Do all cases of DCIS breast cancer need aggressive treatment?

DEAR DOCTOR K:

I have been diagnosed with ductal carcinoma in situ. My doctor wants me to have surgery. But recently I read about a study that said not all women with this type of breast cancer even need to be treated. Can you help clear this up?

DEAR READER:

Ductal carcinoma in situ (DCIS) is a type of breast cancer. In DCIS, the cancerous cells are contained within the breast’s ducts (which carry milk to the nipple) but have not invaded surrounding tissue.

The standard treatment for DCIS is surgery. This might mean a mastectomy, which removes the entire breast and usually some nearby lymph nodes. Or it might be a lumpectomy, which removes only the cancerous tumor and a small amount of healthy tissue around it. Surgery may be followed with radiation therapy, designed to kill any possible remaining cancer cells in that breast.

But a recent study suggests standard treatment may be too aggressive. The researchers studied more than 108,000 women with DCIS. The main finding of the study was that the chance of premature death in women of all ages who had DCIS was no greater than in women without DCIS. However, the chance of death from breast cancer was higher in women younger than age 35, and in African-American women, who had DCIS.

Some media coverage of this study left the impression that DCIS doesn’t need to be treated. In fact, all patients in the study received some form of treatment. What the study does say is that none of the treatments differed very much from one another with respect to ultimate survival.

Here is the dilemma: DCIS constitutes about 20 to 25 percent of all breast cancers that are found by screening tests (usually mammograms). Under the microscope, the cancerous cells of DCIS have a similar appearance to the cells of breast cancers that are invading the breast. Even though DCIS is not invading the breast, it looks like it might do so in the future.

About 50,000 to 60,000 DCIS lesions are removed each year in the United States. Yet the number of cases of invasive breast cancer has not gone down. That seems to mean that in most women who have the DCIS surgically removed, it never would have invaded the breast or spread. But in a few, it would have.

The problem is, we haven’t yet figured out a way to identify the relatively few DCIS tumors that will invade and spread from the larger number that won’t.

You and your doctor are going to have to consider your individual risk factors. If your doctor thinks that not having surgery, just closely monitoring the DCIS, is an option, you would need to decide if you are comfortable with that plan.

Some men face a similar dilemma. Some prostate cancers never spread. There are pretty good, but not perfect, ways of identifying those “indolent” cancers. Often, men and their doctors choose not to remove these cancers, but just to monitor them.

Fortunately, the majority of women with DCIS have an excellent prognosis. Their cancer does not spread.