Actress Danielle Fishel shared her breast cancer diagnosis this week, revealing on Monday’s episode of her podcast, “Pod Meets World,” that she is being treated for ductal carcinoma in situ (DCIS).

“It is very, very, very early,” said the “Boy Meets World” alumna, 43. “It’s technically Stage 0. To be specific, I was diagnosed with high-grade DCIS with micro-invasion. And I’m going to be fine. I’m having surgery to remove it. I’m going to be on some follow-up treatment. I’ve had to make a lot of decisions over the last couple of days.”

Here’s everything you need to know about this very early form of breast cancer.

DCIS is a noninvasive form of breast cancer that affects the cells of the milk ducts. DCIS accounts for about 20% to 25% of US breast cancer diagnoses.

Breast surgical oncologist Dr. Bonnie Sun explains that most cases are diagnosed with a mammogram before symptoms start.

Typically, DCIS shows up as calcium deposits in the scan or in rarer cases, a distortion of breast tissue.

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For patients with DCIS, the cells that make up the lining of their milk ducts turn cancerous but remain in place, or in situ, meaning they do not grow through the duct wall or spread to the bloodstream or lymph nodes.

As DCIS is a noninvasive form of cancer that does not spread throughout the body, a.k.a. metastasize, the condition does not require chemotherapy.

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When cancerous cells begin to populate the milk duct, patients may experience itching or the forming of a sore. Men, who do not typically undergo mammograms, may notice a bloody nipple discharge or lump.

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DCIS is usually detected via mammogram. If calcifications are discovered, a doctor will recommend a breast biopsy. A non-surgical, outpatient procedure known as a stereotactic core needle biopsy can diagnose DCIS.

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The standard treatment for DCIS is a combination of surgery and radiation. Typically, a breast-preserving lumpectomy is performed to remove the cancer, and the remaining tissue is treated with radiation therapy to reduce the risk of reoccurrence.

Fishel’s podcast comments suggest she’ll be pursuing this course of treatment. If so, the risk of local reoccurrence ranges from 5% to 15%.

For patients who have DCIS in more than one quadrant of the same breast, a mastectomy is recommended. If a mastectomy is performed, radiation therapy is not necessary. In those who undergo a mastectomy, the risk of local reoccurrence is less than 2%.

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Sun says proper treatment can completely resolve the problem. “This is a local disease and treatment by surgery can be sufficient,” she explained. “Chemotherapy isn’t necessary, and in some cases, hormone medication and radiation aren’t either.”

She maintains that though vigilance is required, the prognosis is often favorable: “With continued, rigorous monitoring, the prognosis for DCIS is excellent. Your doctor will recommend a regular screening schedule to guard against recurrence in the original breast, and to monitor the other breast for any signs of malignancy.”

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Mammograms cannot prevent DCIS but can aid in early detection, translating to better outcomes.

As Fishel shares, “The only reason I caught this cancer when it is still Stage 0 is because the day I got my text message that my yearly mammogram had come up, I made the appointment…And they found it so, so, so early that I’m going to be fine.”

She encourages others to be alert and actionable when it comes to their health, “If it’s time for your appointment, if you’ve never had an appointment before, get in there. If you have to find out that you have cancer, find out when it’s at Stage 0, if possible.”

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In addition to Fishel, comedian Wanda Sykes, musician Sheryl Crow, model Janice Dickinson and ESPN broadcaster Hannah Storm have been treated for DCIS.