My sister is young and healthy. Or, at least, I thought she was.

At 31 years old, Katie has always been active by hiking, walking or riding bikes with her husband and their 15-month-old daughter. She was a kindergarten teacher before giving birth to Zoe last year and now is a stay-at-home mom with her toddler, who loves sticking her tongue out.

Zoe was playing one day this spring when she hit my sister’s breast. My sister felt the lump, and it seemed out of place. But since she’s had no health problems, Katie wasn’t too concerned. She figured she should get it checked but never considered it could be cancer.

When my sister went to her doctor in April as a precaution, she went through the motions of getting a biopsy done with no weight on her shoulders.

Even her doctor initially told her, “It doesn’t feel like cancer, so I doubt it is.”

But Katie was vacationing over Easter weekend when her doctor called. Despite initially assuming the lump was nothing, her doctor said it was Stage 0 ductal carcinoma in-situ — a form of breast cancer. This seemed impossible since neither she nor anyone in my immediate or extended family had ever tested positive for the disease before.

As the youngest child in the family, hearing that she was diagnosed with breast cancer at 31 years old initially scared me. My sister had just had a healthy pregnancy and childbirth one year before. How could she all of a sudden have cancer?

Her doctor said it is possible that her pregnancy was the culprit for the cancer’s growth as the additional hormones in her system from the pregnancy fed the cancer. Fortunately for my sister, the lump was caught so early that she did not need radiation or chemotherapy. She had a single mastectomy, and all of the cancer was removed in the surgery.

For my family, it was tough because my brother, sister, parents and I all live in different states among three time zones. My sister lives in Colorado, my brother in California and my parents in Ohio. We tried to send text messages, call one another and video chat as much as we could, but I know that was inadequate when all your sister wants is to get her mind off the fact that she has cancer.

This cancer disrupted my sister in a multitude of ways. She called my father in a panic once the doctor told her her lump was positive for breast cancer and she would need surgery. She had not assumed the worst, and this was a shock to hear in the middle of a vacation.

Secondly, the surgery would not allow her to pick up Zoe for six weeks. If you have a child or a relative younger than 2, you understand what a major change that is. Not only could she not pick her child up to put her in a car seat, but she couldn’t be the one to reach for Zoe when she fell, needed to be comforted in the middle of the night or just wanted to be with her mother.

The surgery disrupted my mother’s life, as she had to suddenly change her plans for about two months and become a live-in nanny for her granddaughter, my niece. Even though my sister would be around her own daughter, she had to refuse to pick her daughter up for her own safety.

And lastly, the cancer effect trickled down to me. My sister does not have the so-called “cancer gene” that would make her more likely to get cancer a second time, so we don’t have to worry about our DNA. But since I am younger than my sister, I need to start getting a mammogram — more than 20 years earlier than when doctors suggest women should get them.

When I walked in to get a mammogram recently at Johnson Memorial Hospital’s breast cancer center, I wasn’t quite sure what to expect.  I knew they would examine my breasts and get X-rays of them, but I had no idea they would need to force my breasts into odd positions in order to do it.

I also had to recall many minute details about Katie’s surgery and condition. Which side of her body was the cancer? Was the lump near the front or the back of her body? Did she have genetic testing done? What kind of treatment did she have?

But now that is my sister’s and my new normal. She and I will have to get used to breast cancer screenings, genetic testing, annual checkups on her part and years more of mammograms to come.

Who knows what the future will bring for my sister and her health or my own health, but at least we’re on full alert.

Although that can seem gloomy to some, I have to be thankful for the fact that my sister wasn’t more sick than she was. So far, no one else in our family has been affected by breast cancer. My sister’s cancer struck when she was young enough that she could defeat it. My mom thankfully has a job where she can put it on hold for two months as she serves my sister in taking care of her granddaughter.