The management of DCIS has evolved significantly since the introduction of widespread population screening. Historically, DCIS made up a very low percentage of breast malignancies, and was treated in a similar way to invasive disease (mastectomy). Management of DCIS has lagged behind that for invasive breast disease, as most of the studies examining breast conservation did not include DCIS in their cohorts. Modern treatment is typically lumpectomy followed by radiotherapy except in cases where the woman requests mastectomy or where lumpectomy is not possible due to disease extent.
There have been no trials comparing mastectomy to wide local excision +/- radiotherapy in the setting of DCIS, as opposed to numerous trials that been performed on invasive carcinoma of the breast.
The evidence for radiotherapy following wide local excision is provided by:
- NSABP B17: Radiotherapy added to wide local excision reduced risk of local recurrence from 32 to 16%, nearly equal between invasive and non-invasive recurrences
- EORTC 10853: Addition of radiotherapy improved local control from 25 to 15%.
- UKCCCR DCIS Working Group: Addition of radiotherapy improved local control from 14 to 6%; tamoxifen had no benefit in addition to radiotherapy but provided a small benefit alone
- Wang et al: Low grade DCIS not treated with radiotherapy had a recurrence rate of 70% and recurrence with invasive carcinoma of 30%.
- Holmberg et al: Addition of radiotherapy reduced local recurrences from 22% to 7% (similar reduction between invasive/non-invasive malignancies).
- The Cochrane Collaboration performed a meta-analysis in 2009 (Goodwin et al); this demonstrated that radiotherapy reduced the risk of both invasive and non-invasive recurrence:
- In all women (RR 0.5)
- In both young and older women (over or under 40/50 years of age), with the greatest benefit in the older age group (RR 0.36) but a significant benefit in younger women (RR 0.67)
- In women with positive margins (RR 0.51) and with negative margins (RR 0.49)
- In women with high grade disease (RR 0.44) and with lower grade disease (RR 0.60)
- In women with small lesions (RR 0.43) and with larger lesions over 10 mm (RR 0.32)
Regarding tamoxifen, two important trials in the management of DCIS include:
- NSABP B24: This was a study looking into the effects of tamoxifen in DCIS; local recurrence with radiotherapy was about 15% without and 11% with tamoxifen (modest benefit)
- UKCCCR Trial (2003): This study had a 2x2 randomisation. Recurrence was 8% with RT alone and 6% with RT + tamoxifen (questionable benefit)
Surgical excision forms the mainstay of treatment. There are two competing goals: prevention of local recurrence and preservation of the breast
- Mastectomy was the historical treatment of choice, with close to 100% local control and 1-2% mortality from, most likely, unrecognised invasive disease.
- Wide local excision has a better cosmetic result but leaves up to a 40% risk of recurrence for high grade DCIS; there are no randomised trials comparing mastectomy to wide local excision alone
- There is minimal evidence comparing wide local excision + radiation versus mastectomy alone
- Axillary clearance or sentinel node biopsy is not required as metastasis rate is < 5%.
- Surgical margins should be > 2 mm (less margin has a 50% increased rate of recurrence) - See Dunne et al from 2009.
- Mastectomy should be offered in patients in whom clear margins can never be obtained or with disease extending beyond 2 quadrants
Following breast conserving surgery, the following features are important to consider:
- The aggressiveness of the DCIS (low - medium - high), with high grade DCIS most likely to recur locally
- Recurrences after wide local excision are about equal between invasive and non-invasive disease, with rates of up to 40% with no additional treatment
Radiotherapy is nearly always recommended following breast conservation radiotherapy. It has no impact on overall survival, but does reduce local recurrences by about 50%. The decision to treat can be impacted by several factors. However, radiotherapy has been shown to consistently have some benefit in local control, regardless of age, grade or margin status. Radiotherapy can be omitted in patients with low grade disease, who are older, and if there are very wide margins of resection (> 1 cm).
Radiation dose is 50 Gy in 25 fractions, delivered using opposed whole breast tangents. Studies exploring hypofractionation for invasive breast cancer have not included DCIS and the evidence for this approach is lacking.
The use of a 10 Gy boost to the tumour bed is controversial
* Boost has only been examined in retrospective series, which have shown a significant reduction in local recurrences
* Most centres would only use a boost in young women with high grade DCIS or for patients with close margins and inability to have further resection.
Addition of tamoxifen for hormone receptor positive DCIS following breast conserving surgery and radiotherapy reduces recurrence by a modest amount (NSABP B24: from 15% to 11%); tamoxifen alone does not lead to sufficient reduction in recurrence risk. In contrast, the UKCCCR trial in 2003 demonstrated a minor improvement in ipsilateral breast tumour recurrence of just 2% (from 8% to 6%).
Systemic cytotoxic therapy has no role in DCIS treatment.
Mastectomy provides the highest rate of cure, but since 85-95% of women can be cured with less extensive surgery, it is used only when DCIS is too extensive to resect or if the patient wishes the procedure
Four large randomised controlled trials and a meta-analysis of these has shown that radiotherapy reduces the relative risk of local recurrence by about 50%
In some women (very clear margins, older, low grade disease) the risk of local recurrence is lower and radiotherapy may be omitted
Boost has never been studied prospectively in DCIS, but some consider it useful particularly when there is high risk disease, margins are close, or the woman is young, as they have the highest risk of local recurrence and potentially the greatest benefit.