In Situ Ductal Carcinoma: How Much of a Cancer Threat? 

Paul Loethen, M.D., Surgeon
By Paul Loethen, M.D.
Board Certified General Surgeon
Saint Anthony's Physician Group 


The term in situ could be seen as positive when used to describe a cancer. In situ means “in place,” indicating that the cancer has not moved from the place where it started and, as a result, is not invasive.     

Ductal carcinoma in situ (DCIS) is a cancer that has not moved or spread from the milk duct where it formed. Usually too small to be detected as a lump, it’s a stage 0 cancer and may never become anything else. It may, on the other hand, progress to become invasive cancer, and that is the problem.     

About 1 in 5 new breast cancer cases will be DCIS, according to the American Cancer Society. Nearly all women diagnosed at this early stage of breast cancer can be cured. A mammogram is often the best way to find DCIS early.     

And with increased use of screening mammography, this diagnosis has become increasingly common, now accounting for nearly 25 percent of new breast cancer diagnoses (invasive and non-invasive) compared to only 18 percent as recently as 1998.     

There are several types of DCIS, some more aggressive than others. Overall, though, the cure rate is nearly 100 percent if standard treatments are used. Because this in situ cancer is not an emergency, a woman who receives the diagnosis should take the time to educate herself and weigh her options carefully before deciding on a course of action.    

In the past, when DCIS was rarely encountered, standard treatment was a mastectomy, and this treatment still results in a 10-year survival rate of 98 percent.     

Since 1983, following publication of results from the large National Surgical Adjuvant Breast and Bowel Project (NSABBP), women with small invasive breast cancers have often opted for a breast-conserving option, usually lumpectomy. This procedure removes only the cancer plus a safe margin of healthy tissue.    

NSABBP indicated that for women with small invasive tumors this option results in long-term survival similar to that of mastectomy. More recently, several large studies have confirmed that breast-conserving surgery is also a safe treatment for many cases of DCIS.     

Pathology Report Important 

Ductal carcinoma in situ is suspected when tiny calcium deposits show up as lines or clusters on the x-ray image. The diagnosis must then be confirmed by a biopsy of these areas.     

A tumor will be graded as low, intermediate or high depending on how cells look under the microscope and how likely they are to develop into an invasive cancer.    

Women with ductal carcinoma in situ rarely have symptoms, and many will likely never develop breast cancer even without treatment. Some tumors become invasive, however, and sometimes DCIS is a marker for cancer that develops elsewhere in the breast or in the other breast.     

Since there is still uncertainty about which tumors are likely to become invasive, nearly all doctors today recommend treatment rather than watchful waiting – either 1) lumpectomy, usually with radiation, but sometimes without, or 2) very rarely, simple mastectomy (but usually without removal of lymph nodes).     

Generally, breast-conserving surgery is recommended as long as the cancer is confined to one site and can be removed along with a margin of several millimeters of healthy tissue.      

If cancer cells are found near the margins of removed tissue, additional surgery may be needed. But if the margins are cancer free, the cure rate with lumpectomy is close to 100 percent, similar to that for mastectomy. Recurrence rates, however, are slightly higher with a lumpectomy.     

To prevent recurrence, breast-conserving surgery is typically followed by radiation therapy administered in a hospital or cancer center five days a week for five to eight weeks.     

Although survival rates for lumpectomy and mastectomy are about the same, mastectomy offers a woman the best chance of remaining free of both invasive cancer and DCIS

through a single surgical procedure.     
Because it’s still “in place,” ductal carcinoma in situ is not life threatening. Breast cancer is, however, and that’s why women are understandably concerned when they hear the diagnosis. By the same token, doctors are glad to be able to detect cancer and treat it successfully before it has had a chance to do harm. The challenge is to find the right level of treatment – avoiding both under- and over-treatment.     

For more information abour Dr. Paul Loethen, call Saint Anthony's Physician Group at 618/465-9024.  To make an appointment for a mammogram, call Saint Anthony’s scheduling representatives at 618-474-6152. Saturday and evening appointments are available. 

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