What is ductal carcinoma in situ? Constance Zimmer, popular TV star and an Emmy nominee, opens up about her breast cancer

Constance Zimmer, a popular TV star, opened up about her battle with breast cancer on Sunday (October 4, 2026). In an Instagram post, she revealed that she was diagnosed with Ductal Carcinoma In Situ (DCIS) on March 13, 2026.

The 55-year-old Emmy nominated star, who has appeared in several TV shows and has played multiple standout characters, kept her fight with cancer under wraps while on a "very public press tour" for FX's Love Story, as reported by Us Weekly. Doctors suggested a mastectomy, but she went for a lumpectomy that took three surgeries over three consecutive weeks, followed by radiation.

“On March 13th when I was away from home– I heard these words from my doctor over zoom: “You have DCIS, also refereed to as Stage 0 breast cancer.“ The silence was deafening. Here I was surrounded by women sharing their secrets about their Midlife truths – and I was holding onto the biggest secret I’d ever hel,” she said in her Instagram post. [sic]


Speaking about how things took a toll on her mental health, she said, “The mental toll that followed was overwhelming on certain days as I began talking to many more doctors then I would’ve liked. Feeling like my options were limited and most suggested what was the quickest way to get this mass out ASAP, which was a mastectomy.”

What is ductal carcinoma in situ?

Ductal carcinoma in situ (DCIS) is the earliest stage of breast cancer. It is often referred to as stage 0 breast cancer. According to the Breast Cancer Research Foundation (BCRF), it is a type of cancer that starts in the cells lining the milk ducts (carcinoma) and remains in the area where it originates (in situ).

DCIS does not spread through the duct walls into the surrounding breast tissue. It tends to remain in the milk duct. According to BCRF, Stage 0 breast cancer is considered to be a precursor to invasive, stage 1–4 breast cancers.