| In the medical journal Lancet recently, Danish | | | | factors which suggest that screening reduces the |
| researchers criticised clinical trials looking into breast | | | | number of deaths more than was estimated(4). |
| cancer screening. Their article has attracted wide | | | | Include all evidence |
| publicity. They claimed that some of the medical | | | | Eminent scientists who are independent of these |
| research supporting the value of screening for breast | | | | trials agree with this analysis. Sir Richard Peto, one of |
| cancer was not reliable. The only two clinical trials | | | | the most respected researchers in this field, said |
| they thought were acceptable either did not find any | | | | 'evidence from all trials should be included' (New |
| reduction in deaths from breast cancer through | | | | Scientist, 15th January 2000). And Professor Jack |
| screening, or found that screening increases the risk | | | | Cuzick wrote in the British Medical Journal on 15th |
| of death from other causes. | | | | January: 'Screening detects cancers when they are |
| A major target for this attack was the largest study, | | | | smaller and more easily treated; cancer rates are |
| the Swedish two-county trial. The objection of the | | | | reduced following screening; and trials have shown |
| researchers (PC Gatzsche and O Olsen) to this study | | | | that mortality is reduced by 20-30%.' |
| was that the group of people invited to screening | | | | Balanced reviews which include all the evidence show |
| were on average five months older than the other | | | | that deaths from breast cancer are reduced by |
| group (in 133,000 women aged 40-74). In fact, the | | | | nearly a third (30%) in women invited to screening; |
| Swedish two-county study investigators showed that | | | | and there is no increase in deaths from other causes |
| taking age into account, there was a 30% reduction | | | | in this group. |
| in breast cancer deaths and a 1% reduction (no | | | | Ill-considered publications must not be allowed to |
| increase) in deaths from all causes in the group of | | | | cause anxiety to women invited to screening, nor to |
| people invited to be screened(2). There are other | | | | damage the morale of the staff who provide the |
| problems with Gatzsche and Olsen's interpretation. | | | | screening. People need to know that Gatzsche and |
| They ignore evidence of errors in one of the trials | | | | Olsen's paper is not worth a moment's attention. |
| they thought were acceptable(3). And they ignore | | | | |