Mammary ductal carcinoma
|Classification and external resources|
Histopathologic image from ductal cell carcinoma in situ (DCIS) of breast. Hematoxylin-eosin stain.
Mammary ductal carcinoma is the most common type of breast cancer in women. It comes in two forms: invasive ductal carcinoma (IDC), an infiltrating, malignant and abnormal proliferation of neoplastic cells in the breast tissue, or ductal carcinoma in situ (DCIS), a noninvasive, possibly malignant, neoplasm that is still confined to the lactiferous ducts, where breast cancer most often originates.
Invasive Ductal Carcinoma
Invasive Ductal Carcinoma (IDC) is the most common form of invasive breast cancer. It accounts for 55% of breast cancer incidence upon diagnosis, according to statistics from the United States in 2004.<ref name=USA-2004>Percentage values are from United States statistics 2004. Subtype specific incidences are taken from Table 6 (invasive) and Table 3 (in situ). These are divided by total breast cancer incidence (211,300 invasive and 55,700 in situ cases) as reported from Breast Cancer Facts & Figures 2003-2004 </ref> On a mammogram, it is usually visualized as a mass with fine spikes radiating from the edges. On physical examination, this lump usually feels much harder or firmer than benign breast lesions such as fibroadenoma. On microscopic examination, the cancerous cells invade and replace the surrounding normal tissues. IDC is divided in several histological subtypes.
Prognosis for IDC
The prognosis of IDC depends, in part, on its histological subtype. Mucinous, papillary, cribriform, and tubular carcinomas have longer survival, and lower recurrence rates. The prognosis of the most common form of IDC, called "IDC Not Otherwise Specified", is intermediate. Finally, some rare forms of breast cancer (e.g. sarcomatoid carcinoma, inflammatory carcinoma) have a poor prognosis.
Treatment options for IDC
Treatment of IDC depends on the size of the mass: a. <4cm mass: surgery to remove the main tumor mass and to sample the lymph nodes in the axilla. The stage of the tumor is ascertained after this first surgery. Adjuvant therapy (i.e. treatment after surgery) usually includes chemotherapy, radiotherapy, hormonal therapy (e.g. Tamoxifen) and targeted therapy (e.g. Trastuzumab). More surgery is occasionally needed to complete the removal of the initial tumor or to remove recurrences. b. 4cm or larger mass: modified (a less aggressive form of radical mastectomy) radical mastectomy (because any malignant mass in excess of 4cm in size exceeds the criteria for a lumpectomy) along with sampling of the lymph nodes in the axilla.
The treatment options offered to an individual patient are determined by the form, stage and location of the cancer, and also by the age, history of prior disease and general health of the patient. Not all patients are treated the same way.
Additional images of invasive ductal carcinoma
Ductal Carcinoma in Situ (Intraductal Carcinoma)Carcinoma In Situ, DCIS (aka Intraductal Carcinoma) is the most common type of noninvasive breast cancer in women. It accounts for 13% of all breast cancer incidence upon diagnosis, according to statistics from the United States in 2004. It is often referred to as "stage zero breast cancer" and experts disagree on whether it should even be called "cancer." "Ductal carcinoma" refers to the development of cancer cells within the milk ducts of the breast. In situ means "in place" and refers to the fact that the cancer has not moved out of the duct and into any surrounding tissue.
As screening mammography has become more widespread, DCIS has become one of the most commonly diagnosed breast conditions, now accounting for 20% of screening detected breast cancer. In countries where screening mammography is uncommon, DCIS is sometimes diagnosed at a later stage, but in countries where screening mammography is widespread, it is usually diagnosed on a mammogram when it is so small that it has not yet formed a palpable lump. DCIS is not traditionally regarded as being harmful in itself, however there is evidence of metastases in up 2% of cases of DCIS.
DCIS is usually discovered through a mammogram as very small specks of calcium known as microcalcifications. However, not all microcalcifications indicate the presence of DCIS, which must be confirmed by biopsy. DCIS may be multifocal, and treatment is aimed at excising all of the abnormal duct elements, leaving "clear margins", an area of much debate. After excision treatment often includes local radiation therapy. With appropriate treatment, DCIS is unlikely to develop into invasive cancer. Surgical excision with radiation lowers the risk that the DCIS will recur or that invasive breast cancer will develop.
Treatment options for DCIS
DCIS patients have two surgery strategy choices. They are lumpectomy (most commonly followed by radiation therapy) or mastectomy. The survival rate is equally high for both treatments, 96 percent or higher, according to a 2009 Consensus Conference at the National Institutes of Health (NIH) in the United States.
They also have the 'no surgery' option. The survival rate here is unknown.
Biomarkers can identify which women who were initially diagnosed with DCIS are at high or low risk of subsequent invasive cancer.
Adjunct radiotherapy after lumpectomy offers equivalent survival to mastectomy, although there is a slightly higher risk of recurrence of DCIS or breast cancer. According to the 2009 DCIS Consensus Conference held by NIH, the addition of radiation therapy to lumpectomy reduces the risk of local recurrence to approximately 12 percent, approximately half will be DCIS and half will be breast cancer; the risk of recurrence is 1 percent for women undergoing mastectomy. In addition radiation therapy may reduce recurrence among patients with patients with DCIS getting breast conserving surgery (lumpectomy) as compared to breast conserving therapy alone according to a systematic review . <ref name="pmid20071685"> </ref> Patients who received breast conserving surgery plus radiation therapy had a lower DCIS recurrence rate than patients who received breast conserving surgery alone. In the NSABP study, relative risk of 0.56 with 95% CI = 0.44-0.73. In the EORTC study, relative risk was 0.459 and 95% CI = 0.34-0.59. The use of radiation therapy did not have an affect on mortality. NSABP relative risk was 1.12 with 95% CI = 0.57-2.23. In EORTC, relative risk of 0.33 with 95% CI = 0.34-3.16. However, this study's results may be biased due to the broad nature of the systematic review.
The Consensus Conference also reported that Black patients face higher risks of local recurrence of DCIS or breast cancer than White patients. Extensive DCIS of high grade, large size, and resected with minimal surgical margins, even with radiotherapy, also have a higher risk of recurrence.
Because of the higher risk of recurrence, mastectomy may be the preferred treatment for some women or in certain instances e.g. if:
- DCIS is "multi-focal" in two or more areas of the breast
- The DCIS tumor is relatively large or of high grade
- Failure to achieve adequate margins on attempted lumpectomy.
- The breast has previously received radiation treatment.
- The patient has had scleroderma or another disease of the connective tissue, which can complicate radiation treatment.
- The patient lives in an area where radiation treatment is inaccessible or inconvenient
- The patient is less than 40
A system for analysing the suitability of DCIS patients for the options of breast conservation without radiation, breast conservation with radiation, or mastectomy is called the VanNuys Prognostic Scoring Index (VNPI). This VNPI analyzes DCIS features in terms of size, grade, surgical margins, and patient age and assigns "scores" to favourable features.
Tamoxifen or another hormonal therapy is recommended for some women with estrogen-receptor positive DCIS to help prevent breast cancer. . Hormonal therapy further decreases the risk of recurrence of DCIS or the development of invasive breast cancer. However, hormone treatment increases the risk of endometrial cancer, severe circulatory problems, or stroke. In addition, hot flashes, vaginal dryness, abnormal vaginal bleeding, and a possibility of premature menopause are common for pre--menopausal women who start treatment.
Unlike women with invasive breast cancer, women with DCIS do not undergo chemotherapy and have traditionally not been advised to have their lymph nodes tested or removed. Some institutional series reporting significant rates of recurrent invasive cancers after mastectomy for DCIS, have recently endorsed routine sentinel node biopsy (SNB) in these patients while other have concluded it be reserved for selected patients. Most agree that SNB should be considered with tissue diagnosis of high risk DCIS (grade III with palpable mass or larger size on imaging) as well as in patients undergoing mastectomy after a core or excisional biopsy diagnosis of DCIS.Experts are not sure whether all women with DCIS would eventually develop invasive breast cancer if they live for a long time and are not treated.
What happens if DCIS is not treated?
According to the NIH Consensus Conference, many DCIS lesions will never become breast cancer, and some will disappear without treatment. If DCIS is allowed to go untreated, the natural course or natural history tends to vary according to the grade of the DCIS. Approximately 60 percent of low grade DCIS lesions will become invasive at 40 years follow-up. High grade DCIS lesions which have been inadequately resected and not given radiotherapy have a 50 percent risk of becoming invasive breast cancer at 7 years follow-up. Approximately 50% of low grade DCIS detected at screening will represent overdiagnosis, but overdiagnosis of high grade DCIS would be rare. The natural history of intermediate grade DCIS is difficult to predict. Approximately one-third of malignant calcification clusters detected at screening mammography already has an invasive focus."