Screening tests for cancer
At present we have no single test to screen for cancer. By the time one waits for lumps or symptoms to develop it is likely to be too late. It is much better to be aware of the risk factors for cancer and target those one is at risk of.
Firstly observe all the lifestyle changes to protect against cancer. See The general approach to maintaining and restoring good health.
If Governments were serious about cancer screening they would instigate routine blood tests for DNA adducts. This looks at substances stuck on to DNA which should not be present. DNA adducts are pre-malignant lesions.
Increasingly private labs such as Lifescan are offering whole body screening scans for cancer. Do find out if they use CT scanning (in which case you are exposed to radiation) or MRI scanning (no radiation).
Many cancers have cancer markers. See The Doctors Laboratory "Tumour markers at a glance" but this would be a very inefficient way of screening for cancer because so many tumour markers would have to be measured and this would be very expensive. However once a cancer has been diagnosed, cancer markers are often very helpful to monitor response to treatment. The best example is a PSA for prostate cancer, but ovarian cancer can be monitored with a CA 125, melanoma with S 100 or melanin, many cancers with a CEA and so on.
If you have risk factors, then screen for specific cancers. In order of what is common:
Suspect in smokers, passive smokers, asbestos exposed, radon exposed, industrial pollution exposed. By the time a lung cancer is seen on an X ray, it is too late for curative treatment. The best bet as this stage is probably regular MRI scanning - expensive but at least free from radiation exposure.
There is evidence to suggest that with oestrogens and female cancers, there are "good" and "bad" oestrogens. Oestrogens can be broken down into "good" and "bad" oestrogens with the 2 being good and 16 bad. Measuring the 2/16 alpha hydroxyoestrone ratio may be important. The ratio can be improved by eating cabbage and other brassicas - more reason to eat a stoneage diet!
- Colonoscopy every three years is the current gold standard but time consuming and uncomfortable.
- Faecal calprotectin has great promise as a useful screening test for cancer - at present the statistics are good.
- Virtual MRI scanning is here to stay and will be a useful tool in the future but currently expensive.
- Faecal occult blood will pick up some tumours at an earlier stage but cannot be relied on to completely eliminate a diagnosis of bowel cancer.
Melanoma is the nasty one which needs diagnosing early and excising early. They are most often mistaken as warts - the latter haev a fine bumpy surface and are slightly raised above the level of the skin. Melanomas are irregular in size, shape, colour, thickness, may itch of bled. If in doubt ask a doctor to look at it. Many hospitals have pigmented lesion clinics which anyone can walk in to. Look at some pictures on line.
Other skin cancers are less serious. Basal cell tumours (rodent ulcers) are slow growing and rarely metastasise. Squamous cell cancers are a bit more tricky but in both cases early treatmetn is best. Again look at pictures on line.
There is an interesting topical treatment for these two cancers said to have a very high success rate. It works with virgin untouched skin cancers, not those which have already been chopped, burnt or otherwise treated. Look up Curaderm - a natural treatmetn derived from eggplant. Also said to be good for solar keratosis - sun damaged skin (looks like a brownish flake) which is a pre-malignant lesion.
Routine screening regularly is essential for all women with HPV virus. Other major risk factors include the Pill and HRT, first sexual intercourse at a younger age, multiple sexual partners.
A blood test for a prostate specific antigen (PSA) will be raised if there is more prostate tissue. This maybe because of benign prostatic growth or may be because of a tumour. So a PSA is a useful screening test which then needs follow up ideally with a PCA3 urine test. This looks at cells in the urine after a rectal examination. To my mind this is preferable to prostate biopsy where one risks spreading tumour cells along the biopsy tract.
Routine blood tests would show early leukaemia changes. Leukaemia often results from chemical poisoning because the problem is in the bone marrow and this fatty area is where many fat soluble chemicals bio-accumulate.
The ideal in any malignancy is to have some sort of marker to know if the above regimes are being effective. We already have some blood tests for some cancers. Dr Papasotiriou of the Research Genetic Cancer Centre, has developed a very much more sensitive test for minimal residual disease detection, done on a blood sample, which he maintains will be a useful screening test for any cancer. This method involves a selection of tumour cells (negative and positive selection) by specific immuno-magnetic beads coating the monoclonal antibodies followed by cell detection using laser optics. Tumour stem cells are also detected for additional accuracy. The presence of any malignant cells would suggest a tumour somewhere in the body without being able to know where that tumour was coming from. These tests can also be used to help monitor disease activity.
To put this test in context, cell counts as low as one cell per ml can be detected. For a tumour to be visible on a scan, between a thousand million and a million million cells must be present. If significant malignant cells are detected then Dr Papasotiriou can go on to do the above chemo-sensitivity test to see to what these cells are sensitive to. These tests by Dr Papasotiriou are increasingly being used in this country. The pioneer of their use in this country is Dr Nicola Hembry. It is essential to have a trained adviser to interpret this test!
- Faecal calprotectin
- Faecal occult blood
- Full blood count
- Liver profile (liver function test)
- Prostate specific antigen (PSA)
- Disease screening tests
- DNA adducts
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