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Home What is Breast Cancer Types of Breast Cancer Ductal Carcinoma In Situ - DCIS

Ductal Carcinoma In Situ - DCIS

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Invasive carcinoma versus In situ carcinoma.
An  important prognostic factor for breast cancer is whether the cancer is in situ or invasive. In situ is a Latin term that literally means in place, but when used to define a tumor it describes whether the tumor has spread beyond a boundary that may affect the prognosis and possibly the treatment of the patient. The boundary that we are referring too is a wall of cells and other structural elements called the basement membrane. In Fig.1 you can see how normal cells remain within the basement membrane that surrounds them. A tumor becomes invasive when it has broken through and crossed this membrane. Once having crossed the basement membrane and become invasive, it is easier for tumor cells to enter the blood stream and spread to other places in the body. Invasive tumors generally have a poorer prognosis and can be more difficult to treat than in situ cancers. Since the tumor is localized, in situ tumors are generally easier to treat and carry better prognosis. In situ cancers can, however, progress to invasive cancers if not treated. About 1% of untreated low-grade DCIS will progress to an invasive tumor, yearly. [2]


Courtesy of: http://www.breastcancer.org/Images/dcis_range_tcm8-78725.jpg

Courtesy of: http://www.breastcancer.org/Images/dcis_range_tcm8-78725.jpg

What is DCIS?
Ductal Carcinoma In Situ or DCIS is an intraductal breast cancer that accounts for 20-30% of all newly diagnosed breast cancers. DCIS is a population of malignant cells that limits itself to the lobules and ducts of the breast. These are the same ducts that transport milk from breast tissue to the nipple[2].

DCIS is generally limited to the milk duct by a boundary of cells (basement membrane), except for one variant known as DCIS with microinvasion or DCIS-MI. DCIS is classified as DCIS-MI when there is a invasion of tumor cells into breast stroma through the basement membrane of no more than 0.1cm. If there are only a few microinvasions the prognosis of DCIS-MI is very similar to that of DCIS [2].

Risk factors for DCIS
There are a number of factors that may increase a patient’s risk for developing DCIS. A family history of breast cancer and mutations in the breast cancer genes BRCA1 and BRCA2 have been strongly coordinated with increased risk of developing breast cancer. Other factors such as increasing age, first pregnancy after 30 years of age, use of estrogen-progestin hormone replacement therapy, radiation exposure, and alcohol abuse have all been associated with an increased risk of developing breast cancer [4].

Symptoms of DCIS
DCIS usually does not present with any physical symptoms. Most patients with DCIS do not have a palpable mass. Rarely there may be some unilateral nipple discharge or a palpable mass. Some patients with DCIS that experience nipple discharge may have Paget’s disease of the nipple. Paget’s is a rare manifestation, only occurring in 1-4% of breast cancers. It is characterized by unilateral nipple discharge with a red, inflamed, itchy, scaly lesion around the nipple. Paget’s occurs when malignant cells travel through the duct to the nipple. The prognosis of the patient is not necessarily affected by the presence of Paget’s, as it is the characteristics of the primary tumor that determines prognosis [2].

Diagnosis of DCIS
Among all breast cancers that are detected through mammography, approximately 40-50% are DCIS. Most DCIS tumors detected by mammography are seen as microcalcifications (small collections of calcium) with fibrosis surrounding the duct or a mass being less commonly seen. 75% of the time calcifications are seen without an associated density on mammography in patients with DCIS. 15% of the time calcifications with a coexistent density are seen and a density alone is seen 10% of the time. [1]

If the radiologist sees microcalcifications or a mass/density on a screening mammogram they may recommend further imaging studies. Commonly a diagnostic mammogram, MRI, or possible breast biopsy will be used to further evaluate a screening mammogram with suspicious findings. A breast biopsy may involve a needle to extract a tissue sample from the suspicious area or, if necessary, a surgical excision biopsy. The tissue samples will be examined by a pathologist, who will determine if malignant cells are present and if so how aggressive the cells are. The information provided by the pathologist will help guide what therapies will be most effective to treat the cancer [4].

Treatment options for DCIS
Treatment for DCIS is tailored for each patient and is determined by a number of factors. When deciding on what treatment modality to select, your physician must consider the extent of the cancer, presence of microinvasion, how interested the patient is in breast conservation, the patient’s age, and whether the tumor has receptors sensitive to estrogen.

Treatment options include mastectomy, wide excision, and wide excision with radiation therapy. If the patient desires breast conservation, local excision (lumpectomy) followed by radiation therapy or hormone therapy  for ER-positive DCIS can be considered.

Indications for a total mastectomy include:

1. Extensive, diffuse microcalcifications on mammography suggesting extensive disease.
2. Low probably of obtaining clear margins on wide excision ensuring that the entire tumor has been resected.
3. Increased likelihood that a wide excision will result in a poor cosmetic result.
4. Patient’s low desire to preserve her breast.
5. Contraindications to radiation therapy or wide excision, including:

a. First- or second-trimester pregnancy
b. History of previous breast or chest wall radiation therapy
c. History of collagen vascular disorders [1].

 

Treatment efficacy
Mastectomy has proven to be the most effective treatment for DCIS with curative rates over 95% [2]. Local recurrence rates for DCIS after mastectomy are less than 1%. Adding radiotherapy to a simple mastectomy, data has shown a decrease in local recurrence rate from 16.4% to 7% [3].

In patients that underwent breast-conserving treatments, those that had radiation therapy after surgery had rates of recurrence 50% lower than lose that underwent local excision only. For patients with ER-positive breast cancers, the use of hormonal therapy in addition to local excision and radiation therapy lowered the risk of recurrence from 9% to 6% at 7 years out from surgery[1].

Regardless of what treatment option is chosen, the rate of death for DCIS patients is less than 2% per year [2]. Survival rates have not shown to differ if a patient undergoes mastectomy versus breast conserving surgery.

References:

 

1. Iglehart J.D. and B.L. Smith. "Diseases of the Breast." Sabiston Textbook of Surgery. 18th ed. Eds. CM Townsend, et al. Philadelphia: Elsevier, 2008. 851-897.
2. Lester SC, Cotran RS. Breast. In: Cotran RS, Kumar V, Collins T, editors. Robbins Pathologic Basis of Disease. 6th ed. Harcourt Asia: WB Saunders Company; 2000.
3. Bope, E. T., Rakel, R. E., Kellerman, R. D., & Conn, H. F. (2011). Conn's current therapy 2011. Philadelphia, Pa: Saunders/Elsevier.
4. http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001911/

 

Author:
Vikramjit Khangoora BS, MS-IV University of Sint Eustatius School of Medicine

Edited:
Jigisha P Thakkar