The aim of breast conserving surgery (BCS) is to excise all invasive and
in situ cancer and to achieve long-term disease control whilst at the same time minimising local morbidity and ensuring a good cosmetic result. BCS is as effective as mastectomy in terms of disease outcome and overall survival
1 but confers the advantages of better cosmesis, less psychological morbidity, improved body image, sexuality and self-esteem.
2Not all patients are suitable for BCS and appropriate selection has a major influence on both short- and long-term outcome. The choice in unifocal cancers is determined by a balance between tumour size and breast volume. Clinical and pathological factors also influence patient selection for BCS because of their impact on local recurrence. These include young age (under 35–39 years), an extensive
in situ component associated with an invasive tumour, grade 3 histology and the presence of lymphatic/vascular invasion.
3,4Excising skin directly overlying a cancer is only necessary if a carcinoma is very superficial or tethered to skin. Routine excision of skin when performing a wide excision falls outwith current guidelines.
3,6 Specimens should be immediately orientated prior to submission to the pathologist. The use of radio-opaque markers in conjunction with an intra-operative specimen X-ray allows any margins to be fully assessed and re-excised if necessary.
The histological factor which most frequently shows an association with local recurrence is the presence of an extensive
in situ component (EIC) within and surrounding an invasive cancer. EIC is also a predictor of residual disease within the breast.
5 Reports indicating that local recurrence rates were 3–4 times higher in cancers with EIC took no account of margins.
10–12 Further studies suggest that it is only patients who have both EIC and involved margins in whom local recurrence rates are unacceptable; if clear margins are obtained, there is not an increased rate of local recurrence in patients with EIC.
13,14The most important surgically related factor for local recurrence is completeness of excision. Ideally, there should be a clear rim of normal tissue (≥ 1 mm) around the carcinoma.
14 Controversy has surrounded how much extra tissue should be removed and what constitutes an involved or positive margin. Almost all studies have reported increased local recurrence rates in patients who have tumours with involved margins compared to those who do not (relative risk of 1.4–9).
7–18 This was despite the fact that those with involved or close margins received higher doses of radiotherapy than patients with clear margins in almost half these series. There is no suggestion that patients with narrow margins (< 2 mm) have a worse rate of local recurrence than those with wider margins (2–5 mm). Patients with extensive positive margins have an unacceptably high rate of local recurrence (27% at 8 years in one study
13). A recent review of all the literature concludes that wider margins do not equate with an improved rate of local control.
27 The presence of lobular carcinoma
in situ19 and atypical ductal hyperplasia (ADH)
20 at the margins has also been shown not to significantly increase local recurrence rates. Clear margins are crucial in younger women; if wider margins are important then it is likely to be in women under 45 years of age.
17The overall recurrence of ductal carcinoma
in situ (DCIS) following BCS alone is about 25% at 8 years' followup, with up to 50% of recurrences being invasive disease.
21–23 As with invasive cancers, an inadequate excision is the most important risk factor for local recurrence.
21,24,25 One study reported that clear margins (> 1 mm) had an 8.1% recurrence rate compared to 37.9% recurrence when excision margins were close (≤ 1 mm), but there was no improvement in recurrence rates in more widely excised lesions.
22 High-grade tumours, poorly differentiated tumours and those showing comedo necrosis have also been shown to be risk factors for recurrence. A further risk factor for recurrence irrespective of tumour grade or type is a young age (< 40 years) at diagnosis. The EORTC 10853 trial
21,25 found that women less than 40 years of age at diagnosis were more likely to recur than older women. None of the major trials have found any statistical significance between recurrence and tumour size. The NSABP-B17,
23 EORTC-10853
21 and UK/ANZ DCIS
26 trials all found a significant reduction in ipsilateral recurrence following radiotherapy, although there was no overall effect on survival.