When surgically removing an invasive breast cancer tumor, if the surgeon also removes 2mm of tissue surrounding the tumor the risk of residual disease is minimized in 98% of cases, according to a new study carried out by British surgeons and published in the peer-reviewed medical journal the International Journal of Clinical Practice. Residual disease refers to cancer cells that remain after attempts have been made to remove the cancer.
The study involved 303 female patients who had undergone breast conserving surgery at the Department of Breast Surgery at Good Hope Hospital, Sutton Coldfield, England.
Dr Stephen Ward, lead author, said:
Breast conserving surgery followed by radiotherapy is a well-established alternative to breast removal and studies have demonstrated similar survival rates in patients undergoing these procedures” explains lead author Dr Stephen Ward. However patients undergoing breast conserving surgery are more likely to have recurrent cancer and the amount of tissue removed around the tumour, known as the free margin, remains controversial.
A survey of 200 UK breast surgeons published in 2007 revealed wide variations in what they considered to be an adequate margin, with 24% wanting a clear margin of 1mm and 65% wanting a margin of 2mm or more. This study highlighted differences in practice across different units and the need for evidence-based guidelines.
Dr. Ward and colleagues performed further excision* specimens to check for residual disease on 31% of the patients – all of them had undergone conserving surgery. They collected a total of 139 samples from 93 breast cancer patients. Fifty-two of the samples came from women who had had non-invasive cancer surgically removed – the cancer had not spread beyond the milk ducts and lobules. 87 samples came from patients with invasive cancer – the cancer had spread to surrounding breast tissue.
The authors report that in patients who had undergone surgery for invasive cancer, the amount of cancer cells remaining behind (residual disease), defined as the presence of invasive or non-invasive cancer, went down as the free margin increased – from 35.3% among those with no margin to 2.4% among those with a margin of at least 2mm.
Residual disease was higher and the pattern less clear among those who had undergone surgery for non-invasive cancer, the surgeons reported. Incidence varied from zero percent at over 5mm to 57% among those with a margin of between 0.1 to 0.9mm, but 44% when no margin was involved.
They also examined the features of the 202 patients who had had a close free margin of under 2mm and the 101 patients who had had a clear free margin of at least 2mm. There was a higher risk of large grade three tumors (46%) than the clear margin group (42%), and with lymphovascular invasion (52% versus 40%) and nodal involvement (48% versus 33%).
Among the patients who underwent wider re-excision* to determine any residual disease, 13% eventually had a mastectomy, while 56% did not require any subsequent surgery.
The authors wrote:
Our research found that the overall probability of finding residual disease was 2.4% if a woman had surgery where the free margin was 2mm or more from the invasive cancer. But the same pattern was not observed when the woman had surgery for non-invasive cancer, where the incidence of residual disease was higher.
Based on these results, we feel confident that a free margin of 2mm from the area of invasive cancer is adequate to minimise residual disease, but the equivalent free margin for non-invasive cancer remains unclear.
Eliminating the possibility of residual disease during breast conserving surgery is very important as nearly 50 per cent of patients with local recurrence go on to develop secondary breast cancer, which is a progressive incurable disease.
The authors suggest that a 2mm free margin from invasive tumor is adequate to minimize residual disease, whereas 2mm for DCIS (Ductal carcinoma in situ) is unclear. Breast cancer patients with large tumors and lobular cancer types need to be counseled at the time of initial surgery so that they are aware of the risk of subsequent excision* and mastectomy.
* “Excision” refers to the surgical removal, which in this text means the surgical removal of a tumor.
S. T. Ward, B. G. Jones, A. J. Jewkes
International Journal of Clinical Practice. Volume 64, Issue 12, pages 1675-1680, November 2010
Article first published online: 14 OCT 2010. DOI: 10.1111/j.1742-1241.2010.02508.x
Written by Christian Nodqvist