Prevention stages of cancer

Health and length of life benefit much better from preventive actions to avoid disease than from treatment of disease. Most factors that contribute to the development of cancer arise from individual decisions regarding personal lifestyle, and many of them can be monitored [1]. Cancer risk factors [2]:

smoking tobacco 30%
diet 30%
hereditary factors 15%
infections 5%
job-related factors 5%
obesity and lack of physical activity 5%
alcohol 3%
UV radiation 2%
drugs 2%
environmental contamination 2%
other 1%

Prevention of disease – in a strict sense, refers to counteracting the development of a disease; in a broader sense, the concept also encompasses actions aimed to stop or delay further progression of the disease at a pre-clinical or clinical stage [3].

There four stages of disease prevention [4]:

Early prevention – seeks to eliminate such social, economic and cultural lifestyle factors that contribute to a higher risk of cancer. A good example of early prevention activities is the so-called new tobacco directive which is aimed to prevent smoking and its effects (cancer), an initiative taken by the European Parliament to protect public health by actions addressing the sources of pathology.
First stage (primary) prevention – refers to counteracting a disease by reinforcing individual’s immunity to illness (protective vaccinations, e.g. against HPV) or reducing the exposure to harmful factors in susceptible individuals (e.g. regulations that protect non-smokers against passive smoking). Around 70% of cancer cases are estimated to result from the effects of harmful factors related to lifestyle and diet or present in the environment. Many of them may be removed to reduce the risk of disease.
Second stage (secondary) prevention – means counteracting health consequences of a disease by early diagnosis (at the pre-clinical stage) and treatment (including screening, periodical examinations, improvement of treatment and rehabilitation efficacy). Screening is a procedure performed to detect an undiagnosed diseases or pathologies by means of massively applied simple tests. Screening tests allow to separate individuals who are probably healthy from those who are likely to be ill. It should be stressed that screening is just a preliminary examination and may not be considered as diagnosis; it requires further tests or treatment [4]. The safety of patients is of particular importance in this case, as screening is done for high risk yet potentially healthy individuals. Some types of cancer are preceded by pre-malignant conditions whose occurrence indicates a higher likelihood for cancer to grow in the nearest future. Early treatment combined with good response to treatment prevents cancer from developing. A good example is cancer of the cervix which is often preceded by the growth of abnormal cells in the cervical intraepithelium. That condition can be effectively cured before an invasive cervical cancer develops. Some types of cancer are considered to be strongly associated with certain infections. Human papilloma virus (HPV), for instance, is the main contributing factor to cervical cancer [5]. Most cancers exhibit a strong correlation between survival and stage of disease which is usually determined by the size of the primary tumour or cancerous process being limited to a local state. There is a high chance, then, that early detection of the disease will prevent it from developing and cause the mortality rate to be reduced in the future. Breast cancer is a classic example of that with a demonstrated relationship between the size of the tumour at diagnosis and survival after diagnosis [5].
Third-stage (tertiary) prevention – used at an advanced stage of disease to prevent death or exacerbation of disability in patients who cannot be cured. Third-stage prevention involves actions aimed to halt the progression or complications of already developed disease as a significant aspect of curative medicine and rehabilitation. Third-stage prevention consists of efforts to reduce disability and injury caused by existing deviations from a healthy condition and promote proper treatment methods among patients. Tertiary prevention is hard to separate from treatment, as the main objective of treatment in chronic diseases is to prevent those diseases from recurring [4]. In particular stages of disease, various measures can be used to prevent the progression of the pathological process – this, however, requires a thorough knowledge of the natural history of the disease, its stages in particular [3].

References:

1. Kordek R, Jassem J, Jeziorski A, Kornafel J, Krzakowski M, Pawlęga J (ed.). Onkologia. Handbook for students and physicians. Fourth edition, revised and updated. Via Medica, Gdańsk 2013.
2. Beliveau R., Gingras D. Dieta w walce z rakiem. Profilaktyka i wspomaganie terapii przez odżywianie. Delta 2007.
3. Jędrychowski W. Podstawy epidemiologii. Handbook for students and physicians. Wydawnictwo Uniwersytetu Jagiellońskiego. Krakow 2002.
4. Beaglehole R., Bonita R., Kjellström T. (translations by Szeszenia-Dąbrowska N.). Podstawy epidemiologii. Prof. J. Nofer Occupational Medicine Institute Łódź 2002.
5. Didkowska J., Wojciechowska U. Populacyjne programy przesiewowe w onkologii, Oncology Center – Institute, Warsaw 2007.