What Doctors Don’t Tell You. Lynne McTaggart
because benign tumours are often mistaken for malignant ones. In one study of over a thousand women undertaken by Harvard Medical School, only a quarter of the women whose mammograms had recorded some abnormality were actually found to have malignant tumours. Other radiology departments referring patients to the Harvard Center had an even worse batting average – getting it right only one-sixth of the time. And of course an inappropriately strong mammography report, which might include statements such as ‘malignancy cannot be excluded’, raises the anxiety level of the patient and referring physician and often ends up with the woman on the operating table.57
Routine screening is undoubtedly responsible for the huge increase in the aggressive treatment of ductal carcinoma in situ (DCIS) – some 40,000 cases in the US alone.
Since the advent of screening, the incidence of DCIS has sky-rocketed, from 2.4 per 100,000 women in 1973 to 15.8 cases per 100,000 in 1992.58 Although many women being diagnosed with DCIS are undergoing radical mastectomies, this abnormality, or ‘pre-cancer’ is ‘not a synonym for other forms of cancer’, says Professor McCormick. Not only do many experts misunderstand DCIS, but most cases of this condition, says McCormick, would not do a woman any harm.59
Up until now, only relatively high doses of radiation have been associated with an increased risk of breast cancer. However, new evidence demonstrates that even moderate strengths of strong x-rays raise the risk of breast cancer five or six times in women who carry a certain gene, occurring in about 1 per cent of the population – or in at least one million American women. In 1975, Dr C. Bailar II, editor in chief of the Journal of the National Cancer Institute, concluded that accumulated x-ray doses in excess of 100 rads over 10 to 15 years may induce cancer of the breast.60 A single-view mammogram offers the average breast a dose of about 200 millirads (0.2 rad).61
However, women with the ataxia-telangiectasia gene, says Dr Michael Swift, chief of medical genetics at North Carolina University, have an unusual sensitivity to radiation and could develop cancer after exposure to ‘appallingly low’ doses. He estimates that, in the US, between 5,000 and 10,000 of the 180,000 breast cancer cases diagnosed each year could be prevented if women with the gene were not exposed to the radiation from mammograms.62
Just four breast films (the usual pictures for one mammogram session) expose you to 1 rad (radiation absorbed dose) – about 1,000 times more than that of a chest x-ray. Each rad increases the risk of a premenopausal woman’s cancer risk by 1 per cent, so that women screened for over a decade would have raised their cancer risk by 10 per cent.
Besides a genetic susceptibility, the physical trauma caused by the force of mammograms could be a factor in spreading cancer. At the moment, mammograms use 200 newtons of compression, the equivalent of 20 1kg bags of sugar per breast. Some of the modern foot-pedal operated machines are designed to exert one-third again as much force – the equivalent of your breast being squashed by 30 bags of sugar.63 The force is thought to be necessary in order to get the best quality of image while keeping the radiation dose to a minimum.64 A number of researchers believe that compression during mammography can rupture cysts and disseminate cancer cells.65 This phenomenon has been observed in animal studies; if a tumour is manipulated, it can increase the rate of its spread to other parts of the body by up to 80 per cent.66
Many biopsies to investigate a suspicious lump found on mammography have their own set of problems. In this standard procedure, a thick needle is inserted into the breast under local anaesthetic to remove a small piece of tissue. This is then examined for cancerous cells. In one study of women undergoing biopsy, a quarter had problems afterward with the wound left by the needle such as infection or bleeding. Nine patients reported a new breast lump (all benign) developing under the biopsy scar between one to seven years after surgery. Eight patients continued to have pain in the area where the biopsy had been taken up to six years after the operation, and seven reported unsightly scars.67
Fine-needle aspiration, which can be done on an outpatient basis, has been served up as the less invasive alternative when a lump has been found; in this instance, a fine needle with a syringe is inserted in the breast to draw out a specimen of the lump’s contents. However, doctors have been known to puncture the lung during this procedure, causing pneumothorax (in which air enters the chest, causing the lung to collapse). In 74,000 fine-needle aspirations of the breast, this occurred in about 133 patients (0.18 per cent).68
The experience in many countries suggests that mammograms also have a high rate of inaccuracy. In Canada, during the first four years of the eight-year trial on breast cancer screening, nearly three-quarters of test results were unacceptable. Only in the last two years of the trial were more than half the tests up to the required standard.69
As for women under 50, another Canadian study showed that some 87 per cent of so-called cancer cases detected by mammograms were false alarms.70
The high level of false-positives is partly due to poor standards in equipment. A third of women’s clinics in the US were not accredited, as of early 1994. The FDA admitted that many of them were inaccurately reporting mammograms and that some women were receiving doses of radiation that were far too high.71 Just how poor the standards are was revealed by a 1989 survey of a cross-section of mammography units carried out by the Department of Health in Michigan. One-third of the units studied routinely exceeded the various standards of radiation exposure.72
The US aimed to correct this problem with the Mammography Quality Standards Act, passed in October 1992, which was to establish quality-control standards and a certification system for the more than 10,000 medical facilities that perform and interpret mammograms. These quality-control standards relate to the training and education of personnel, the equipment and the dosage used, among other criteria. Doctors would also have to have continuing education in reading mammograms and be expected to interpret an average of 40 mammograms a month.
As of October 1994, every facility performing mammograms had to obtain a certificate or provisional certificate to continue to operate legally.
However, although setting standards has undoubtedly improved some of the appalling mistakes made in the past, it may do nothing to improve the inherent imprecision of the technology itself. Even mammograms of the best quality can be misread by highly experienced radiologists. In one study carried out by Yale University, 10 seasoned radiologists, with 12 years’ experience in reading mammograms, each given the same 150 good-quality mammograms, differed in their interpretation a third of the time. In a quarter of cases they also radically disagreed over how the patients should be managed (such as whether they should have follow-up mammograms or exploratory surgery). Even among the 27 patients later definitely diagnosed as having breast cancer, the radiologists varied widely in their diagnosis. Nearly a third of cancers were wrongly categorized. One radiologist did not detect a cancer that was clearly visible, while another thought it was developing on the breast opposite the one where it actually was.73
Even if regular screening doesn’t spread or cause cancer, its dubious benefits may not be worth the pain reported by a third of women undergoing the screening.74 Helen, from Westcliff on Sea, now in her early fifties, has suffered with lumpy breasts