, clinical or area-related factors that contribute to these survival differentials need to be identified.