This blog is the 4th in a series of 5 on the topic of cancer written by Dr Philip Borg MD FRCR FAAMFM.
Dr Borg is a Consultant Cancer Interventional Radiologist and a Longevity Medicine Specialist.
Prevention is better than cure. In the previous blogs we learnt about what you can do to reduce your risk of developing cancer through various cancer prevention strategies.
We also learnt about the huge differences in chances of cure and survival of cancer depending on the stage at which the tumour is first detected. If we were to take colon cancer as an example, for tumours diagnosed at stage 1 (small tumours localised to the surface of the bowel) the 5 year survival rate is 90%. For tumours diagnosed at stage 4 (large tumours, spread beyond the bowel to other organs), the 5 year survival rate is 10%.
This correlation between tumour stage at diagnosis and survival is true for nearly all cancers. So if one does develop cancer (50% will develop some form of cancer in their lifetime), it is so important to catch cancer early as this will affect chances of cure and survival immensely.
From these statistics we can understand the importance of looking out for early signs and symptoms of cancer. However sometimes tumours can grow and progress to cancer without causing any signs or symptoms.
In this blog we will discuss various tools of cancer screening - tests we can carry out to identify tumours before any symptoms occur. The purpose of cancer screening is to help find pre-cancerous tumours or cancers at an early stage which may be easier to treat successfully and improve chances of cure and survival.
National cancer screening programmes for example colorectal, cervical and breast cancer screening programmes have shown improved outcomes in cancer survival. Recommendations regarding cancer screening differ between countries, in terms of which cancers to screen for, how to screen for the same cancer type, what age to start and stop and how often to perform a test. These differences are partly due to finances available in that country’s healthcare system as well as other factors such as how common certain cancers are in different populations.
For example colorectal cancer screening programmes exist in the USA and in the UK but are very different. In the USA patients are invited to have a colonoscopy (the gold standard test) from ages 45-75. In England patients are offered a FIT (Faecal Immunochemical Test) between the ages of 60-74. If the FIT test is positive for blood then the patient is invited for a colonoscopy. Colonoscopy is better test overall and the endoscopist can also treat and remove a tumour / cancerous growth during the procedure. The screening method in the USA detects and treats tumours at an earlier stage than the UK, but uses more resources. Lung cancer screening with low dose CT in high risk patients (smokers) is offered in the USA but not yet offered nationally in the UK.
Governments decide on cancer screening programmes depending on cost effectiveness. This blog and the cancer screening programme offered at Longevitydoctor aims to describe an optimal cancer screening programme in the private healthcare system. There is no ideal one size fits all programme, ideally each programme is personalised according to each patient’s personal and family risk factors.
Different cancer screening methods
Cancer screening has different methods depending on the type of cancer we are trying to detect, your age and risk factors.
Physical examination (eg. visual inspection for skin lesions, breast examination for lumps, examination of lymph nodes in neck, armpit, groin);
Imaging (CT for lung tumours, mammograms and ultrasound for breast, MRI for brain tumours, ultrasound for testes);
Liquid biopsy (blood test that can detect circulating tumour cells or tumour DNA which may detect the presence of a cancer before it causes signs or symptoms);
Blood tests (PSA for prostate cancer, other tumour markers for example CEA, CA125 and CA19-9 may indicate cancer).
Smear test (pathology test of cervical cells for cervical cancer);
Genetic tests (testing your genetic profile for genes that you have inherited from your parents that may increase your risk of developing g certain cancers);
FIT (Faecal Immunochemical Test detects blood in faeces which may indicate a tumour);
Endoscopy (upper GI (stomach oesophagus) or lower GI endoscopy involves the use of a camera that can detect tumours and biopsy or even treat abnormalities).
After taking a history of your individual risk factors and family history, your doctor or cancer specialist will be able to advise the correct screening method and how often screening should take place.
Liquid biopsy
Liquid biopsy based multi cancer early detection tests (MCED) are a relatively new technology that can be used for cancer screening. A blood sample from a patient without any signs or symptoms of cancer is analysed in a lab for DNA (cell-free DNA coming from cancer cells elsewhere in the body) or CTCs (circulating tumor cells). A liquid biopsy test can detect up to 70 different types of cancer with a sensitivity of 88.2%.
The advantages of liquid biopsies is that they are non invasive, do not involve ionising radiation and are easy to perform. They are particularly important in detecting cancers like pancreatic, ovarian, and brain cancers, for which no screening tests exist and are usually not diagnosed until they are advanced and difficult or impossible to treat.
The difference between liquid biopsy and genetic cancer screens
Liquid biopsies look for evidence of cancer in a patient’s body at the time the test is performed. Genetic cancer tests assess risk of developing cancer by analysing a patient's DNA for genes that a patient may have inherited from their parents which increases their risk of developing a particular cancer. For example, the presence of particular variants of the BRCA genes increase the risk for breast or ovarian cancers. It is estimated that only 5-10% of cancers are due to inherited genes. The great majority of cancers are caused by other factors including ageing, viral infections, smoking, being overweight, not exercising regularly and not having a healthy balanced diet.
Cancer screening drawbacks
Cancer screening can detect tumours at an early stage and allow early treatment and improve cancer survival. However, no cancer screening test is perfect and it is important to discuss which tests are right for you with a qualified medical professional. Drawbacks of cancer screening include false positives results, complications from invasive procedures and overdiagnosis. Some very early stage cancers may never cause any symptoms throughout a person's lifetime, prostate cancer is a good example.
Cancer screening programmes save thousand of lives every year and are a valuable tool in detecting cancer early and improving cancer survival.
If you are interested in a private cancer screening programme including access to a multi cancer screening blood test, please visit the Longevitydoctor cancer screening section.
In our next and final blog in this cancer series we will discuss cancer treatment including immune based therapies and interventional oncology treatments.
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