More than 50% of adults with cancer in the UK will survive for at least 5 years following their initial diagnosis (Cancer Research UK, 2006
). Recent improvements in cancer survival are largely due to earlier diagnosis and advancements in treatment. Despite having favourable effects on cancer survival, radiotherapy, hormone treatment and combination chemotherapy regimens can cause long-term organ damage and functional disabilities. These long-term toxicities, or late effects, defined as ‘unrecognised toxicities that are absent or subclinical at the end of therapy' can manifest as new diagnoses months to years after the completion of primary cancer treatment (Hewitt et al, 2006
). Late effects related to treatment are widely variable and are linked to characteristics of the cancer, the modality and intensity of treatment and the underlying health status of the individual experiencing cancer.
Some late effects are predictable, for example, the effect of radiotherapy treatment on adjacent organs. This may result in the increased incidence of hypothyroidism and heart failure in breast cancer patients (Clarke et al, 2005
; Darby et al, 2005
; Smith et al, 2008
). The effects of hormonal treatments are also predictable; changes in bone physiology and increases in osteoporosis are increasingly found in patients treated with hormone therapy (Chen et al, 2005
; Lopez et al, 2005
; Shahinian et al, 2005
; Saad et al, 2008
; Brown et al, 2010
). The late effects of chemotherapy are less easy to predict and are often drug specific. For example, cognitive impairment is a well-recognised late effect of chemotherapy (Hewitt et al, 2006
). A conceptual framework of its aetiology proposes interactions between treatment effects on clotting in small blood vessels and endogenous hormones, in addition to chemotherapy mediating depression and fatigue through cytokine involvement leading to cognitive impairment (Heflin et al, 2005
). Finally, some associations are difficult to explain with current knowledge. There is a reported association between diabetes mellitus and colorectal cancer: both diseases share common risk factors, but diabetes has also been shown to be a potential independent risk factor of several common cancers including colorectal cancer (Larsson et al, 2005
). In addition to the effects of treatment, cancer patients are also at increased risk of developing subsequent disease because of the risk factors that led to the original cancer. Some of these risk factors are modifiable, for example, smoking and alcohol, and a cancer diagnosis may provide motivation for lifestyle change. Other factors, such as genetic mutations and polymorphisms, are currently immutable. A summary of common long-term and late effects of treatments for breast, colorectal and prostate cancer is shown in .
Examples of potential long-term and late effects of treatment amongst breast, colorectal and prostate cancer survivors
The prevalence of these late effects in a general population of adult cancer survivors is still uncertain; however, it is likely that with sophisticated and intense treatments long-term effects will become more common (Carver et al, 2007
). The complicated interaction of cancer, cancer treatment and risk factors means that community-based prevalence is difficult to predict. It is important to determine the burden of late effects in cancer survivors in order to provide guidance on long-term monitoring, case finding for disease, health promotion and planning service provision.
The main aim of the research reported here was to assess the size of this problem by documenting the incidence of late effects related to cancer treatment in a population-based cohort of cancer survivors in the UK. Our data, which were derived from comprehensive primary care records, also allowed us to explore the relative incidence of all health problems in cancer survivors compared with a control population.