Reality star Diem Brown, battling her third bout with cancer in the past decade, was dealt another blow this week when she was hospitalized for a new tumor blocking her kidneys.

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UPDATE (Nov. 14, 2014): Diem Brown has lost her long battle with cancer, reports.

Reality star Diem Brown, battling her third bout with cancer in the past decade, was dealt another blow this week when she was hospitalized for a new tumor blocking her kidneys, reported. Brown is 30 years old.

Famous for competing (in between cancer diagnoses) in MTV's grueling "Real World/Road Rules Challenge" series, Brown's first battle with ovarian cancer started at 23. She had a recurrence in 2012, but had been enjoying a steady remission until she collapsed on set in Panama this past August. After being airlifted to New York, doctors had bad news: they found multiple malignant tumors in her colon, which had to be removed in an emergency surgery.

Since August, Diem has been trying to put on weight in hopes of starting chemotherapy. The new kidney tumors are devastating news, but she's hanging in there: “I was so frustrated that it seems my body keeps throwing me curve balls over and over. It’s hard to keep your spirit and your mind positive … But I’m glad we are catching these curve balls and fixing them, one by one,” Brown told

Even if you've never seen her on The Challenge shows, Brown's story is gripping. Partly because of her positive spirit in the face of it all, but also because she's so young, yet she's dealt with more than many of us will face in a lifetime. (And of course, for the show-watchers out there, we all remember being reduced to tears that time on-again, off-again boyfriend CT sweetly convinced her to remove her post-chemo wig on national television.)

Aside from the philosophical "This is so unfair! Why?," there are also some science questions here: Why do some people get multiple cancers? Is it a side effect of harsh treatments, or are some cancers are related? We asked Robert Morgan, M.D., co-director of City of Hope National Medical Center's Gynecological Cancers Program in Los Angeles to help us shed some light.

The first thing to understand, he explains, is that ovarian cancer can (and often does) spread all over the abdomen. "Though it's being reported as 'colon' or 'kidney' that may be a generalization that just describes where new tumors were found. In other words, it may be ovarian cancer recurrence found in other parts of her body," Dr. Morgan says. (Note: Dr. Morgan is not treating Brown and doesn't know the specifics of her case.)

Chemotherapy and radiation for one cancer can contribute to another one down the road because they can also cause DNA changes. "But on the other hand those are the best treatments you have. Thankfully, the incidence of developing second cancers is quite low," Dr. Morgan says.

That said, it is unusual to be diagnosed with any type of cancer at such a young age.

"The reality is that most people get cancer when they're much older," Dr. Morgan explains. "Every day your cells are multiplying and every day genetic changes, called mutations, happen. Most of the time your body repairs them. But we're finding that the reason cells become malignant is that multiple mutations can build up in a specific order."

Some people are more prone to these mutations, often for reasons unknown, but there are a variety of rare genetic syndromes that can predispose you to multiple types of cancer.

The most common of these is likely one you've heard of (thanks to the "Angelina Effect"): BRCA, which is famously linked to breast and ovarian cancer, but can also up risk for pancreatic and prostate cancer, too.

"There are many different syndromes, many of which are very rare, so the best advice for someone who's diagnosed with cancer young is to see a genetic counselor," Dr. Morgan says. "We're not quite there yet as far as being able to prescribe targeted drugs, but there are some things you can do. I know of one patient who had a very strong family history of pancreatic cancer and tested positive for BRCA2. He decided to have his pancreas removed."

"He has an insulin pump now, but he doesn't have cancer," Dr. Morgan adds.