Wednesday July 16 2008
Women should be breast aware
”DIY breast checks ‘do more harm than good’” is the headline in the Daily Mail. Along with several other news sources, the newspaper warns that a study has found “no evidence that regular self- examination” decreases the risk of breast cancer death, and that women who do so increase their risk of having unnecessary biopsy examinations. According to the reports, the Department of Health now advises that women should be “breast aware” rather than carrying out monthly, complicated breast self-examinations.
Although there was no evidence from this review for any beneficial effects of extensive self breast examination, there were limitations to the two studies (carried out in Russia and Shanghai) in terms of methodology and follow-up. It is important that women seek medical attention immediately if they have any concern about changes in their breasts. Early diagnosis and treatment remains the most effective way to reduce the impact of breast cancer.
Where did the story come from?
This is a review by Jan Peters Kösters and Peter C Gøtzsche, published by the Cochrane Collaboration.
What kind of scientific study was this?
This was a systematic review in which the researchers aimed to identify any studies evaluating self breast examination and clinical examination by a doctor or nurse, their possible benefits and harms, and effects upon decreasing death and illness from breast cancer.
Using data from the Cochrane Breast Cancer Group Specialised Register, The Cochrane Library and the PubMed electronic database, the researchers identified randomised controlled trials of women who were not diagnosed with breast cancer and had been randomised to either regular self examination, regular clinic examination or a combination of both methods compared with no examination, or studies comparing one examination method with another. They looked at the main outcome of death from breast cancer, and other outcomes of total death rate, death from any cancer, characteristics of identified tumours, use of surgical interventions (e.g. biopsy, mastectomy), use of chemo- or radiotherapy, and any adverse effects of breast examination and false positive results. The two researchers examined identified trials, and also looked at other details such as trial quality and methodology, the women included, examination techniques used, and additional investigations etc.
What were the results of the study?
Of six potential trials, three were considered suitable for inclusion in this review: a 1999 Russian study and a 2002 Shanghai study comparing regular self examination with no examination, and a 2006 Philippines study comparing the combination of self and clinical examination versus no examination.
- From the Russian study, only recruits from one of the two study centres were included for analysis (St Petersburg) due to methodological problems in the other (Moscow). This included 120,000 to 123,000 women between the ages of 40 and 64 who had never previously been diagnosed with breast or any other cancer. Detailed self breast examination was taught by nurses and doctors and recommended to be carried out at least five times per year. Clinical examinations were performed during routine health checks. The Russian trial lasted for 15 years. However, different reports of the study were written and contain inconsistencies in study population, duration and follow-up.
- The Shanghai trial randomised 289,392 women without prior breast cancer (between the ages of 30 and 66) who were employed in 519 factories. Breast examination was taught at the start of the study and reinforced at intervals during the trial. Supervised self examination was recommended four times in the first year and six-monthly thereafter. The trial duration was 10 years. However drop-out rates at supervised examination sessions were high (dropping to 48.7% five years into the trial). A total of 1,760 cases of breast cancer were identified.
- In the Philippines study, there was poor compliance and follow-up over women screening positive, so the trial was discontinued after the first screening round. A total of 404,947 women (aged 35 to 64) from 202 health centres were randomised, and the single screening round was conducted in 1996. Only 64% of the group randomised to receive combined examinations actually attended for clinical examination and instruction on self examination. Of the women examined, 3% of them were found to have a breast lump, and 42% of these women refused to have any further investigation; therefore the trial was discontinued.
The Russian and Shanghai trials combined gave a total of 388,535 women. There were 587 breast cancer deaths – 292 in the examination groups and 295 in the control groups. There was no significant difference in breast cancer mortality between the examination and no examination groups. In the Shanghai trial there was no difference in overall deaths between the examination and no examination groups. In the Russian trial, more of the identified breast cancer cases came from the examination group. The opposite was seen in the Shanghai trial. There was increased risk of having undergone a biopsy with negative results (no cancer) in the examination groups compared with the no examination groups. Treatment for identified cancers was no different in either group.
What interpretations did the researchers draw from these results?
The researchers conclude that they were unable to find any benefit of self breast examination and that it cannot currently be recommended on the basis of this review.
What does the NHS Knowledge Service make of this study?
It is important that women continue to be alert to changes in their breasts, such as appearance or the presence of lumps. Despite there being no evidence from this review for any beneficial effects of extensive self breast examination, there were some limitations to the two studies:
- As the researchers note, the two trials had very different methodologies and follow-up. The Shanghai trial was “better designed”, with more extensive instructions given for examination and better compliance. Additionally, the variable reports from the Russian study raise questions about its reliability.
- The news headlines that breast examination “does more harm than good”, such as those in the Daily Mail and The Guardian, should be interpreted with caution. Although there were no differences in breast cancer death rates in women who examined themselves compared with those who did not, no direct harms have been noted from these studies, with the exception of women in the self-examination groups being more likely to undergo a biopsy that gave negative results (cancer free).
- Women were instructed in breast examination. As both of these trials were commenced some time ago (recruitment 1985-89 in the Russian study; 1989-95 in the Shanghai study), they cannot be assumed to be directly comparable to advice currently given, or advice given in other countries.
- Additional information, such as specific details of the women included (such as health and other risk factors for breast cancer), how they were randomised and followed up, and how outcomes were assessed is not available. Therefore there are other factors that may affect the reliability of the original studies.
More research into this subject, including large samples from other countries, will be needed to better answer the questions surrounding breast self examination. The research to date, which is limited, suggests that as a single general screening method, it may not be very effective. However, it is important that women seek medical attention immediately if they have any concerns about changes in their breasts. Early diagnosis and treatment remains the most effective way to reduce the impact of breast cancer.