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Clinical challenge: overdiagnosis of DCIS and high risk breast lesions

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Before breast screening by mammography became routine, ductal carcinoma in situ (DCIS) and high-risk breast lesions were rarely found. Now, with the widespread use of mammography, these breast abnormalities are more common; but the question of whether and what kind of treatment is justified remains controversial.

Evidence for this problem is the fact that DCIS was estimated at 16% of breast cancer diagnoses between 2012 and 2016, but more recent estimates place the incidence between 20% and 25%.

In addition, a study of over 375,000 screening mammograms found that the frequency of detecting a high-risk breast lesion after a needle biopsy tripled over the 6-year study period, rising from 3.2% in 2011 to 9.5% in 2016. An increase in surgeries has also been seen.

But detecting more DCIS and high-risk breast lesions did not improve outcomes, especially for DCIS.

“As we diagnose more DCIS and treat more DCIS, you would think it would translate to a decrease in invasive cancer, but it doesn’t,” said Susie X. Sun, MD, surgeon and Assistant Professor at the MD Anderson Cancer Center at the University of Texas at Houston. She explained that the incidence of invasive cancer has remained stable despite the discovery of more DCIS and the treatment of more DCIS, according to the latest breast cancer facts and figures.

Work together

Sun said there is “a lot of variability” around the treatment of high-risk breast lesions, such as atypical ductal hyperplasia (ADH) and atypical lobular hyperplasia (ALH). She works with a multidisciplinary team to more precisely determine the high risk of injury in order to avoid overtreating these patients.

She explained that although not all high-risk lesions require excision, they are excised in many facilities. At its center, a conference each week is dedicated to discussing patients’ high-risk injuries, attended by surgeons, pathologists, radiologists and other relevant experts, Sun said.

Together, the team examines the cases and details of patients, from their imaging studies to biopsy slides, and reaches a multidisciplinary consensus regarding the risk of finding breast cancer at the time of excision, also known as the upgrade rate name. Based on this risk, the team recommends whether excision is warranted or whether the patient’s injury can be safely monitored with imaging.

Change in conventional thinking

“Historically speaking, the idea was that if you have DCIS, you will end up having invasive cancer,” Sun said. “But we really don’t know if it’s true or not.”

Although DCIS is considered a precursor to invasive breast cancer, long-term evidence suggests that although a proportion of patients develop invasive breast cancer, many do not. For example, a 2006 literature review indicated that between 14% and 53% of patients with DCIS develop invasive breast cancer over a period of 10 years or more.

A 2015 retrospective study with long-term follow-up of 45 women with low-grade DCIS who did not receive treatment beyond tissue biopsy found that 16 women, or 36%, had subsequently been diagnosed with invasive breast cancer.

The presence of a previously unknown DCIS was even discovered during autopsies of women. “Who knows how long these women have had this DCIS that they have lived with all their lives,” Sun said.

“Now there is this concern with the overprocessing of DCIS,” Sun said. Most women are treated with surgical excision, usually followed by radiation therapy, and mastectomy is not uncommon.

Sun explained that some people believe that if DCIS does not tend to spread elsewhere in the body, the treatment will not impact overall survival.

“So why are we doing all of this? Why do we treat it the same way we treat invasive cancer? She asked.

An observational study in JAMA Oncology with 20 years of follow-up found that while DCIS patients who underwent more aggressive treatment generally had a lower risk of ipsilateral recurrence, their risk of dying from breast cancer was the same as those with less treatment .

For example, among patients who had lumpectomy, those who also underwent radiation therapy had a lower risk of invasive recurrence in the ipsilateral breast than those who had not received radiation therapy but had no greater risk. weak to die from breast cancer at age 10.

“We know we overtreat DCIS which, once diagnosed, will never harm women,” said Charles Shapiro, MD, hematologist-oncologist at the Icahn School of Medicine at Mount Sinai in New York City, echoing a similar point of view. “We’re just not smart [enough] to choose them, but I have no doubts that we will get there in the next 5-10 years. “

De-escalation treatment

Sun and Shapiro noted that there are several ongoing studies aimed at defusing treatment for DCIS: the COMET, LORIS, LORD and LORETTA trials.

The LORIS trial, conducted in Europe, and the LORD trial, conducted in the UK, both initially compared active surveillance for low-risk DCIS to surgery (LORIS) or standard treatment (LORD), but have had to convert to registry trials for a slow patient. accumulation. LORETTA is a single-arm trial in Japan evaluating active surveillance and hormone therapy in patients with low-risk DCIS.

The COMET trial, conducted in the United States, is currently the only prospective randomized clinical trial evaluating active surveillance versus surgery in patients with low-risk DCIS. It is expected to end in 2023.

“These trials will provide information on the natural history of DCIS and help identify situations in which DCIS can be monitored without surgical excision,” Sun said.

Disclosures

Sun did not disclose any conflict of interest.

Shapiro did not disclose any conflict of interest.