Determining when DCIS is more likely to morph into invasive breast cancer could save patients from unnecessary and expensive treatment.

Researchers from the Manchester Cancer Research Centre may have figured out how to predict which patients with ductal carcinoma in situ (DCIS) are likely to develop breast cancer.

Right now, doctors can’t tell which DCIS patients are at higher risk of developing invasive breast cancer. Because the risk is unknown, treatment is recommended for all DCIS patients.

In invasive breast cancer, recurrence rates vary according to subtype. The research team set out to determine if the same holds true of DCIS subtypes.

The study involved patients with primary DCIS. Researchers tested tissue samples for estrogen receptors and progesterone receptors. They also tested for the human epidermal growth factor known as HER2. Patients were then divided into categories to compare recurrence rates.

Of the 314 participants, 57 had recurrences. Of those, 35 were DCIS and 22 were invasive breast cancer.

Patients who tested positive for estrogen and progesterone receptors but were negative for HER2 had the lowest rate of recurrence. It was 7.6 percent at five years. Patients with other subtypes had a 15 to 36 percent recurrence rate. Details of the study are published in the Annals of Oncology.

DCIS is stage 0 breast cancer. In DCIS, abnormal cells are found within the milk duct, but they have not spread beyond the duct. DCIS is noninvasive and not life threatening at this stage. For some, DCIS will never progress. For others, it will lead to invasive breast cancer.

DCIS doesn’t necessarily cause symptoms. There’s seldom a noticeable lump. It is often detected by routine mammogram screening. According to the American Cancer Society, about one of every five new breast cancer diagnoses will be DCIS.

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Doctors generally treat DCIS as they would early-stage invasive breast cancer. This involves either lumpectomy or mastectomy. For many women, mastectomy is followed by reconstructive surgery. Some patients may also be treated with radiation or tamoxifen, a drug that blocks the effects of estrogen.

The study authors concluded that testing DCIS for type can help predict future recurrence of DCIS or invasive breast cancer. If so, it could lead to more personalized treatment.

Knowing which cases of DCIS are likely to become invasive could help patients avoid unnecessary and expensive treatments. It may also reduce the emotional toll of aggressive treatment.

“I have personally witnessed women agonize over the decision to do a mastectomy or even a bilateral mastectomy, procedures that may or may not be medically necessary,” said Mary Beth Gibson, executive director of the nonprofit women’s health initiative Beyond Boobs!

“Much of the anguish comes from having to decide if facing the immense physical and emotional trauma of losing a breast or breasts is worth the peace of mind of having done everything medically possible to reduce the risk of the cancer becoming invasive,” Gibson told Healthline. “This test would be an absolute godsend to these women.”

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Dr. Don S. Dizon, of the Massachusetts General Hospital Cancer Center, cautions that this test needs to be validated.

“How it influences treatment is not at all clear. It’s another prognostic study but is in no way predictive,” he said. “This suggests a good prognostic subtype (ER and PR positive and HER2 negative, which most are), but are you really not going to do ‘aggressive treatment,’ which I infer means surgery and radiation therapy?”

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