Young age appears to be a risk factor for locoregional recurrence after mastectomy for ductal carcinoma in situ (DCIS) with or without microinvasion, according to data presented at the 2019 Society of Surgical Oncology Annual Cancer Symposium.¹

The retrospective analysis of more than 3,000 cases over 22 years found that locoregional recurrence after mastectomy for DCIS is uncommon, but it is significantly more frequent among women younger under age 50, especially those younger than age 40. The rate of locoregional recurrence was 4.2% in women younger than age 40 vs just 0.2% in women at least 50 years old, the study authors reported.

The overall risk of having a locoregional recurrence after mastectomy for DCIS is very low, but it is higher in younger women.

— Anita Mamtani, MD

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“The risk of recurrence is still low, but based on these data, we can acknowledge that it is a little higher in younger women,” said Anita Mamtani, MD, a breast surgical oncology fellow at Memorial Sloan Kettering Cancer Center (MSK), New York. “For patients coming to our clinic to discuss their individual risk, these results will provide a more informed and accurate objective measure, which will help decision-making. Until this point, we didn’t have specific numbers to compare the risk of a 42-year-old woman with a 75-year-old, for example, and it turns out that their level of risk is different.”

Study Rationale and Details

As Dr. Mamtani explained, although the risk of locoregional recurrence after breast-conserving surgery for ductal carcinoma in situ has been shown to be increased in younger women, the impact of age on recurrence after mastectomy has not been well studied. Moreover, because younger women are increasingly opting for mastectomy over time, she said, understanding these risk factors is important when counseling patients.

For this retrospective study, Dr. Mamtani and colleagues identified consecutive patients with ductal carcinoma in situ with or without microinvasion treated with mastectomy between 1995 and 2017 at MSK and Dana-Farber Cancer Center. The researchers defined locoregional recurrence as any recurrence at the ipsilateral chest wall or regional lymph nodes. Although age was the primary variable of interest, researchers also studied the presence of microinvasion (≤ 1 mm of invasive cancer), nuclear grade, and margin status.

Of the 3,063 cases identified by the researchers, the median age was 49 years, and more than 1,500 were women younger than age 50. The median follow-up was 76 months. As Dr. Mamtani reported, of the 33 locoregional recurrences observed, 32 (97%) were invasive, 22 (67%) occurred in the chest wall, 8 (24%) occurred in regional lymph nodes, and 3 (9%) occurred in both the chest wall and regional lymph nodes.

Although the 10-year rate of locoregional recurrence was just 0.2% of women older than age 50, said Dr. Mamtani, the rate increased to 2% in women between the ages of 40 and 49 and 4.2% in women younger than age 40. Overall, the cumulative 10-year incidence of locoregional recurrence was 1.4%.

Emily Craig Zabor, DrPH

“The overall risk of having a locoregional recurrence after mastectomy for DCIS is very low, but it is higher in younger women,” said Dr. Mamtani. In addition to age (< 50 years), high nuclear grade and the presence of microinvasion were also associated with higher rates of locoregional recurrence (P < .001). What’s more, patients with all three risk factors were found to bear the majority of excess risk. Margin status was not shown to be associated with recurrence.

“Strikingly, the presence of microinvasion seemed to interact with age in a way that young women with ductal carcinoma in situ with microinvasion had a much higher cumulative incidence of locoregional recurrence at 10 years,” said Emily Craig Zabor, DrPH, a senior research biostatistician at MSK.

Why Are Younger Women at Greater Risk?

As Dr. Mamtani explained, the higher risk of recurrence in younger patients is most likely associated with more aggressive disease. Women younger than age 40 in this study more frequently had close/positive margins (P = .007), high nuclear grade (P < .001), and microinvasion (P = .02). However, there’s also simply more time for a recurrence to appear.

“A woman in her 80s is going to have other issues that may impact her life span, before she has a chance to experience a recurrence, whereas a young woman may have 50 years of risk ahead of her,” suggested Dr. Mamtani. And these data should not frighten younger patients, she noted. “This study has given us better data and the ability to more meaningfully stratify risk when counseling our patients, but these rates should not alarm anyone,” she said. “The numbers are still very low. The purpose here is to focus on individualized risk assessment and helping patients make better decisions.”

For now, Dr. Mamtani and colleagues will continue to gather follow-up data. The researchers plan to redo the analysis in a few years with a higher number of event rates from more recent patients. ■

DISCLOSURE: Drs. Mamtani and Zabor reported no conflicts of interest.

REFERENCE

1. Mamtani A, et al: Impact of age on locoregional recurrence after mastectomy for ductal carcinoma in situ ± microinvasion. 2019 Society of Surgical Oncology Annual Meeting. Abstract P47. Presented March 29, 2019.