The patient population
It is estimated that one in two people born after 1960 will develop cancer. In addition, cancer is the leading cause of mortality in the UK and responsible for more than one in four deaths (Cancer Research UK statistics). Due to an ageing population, the overall incidence and death rates from cancer are rising, although age-specific incidence rates are falling.
There is wide geographical variation in the incidence of cancer and cancer-related mortality in the UK. This is in part attributable to differences in the prevalence of modifiable risk factors in local populations. It is estimated that approximately 42% of all cancers in the UK are preventable and due to modifiable risk factors such as smoking, obesity, alcohol, sun exposure, diet and physical inactivity (Cancer Research UK statistics; Parkin et al, British Journal of Cancer (2011)). There is also an association between income inequalities, ethnic minority populations and cancer incidence and late presentation.
Given the scale of the burden of cancer mortality and morbidity, and the one in two lifetime risk, a broad population-based strategy coupled with local risk factor prevalence-linked focused prevention strategies are likely to be most effective in combating this disease, as highlighted in the National Cancer Taskforce report (opens PDF, 577.23KB) from 2016.
Prevention of disease
There are extensive data linking modifiable risk factors to cancer, and evidence to support that primary prevention is effective in reducing cancer risk.
The most important lifestyle factors responsible for cancer in men are: smoking (23%), deficient intake of fruits and vegetables (6.1%), occupational exposures (4.9%) and alcohol consumption (4.6%). In women these are: smoking (15.6%), being overweight and obesity (6.9%) and infectious agents (3.7%).
The single most effective and important cancer prevention strategy is therefore smoking cessation. This has been targeted through government policies on taxation and advertising, public health campaigns, access to stop smoking clinics, availability of nicotine substitutes, and drugs to help people to stop smoking.
Similar strategies to combat alcohol, obesity and dietary causes of cancer such as deficient intake of fruit and vegetables, low fibre intake, high salt intake, and red and processed meat are being championed by government policies and public health initiatives.
Cervical, anal and oropharyngeal cancers are associated with human papilloma virus (HPV) infections. HPV vaccination has been shown to reduce the incidence of HPV-associated malignancies, and has now been incorporated into the national immunisation programme.
In addition, the national cancer screening programmes for breast, bowel and cervical cancer have had a key role in identifying and treating patients with pre-malignant disease, and reduce the risk of cancer-associated mortality.
Chemoprevention with tamoxifen and raloxifene have been recommended by NICE for patients at high-risk of developing breast cancer, and aspirin is effective in preventing colon cancers in patients with Lynch syndrome.
Patients with a cancer and their relatives, even in the absence of identifiable cancer risk genes, are at increased risk of further cancers. The role of medical oncologists is therefore to act in conjunction with the above, providing information on risk factors, signposting to stop smoking and other health promotion programmes, and encouraging patients and their relatives to participate in cancer screening programmes.
Planning effective services
Cancer Research UK has extensive published guidance on the prevalence of cancer risk factors, and priorities for cancer prevention (Cancer Research UK stats). This is also reflected in the recommendation of the Independent Cancer Taskforce Report, which sets out key areas and targets for reduction in cancer mortality due to modifiable risk factors.
While much of the emphasis is in on population-based strategies aimed at reducing smoking, alcohol, sugar and obesity through government policy interventions, there remains a key role for primary, secondary and tertiary care physicians to promote these initiatives, in addition to encouraging uptake of screening and immunisation programmes.
An area that that is lacking in implementation, despite NICE guidance, is the implementation of cancer chemoprevention programmes for breast cancer. Services to cater for this group of women at high risk of breast cancer are extremely variable across the country, and would benefit from more uniform commissioning and implementation.
Given the sheer scale of the burden of cancer, effective prevention, and early detection strategies are likely to be the cornerstone of disease control at a national and international level for the foreseeable future.