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Women who undergo breast conserving surgery for early breast cancer should be followed up for much longer than the three to five years recommended in current guidelines, warns a study published this week. The study shows that relapses can occur at least 10 years after initial treatment.
The study, published in the British Journal of Cancer, analysed relapses in 1312 women with early stage breast cancer who underwent breast conserving surgery and postoperative radiotherapy between 1991 and 1998 and who were followed up at two centres in Edinburgh (doi: 10.1038/sj.bjc.6603815). Analysis of the 110 treatable relapses showed that they occurred in 1% to 1.5% of the women in each year of the follow-up period.
But different types of relapse varied in their time scales. The incidence of metastatic relapse peaked at just over 3% a year at two to three years after initial surgery and remained at just over 2% a year for up to five years before decreasing. In contrast, the incidence of locoregional relapse remained constant at 1% to 1.5% over the whole follow-up periodperiod.
Guidelines in North America and the United Kingdom recommend that follow-up of patients who have been treated for breast cancer concentrate on the first three to five years after initial treatment and that after this follow-up visits should become less frequent or the patient should be discharged. Although some variation exists, all the guidelines assume that relapse is commonest in the first few years after treatment.
The Edinburgh study has confirmed previous results showing that the rate of distant relapse peaked in the first five years, but in contrast it found that the incidence of locoregional relapse remained constant, at 1% to 1.5% a year, for at least 10 years.
David Montgomery, clinical research fellow at Glasgow Royal Infirmary and the study's lead author, said, “Our data reveal that the basic assumptions behind the guidelines for follow-up are incorrect. If a central aim is the detection of treatable relapse, there is no justification for focusing on the first two to three years after treatment; treatable relapse occurs at a constant rate for at least 10 years.”
He concluded, “Long term follow-up is warranted for all patients with breast cancer treated with breast conserving surgery.”
The study also showed the value of mammography in follow-up, rather than clinical examination as recommended in some guidelines. Of the 110 treatable relapses, 37 were detected after symptoms developed and 56 were found by mammography, but only 15 were clinically detected and two were diagnosed incidentally.
Women who had a relapse of ipsilateral breast cancer that was detected after symptoms developed or by mammography had significantly longer survival after the original diagnosis (P<0.001) and after the recurrence (P=0.001) than women whose relapse was detected by clinical examination. Mammography detected 5.4 relapses per 1000 mammograms—similar to the rate achieved in the national three yearly screening programme to detect new breast cancers in the UK.
“In ten years of follow up in 1312 women, only 15 relapses were detected clinically,” Mr Montgomery noted. This is a very low yield. Mammography, in contrast, makes a much larger and more significant contribution to relapse detection.
“There is no place for not doing annual mammography in these patients and for following them up for at least 10 years.”