Ductal carcinoma in situ

Ductal carcinoma in situ (DCIS) literally means groups of "cancerous" epithelial cells which remained in their normal location (in situ) within the ducts and lobules of the mammary gland.[12] Clinically, it is considered a premalignant (i.e. potentially malignant) condition,[13] because the biologically abnormal cells have not yet crossed the basement membrane to invade the surrounding tissue.[12][14] When multiple lesions (known as "foci" of DCIS) are present in different quadrants of the breast, this is referred to as "multicentric" disease.[7]

For statistical purposes, some count DCIS as a "cancer", whereas others do not.[11][15] When classified as a cancer, it is referred to as a non-invasive or pre-invasive form.[12][16] The National Cancer Institute describes it as a "noninvasive condition".[11]

A drawing of ductal carcinoma in situ in the anatomical context of the whole breast

A drawing of a breast duct containing ductal carcinoma in situ.

Most of the women who develop DCIS do not experience any symptoms. The majority of cases (80-85%) are detected through screening mammography. The first signs and symptoms may appear if the cancer advances. Because of the lack of early symptoms, DCIS is most often detected at screening mammography.

In a few cases, DCIS may cause:

• A lump or thickening in or near the breast or under the arm
• A change in the size or shape of the breast
• Nipple discharge or nipple tenderness; the nipple may also be inverted, or pulled back into the breast
• Ridges or pitting of the breast; the skin may look like the skin of an orange
• A change in the way the skin of the breast, areola, or nipple looks or feels[17] such as warmth, swelling, redness or scaliness.[18]

The specific causes of DCIS are still unknown. The risk factors for developing this condition are similar to those for invasive breast cancer.[19]

Some women are however more prone than others to developing DCIS. Women considered at higher risks are those who have a family history of breast cancer, those who have had their periods at an early age or who have had a late menopause. Also, women who have never had children or had them late in life are also more likely to get this condition.

Long-term use of estrogen-progestin hormone replacement therapy (HRT) for more than five years after menopause, genetic mutations (BRCA1 or BRCA2 genes), atypical hyperplasia, as well as radiation exposure or exposure to certain chemicals may also contribute in the development of the condition.[20] Nonetheless, the risk of developing noninvasive cancer increases with age and it is higher in women older than 45 years.

Immunohistochemistry for calponin in ductal carcinoma in situ, highlighting myoepithelial cells around all tumor cells, thereby ruling out invasive ductal carcinoma.

80% of cases in the United States are detected by mammography screening.[21] More definitive diagnosis is made by breast biopsy for histopathology.

• 
  Histopathology of the cribriform type of breast ductal carcinoma in situ.

There are different opinions on the best treatment of DCIS.[22] Surgical removal, with or without additional radiation therapy or tamoxifen, is the recommended treatment for DCIS by the National Cancer Institute.[23] Surgery may be either a breast-conserving lumpectomy or a mastectomy (complete or partial removal of the affected breast).[24] If a lumpectomy is used it is often combined with radiation therapy.[11] Tamoxifen may be used as hormonal therapy if the cells show estrogen receptor positivity.[11] Research shows that survival is the same with lumpectomy as it is with mastectomy, whether or not a woman has radiation after lumpectomy.[25] Chemotherapy is not needed for DCIS since the disease is noninvasive.[26]

While surgery reduces the risk of subsequent cancer, many people never develop cancer even without treatment and the associated side effects.[24] There is no evidence comparing surgery with watchful waiting and some feel watchful waiting may be a reasonable option in certain cases.[24] Tamoxifen may be used as hormonal therapy if the cells show estrogen receptor positivity.[11] Chemotherapy is not needed for DCIS since the disease is noninvasive.[26]

With treatment, the prognosis is excellent, with greater than 97% long-term survival. If untreated, DCIS progresses to invasive cancer in roughly one-third of cases, usually in the same breast and quadrant as the earlier DCIS.[37] About 2% of women who are diagnosed with this condition and treated died within 10 years.[38] Biomarkers can identify which women who were initially diagnosed with DCIS are at high or low risk of subsequent invasive cancer.[39][40]

Histopathologic types of breast cancer, with relative incidences and prognoses. "Ductal carcinoma in situ" is near top.

DCIS is often detected with mammographies but can rarely be felt. With the increasing use of screening mammography, noninvasive cancers are more frequently diagnosed and now constitute 15% to 20% of all breast cancers.[32]

Cases of DCIS have increased 5 fold between 1983 and 2003 in the United States due to the introduction of screening mammography.[38] In 2009 about 62,000 cases were diagnosed.[38]