About Ductal Carcinoma in Situ of the Breast
Ductal carcinoma in situ (DCIS) of the breast is an early, localized cluster of cancer cells that start in the milk passages (ducts) but have not penetrated the duct walls into the surrounding tissue. The term "in situ" refers to a tumor that has not spread beyond the place where it originally developed. By definition, DCIS is a non-invasive form of breast cancer because the cancer cells are confined to the milk ducts of the breast.
Ductal carcinoma in situ is sometimes described as "pre-cancerous", "pre-invasive", "non-invasive", or "intraductal carcinoma". Although, by definition, DCIS is a non-invasive form of breast cancer, if left untreated, it may progress to 'true' breast cancer by spreading into and invading the surrounding healthy breast tissue. Because doctors cannot predict with any degree of certainty whether DCIS will develop into invasive breast cancer, early diagnosis and treatment is crucial. With appropriate treatment, the prognosis (outlook) for women with DCIS is excellent.
Fortunately, DCIS can often be detected on screening mammography before any symptoms develop. Ductal carcinoma in situ usually appears on mammography as an area of microcalcification (groups of small calcifications clustered together within the breast). With the increased availability of mammography, breast cancers are being detected earlier.
In the past, most women with ductal carcinoma in situ had a mass large enough to be felt or had nipple discharge before the diagnosis could be made. Since screening mammography became more widely available in the 1980s, many cases of DCIS are discovered before any symptoms develop and the average size of DCIS has been reduced to 10 mm at the time of discovery. It has been estimated that DCIS accounts for about 20% of all mammographically detected breast cancers.
When an abnormal area has been detected by mammography and ductal carcinoma in situ is suspected, the diagnosis must be confirmed by removing a sample from the suspicious area of the breast and examining the specimen under a microscope. This procedure is known as a diagnostic biopsy. Traditionally, most cases of mammographically detected, nonpalpable DCIS have been diagnosed by a procedure known as wire-localization open surgical biopsy. Recently, a more accurate diagnostic biopsy technique for women with suspected DCIS has been developed called directional vacuum-assisted biopsy (DVAB). Currently, there are three types of DVAB systems available:
- Minimally Invasive Breast Biopsy (MIBB)
The primary goals of treatment of DCIS is prevention of local recurrence and invasive breast cancer. When breast-conserving surgery is appropriate, the goals of treatment include the total surgical removal of the DCIS with minimal cosmetic deformity.
Current treatment options for women with DCIS include:
- Surgery alone (mastectomy or breast-conserving surgery)
- Breast-conserving surgery followed by radiation therapy
- Breast-conserving surgery followed by radiation therapy and hormonal therapy.
As noted, most women who are diagnosed with DCIS by screening mammography have no clinical symptoms of the disease (such as a palpable breast mass). Because most DCIS lesions that are detected mammographically are small, there has been a shift in recent years from mastectomy to breast-conserving surgery. In fact, at the present time, in the United States most women with DCIS are treated with breast-conserving surgery.
The rate of tumor recurrence in women with ductal carcinoma in situ has been estimated to be approximately 0.5% to 1% per year. Although research suggests that the rates of local or regional recurrence are significantly lower after mastectomy than after breast-conserving surgery, the 10-year survival rate is approximately 98% with each of these surgical procedures.
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