Clinical trials in Australia are neglecting cancer types responsible for the heaviest burden of disease in the category, suggests an analysis of data from the Australian New Zealand Clinical Trials Registry (ANZCTR) and the US-based registry ClinicalTrials.gov.
A University of Sydney team led by Dr Rachel Dear, medical oncologist at the Centre for Medical Psychology and Evidence-based Decision-making, sought to map out current clinical trial activity in Australia by extracting data from the ANZCTR and Clinical Trials.gov on interventional trials for cancer that were recruiting patients as of 31 March 2009.
Specifically, the researchers wanted to explore whether trial activity in Australia reflected the burden of disease for cancer and whether it might be associated with different sponsorship sources. Their findings were published in the Australian Medical Association’s Medical Journal of Australia.
Clinical trials were described in terms of cancer type; the intervention tested; sponsorship and funding source; phase and design (randomised versus non-randomised); characteristics of the enrolled subjects; trial registry (the ANZCTR or CT.gov); and location of recruitment (Australia only or Australia and overseas).
Dear et al also obtained for each cancer covered data on disability-adjusted life-years (DALYs) for 2003. These represent the sum of the years of life lost due to premature mortality in the population and the equivalent ‘healthy’ years lost due to disability for incident cases.
The researchers then examined whether the number of clinical trials for each cancer in the analysis was proportionate to the number of DALYs for that cancer.
Breast cancer emphasis
The analysis identified 368 cancer trials that were recruiting in Australia as of 31 March 2009. Among these, 131 trials (36%) were registered with the ANZCTR and 237 trials (64%) with CT.gov. Randomised controlled trials accounted for 57% of the total.
Breast cancer was far and away the most represented disease type in the trial sample, with 62 interventional trials (17% of the total) open for recruitment, followed by lymphoma, leukaemia or all/multiple cancers (31 trials apiece), lung cancer (24), colorectal and brain cancer (21 each) and melanoma (17).
In terms of DALYS, though, breast cancer ranked only third in the sample, lymphoma sixth and leukaemia eighth. The heaviest burden of disease was for lung cancer, which ranked only fifth in terms of the number of trials underway in Australia, followed by colorectal cancer (sixth by number of trials).
Influence on sponsorship
Industry sources were the primary sponsor in 43% of the trials, Dear et al reported. Industry sponsorship was more likely for randomised controlled trials investigating systemic interventions (i.e., drugs or biological agents) in patients with advanced disease than it was for non-randomised trials of local therapies in patients with early disease.
The picture was different, though, for breast cancer, where most trials included women with early-stage disease and a large proportion were investigating non-drug interventions. Moreover, a higher proportion of breast cancer trials were non-industry sponsored and funded, which the researchers suggested “might be a consequence of consumer influence on the research agenda”.
While there was strong evidence overall that intervention type, cancer extent and allocation to intervention were related to sponsorship by industry after allowing for cancer type, the researchers were surprised to discover that cancer type was not significantly associated with industry sponsorship. The type of treatment rather than the type of cancer was more strongly associated with industry sponsorship.
Gaps in activity
“Cancers causing the greatest burden of disease in Australia are underrepresented in recruiting trials, revealing gaps in current research activity,” the researchers commented. “Industry sponsorship is associated with supporting randomised controlled trials of systemic therapies that include patients with advanced cancer but not with cancer type.”
The analysis of data from the ANZCTR and ClinicalTrials.gov “raises concerns about the direction of the research agenda and may be useful when designing and funding future cancer clinical trials”, Dear et al suggested. “Clinical trial registries are a largely untapped resource to describe the clinical trial research landscape and guide future trial activity.”