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What was the research about?

Ductal carcinoma in situ, or DCIS, makes up about 25 percent of new breast cancer diagnoses. In DCIS, the cancer cells occur inside milk ducts. DCIS may or may not turn into invasive cancer, which spreads and causes illness.

Women with DCIS often have breast-conserving surgery to treat DCIS. This surgery removes the abnormal cells and some of the tissue around them. Sometimes the surgeon also removes some lymph nodes around the tumor, called sentinel lymph nodes, to test if the cancer has spread. This sentinel lymph node biopsy may cause side effects like pain or infection.

In this study, the research team compared older women with DCIS who’d had surgery with and without sentinel lymph node biopsy. They wanted to learn if the biopsy

• Increased side effects
• Reduced the spread of cancer
• Helped patients live longer

The research team looked at four types of side effects in the short term and in the longer term. The side effects included swelling, infections, pain, and fluid under patients’ skin where they’d had surgery.

What were the results?

Short-term side effects. Women who had sentinel lymph node biopsy were more likely to have one or more of the four types of side effects within nine months of DCIS diagnosis compared with women who didn’t have a biopsy.

Long-term side effects. Compared with women who didn’t have a biopsy, those who had sentinel lymph node biopsy were also more likely to have swelling up to 12 years after DCIS diagnosis. The two groups didn’t differ in how likely they were to have infections, pain, and fluid under the skin.

Health effects. The study didn’t show differences between the two groups of women in how often the cancer spread or how long they lived after DCIS diagnosis.

Who was in the study?

The research team used data from a national Medicare database that included 7,127 women with DCIS who were between the ages of 67 and 94 and who had breast-conserving surgery. Of these women, 88 percent were white, 8 percent were black, and 5 percent were other races; also, 5 percent were Hispanic. The average age was 75.

What did the research team do?

The research team compared the Medicare data for women diagnosed with DCIS who did and didn’t have sentinel lymph node biopsy. They looked at side effects that happened within 9 months after diagnosis, and at side effects, cancer spread, and length of life up to 12 years after diagnosis. The team took into account other things that might affect how likely patients were to have side effects, such as their age, year of diagnosis, and tumor size.

An advisory group of breast cancer survivors and doctors who treat cancer helped design the study.

What were the limits of the study?

Most women in the study were white and older than 66. Results may differ if the research team included women from different backgrounds. The women who had biopsies may have been different from the women who didn’t have them. The data didn’t include some information about patients, like other health problems, which could have affected the results.

Future research could include women who are younger and from more diverse backgrounds. Research could also include information about other health problems that might affect the results.

How can people use the results?

Older women and doctors can consider the results when making treatment decisions for DCIS.

Objective

To compare the effectiveness of sentinel lymph node biopsy (SLNB) and no SLNB on (1) short- and long-term complications and (2) long-term outcomes in women over age 67 diagnosed with DCIS who underwent breast-conserving surgery

Study Design

This study used a retrospective observational cohort design to compare the effectiveness of SLNB and no SLNB in women diagnosed with DCIS who underwent breast-conserving surgery. Researchers looked at short- and long-term complications, cancer recurrence, and mortality.

The study included data from the Surveillance, Epidemiology, and End Results (SEER)-Medicare database for 7,127 women, ages 67–94. Of these women, 88% were white, 8% were black, and 5% were other races; 5% were Hispanic. The average age was 75.

Using the SEER-Medicare data, researchers identified women who received breast-conserving surgery as their first breast surgery within six months after DCIS diagnosis. Using Mahalanobis matching based on baseline age, tumor grade, tumor size, hormone receptor status, year of diagnosis, SEER registry state, and geographic region, researchers matched women who had SLNB with women who did not have SLNB. The study examined SEER-Medicare data records up to 12 years after DCIS diagnosis.

An advisory committee including breast cancer survivors and oncologists provided input throughout the study, including input formulating research questions and choosing outcomes.

Results

Short-term complications. Compared with women who did not have SLNB, women who had SLNB were more likely to experience any complications, lymphedema, infections, seromas, and pain within nine months of diagnosis (p<0.01).

Long-term complications. Women who had SLNB were more likely to have long-term lymphedema (p<0.001). The two groups did not differ significantly in long-term seromas, infections, and pain.

The two groups were not significantly different in treated recurrence, ipsilateral invasive occurrence, and breast cancer mortality rates.

Limitations

Most women in the study were white and older than 66. Results may differ for women from more diverse backgrounds. Because researchers did not randomize participants, selection bias may have been present. Factors not included in the data may account for some of the results.

Conclusions and Relevance

Having SLNB was associated with a higher risk of both short-term and long-term complications. It was not associated with an improvement in long-term outcomes.

Future Research Needs

Future research could explore the benefits and harms of SLNB for women of all ages and more diverse backgrounds who have breast-conserving surgery to treat DCIS with high-risk characteristics, such as a high-grade tumor. Researchers could also include information about potentially confounding variables.