Well-conducted cancer clinical trials are essential for improving patient outcomes. However, recruitment to oncology clinical trials remains poor, and it has been observed that barriers to enrollment of minority populations limit the interpretation and applicability of cancer clinical trials findings.1 Extensive investigation of the factors that influence inclusion in clinical trials has been undertaken.2 Although the availability of appropriate trials is often a significant barrier, patient and physician factors also limit accrual. Lara et al. specifically demonstrated a positive correlation between patient awareness of cancer clinical trials and their willingness to participate, especially among patients of lower socioeconomic status (SES) and other minority populations.3 Socioeconomic factors, including lack of medical insurance, high unemployment rates, and low income levels, have been associated with poor trial accrual.4 Furthermore, the group at highest risk for cancer, older patients, is least likely to be represented in trials.5 Reports in the literature indicated that individuals aged ≥65 years represent from 22% to 32% of trial accruals5–8 compared with a 63% overall proportion in the United States cancer population. Geographic barriers that limit access to oncology clinical trials also have been cited commonly by patients as reasons for their nonparticipation.9

Despite knowing that accrual rates are low and identifying the factors involved, there has been little progress. Less than 4% of adult cancer patients in the United States participate in National Cancer Institute-sponsored clinical trials annually, a rate that has not improved in almost 2 decades.10 This is despite recommended target participation rates of between 10% and 15%.11 To provide state-of-the-art therapy for all patients, attention to differential group access and participation in research is warranted.

Many of the barriers to trial participation that have been recognized are modifiable; however, data are scarce on how successful or unsuccessful trialists have been in overcoming these barriers. We believe that there is a need to move forward and target recognized barriers to trial recruitment. Our group has aimed to increase trial awareness and subsequent accrual by developing a satellite clinical trials center in an area of socioeconomic disadvantage where easy access to cancer clinical trials normally would not be available. Our objective has been to improve awareness of trials by allocating particular trials based on the interest of physician and clinical nurse research assistants (CRAs).

We have examined prospectively collected clinical and sociodemographic data from patients enrolled into oncology clinical trials between 1997 and 2005 at the Queen Elizabeth Hospital (TQEH) and at a satellite clinical trials unit that was developed at the Lyell McEwin Hospital (LMHS) in 2000. In particular, we were interested in the impact that the satellite center had on clinical trial accrual rates and patterns, especially among socioeconomically disadvantaged and elderly patients. To investigate this further, the postal codes of trial participants who were recruited from the satellite center were linked to key SES indicators for the area.12

TQEH is a 367-bed public hospital that services to a population base of approximately 250,000 individuals who primarily live in the western suburbs of Adelaide, South Australia. The LMHS is a public hospital with 198 beds in the northern suburbs of Adelaide. The 2 hospitals had serviced >700,000 individuals as of June 30, 2004, just over 50% of the state's population. The Index of Relative Socio-Economic Disadvantage Score for the western and northern regions is lower than for the state as a whole, especially within the region serviced by the LMHS.12 Within the northern region, there are higher than average levels of single-parent families (13.3%), unemployment levels (7.8–21.1%), low-income households (24.8%), jobless families with dependent children (24.1%), and unskilled and semiskilled workers (22.9%). The proportion of the population aged ≥65 years in this region is 12%, which is lower than in the more advantaged areas of the state. The use of income support, including aged pensions (78%), disability support pensions (7.6%), and sole-parent pensions (10.4%), is higher within this region. In addition, a significant number of dwellings do not have access to a motor vehicle (maximum rate of no access, 19.9%). Having private health insurance increases the range of health services that can be accessed. In the most disadvantaged areas within the northern region, the population that is covered by private health insurance was only half that (34.9%) of the more advantaged areas in Adelaide (69.1%). Furthermore, more patients from the northern area spend >6 months on hospital surgical waiting lists compared with patients from more advantaged parts of the state.

Oncology clinical trials were not easily accessible to patients living in the northern suburbs until 2000, when the satellite center was established at the LMHS. This was coordinated and administered by staff based at TQEH. It has been demonstrated that physician interest is crucial to successful trial recruitment.13 In addition, nurses and CRAs have great influence and appear to have a unique role in the process of recruiting patients to active clinical trials.2 From our experience, tumor streaming by physician and CRA interest has been a valuable way of improving the identification and recruitment of patients to a clinical trial and has been incorporated into the structure of the satellite trials unit at the LMHS. Tumor streaming is an extension of subspecialization that is being practiced increasingly by many centers around the world. It has the potential to improve many of the practical matters that previously have added to the physician's reluctance to accrue patients, including recall of active clinical trials, eligibility criteria, and time taken to perform other recruitment activities.

Between 1997 and 2005, the hospital-based cancer registry identified 3051 patients who had a new diagnosis of cancer. Of these patients, 346 (11.34%) were enrolled into oncology clinical trials during the period. Higher overall clinical trial accrual rates coincided with the development of the clinical trials unit at the LMHS in 2000. An analysis of accrual rates from each site demonstrated that the satellite center is capable of achieving recommended target participation rates of between 10% and 15% and, in fact, can attain results similar to those attained at the parent site. The percentage of patients participating in clinical trials annually from TQEH were 13% in 2000, 15% in 2001, 18% in 2002, 19.8% in 2003, 13% in 2004, and 17% in 2005. Corresponding participation rates for the satellite center at the LMHS were 2% in 2000, 7.5% in 2001, 8.2% in 2002, 12% in 2003, 10.4% in 2004, and 18.6% in 2005. In total, close to 25% of all participants were recruited from the LMHS, a population with considerable socioeconomic disadvantage. Combined accrual rates for TQEH and LMHS for 2005 were 17.5%. Overall, 42% of patients were women, and 58% of patients were men. Patients aged ≥65 years made up 45% of participants, a higher proportion than that reported by many others. Patients enrolled into colorectal cancer trials made up 44.2% of the total, and breast cancer trial enrollments made up 17.6% of the total.

The success of clinical trials, which are critical to the advancement of medical oncology, depends on the recruitment of eligible participants in a timely manner. Participation of specific minority populations, including socioeconomically disadvantaged and elderly patients, is desired to increase the validity and general applicability of results. Accrual rates in oncology clinical trials within our region are higher than the rates reported by others. In particular, patients of lower SES and the elderly are well represented. The strategy of improving disparities in access to clinical trials by establishing a satellite clinical trials center in an area of lower SES does appear to have a positive impact on trial accrual. Tumor streaming by physician and CRA interest also has improved awareness of clinical trials and subsequent recruitment. However, there is a need for further prospective studies of targeted strategies aimed at improving trial recruitment and retention among traditionally underserved populations.


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