This is a chapter from Chris Woollams’ top selling and easy to read book Everything You Need to Know to Help You Beat Cancer. Certain screening techniques are invaluable in the fight against cancer - for example, colonoscopy can tell you about the presence of polyps before they become cancers. However, many tests are simply not accurate enough - the PSA test has been under severe criticism in the USA and breast cancer screening has proven of little benefit to 40-50 year old women (CRUK).
Can screening help beat cancer?
All the best advice is that the earlier you discover a cancer the greater your odds are of beating it. Screening can play an important part in this process. However it is nowhere near as accurate
as the medical profession would have us believe. Basically screening can be simplified under three headings.
(i) Tried and trusted methods?
Palpation (looking for a lump with your fingers)
Women over 30 should examine their breasts at least every month. In the USA if you have ever had radiation treatment on the chest region, it is recommended that start self-screening much earlier.
The self-test should be performed seven to ten days after the start of the menstrual period, since the texture and density of the breast tissue will change during the monthly cycle. Women who are postmenopausal should choose the same day every month.
Firstly conduct a visual examination studying the size, dimpling, and shape of each breast including the nipple. Then gently feel your breasts using the pads of your three longest fingers looking for lumps, bumps and changes. A fuller description can be obtained from the breast cancer charity.
Mammography
Years of usage of the mammogram, especially in the USA, has created a popular belief in its importance. And during the 70s and 80s as mammograms came into widespread use, coupled
with early detection and a greater consciousness of breast cancer, breast cancer deaths fell by 30 per cent. Mammograms provide a detailed image of the breast tissue. If the tissue is soft, detection of an unusual lump is relatively easy, but becomes harder the more ’lumpy’ the breast tissue. The problem
is that women most at risk of breast cancer are far more likely to have dense breast tissue, making emerging small tumours very hard to spot.
Doctors recommend women over 40 should have the test annually as early detection provides better rates of cure and can offer the each mammogram delivers a high dose of radiation - up to 1,000
times that of a normal X-ray - and there is much debate as to whether the mammograms themselves do more harm than good. A two-year study in Denmark, originally published in the Lancet and updated in October 2001 suggests that a number of flaws in the mammography process makes the test ’virtually useless’. This has caused controversy and even anger amongst the medical profession.
The European Breast Cancer conference in March 2004 stated that in dense tissue mammograms were no more effective than 59 per cent. (In soft tissue the maximum figure was 67 per cent.) Dr Van der Horst said that dense tissue was on the increase and made it "harder to pick up tumours ... and may lead to unnecessary biopsies". Dr Kelly McMasters, a surgical oncologist at the University of
Louisville is quite clear that the current technology is still showing results and is a lot better than examining yourself. ’The problem with palpation is that when a tumour is big enough to feel it’s
often spread already to the lymph nodes. This makes it more likely to be fatal’. The jury is out, and women should make absolutely sure they understand all the risks, and whether they will feel confident in the results.
They must also be clear that they understand the results. 50 per cent of the ’findings’ of mammograms are in fact DCIS, calciferous particles in the ducts. At least 80 per cent never lead to a cancer, and these deposits at worst are only pre-cancerous (UCLA, March 2004).
Testicular self-examination
It is not hard to examine the testes. Testicular cancer is most common in the 15-40 age group. The test should be carried out monthly after a warm shower, by rolling each testicle slowly and gently between the thumb and fingers. Any small lump or hard object should be examined by a doctor. Other signs to watch for are dull aches in the testicle, groin or abdomen. This is a highly
curable disease especially if caught early.
Sigmoidoscopy
A sigmoidoscope is a narrow tube with a light at the end. Inserted in the rectum it can find polyps and tumours in the lower colon. By contrast a colonoscopy is a longer tube and looks further in to the colon. A newer system called flexible sigmoidoscopy, aims to detect precancerous growths using a miniature camera inserted into the bowel. The UK Health Minister announced at a national cancer
conference that he is intending to introduce a national bowel cancer screening programme for everybody over the age of 50, and is awaiting final results from a Cancer Research UK study.
Two approaches to screening are under consideration, one of which involves testing faeces for early signs of cancer, while the other uses sigmoidoscopy to detect the pre-cancerous growths.
Pap smear
Created by Dr Papaniculaou in the 1940s it has been a major contributor to the lowered rates of cervical cancer since that time. The test can detect both pre-cancerous and cancerous cells in the
cervix. The test involves inserting a speculum into the vagina so the cervix can be clearly seen. Sample cells are then taken from the outer part of the cervix using a spatula and using a brush from
the inner part. A pelvic examination is also conducted at the same time. An annual smear is recommended after the commencement of sexual activity.
In July 2004 Professor Julian Peto at Cancer Research UK estimated that smear testing was saving 5,000 lives per year in the UK, as up to half the young women in Britain were infected with a high risk strain of HPV by the time they were 30 years old.
Tumour markers
A number of factors are to be found in the blood each indicating the presence of a cancer. Measuring their presence and level can be helpful not just to indicate the cancer but to monitor the effectiveness
of treatments.
PSA test
If you are 50 years or over and living in the West there is a very good chance you will have an enlarged non-malignant prostate (termed benign prostatic hyperplasia). This carries with it certain
symptoms, which are virtually identical to those of prostate cancer. The UK charity, The Prostate Cancer Charity, defines them as:
• Difficulty or pain when passing urine
• The need to pass urine more often
• Broken sleep due to the need to pass urine
• Waiting for long periods before the urine flows
• The feeling that the bladder has not completely emptied.
With prostate cancer you may also suffer from blood in the urine, and/or lower back pain and/or dribbling. But be aware that many of the above symptoms can be caused by other factors e.g.
bacterial infection. Your doctor can simply feel if you have an enlarged prostate (a digital rectal examination). If he finds such an enlargement he will probably send you for a PSA test (prostate-specific antigen). This measures a specific protein in a man’s blood, the level of which was thought to correlate with prostate cancer. However, this test has been found to be flawed. In one research
study, factors found in the blood from high dairy consumption, vigorous exercise, or riding a bicycle in the previous 24 hours increased PSA levels. Indeed, the test does not seem to fully distinguish between enlarged malignant prostates and non-malignant ones, and one USA report concluded that as many as two thirds of those testing positive, probably are not! Never just have a single test, but three to six across a two month period.
CA125
CA125 levels can be used to detect ovarian cancer at an early stage. However although a number of other cancers can increase the level of CA125, so too can a number of benign conditions like endometriosis, fibroids and even pregnancy. For this reason the test is seen as flawed.
Pyruvate kinase
The majority of solid tumour cancers over-express this enzyme and this can aid detection. Pyruvate kinase testing in the blood is used as a diagnostic by a number of specialist clinics and seems
to be pretty accurate. Unfortunately the majority of GP’s and oncologists neither perform the test, nor are qualified to read the results.
Others
There are several current tests to ascertain whether a cancer is present. No one is particularly decisive but together they can give a reasonably accurate picture of events: Interleukin and Interferon: can both show immune response levels
CA15-3 : breast cancer
CA19-9 : oesophageal, bile duct and pancreas
CEA : oesophageal, lung, bile, colon, pancreas and bladder.
However, as before, no one of these is perfect and a complex picture has to be studied.
Now scientists from the Federal Drug Agency (FDA) and National Cancer Institute (NCI) in the USA have reported on another as yet unnamed protein test taking just 30 minutes and using a small sample of patient’s blood. Although the authors caution that more work is needed to understand the sensitivity of the test, the initial tests identified 50 out of 50 cancer, and 63 out of 66 non-cancer samples.
There is no doubt accurate protein tests could be of significant benefit. For example, currently more than 80 per cent of ovarian cancer patients are diagnosed at a late clinical stage and have a less than 20 per cent chance of five-year survival. In contrast early diagnosis results in 95 per cent survival over the same period making the possibility of protein tests a truly exciting development.
For more information use: www.cancer.gov/newscenter.
(ii) Some examples of new methods being developed
The camera you swallow
The M2A is a camera the size of a vitamin pill and developed by the US firm Given Imaging. When swallowed this battery powered device generates 57,000 images as it passes through the stomach and through the intestine. To date it has been used at the Royal Hallamshire Hospital to discover the causes of intestinal bleeding, but its potential to study polyps, tumours and bowel cancer is enormous. At £300 a time it is the ultimate disposable camera!
Testicular scanner on trial
The world’s largest trial to see if a new scanner can improve treatment for testicular cancer patients has been launched by Cancer Research UK.
Scientists funded by the charity will use a sophisticated Positron Emission Tomography (PET) scan to search for early signs of cancer spread in order to identify those at risk of relapse after surgery.
The PET scanner relies on differences in the way tumour cells and normal tissue metabolise glucose to hunt down the active tumour tissue.
New prostate tests
Scientists now believe they have a way to identify prostate cancers, which are aggressive and those that are not. To date measurement has always looked at the stage, or spread, of the cancer but there has been little evidence on the grade, or how rapidly the cancer is growing. The problem is that some men with small, yet rapidly growing cancers have not been spotted in time. Now scientists can test the tumours of newly diagnosed patients to discover how aggressive the cancer is. The test involves
measuring the amount of an enzyme present in the blood. This enzyme is only produced by cancer cells. A trial, reported in the scientific journal Cancer in September 2002, involved 105 prostate surgery samples. The test is probably applicable to breast and colon cancers as well.
(iii) Genetic testing
An example:
Women can now be screened for the presence of faulty BRCA1 and BRCA2 genes. Genes are little messages sitting on the ball of string which is your DNA. These are dubbed erroneously the
’breast cancer genes’ as, in the 6-7 per cent of women who have these genes, breast cancer is a high risk. In fact BRCA1 is connected with the immune system and BRCA2 with DNA repair. Both genes have also been linked to a percentage of prostate cancers whilst other, similar genes have been identified for colon and other cancer risks.
The hope is that drugs can be developed to switch off these genes, if their mechanism of cause can be accurately determined. For the time being women identified as having these genes are offered preventative mastectomies or the drug Tamoxifen. This drug has been shown to have benefits, but also it is itself classified as a carcinogen by the World Health Organisation, as it has definite cancer causing risks. It is appropriate that women with these genes are not influenced by scare mongering, but do take sensible lifestyle and dietary precautions. Recent research covered in icon has shown
that 50 years ago less than 40 per cent of people with these faulty genes developed cancer but now this figure is approaching 75 per cent. Clearly then, modern diet and lifestyle factors are playing a
significant role and people (women and men) with any of these genes could do a lot worse than follow some of the recommendations in this book, to build themselves their own microclimate
of health.