Background
Self-tests are those where an individual can obtain a result without recourse to a health professional: by getting a result immediately (e.g. most prostate specific antigen (PSA) and faecal occult blood (FOB) tests), or by sending a sample to a laboratory that returns the result directly to the individual (e.g. some chlamydia tests). Self-tests can be diagnostic (e.g. urine tests for pregnancy), for disease monitoring (e.g. blood pressure), or both (e.g. PSA tests). There are currently tests for more than 20 different conditions available to the UK public [
1].
A number of reports have expressed concern about the development of self-testing [
2,
3]. Potential problems highlighted include: lack of professional support when receiving bad news; lack of expertise in interpreting results and action needed; unreliable results generating false security or anxiety; that individuals may be forced to take tests by people other than health professionals (e.g. employers); the potential break-down of public health surveillance; that commercially driven test development may lead to demands for further testing or treatment which the NHS is unable to meet. Much coverage of self-testing in the press is also negative, warning of the unreliability of tests and dangers of misunderstanding medical information [
4‐
7]. However, such reports do not seem to have deterred users. Market research reports that "almost six in ten Britons diagnose themselves at home with self-testing equipment instead of going to the doctor", although this does include thermometers [
8]. Sales of self-testing equipment are reported to have increased dramatically: almost £54.3 m was spent on self-diagnostic products in 2002, a 32% growth since 1998 [
9], and it has been predicted that this will rise to over £60 m by 2007 [
8]. Market surveys in the US indicate at least 25% of all medical tests are conducted outside the hospital laboratory and predict that by 2008 up to 45% of testing will be either near patient or self-testing [
10]. Revenue from the self-testing market in the US doubled from $1.19 billion in 1994 to $2.34 billion in 2000 and is anticipated to continue to grow. Long waits to see a GP and an increasingly health-conscious population are among the factors thought to contribute to the increased sales [
8]. Some areas are growing fast, particularly the use of rapid manual or self-test kits [
11].
Reasons for using self-tests may include: tests not being available from a doctor (e.g. PSA tests to young men); convenience; privacy; not wanting to bother doctors or use NHS resources; dissatisfaction with, or mistrust of doctors and/or medicine. In the UK, NHS Direct and drop-in health centres aim to increase access to health services and health information [
12]. Such initiatives, together with interventions aiming to redefine patients as consumers, the increased availability of over the counter medication, and funding pressures for health services, have encouraged the development of a self-care culture. People are taking more responsibility for their own health and adopting more consumerist attitudes to health care [
13‐
15]. Self-testing may be part of this. Also, such test results may empower people within a consultation with their doctor, as has been seen in the use of Internet resources [
16].
Self-testing is marketed as a valuable way of alerting people to serious health problems so they can seek medical help [
17]. Traditionally diagnosis, decision-making and definitions of illness occur within a health service [
18]. Having test results in isolation (e.g. slightly raised PSA levels) without an assessment of signs and symptoms may result in inappropriate labelling as a 'patient' [
19] and increase perceived risk. Self-testing may have beneficial psychological effects (true negatives), but it could also impact on the delivery of population based screening programmes, increase demands on health care services (investigation and treatment of positive tests), lead to false re-assurance (false negative tests) or raised anxiety, and alter health behaviour/perceptions of risk. There is some evidence that GPs feel that they are increasingly consulted by the 'worried well', that their prescribing behaviour is affected by patient demand, and that they are pressured by their role as gatekeepers to specialist services [
20‐
22], and increased self-testing may exacerbate this situation.
No systematic reviews relating to self-testing generally or self-testing for cancer have been identified. The only UK surveys addressing the issue of self-testing state that 18.3% and 24.9% of people reported that they would prefer self-testing to testing by a doctor and a pharmacist respectively [
23], and that 32% of people had bought a self-test kit (although this did include pregnancy tests) [
24]. Although other work is ongoing [
25], there is currently a lack of published research examining the impact of self-testing on individuals or on the healthcare system. The literature that does exist has limitations; it tends to concentrate on efficacy and reliability [
26,
27], has been carried out in different health cultures in the US or Europe [
28], or is based on opinion only without empirical data [
29]. There has been research in areas which may be relevant to self-testing for cancer, for example attendance for routine screening, self examination and use of over the counter medication [
30‐
33]. Such behaviours have been associated with socio-economic status, age, gender, ethnicity, and level of trust of the medical profession [
32,
34,
35]. The relevance of these factors to self-testing for cancer may depend on whether self-testing is used to inform choice and complement standard care, or to challenge standard care.
A variety of cancer related self-tests are available to buy by members of the UK public, including tests for faecal occult blood [
36], prostate specific antigen [
37], haematuria [
38], serum α-Fetoprotein and serum carcinoembryonic antigen (CEA) [
39], and breast cancer self-examination kits [
40]. Cancer related self-tests are not only widely available but also relatively inexpensive, costs range from less than £1 for an FOB test to £25 for devices to feel for breast irregularities.
Advertising directly to the public for genetic tests for the familial breast cancer genes BRCA1 and BRCA2 began in the USA in 2001 [
41]. Advertising cancer genetic services increases demand for products that are likely to be of little benefit outside high-risk families [
42]. A number of companies have promoted the idea of "predictive medicine" (using genetic tests to predict the chances that someone will get serious illnesses like cancer), and then offering either lifestyle advice or medication [
43,
44].
Health Which (December 2002), the press (Guardian November 4 2003 and February 6 2004) and BACUP [
45] have advertised the availability of cancer self-test kits from high street chemists. Should Internet sales be shown to be profitable, a wider range of cancer self-test kits is likely to become available from pharmacies. The possible range of new products related to the prevention, diagnosis and treatment of cancer is wide, and potential new developments include a saliva test for breast cancer [
46], bladder cancer home tests (currently prescription only) [
47], ultraviolet monitors to avoid skin cancer [
48], and kits for testing your response to alternative cancer treatments [
49].
Cancer related self-testing may develop to include tests for the early diagnosis of cancers at more sites, the genetic determinants of disease [
50] and drug effectiveness [
51]. The characteristics of those who participate in population based screening and the impact of screening programmes (i.e. costs and benefits to the NHS and participants) have received considerable attention [
52]. Almost nothing is known about the extent to which people screen themselves for cancer or why they do this. Self-tests for cancer could alter perceptions of risk and health behaviour, cause psychological morbidity and have a significant impact on the demand for healthcare. Furthermore, they may impact on the cost-effectiveness of population-based screening. It is essential that we gain an understanding of the frequency of self-testing for cancer, characteristics of users and the effects of test results on both users and the health service. It is important that we obtain this information before self-testing for cancer becomes more widely available, to be able to determine the potential impact on both the public and health services.
Study aims
To estimate the prevalence of cancer-related self-testing use and compare characteristics of users, non-users and potential users of self-tests for cancer.
Competing interests
The author(s) declare that they have no competing interests.
Authors' contributions
All the authors contributed to the design of the study. Sue Wilson drafted the study protocol with input from all authors. All of the authors have read and approved the final draft.